PRODUCTIVITY OF SUNFLOWER HYBRIDS AS INFLUENCED BY...
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i PRODUCTIVITY OF SUNFLOWER HYBRIDS AS INFLUENCED BY SULPHUR-NITROGEN NUTRITION AND VARYING PLANT POPULATION By MUHAMMAD ISHFAQ M.Sc. (Hons.) Agricultue A thesis submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN AGRONOMY FACULTY OF AGRICULTURE UNIVERSITY OF AGRICULTURE FAISALABAD, PAKISTAN 2010
Transcript of PRODUCTIVITY OF SUNFLOWER HYBRIDS AS INFLUENCED BY...
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PRODUCTIVITY OF SUNFLOWER HYBRIDS AS INFLUENCED BY SULPHUR-NITROGEN
NUTRITION AND VARYING PLANT POPULATION
By
MUHAMMAD ISHFAQ
M.Sc. (Hons.) Agricultue
A thesis submitted in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
IN
AGRONOMY
FACULTY OF AGRICULTURE UNIVERSITY OF AGRICULTURE
FAISALABAD, PAKISTAN 2010
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To
The controller of Examinations, University of Agriculture, Faisalabad
We the supervisory committee, certify that contents and form of thesis
submitted by Mr. Muhammad Ishfaq have been found satisfactory and recommend
that it be processed for evaluation by the external Examiner(s) for the award of degree.
SUPERVISORY COMMITTEE
CHAIRMAN ______________________ (DR. ASGHAR ALI) MEMBER _______________________ (DR. ABDUL KHALIQ)
MEMBER ________________________ (DR. MUHAMMAD YASEEN)
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DECLARATION
I hereby declare that the contents of the thesis, “Productivity of sunflower hybrids as
influenced by sulphur-nitrogen nutrition and varying plant population” are product of
my own research and no part has been copied from any published source (except the
references, standard mathematical or genetic models/equations/formulate/protocols
etc.). I further declare that this work has not been submitted for award of any other
diploma/degree. The university may take action if the information provided is found
inaccurate at any stage. (In case of any default, the scholar will be proceeded against as
per HEC plagiarism policy).
Signature of the Student
Muhammad Ishfaq
85-ag-1479 Ph. D student
Dept. Agronomy
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DADICATED TO
my parents
my wife
my kids
(Talha Sandhu, Hamza Sandhu and Mashaf Ishfaq)
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ACKNOWLEDGEMENTS
Allah Almighty the eternal of the universe. All worships and praises are only for the Lord of creation, the most Merciful, Beneficent, Gracious and Compassionate whose numerous blessings enabled me to pursue and perceive higher ideas of life. I offer my humblest thanks to the Holy Prophet Muhammad (S.A.W.) who is forever a torch of guidance and knowledge for the humanity as a whole.
I feel highly honored to express the deep sense of gratitude to my supervisor Professor Dr. Asghar Ali, Department of Agronomy, University of Agriculture, Faisalabad, under whose kind supervision, sincere help and inspiring guidance the research work presented in this dissertation was carried out.
Special thanks are extended to the Supervisory Committee Members Associate Professor Dr. Abdul Khaliq, Department of Agronomy whose animate directions, observant pursuit, scholarly criticism, cheering perspective and enlightened supervision not improved the quality of this exposition but also my overall understanding of this research project, and Associate Professor Dr. Muhammad Yaseen, Institute of Soil and Environmental Sciences for their precious advice and energizing support during the course of present studies.
I extend my admirations and appreciation to my friends, Dr.Arif Raza, Dr.Ishtiaq Hassan, Dr. Arif Rehman, Dr. Azhar Mahmood and Dr.Muhammad Akram who gave me not only their excellent cooperation but also a lot of smiles and enjoyable moments throughout my study period. I owe a special gratitude to my fellow Dr. Manzoor Ahmad Gill who very graciously extended all help and cooperation in carrying out trials and managing this manuscript.
I owe a debt to my cooperating/inspiring wife whose moral support and patience has been invaluable in aiding me to complete this thesis.Finally, I extend my heartiest and sincere sense of gratitude to my loving mother, brothers, sisters, , beloved sons (Talha) and Hamza) daughter (Mashaf Ishfaq) for their prayers for my success. (MUHAMMAD ISHFAQ)
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TABLE OF CONTENTS
CHAPTER TITLE PAGE ACKNOWLEDGEMENTS v CONTENTS vi LIST OF TABLES xi LIST OF FIGURES xiv ABSTRACT xvi 1 INTRODUCTION 1-5 2 REVIEW OF LITERATURE 6-26 2.1. Nitrogen in relation to plant growth 6 2.1.1. N nutrition of sunflower 7 2.1.1.1. Nitrogen in relation to yield and yield components 8 2.1.1.2. Nitrogen in relation to achene-oil quality 9-10 2.2.. Sulphur and plant growth 11 2.2. 1 Sulphur nutrition of sunflowers 12 2.2.1.1. Agronomic and yield traits 12-13 2.2.1.2. Sulphur and achene-oil quality 14 2.3. Interactive effects of N and sulphur 15 2.4. Nutrient uptake by sunflower 16 2.5. Performance of diverse sunflower hybrids 17-19 2.6. Row spacing and plant density 20-21
2.7. Canopy development, light interception and radiation use efficiency
22-23
2.8 Oil yield and its composition in sunflower seed 24-26 3 MATERIALS AND METHODS 27-37 3.1 Site and soil 28 3.1.1 Mechanical analysis. 28 3.1.2. Chemical analysis 28 3.1.2.1. pH of saturated soil paste 28 3.1.2.2 Electrical conductivity of saturated soil extracts( ECe ) 28 3.1.2.3. Organic Matter 28 33.1.2.4 Total Nitrogen 28 3.1.2.5. Available Phosphorus 28 3.1.2.6 Available sulphur 28 3.2 Metrological data 29 3.3 Experimental details 30
3.3.1 Experiment1Response of agro-physiological traits of autumn planted sunflower grown under varying sulphur-nitrogen nutrition.
30
3.3.2 Experiment II: Radiation interception, radiation use 31
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efficiency and productivity of different genotypes of sunflower under varying row spacing/planting densities
3.3.3 Crop husbandry 31 3.4. Data recorded 32 3.4.1. Agronomic and yield related traits 32-33 3.4.2. Growth and development 33 3.4.2.1 Sampling 34 3.4.2.2. Leaf area index (LAI) 34 3.4.2.3. Leaf area duration (days) 34 3.4.2.4. Crop growth rate (g m-2 day-1) 34 3.4.2.5. Net assimilation rate (g m-2 day-1) 34 3.4.2.6. Light interception (MJm-2 ) 35 3.4.2.7. Radiation use efficiency (g MJ-1) 35 3.4.3. Achene oil quality traits 35 3.4.3.1 Achene oil content (%) 35 3.4.3.2. Protein content (%) 35 3.4.3.3. Achene fatty acid profile (%) 35 3.4.4 Nutrient uptake pattern (kg ha-1) 36 3.4.4.1 Sample preparation: 36 3.4.4.2. Nitrogen uptake(kg ha-1) 36 3.4.4.3. Phosphorus uptake (kg ha-1) 36 3.4.4.4. Potassium uptake (kg ha-1) 36 3.4.4.5. Determination of sulphur uptake (kg ha-1) 37 3.5. Statistical analysis 37
4 RESULTS AND DISCUSSION 38-176
4.1
Experiment1:Response of agro-physiological traits of autumn planted sunflower grown under varying sulphur-nitrogen nutrition
38
4.1.1. Agronomic and yield related traits 38 4.1.1.1. Number of plants m-2 38 4.1.1.2 Plant height at maturity 38 4.1.1.3 Stem diameter 41 4.1.1.4 Head diameter 43 4.1.1.5 Number of achenes head-1 45 4.1.1.6. 1000 achene weight 49 4.1.1.7. Stover yield 51 4.1.1.8 Achene yield 51 4.1.1.9. Harvest index (%) 58 4.1. 2. Growth 58 4.1.2.1 Leaf area index 58
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4.1.2.2 Leaf area duration 68 4.1.2.3 Crop growth rate 68 4.1.2.4 Net assimilation rate 73 4.1.2.5 Cumulative light interception 73 4.1.2.6 Radiation use efficiency (TDM) 80 4.1.2.7 Radiation use efficiency (grain 82 4.1.3 Quality parameters 82 4.1.3.1 Achene protein contents 82 4.1.3.2. Achene oil content 85 4.1.3.3 Oil yield 86 4.1.3.4 Fatty acid profile 90 4.1.3.4.1 Oleic acid concentration 90 4.1.3.4. 2 Linoleic acid concentration 92 4.1.3.4.3 Palmitic Acid concentration 92
4.1.3.4.4 Stearic acid concentration 95
4.1.4 Nutrient uptake 97 4.1.4.1 Nitrogen uptake 97 4.1.4.2 Phosphorus uptake 100 4.1.4.3 Potassium uptake 103 4.1.4.4 Sulphur uptake 103 DISCUSSION 110
4.2 Experiment II: Radiation interception, radiation use efficiency and productivity of different genotypes sunflower under varying row spacing/planting densities
121
4.2.1 Agronomic traits 121 4.2.1.1 Number of plants m-2 121 4.2.1.2 Number of days taken to maturity 121 4.2.1.3 Plant height 124 4.2.1.4 Stem diameter 124 4.2.1.5 Head diameter 127 4.2.1.6 Number of achenes per head 129 4.2.1.7 Number of achenes m-2 131 4.2.1.8 1000-achene weight 133 4.2.1.9 Achene yield 135 4.2.1.10 Stover yield 137 4.2.1.11. Harvest Index (%) 137 4.2.2 Growth 140 4.2.2.1. Leaf area index 140 4.2.2.2 Crop growth rate 143 4.2.2.3 Net assimilation rate 148 4.2.2.4 Dry matter accumulation 148 4.2.2.5 Leaf area duration 154
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4.2.2.6 Cumulative radiation interception 156 4.2.2.7. Radiation utilization efficiency(TDM) 160 4.2.2.8. Radiation use efficiency for grain 162 4.2.3. Quality Characteristics 162 4.2.3.1. Achene oil content 162 4.2.3.2 Achene oil yield 165 4.2.3.3 Achene protein content 168 4.2.3.4 Fatty acid profile 168 4.2.3.4.1 Palmitic acid concentration 168 4.2.3.4.2 Stearic acid concentration 171 4.2.3.4.3 Oleic acid concentration 171 4.2.3.4.4 Linoleic acid concentration 174 Discussion 176 5 SUMMARY 186 Conclusion 191 Future Recommendations 192
6 LITERATURE CITED 193-216
7 Appendices 217-218
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LIST OF TABLES TABLE NO.
TITLE PAGE
3.1 Pre-sowing physico-chemical soil analysis 27 4.1 Influence of sulphur and nitrogen nutrition on plant population(m-2)
of sunflower
39
4.2 Influence of sulphur and nitrogen nutrition on plant height (cm) of sunflower
40
4.3 Influence of sulphur and nitrogen nutrition on stem diameter (cm) of sunflower
42
4.4 Influence of sulphur and nitrogen nutrition on head diameter ( cm) of sunflower
44
4.5 Influence of sulphur and nitrogen nutrition on number of achenes head-1 of sunflower
48
4.6 Influence of sulphur and nitrogen nutrition on 1000-achene weight (g) of sunflower
50
4.7 Influence of sulphur and nitrogen nutrition on Stover yield (kg ha-1) of sunflower
52
4.8 Influence of sulphur and nitrogen nutrition on achene yield (kg ha-1) of sunflower
53
4.9 Influence of sulphur and nitrogen nutrition on Harvest Index (%)of sunflower
59
4.10 Influence of sulphur and nitrogen nutrition on leaf area index (75DAS) of sunflower
63
4.11 Influence of sulphur and nitrogen nutrition on leaf area duration (days) of sunflower
69
4.12 Influence of sulphur and nitrogen nutrition on seasonal crop growth (g m-2 day -1) of sunflower
72
4.13 Influence of sulphur and nitrogen nutrition on net assimilation rate (g m-2 day -1) of sunflower
75
4.14 Influence of sulphur and nitrogen nutrition on cumulative light interception ( M J m-2) of sunflower
77
4.15 Influence of sulphur and nitrogen nutrition on radiation use efficiency for total dry matter ( g M J-1) of sunflower
81
4.16 Influence of sulphur and nitrogen nutrition on radiation use efficiency for grain ( g M J-1) of sunflower
83
4.17 Influence of sulphur and nitrogen nutrition on achene protein contents (%).of sunflower
84
4.18 Influence of sulphur and nitrogen nutrition on achene oil contents(%) of sunflower
87
4.19 Influence of sulphur and nitrogen nutrition on oil yield Kg ha-1 of sunflower
88
4.20 Influence of sulphur and nitrogen nutrition on oleic acid concentration (%) of sunflower
91
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4.21 Influence of sulphur and nitrogen nutrition on linoleic acid concentration (%) of sunflower
93
4.22 Influence of sulphur and nitrogen nutrition on palmitic acid concentration (%) of sunflower
94
4.23 Influence of sulphur and nitrogen nutrition on stearic acid concentration (%) of sunflower
96
4.24 Influence of sulphur and nitrogen nutrition on total nitrogen uptake (Kg ha-1) by sunflower
98
4.25 Influence of sulphur and nitrogen nutrition on total phosphorus uptake (Kg ha-1) by sunflower
101
4.26 Influence of sulphur and nitrogen nutrition on total potassium uptake (Kg ha-1) by sunflower
104
4.27 Influence of sulphur and nitrogen nutrition on sulphur uptake (Kg ha-1) by sunflower
107
4.27a Benefit cost ratio for experiment I 109 4.28 Influence of different row spacing on number of plants m-2
of diverse sunflower hybrids 122
4.29 Influence of different row spacing on days taken to maturity of diverse sunflower hybrids
123
4.30 Influence of different row spacing on plant height(cm) of diverse sunflower hybrids
125
4.31 Influence of different row spacing on stem diameter (cm) of diverse sunflower hybrids
126
4.32 Influence of different row spacing on head diameter (cm) of diverse sunflower hybrids
128
4.33 Influence of different row spacing on number of achenes per head of diverse sunflower hybrids
130
4.34 Influence of different row spacing on number of achenes m-2 of diverse sunflower hybrids
132
4.35 Influence of different row spacing on 1000-achene weight of diverse sunflower hybrids
134
4.36 Influence of different row spacing on achene yield (Kg ha-1) of diverse sunflower hybrids
136
4.37 Influence of different row spacing on stover yield (Kg ha-1) of diverse sunflower hybrids
138
4.38 Influence of different row spacing on Harvest Index (%) of diverse sunflower hybrids
139
4.39 Influence of different row spacing on crop growth rate (g m-2 day-1) of diverse sunflower hybrids
146
4.40 Influence of different row spacing on net assimilation rate of diverse sunflower hybrids
149
4.41 Influence of different row spacing on dry matter accumulation (g m-
2) of diverse sunflower hybrids 152
4.42 Influence of different row spacing on leaf area duration of diverse sunflower hybrids
155
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4.43 Influence of different row spacing on cumulative light interception ( M J m-2) of diverse sunflower hybrids
157
4.44 Influence of different row spacing on radiation use efficiency for total dry matter ( g M J-1) of diverse sunflower hybrids
161
4.45 Influence of different row spacing on radiation use efficiencygrain of diverse sunflower hybrids
163
4.46 Influence of different row spacing on achene oil contents (%) of diverse sunflower hybrids
166
4.47 Influence of different row spacing on oil yield (Kg ha-1) of diverse sunflower hybrids
167
4.48 Influence of different row spacing on protein contents (%) of diverse sunflower hybrids
169
4.49 Influence of different row spacing on palmitic acid concentration (%) of oil of diverse sunflower hybrids
170
4.50 Influence of different row spacing on stearic acid concentration (%) of oil of diverse sunflower hybrids
172
4.51 Influence of different row spacing on oleic acid concentration (%) of oil of diverse sunflower hybrids
173
4.52 Influence of different row spacing on linoleic acid concentration (%) of diverse sunflower hybrids
175
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LIST OF FIGURES FIGURE
NO TITLE PAGE
3.1 Meteorological data during year (a) 2006 (b) 2007 29 4.1 Relationship between number of achenes per head and head
diameter during (a) 2006 and (b) 2007 46
4.2 Relationship between achene yield and head diameter during (a) 2006 and (b) 2007
47
4.3 Relationship between achene yield and head diameter during (a) 2006 and (b) 2007
55
4.4 Relationship between achene yield and number of achenes per head during a) 2006, b) 2007
56
4.5 Relationship between achene yield and 1000-achene weight during a) 2006, b) 2007
57
4.6 Pattern of Leaf area index as influenced by sulphur nutrition during a) 2006, b) 2007
61
4.7 Pattern of leaf area index as influenced by nitrogen nutrition a) 2006, b) 2007
62
4.8 Relationship between number of achenes per head and leaf area index during a) 2006, b) 2007
64
4.9 Relationship between1000-achene weight and leaf area index during a) 2006, b) 2007
65
4.10 Relationship between crop growth rate and leaf area index during a) 2006, b) 2007
66
4.11 Relationship between achene yield and leaf area index during a) 2006, b) 2007
67
4.11 Pattern of crop growth rate as influenced by sulphur nutrition a) 2006, b) 2007
70
4.12 Pattern of crop growth rate as influenced by nitrogen nutrition a) 2006, b) 2007
71
4.13 Relationship between achene yield and crop growth rate during a) 2006, b) 2007
74
4.14 Relationship between cumulative intercepted radiation and leaf area index during a) 2006, b) 2007
78
4.15 Relationship between cumulative intercepted radiation and achene yield during a) 2006, b) 2007
79
4.16 Relationship between achene oil yield and achene yield during a) 2006, b) 2007
89
4.17 Relationship between achene yield and total nitrogen uptake during a) 2006, b) 2007
99
4.18 Relationship between achene yield and total phosphorus uptake during a) 2006, b) 2007
102
4.19 Relationship between achene yield and total potash uptake during a) 2006, b) 2007
105
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4.20 Relationship between achene yield and total sulphur uptake during a) 2006, b) 2007
108
4.21 Pattern of leaf area index with time: comparison of different sunflower hybrids during (a) 2006 and (b) 2007 ±SD
141
4.22 Pattern of leaf area index with time: comparison of different row spacing during (a) 2006 and (b) 2007 ±SD
142
4.23 Pattern of crop growth rate with time : comparison of different sunflower hybrids during (a) 2006 and (b) 2007 ±SD
144
4.24 Pattern of crop growth rate with time: comparison of different row spacing during (a) 2006 and (b) 2007 ±SD
145
4.25 Relationship between crop growth rate and leaf area index a) 2006, b) 2007
147
4.26 Pattern of total dry matter accumulation with time : comparison of different sunflower hybrids during (a) 2006 and (b) 2007 ±SD
150
4.27 Pattern of total dry matter accumulation with time: comparison of different row spacing during (a) 2006 and (b) 2007 ±SD
151
4.28 Relationship between achene yield and dry weight a) 2006, b) 2007 153
4.29 Relationship between cumulative intercepted radiation and leaf area index a) 2006, b) 2007
158
4.30 Relationship between achene yield and cumulated intercepted radiation a) 2006, b) 2007
159
4.31 Relationship between achene yield and radiation use efficiency (RUETDM) a) 2006, b) 2007
164
4.32 Relationship between achene yield and radiation use efficiency (RUEGrain) a) 2006, b) 2007
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ABSTRACT
The present research work was carried out to investigate the effect of sulphur-
nitrogen nutrition and varying plant population on productivity of sunflower hybrid at
the agronomic research Area, University of Agriculture Faisalabad. Two years field
oriented research experiments were conducted for 2006 and 2007. In the first
experiment sunflower hybrid Hysun-33, was subjected to four sulphur level (0, 40, 80,
120 Kg ha-1) and four nitrogen levels (0, 40, 80,120Kg ha-1). The experiment was laid
out in RCBD factorial with three replications. In the second experiment three sunflower
hybrid viz., FH-331 (early maturing), SF187 (medium maturing) and Hysun-33 (late
maturing) were tested at three row spacing (45cm, 60cm and 75cm).The variation in
agronomic and physiological characteristics of sunflower was analyzed with varying
levels of sulphur and nitrogen. During both years of study sulphur and nitrogen
application @ 80 and 140 Kg ha-1 produced maximum achene yield (3167-3000Kg ha-
1), which was the out come of better yield contributing attributes (higher leaf area,
maximum crop growth rate, better light interception, dominant head size, higher 1000-
achene weight).On an average maximum oil yield of 1090 and 1121 Kg/ha were
obtained with the application of 80 and 140 Kg ha-1 sulphur and nitrogen, respectively.
An increase in protein contents (%) was experienced with increasing sulphur levels, and
vice versa with enhancing the nitrogen levels. Radiation utilization efficiency for dry
mater and grain was also significantly increased with higher nitrogen rate and sulphur
application @ 80 Kg ha-1. Computation of benefit cost ratio (BCR) revealed that the
highest BCR 2.38 was also pertinent to the same treatment in sunflower are 80 and 140
Kg/ha-1, respectively. In the second experiment the hybrid Hysun-33, which was a late
maturing hybrid, not only recorded highest leaf area index, but also experienced
maximum crop growth rate, highest plant height, greatest number of achenes, and
maximum achene yield. On an average Hysun-33(late maturing type) produced
significantly higher achene yield (3033-2888Kg ha-1), planted at 60cm apart rows, and
SF-187(medium maturing hybrid) harvested maximum achene yield(2783-2740Kg ha-
1), when sown at 45 cm wider rows. The early maturing (FH-331,a local hybrid)
responded well to the row distance of 45 cm and produced highest achene yield of
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2633-2533 Kg ha-1. Although, with increasing rows spacing from 45-75cm, the
sunflower crop resulted in larger heads, possessing more achenes per head, and heavier
individual achene, but the boost in yield of the hybrids FH-331 and SF-187 with
decreasing the row spacing (increasing plant population) was principally associated
with more achene number per unit area, higher leaf area index and maximum crop
growth rate. Therefore, it is concluded that under tropical to semi-arid region like the
experimental area (located at 73.09o East longitude and 31.25o North latitude and at an
altitude of 184 m), the best sulphur and nitrogen doses to get maximum achene yield.
Highest achene yield 3084 kg ha-1 was recorded where sulphur was applied at the rate
of 80 kg ha-1for along with 140 kg ha-1 nitrogen. Computation of benefit cost ratio
(BCR) revealed that the highest BCR 2.38 was also pertinent to the same treatment in
sunflower are 80 and 140 Kg/ha-1, respectively. Regarding hybrids and their planting
density, late maturing hubris like Hysun-33 should be planted at 60 cm apart rows with
plant to plant distance of 22.5. Medium and early maturing sunflower hybrids may be
preferred to be sown at 45 cm apart rows with plant to plant distance of 22.5 cm.
1
CHAPTER-1
INTRODUCTION
There has ever been a severe shortage of edible oilseeds in Pakistan that can
hardly assemble the demand. Getting higher population and never-ending rise in
urbanization has led to broaden the gap between local availability and requirement owing
to increase in number of mouths as well as rise in per capita consumption. Total domestic
chuck of edible oil stood at about 3.07 million tons, of which 27.20% (0.83 million tons)
came from local production (Govt. of Pakistan, 2009). Thus, the country is constrained to
import edible oil in large quantities (about 72.8% of total requirement). Spending on
import of edible oil accounts largest drain on national exchequer that is second to only
mineral oil. The import bill is imposing a severe drain on foreign exchange reserves.
During 2008-09 (July-March), Pakistan spent Rs. 84000 million for 1290 thousand tons
of edible oil and Rs.13756.83 million for 723.96 thousand tons of oilseeds (Govt. of
Pakistan, 2009) during 2008-2009. A developing country like ours cannot afford such a
mounting export bill indeed. The situation thus warrants enhancing the indigenous oilseed
production to set aside the country from a foremost disaster in not too far a future.
Edible oil in the country comes from conventional (rapeseed (Brassica napus L.),
mustard (Brassica juncea L.), groundnut (Arachis hypogaea L.), sesame (Sesamum
indicum L.), linseed (Linium ustitatissimum L.) and caster bean (Ricinus communis L.),
and non-conventional [sunflower (Helianthus annuus L.), soybean (Glycine max L.) and
safflower (Carthamus tinctorius L.)] crops, in conjunction with oil trees for instance; oil
palm (Elaeis guineensis Jacq.), coconut (Cocos nucifera L.), and olive (Olea europaea
L.). Among these, rapeseed and mustard are the most important winter oilseed crops and
add about 10-13% to the indigenous edible oil making. Higher concentrations of erucic
acid and glucosinolates, restrict the use of rapeseed and mustard oil as regular cooking
oil. Cotton (Gossypium hirsutum L.) seed contributes about 70-75% to the total oil
production. But cotton is primarily grown for fiber purpose, and oil contents and fiber are
inversely interconnected offering little space for breeding cotton in Pakistan for
enhancing seed oil content (Govt. of Pakistan, 2009). Canola offers a good promise for
oilseed production but many of the production constraints including its adjustment in
existing cropping pattern as well as supply of good quality seed pose limitations to its
2
large scale adoption by the growers. Keeping in view this scenario, Pakistan will have to
look away from the extensive recognized oilseed sources (conventional oilseeds) to
appreciably augment local production of vegetable oils. Amongst non-conventional
oilseeds, sunflower stands as a good candidate that cans a bridge the gap between demand
and supply of edible oils in the country.
Although sunflower is a mild region crop, but performs fine under varying agro-
climatic environment. It withstands early frostiness in autumn that generally kills maize
and soybean. Khalifa et al. (2000) reported that due to extensive adjustment of sunflower
crop grown in very hot regions of south west of United States to extremely cold areas in
eastern Canada, this crop had been characterized ideal for diversified environment. This
has made sunflower among the most important oil crops worldwide (Jonic et al., 2000).
In 2004, the world seed production of sunflower stood at 27.74 million tones and the area
under cultivation was 22.23 million hectares. The major sunflower producing countries,
around the globe are Russian Federation (4.87 million ton; m.t), Ukraine (4.2 m.t),
Argentina (3.71 m.t), China (2.0 m.t), Romania (1.51 m.t), France (1.49 m.t), India (1.22
m.t), U.S.A (1.20 m.t), Hungry (0.97 m.t) and Turkey (0.80 m.t), while Pakistan
(0.08.m.t) stands at 23rd position in the world ranking (FAO, 2004).
Agro-climatic circumstances of Pakistan are of such nature that sunflower can be
grown productively in both seasons (spring and autumn), without causing displacement of
any key crop. Presently, in Pakistan, sunflower is sown on an area of 506 thousand
hectares with the total assembly of 755 thousand tons and oil production of 287 thousand
tons and an average seed yield of 1492 kg ha-1, which is far below its potential yield
(Govt. of Pakistan, 2009).
Among major significant factors responsible for low yield show of present day
sunflower hybrids generally cultivated in the country are unprovoked plant nourishment,
indecent choice of genotype/hybrid, suboptimal plant allocation/ population and lack of
balanced crop stands for specific hybrids. It is anticipated that approximately 60 % of
worldwide cultivated soils have growth-limiting troubles coupled with shortage of
mineral nutrient (Cakmak, 2002). FAO (1995) approximation shows that regarding 2/3 of
desirable raise in agricultural crop productivity in developing countries will be achieved
from yield enhancement on the area previously under farming and plant nutrients is the
main contributing factor for realizing such yield increases.
In view of the fact that fertilizers are very costly and revenue margins are very
little in sunflower production, agricultural researchers require information on nutrient
3
interaction to adjust fertilizer recommendations. Sunflower is a crop of hot areas, with a
transitional water requisite and that can be introduced successfully to varying crop
rotations in dry land areas. It can grow successfully in soils of diverse nutrient status
(Connor and Hall, 1997; Sadras and Trapani, 1999). Sunflower achene yield and quality
has been considerably influenced by nitrogen fertilization and present day high-yielding
sunflower hybrids need more N supplies than previous open-pollinated cultivars (Ozer et
al., 2004). Nitrogen deficiency causes reduction in individual and total leaf area as well as
less light interception (Toth et al., 2002). An enhancement in nitrogen accessibility results
in superior leaf nitrogen content and strong encouraging association between
photosynthetic capability and leaf nitrogen content for many C4 and C3 species is well
recognized (Connor and Sadras 1992). Decline in the contents of chlorophyll and rubisco
commotion is often endorsed to lesser rates of photosynthesis under nitrogen deficient
situations (Fredeen et al., 1991; Toth et al., 2002).
Sulphur (S) is one of the indispensable nutrients for plant expansion, metabolism,
enzymatic reactions and fundamental ingredient of sulphur containing amino acids like
cystine, methionine and cysteine. It is also constituent of S-glycosides, coenzymes,
vitamins, biotin and thiamine (Tisdale et al., 1985). Its concentration and uptake vary
with accessibility of sulphur in soil and its fertilization (Singh et al. 1999). Sulphur
deficient areas are increasing day by day and the reasons are intensive utilization of low
sulphur fertilizers, multiple cropping systems and also due to irrational use of plant parts
as food and fuel. Degradation of the soil, by processes of erosion and leaching, also
contributed their share in enhancing the sulphur deficient areas in the world. (Tandon,
1984). An insufficient sulphur supply can affect yield and quality of the crop and it also
affects efficiency of applied N, P and K. Moreover, oilseed crops require more sulphur
than others. Hocking et al. (1987) documented that an ample provision of S to young
sunflower plants is mandatory to attain heavier heads and greatest leaf area. Kernels
receive low levels of essential S-containing amino acids, when the sulphur deficiency
appears during seed filling period.
At field stage, the documentation of the interactive effect of S and N to determine
the physiological aspects of the biomass and yield of sunflower is needed. Fine-tuning of
N and S fertilizer recommendations are desirable to guarantee maximum yield, economic
profitability, and environment friendly cropping systems. Therefore the study was
planned to establish the effect of N, S and their interaction on agronomic, physiological
and quality linked parameters.
4
In the country, the availability of wide range of hybrids belonging to diverse agro-
physiological characteristics makes it difficult for general recommendations due to their
differential response to management strategies. Therefore, independent production
package for specific hybrid is needed to be documented. At field level general
recommendations are often made for production, and hence, the yield of sunflower in
farmer’s field is lower than its potential yield. The presence of cultivars of diverse
maturity groups has also made it possible the yield stability of sunflower by selecting
hybrids of accurate maturity precise to various environmental situations.
Plant density is one of the important factors on which grain yield and other yield
contributing attributes of crop are dependent. Developmental plasticity in terms of plant
architecture and growth has been observed in many crops with varying planting densities.
Density is the single most important management factor that determines the total amount
of intercepted radiation under field conditions. The amount of intercepted radiation that is
responsive to grain yield may be analyzed in the field (Fernando and Miralles,2008).
Sunflower hybrids of different structure recorded beneficial, neutral or counter productive
response at reduced distance between rows. Villalobos et al. (1994) revealed that cultivar
features including the time to maturity and plant stature significantly influenced yield
response to row-spacing and planting-density. Yield responses at different row spacing
and plant population are attributed to radiation interception, plant height, seed setting
efficiency, grain number, grain mass , and seed oil contents, etc. (Calvino et al., 2004).
The radiation intercepted (MJ d-1) by the crop canopy is considered important for
the investigation of crop growth rate (g m-2 d-1) and the effective utilization of that
intercepted radiation for the creation of biomass is termed as radiation-use efficiency (
RUE, g Mj-1) ; Montieth, 1977). Size and arrangement of the canopy determine the
amount of intercepted radiation, while the net gain of assimilates by the whole plant
during growth period expresses radiation use efficiency .Both, light interception and
radiation use efficiency are highly respondent to canopy volume and structure of the
leaves and their orientation. Photosynthesis and Radiation use efficiency can be
influenced by nitrogen fertilization through leaf expansion and canopy development.
A little agronomic information on requirements and productivity effects of sulphur
and nitrogen nutrition on sunflower hybrids under arid land environments is available.
Moreover, the response of diverse sunflower genotypes to narrow row spacing and high
planting densities needs to be quantified in terms of productivity as well as quality of the
produce. The present studies were, therefore, planned with the objectives as follows:
5
To study the influence of sulphur and nitrogen fertilization on productivity of
hybrid sunflower.
To quantify the agro-physiological response of different genotypes of sunflowers
to various planting densities.
To study the patterns of nutrient uptake of sunflower hybrids under varying
sulphur and nitrogen levels.
To evaluate the comparative quality traits of achenes from different sunflower
hybrids produced under varying management levels.
To analyze the growth and yield of sunflower in terms of amount and utilization
of intercepted radiation under Faisalabad conditions.
6
CHAPTER-II
REVIEW OF LITERATURE
Some of the literature relating to different aspects of present study is briefly
reviewed in this portion.
2.1. NITROGEN IN RELATION TO CROP GROWTH
Growth and development of a plant are a combination of many events at many
different levels, from biophysical and biochemical to tissue and organ levels. Crop growth
and development is influenced by different environmental variables and temperature is
considered a main determinant for regulation of both (Ritchi & Ne Smith, 1991). A few
reports are available on the influence of nitrogen fertilization on the phasic development
of sunflower. Hocking and Steer (1983, 1995) and Blanchet et al. (1987) stated that rate
of development and growth of both vegetative (leaves) and reproductive (florets and seed)
organs are very much influenced by scarcity of nitrogen nutrition. During the early
vegetative period, nitrogen deficiency causes reduction in leaves score and retards the
growth of the leave resulting in sluggish LAI development and reduced interception of
radiation.
Adequate supply of nitrogen is required to accelerate all protein based metabolic
processes, responsible for rapid expansion in vegetative and generative growth and higher
yields (Lawlor, 2002).It has been proved in all sort of experiments that by enhancing the
provision of nitrogen fertilizer, a boost in growth and photosynthesis also existed.
Deficiency of N reduces leaf score, individual leaf expansion and leaf area thus causing
reduction in area for light interception and resulting in lowering of photosynthesis rate
(Toth et al., 2002). When nitrogen availability is sufficient, leaf nitrogen content is
higher, and shows a strong association between photosynthesis and nitrogen present in
leaves of many C4 (photosynthetic ally active) and C3 (less photosynthetically active)
species (Connor et al. 1993).Total leaf nitrogen contents (upto 75%) present in leaf
chloroplasts(Browne, 1977) and its major share is utilized only in ribulose biphosphate
carboxylase. Resultantly, under nitrogen deficiency, lower rates of photosynthesis are
often ascribed to lessen green pigments and performance of Rubisco enzyme (Fredeen et
7
al., 1991; Toth et al., 2002). Photosynthetic activity and chlorophyll contents of
sunflower plant enhanced under adequate supply of N (160 kg ha-1) and improved leaf
area as compared with no nitrogen application (Ozer et al., 2004).Greater TDM(shoot)
synthesis by the plant was improved with higher N application, especially in early growth
period (Cechin and Fumus, 2004). This difference in dry matter production was mainly
attributed to the effect of nitrogen on leaf production and on individual leaf dry matter. As
a result of N application (from 30 to 60 Kg ha-1), LAI and dry matter production was
enhanced (Singh et al. 2005).
2.1.1. N nutrition of sunflower
Nitrogen has an imperative position in spurring the vegetative cover of the
sunflower plants. Differential responses of sunflower plant occur under variable nutrient
availabilities (Connors and Hall, 1997). Managing N fertilization is of particular
significance because many environmental and production factors affect sunflower N
requirement. Vegetative and generative growth of plant reduces during N deficiency and
premature senescence also occurs, consequently decreasing yield (Narwal and Malik,
1985; Khokani et al., 1993; Legha and Giri, 1999 and Tomar et al., 1999). Excess N
application also increases the risk of disease and lodging, with a consequent reduction in
oil content and may aggravate ground and surface water pollution. The consumption
efficiency of nitrogenous fertilizers used in the field is stumpy (Ahmad et al. 2001 Abdin
et al. 2003). Heavy annual loss of N from rapeseed-mustard cropping system was
reported and attributed to the insufficient sulphur supply (Schnug et al. 1993; Haneklaus
et al. 2003).
Nitrogen is the most essential mineral nutrient that affects plant composition. Use
of N increases all nitrogenous compounds in the plant but the increase is different
between free amino acids, amides, amines and proteins. The content of soluble amino
compounds increase more swiftly than that of proteins with increasing rates of N
application. This signifies more convincingly that inorganic N is assimilated more quickly
than the amino acids are being used for protein synthesis (Mengal and Kirkby, 1982).
During early growth, a high level of N in the root zone improves shoot elongation and
retards that of roots; these morphological changes in later growth stages are inauspicious
for nutrient and water uptake (Marschner, 1986).
8
Although, sunflower plant can use nitrogen in any of nitrate or ammonium form
but it flourishes well with nitrate (Kirkby and Mengel, 1970) and it also needs high
nitrogen nutrition for photosynthetic enzyme (rubisco).
2.1.1.1. Nitrogen in relation to yield and yield components:
Connor and Sadras (1992) reported that in the formation of yield in sunflower,
there were three stages i.e from floral initiation to first anthesis, first anthesis to last
anthesis and last anthesis to physiological maturity. Effect of N application on yield and
yield components and agronomic traits of sunflower (achene yield, crop growth, plant
height ,head diameter, stem diameter, number of achenes per head,1000 achene weight,
leaf account, and leaf area index) was studied by many researchers around the globe and
have been well documented.
Several authors (Andhale and Kelbhor, 1980; Bhosal et al., 1979; Mathers and
Stewart, 1982; Nazir et al., 1987) reported maximum achene yield of sunflower with
about 75 to 100 kg ha-1 of applied N that decreased with 120 kg ha-1 (Sing, 2007) and that
80-85 kg ha-1 was the optimum level (Smiderle et al., 2005). Ali et al. (2004) concluded
that nitrogen supplemented at the rate of 150 kg ha-1 gave the highest seed yield (992.5 t
ha-1) while 200 kg ha-1 N fertilization did not show significant increase over the former
level. Ogunremi, (1986).concluded that increasing N above 90 kg ha-1 retarded achene
and oil yields drastically due to high percentage of unfilled seeds.
The significant and linear response of N on sunflower achene yield can be
accounted for the positive response of agronomic characteristics to nitrogen application.
Among different components, head diameter is of prime importance for yield
determination. As N fertilizer rate increased, the head diameter also increased (Ozer et
al., 2004).
Nitrogen application has also a significant effect on seed weight. Sing (2007)
reported that seed weight increased with N application up to 80 kg ha-1 and then a decline
was observed at 120 kg N ha-1. Several other authors (Ahmad et al., 2005; Ozer et al.,
2004; Poonia, 2000) observed a progressive and reliable raise in achene weight with
addition in N dose up to 160 kg ha-1.
Quantity of achenes per head is also optimistically linked with head size and
ultimately contributing towards final grain yield. Privileged grain yields designed for
greater N treatments are connected by means of higher grain number (Zubillaga et al.,
2002).The establishment of grain number around seed formation stage is dependent on
9
the translocation of assimilates to some extent (Andrade 1995). Nawaz et al. (2001),
Singh (2007) and Al-Thabet (2006) also highlighted that increasing levels of nitrogen
enhanced the achene numbers.
2.1.1.2. Nitrogen in relation to achene-oil quality
The relationship between the level of N application and seed oil content has
usually been shown to be inversely correlated (Xie and Zhou, 2003). Several authors
(Scheiner et al., 2002); Ali et al., 2004; Ozer et al., 2004; Al-Thabet, 2006) have reported
negative influence of nitrogen on seed oil concentration. The significant negative
relationship between seed oil content and high nitrogen fertilization could be probably
attributed to the sugar translocation effecting oil synthesis (Salisbury & Ross, 1994).
Similarly, alternating enzymes imbalance could also contribute in this reduction (Hussein
et al., 1980; Steer et al., 1986). Kutcher et al (2005) attributed such negative relationship
to the diluting effect of higher seed yield at higher N application and the opposite
relationship between protein and oil content. Jackson (2000) observed that application of
N resulted in prolonged maturity period of crop resulting in poor seed filling and higher
proportion of green seed. Abundant supply of nitrogen enhances protein precursors that
are rich in N and there is strong tendency of photosynthates to be utilized for protein
formation and lesser of these are available for fat synthesis (Holmes, 1980). Rathke et al.
(2005) reported that same held true for oil formation at high nitrogen application.
The positive response to oil contents (39.9%) from 0 to 100 kg N ha-1 (Ali et al,
2004),was observed and further higher doses of nitrogen showed negative influence on
seed oil concentration. Increasing nitrogen rates from zero to 120 kg ha-1 lead to decline
in oil concentration (417.9 to 395 g kg-1.) of the sunflower plant. (Ozer et al;
2004).Similar responses have been reported in other studies (Stear et al, 1986,Geleta et
al.1997,Scheiner et al.2002). The increase in nitrogen level to more than 50 Kg/ha was
associated with a decrease in seed oil percentage (Al-Thabet, 2006). And seed oil % rose
from 40.7 to 41.1 with increasing nitrogen level from 0 to 50 Kg/ha and the further levels
of nitrogen (100,150 and 200 kg ha-1) resulted in oil contents reduction as compared to
the control. (Al-Thabet, 2006). Similarly, alternating enzymes imbalance could also
contribute in this reduction. (Hussein et al.; 1980, Steer et al.; 1986).
Negative response of increasing N levels to oil contents in other oil seed crops has
also been studied by scientists. Ahmad et al; (2007) studied the influence of nitrogen on
quality of Canola crop and observed that the highest N level(80 kg ha-1) resulted in the
10
lowest oil contents(41.6%) and the nitrogen applied at the rate of 40 Kg/ha produced
43.2% oil concentration. In rapeseed mustard, the reduction in oil concentration of seed
caused by increasing N application was not surprising (Ozer, 2003) as similar effects have
been reported in canola crop by (Cheema et al.,2001 Jackson,2000, Kutcher et
al.,2005;Rathke et al.,2005). However, Brennam et al. (2000) reported that the oil
concentration of canola seed remained unaffected by N rate.
Several reasons have been given by different researchers for the decrease in oil
contents with increasing N rates. For example, Kutcher et al. (2005) stated that it might
be due to the dilution effect of increased seed yield with increased N fertilization and the
inverse relationship of protein and oil content. Jackson (2000) believed that N delayed
plant maturity which results in poor seed filling and greater proportion of green seed.
Holmes (1980) reported that a better supply of N increases the formation of N containing
protein precursors so that protein formation competes more strongly for photosynthesis;
as a result less of the latter are available for fat synthesis. Likewise, Rathke et al. (2005)
linked this fact with reduced availability of carbohydrates for oil synthesis at high N
application.
Large nitrogen supply usually increases the amount of seed oil yield and depresses
seed oil concentration,(Steer et al.,1984.) and this is because of dilution of oil in heavier
seeds produced under high N and that was also proved true from the studies presented by
Khaliq;(2004). And hence smaller N concentration does not offset the advantage that
large N supply had on seed number and seed weight. The findings of Ozer et al; (2004)
also supported the significant response of increasing nitrogen doses for increasing oil
yield. In fact, the response was associated directly with the response of seed yield to
applied N rates. Sing et al.,( 2005) recorded an increase in total biomass and oil yield
with nitrogen applied at 30&60 kg ha-1, likewise, Poonia (2003) observed the rise in oil
yield upto 80 kg N ha-1 and was probably due to increased seed yield being the function
of oil content and seed yield.
The inverse relationship between oil and protein contents was reported by
Poonia.(2003), and the protein contents in seed increased upto 120 kg N ha-1. Munir et al
(2007) studied the impact of integration of crop manuring and nitrogen application on
quality of spring planted sunflower. The positive influence of increasing nitrogen rates
was recorded as the treatments with 100 kg N ha-1 gained 15.39% protein contents and
11.5% in the control. Khaliq, (2004), also stated such significant impact and found 12.08,
14.55 and16.21% achene protein concentration with 0,100&200 kg ha-1 N, respectively.
11
Ozer, 2004 reported 9% increase in protein contents with 120 kg N ha-1 than that of no
nitrogen application. Ghani et al. (2000) also reported an increase in seed protein content
in sunflower with increasing N application.
In canola seed, protein contents enhanced progressively with increase in N rates
and the highest protein content of 23.5% was found at the maximum level of 80 kg N ha-
1. (Ahmad et al.,2007). These results confirmed the findings of Malhi and Leach (2000)
and Kutcher et al.(2005). The seed N concentrations of rapeseed were affected
significantly by nitrogen rates and the highest N concentration (39.78 g kg-1) was
obtained in the treatment receiving 240 kg N ha-1. (Ozer, 2003). The high protein content
at high level of N may be due to the negative correlation between oil content and protein
content (Hao et al.,2004). The physiological reason for the negative correlation may be
that the carbohydrate content of protein is lower than that of oils (Lambers&
Poorter,1992); increased N supply intensifies the synthesis of protein at the expense of
fatty acid synthesis and thus reducing the oil contents of the seed (Rathke et al;2005).
Sunflower oil has greater degree of oxidative stability than oils poor in oleic acid
(Fullner et al., 1967) which is a positive trait for frying purpose, its refining and, storage.
Cultivars and environmental conditions influence the fatty acid composition to large
extent (Connor and Sadras, 1992). Moreover there is a strong negative association
between oleic and linoleic acid so that a phenotype low in oleic would definitely be high
in linoleic one (Demurin et al., 2000). The relative proportion of oleic and linoleic acids
are influenced by the genotype and temperature regimes during oil formation, whereas the
influence of N is meager and depends on time of nitrogen application (Steer and Seiler,
1990). Negative influence of nitrogen on oleic acid was reported by Khaliq (2004) while
linoleic acid and palmitic acid concentration increased gradually with increasing levels of
nitrogen. Ghani et al. (2000) also reported similar results. Momoh et al. (2004) revealed
that increasing levels of nitrogen enhanced the composition of palmitic and linolic acids
by (9.0% and 5.5%, respectively) and the difference of other fatty acid contents among
various N levels was non-significant.
2.2. Sulphur and plant growth
Certain soils are sulphur deficient and thus influence plant vigor and crop yield
(Haneklaus et al., 1997). Sulphur deficiency results in chlorosis of younger leaves,
buildup of anthocyanins, twisting of the leaf blade and better root growth (Nikiforova et
12
al., 2003; Lopez-Bucio et al., 2003). Sulphur deficiency is in part shared by other nutrient
stresses, as NO3 (Zhang& Forde, 1998&2000), or PO4 deficiency.
Most of the agricultural soils contain very minute amount of inorganic sulphur
than is agriculturally bound in nature (Bohn et al., 1986). Different crop species vary for
total S requirement and these also differ at varying development stages of plants. In
general, S demand of Cruciferae and Liliaceae is the highest and of small grains is the
lowest; while that for Leguminosae ranges in between. For one ton production of seed in
oilseed crops, about 16 kg S is needed (MacGrath& Zhao, 1996). Similarly, Walker and
Booth (1992) reported that an oilseed rape crop removed more S (20-30 kg ha-1) from
soil, while cereals less (10-15 kg S ha-1).
Sulphur is the fourth major nutrient in crop production. Most of the crops require
as much sulphur as phosphorus. Sulphur is involved in the synthesis of chlorophyll and is
the component of amino acids, cystin, cystein and methionine. (Marschnar, 1995).
2.2.1. SULPHUR NUTRITION OF SUNFLOWERS
2.2.1.1. Agronomic and yield traits
Grain yield is the interplay of many components contributing towards final
harvest. Ability of crop to arrest resources determines the yield potential (Monteith,
1994). Radiation, water, nutrients, are major resources, in addition to those which amend
leaf expansion and root growth, and feed back the ability of the crop to convert these into
yield. Extent of spread and architecture of crop canopy at anthesis provides strong
measure its capacity for capturing light and a measure of the crop size that also exhibits
its ability to capture other resources (Marcau et al., 2001). Number of grains are
positively associated with radiation and negatively with temperature (Cantagello, 1997),
and are an important yield contributing trait. Larger heads (17.3 cm) harvested with S
application were associated with more number of grains thus giving more yield (Hassan
et al., 2007).
In contrary, less number of grains developed on smaller heads would not have
faced any competition for assimilates thus produced heavier individual grain weight.
Sulphur and benzyladenine application enhanced plant height, leaf area, dry matter yield
and seed yield of sunflower so that both of these recorded the crop growth rate and net
assimilation rate during early growth (Reddy and Sing, 1996). Sing et al. (2000) observed
significant increase in plant growth due to various doses of sulphur,viz;0, 30 and 45
Kg/ha. Seed yield of sunflower was the highest (1220 kg ha-1) at 45 kg S ha-1 and this
13
increase was 10 and 18% over 30 Kg/ha and control. Increasing levels of sulphur upto 45
kg ha-1, significantly increased the yield attributes like plant height(72.22cm) and leaf
area(2107.42 cm), This positive response might be due to synthesis of more chlorophyll,
resulted in better utilization of carbohydrate form more protoplasm. Sulphur application
also significantly increased the filled seeds/head, head diameter and test weight.
Several other authors (Poonia, 2000; Wani et al., 2001; Nasreen and Haq, 2002;
Khan et al., 2003; Sajjan and Pawar, 2005; Hassan et al., 2007) have established the
positive response of various sulphur application rates on the agronomic and yield
attributes of sunflower.
Poonia (2000), recorded significant increase in dry matter, plant height, head
diameter, number and weight of seeds, test weight, seed and biological yields of
sunflower when sulphur was applied @ 25 kg ha-1. The increase in seed yield was
observed up to 50 kg S ha-1 ha. Similarly, Sulphur had synergistic effect on nutrient
uptake and sunflower yield. There was a linear increase in seed yield with increase in
sulphur application up to 80 kg ha-1 and yield difference between the highest and lowest
yielding treatments was nearly 74% (Nasreen and Haq,2002). This positive response
could be due to increased absorption of sulphur from the soil resulting in increased
formation of reproductive structure or sink strength and increased production of
assimilates to fill the seeds. Application of sulphur between 60-80 kg ha-1 increased the
seed yield and uptake of NPK and S in leaf, stem, and head.
Khan et al. (2003) concluded that sulphur dose @ 50 kg ha-1 was superior in terms
of producing high yield of fresh matter, dry matter, fresh disc, 1000 seed weight and total
seed yield of sunflower than other two treatments. Application of sulphur above 50 kg ha-
1 reduced yield components and final seed yield, suggesting a classical yield response
curve.
Budhar, et al.(2003), tested five levels of sulphur viz.0, 15,30,45,and 60 kg ha-1
combined with recommended doses of N P K. The number of grains and test weight were
significantly higher at 45 and 60 kg S ha-1. Similarly, application of graded levels of
sulphur significantly increased the grain yield linearly and the increase was 4, 8, 17, and
20 % over no sulphur application.
Bhagat et al. (2005), applied sulphur @ 0, 20 and 40 kg ha-1 and found that higher
rate of sulphur produced significantly highest seed yield (12.35 q ha-1) as compared to
10.08 q ha-1 where no sulphur was applied. This may be attributed to more accumulation
and translocation of amino acids and amide substances to the reproductive organs by
14
sulphur application. Similar results have also been reported earlier by Lega & Giri (1999)
and Sarkar et al. (1999). Hitsudea et al. (2005) evaluated sulphur requirements of eight
crops including sunflower at early stages of growth. They determined tolerance to low
essential sulphur levels and critical tissue concentration for sulphur deficiency. All crops
achieved optimum growth at 2.0 mg S L-1 and critical shoot S concentration at early
stages of growth in sunflower ranged from 1.4 to 1.6g kg-1 for sulphur.
Sajjan and Pawar,2005 studied the response of sulphur and zinc fertilization in
sunflower KBSH-1 hybrid and found that the application of 20 Kg S and 10 Kg Z ha-1
resulted higher yield attributes and seed yield with better quality and was at par with 40
kg S and 10 Kg Zn ha-1.
Hassan et al. (2007), evaluated effect of various levels (0, 10,15and20 kg ha-1) of
sulphur fertilization on seed yield and the yield components. The results showed that head
diameter, 1000 achene weight and achene yield, all showed significant increase with each
increment of sulphur application.
2.2.1.2. Sulphur and achene-oil quality
Sulphur nutrition is associated with modifying the composition of seed in various
crops. Poonia (2003) found significant increase in seed protein and oil contents with
increasing S levels in sunflower. Maximum protein (18.30%) and oil (34.5%)
concentration was achieved with 50 kg ha-1 sulphur application, and statistically was at
par with (18.10 and 34.1%), when S @25 kg ha-1 was applied. This increase might be due
to fact that since protein content is the function of its N content, the significant
improvement in N content of seed due to application of sulphur brought significant
improvement in this parameter. Moreover, sulphur being an integral part of S containing
amino acids viz. cystein, cystine and methionine, also improved protein as well as oil
synthesis in seeds. The oil yield as a function of combined effect of nitrogen and sulphur
(N*S) showed an optimum level of N (107 kg ha-1) and S (49.5 kg ha-1) for getting an
optimum oil yield of 833.6 kg ha-1. With successive increase in sulphur levels, the protein
and oil contents in seed of sunflower, increases significantly. Bhagat et al. (2005)
recorded highest protein (21.42%) and oil (41.72%) contents in seed with the application
of 40 kg ha-1 so that maximum oil and protein yields were also associated with this level
of S, which was significantly superior over 0 and 20 kg S ha-1. This might be attributed to
more nitrogen content in seed and more sulphur uptake by the plants and increase in
sulphur contents in seed which enhance the oil synthesis. . Similar results were obtained
15
by Sreenamannarayana et al. (1998). As, the oil and protein yields are the function of
seed yield and their concentrations, maximum oil (5.18 q ha-1) and protein (2.63 q ha-1)
yields were reported with 40 kg ha-1 S application. Hassan et al. (2007) concluded that
sulphur application improved the oil contents of the autumn-planted sunflower from 38.1
to 45.1%.
Contrary to the response of oil contents to N (Ahmad et al.2007), sulphur had a
positive impact on oil contents of canola. The lowest oil contents (41.9%) were found in
those plots, where no sulphur was applied. Oil contents enhanced to 42.85 with the
application of 20 kg S ha-1 but further increase to 30 kg S ha-1 had no significant influence
on oil contents. Similarly, seed protein content also had a positive response to the
increasing S levels. Higher protein contents of 23.2% and 23.3% were recorded for the
plots that received 20 to 30 kg S ha-1, respectively. The lowest protein content of 22.4%
was noted in the plots that received no S. These results are in agreement with the earlier
findings of Wang et al. (1997) and Malhi and Leach(2000), who stated that applied S
increased protein content of canola.
Oleic acid content is essentially influenced by temperature during seed
development. Each one degree C increase in temperature leads to about 2 % increase in
oleic acid. A strong negative correlation exists between oleic and linoleic acid. A low
oleic phenotype would essentially be high linoleic one (Demurin et al., 2000)
Sulphur increases the oil percentage of the seed (Chaudhhry et al., 1992),
glucosinolate content, and erucic acid (Marschner, 1986) in rapeseed oil. The influence of
sulphur on fatty acid synthesis is often considered along with the nitrogen supply. Zhao et
al. (1997) reported a strong relationship between nitrogen supply and proportion of S in
seed. Sulphur application significantly improved the quality of sunflower oil in terms of
free fatty acids, lesser oleic and linoleic acids, and higher saturated fatty acids like stearic
and palmitic acids (Krishnamurthi and Mathan (1996). Manaf and Hasan (2006) listed
inconsistent differences for oleic and linoleic acid with different rates of Sulphur
application, while Misra et al. (2002) reported significant increase in oleic and linoleic
acid by the application of 0, 25 and 50 ppm sulphur in mustard (Brassica juncea L.).
2.3. INTERACTIVE EFFECTS OF NITROGEN AND SULPHUR
The effects of N fertilization on sunflower growth and its physiological behavior
has been reported by many authors around the globe, but less information on S effects is
16
available and particularly on interactive effects of both with respect to the physiological
attributes that are determinant of final biomass and yield. In a plant most of the reduced N
and S are used in protein formation. There is positive role of sulphate in regulating nitrate
reductase (Pal et al. 1976,and Friedrich and Schrader, 1978), while N role in the
regulation of sulphate assimilation (ATP-sulphurylase step) has been pointed out by
Smith (1975). The inter-relationships of the regulation of NO3- and SO4
2- assimilation
were an effective mechanism to meet the supplies of net protein synthesis (Reuveny et al.,
1980). Cereal plants indicate obvious reduction in taking up nitrate and ammonium when
deficient in sulphur (Clarkson et al. 1989).
The metabolic coupling between N and sulphur has been reported somewhere
else. Relative sulphur-rich seed protein decreases in crop raised with ample N but limited
sulphur supply, and vice versa. Growing legume plants with sufficient sulphur increases
sulphur-rich proteins, improving protein amino acid balance in the seed (Blagrove et al.,
1976; Randall et al., 1979; Sexton et al., 1998).
Sulphur deficiency deferred floret initiation and anthesis, but did not affect seed
maturity (Hocking et al., 1987). S and N deficiencies negatively affect growth and yield
traits (plant height, leaf area, number of seeds per plant and single seed weight), resulting
in reduced yield. Increase in N supply reduces seed oil concentration but different levels
of S do not affect it. It has been reported that N (90 mg kg-1soil) and sulphur 200 (mg kg-1
soil) affected main factors and interaction of seed yield and dry weight of leaves and stem
(Nabi et al., 1995). Significant interactive effect on plant height, head diameter, test
weight and seed yield was recorded when 120 kg N and 45 kg S ha-1 were applied in
sunflower crop (Sing, 2000). Sofi et al. (2004) revealed that chlorophyll and carotenoid
contents increased with increasing levels of both N and S fertilizers, with N being more
effective than sulphur. Seed yield, test weight, harvest index and protein contents all
increased with increasing levels of both fertilizers. On the other hand, oil contents
decreased with increasing levels of N and increased with increasing levels of sulphur.
2.4. NUTRIENT UPTAKE BY SUNFLOWER
Various authors have reported interactive impact of different plant nutrient/s
Application of nitrogen enhanced N and K levels in plant body and N and S in the seed,
lowered P in the seed and plant (Jackson (2000). Significant differences in N uptake at
anthesis and non-significant differences at other stages, respectively were observed by
Zubillaga et al. (2002). Higher levels of applied nitrogen improved soil N at flowering
17
and lead to accumulation of N in plant during grain development. A total of 45 kg N Mg-1
of grain was estimated. Blamey and Chapman (1981) and Andrade (1995) also reported
such values for sunflowers.
Nasreen & Haq (2003) reported that plants treated with 60-80 kg S ha-1 had the
highest N uptake at vegetative (177%), at reproductive (215%) and at mature stages
(117%) as compared with control (without Sulphur) while the uptake of N by leaves
increased from vegetative to reproductive stage and decreased at maturity. Less leaf
biomass and N concentration was the possible reason for this decrease. Similarly head,
stem and seed showed different trend in N uptake. It gradually increased up to maturity
and this may be ascribed to higher dry matter production in stem and head. With the
increase in the level of S (0 to 100 kg ha-1), total N uptake increased from 11.55 to 37.6,
50.01 to 183.6 and 102.31 to 236.66 kg ha-1 at vegetative stage, reproductive and
reproductive stages, respectively. Almost similar pattern of P uptake was observed as
obtained for nitrogen. By increasing the sulphur fertilization till 80 kg ha-1, P uptake
increased from 0.63 to 3.23, 3.46 to 20.79 and 9.81 to 35.04 kg ha-1 at vegetative,
reproductive and mature stages, respectively and then declined. K uptake by leaves
increased up to the reproductive stage and declined at maturity, demonstrating the
translocation of K to developing heads or seeds but, its uptake increased over time by the
stem, which was linked with increased stem dry matter. S absorption by leaves was more
at reproductive stage than that at vegetative and maturity stages. It has been stated that
increase in S levels improved the concentration, uptake and availability of N, P and S in
sunflower (Bhagat et al., 2005). Nitrogen contents in (straw+stalk) increased from 0.40%
to 0.63% and in seed from 3.03% to 3.41% in the treatments without S and 40 kg ha-1
sulphur rates.. Almost comparable results were reported by other authors
(Sreemannarayana et al., 1998; Mrinalini et al., 1998).
The incorporation and buildup of nutrients into callus cells depend not only upon
genotype, but more or less upon the presence of that element (Pajevic et al., 2004). The
results of field studies conducted by Pal (2004) revealed that the contents of N, P, and K
in seed and stalk were significantly affected by cultivars. Removal of N, P and K in
sunflower significantly depends on seed yield (Angelova and Christov, 2003).
2.5. PERFORMANCE OF DIVERSE SUNFLOWER HYBRIDS
Hybrids with different morphological, and particularly, physiological characters
are available under different macroclimatic conditions. There exists significant genetic
18
variation in sunflower cultivars for time of maturity and plant height. Early maturity with
early harvesting allowing timely sowing of subsequent crops has been a tool for
successful sunflower production in certain areas. Accumulation of more degree days and
photosynthetic light harvest for prolonged time has been a determinant of higher yield in
long season hybrids. Early planting rarely accelerate maturity and not a recommended
way for enhancing yields consistently. Moreover, early hybrids also grow and dry rapidly
than later hybrids, and that is more so in regions with smaller growing seasons.
Importance of maturity becomes more peculiar under late planting and in regions with
smaller growing seasons. The length of time taken from planting to physiological
maturity is commonly measured either in days or by accumulation of heat units that
would show variation among genotypes. Temperature is the main environmental
determinant of phenological development in sunflowers (Connor and Hall, 1997).
Medium stature cultivars are superior in producing high yield due to improved
reproductive development as compared to semi-dwarf varieties (Tunio et al., 1999).
However, medium stature cultivars, in general have been reported to require different
management practices as compared to semi-dwarf plant types for successful production.
Steer and Hocking (1987) reported that there were small differences in time taken from
sowing to maturity among short stature (early maturity) and taller (late maturity) hybrids.
Heavier seeds with more oil per plant were recorded in genotypes that showed higher
growth rate through anthesis with better seed development as against the genotype with
more number of smaller seeds. Zaffaroni and Schneiter (1991) reported that semi dwarf
and medium stature sunflower hybrids grown at different row arrangements had non-
significant differences in relative growth rate (RGR), net assimilation rate (NAR), crop
growth rate (CGR) and leaf area index (LAI). Villalobos et al. (1994) after growing four
sunflower hybrids at varying plant populations established that response to biomass, seed
number and yield to plant populations depended on hybrids. Variation in yield potential
of hybrids was attributed to changes in phenological development patterns and
partitioning of dry matter to important yield components (Lopez et al., 1999 a,b). Early
anthesis accounted for a considerable increase in sunflower yields related to genetic
improvement.
Yield increase in response to reduced competition in old and current hybrids was
0-84% and indicated differences among cultivars (Sadras et al., 2000). Yield of modern
hybrids was in range of 780 to 1460 g per plot and expression of yield was largely
independent of phenology in the cultivars in their experiments. Several other authors
19
reported contradictory findings indicating the importance of phenological development in
crop adaptation and yield formation (Passioura, 1996; Sadras and Trapani, 1999). Dosio
et al. (2000) reported that intercepted photosynthatically active radiation (PAR) during
seed filling influenced that weight of individual seeds in low and high oil-concentration
hybrids. Oil concentration was influenced only high-oil-concentration potential hybrids
with black hulls, but was not influenced in low-oil-concentration hybrids.
It has been reported by several authors that the agronomic, physiological and
qualitative characteristics of different hybrids groups vary in heights and maturity (Ready
et al., 2002 a, b and Ekin et al., 2005). Each group behaved independently for growth,
yield, nutrient uptake and dry matter accumulation. SF 100 (semi dwarf) hybrid exhibited
significantly higher achene protein content, while C-206 (tall) hybrid showed higher
achene oil concentration (Ahmad et al., 2001). Sunflower hybrid KBSH-44 showed
significantly higher yield and related growth attributes (plant height, leaf area, leaf area
index, stem diameter and dry matter accumulation) as compared to hybrid KBSH-I
(Reddy et al., 2002b).
Growth, development and yield of five sunflower hybrids was evaluated by
Mirallus et al. (1997) and reported that the S-H-222 with longer life cycle, showed
maximum LAI, LAD after flowering, total LAD, CGR and final TDM. Johnson and
Schneiter (1998) reported hybrids representing the greatest available diversity for
maturity and plant height. Some sunflower traits (test weight, head diameter, and plant
height) were influenced by inter-hybrid competition while characters (achene weight,
achene oil concentration, days to anthesis, and leaf number) remained unaffected. The
achene yield of different hybrids, respond differently for one-row and the two-row
arrangement, resulting in a significant interaction. Majid and Schneiter (1988) also
reported a reduced inter node length for hybrid SD. Several reports (Monoth et al., 2000;
Unagaro et al., 2000; Smiderele, 2001; Reddy et al., 2002; Saleem and Malik, 2004),
showed differential agronomic and productive potential of sunflower hybrids.
The yield, grain quality and oil quality of crops grown with ample soil moisture
and nutrient supply is determined to large extent by solar radiation and temperature.
Different studies describe the physiological basis for such factors affecting yield and oil
quality (Connor and Hall, 1997; Hall, 2004). Cumulative growing degree-days or heat
units for growth, development and maturity vary amongst different sunflower hybrids that
are adapted to range of environments. Cultivars and environmental optima also have
significant bearing on fatty acid composition (Connor and Sadras, 1992). Ahmad and
20
Hassan, (2000) reported that oil contents in sunflower hybrids maturing and harvested at
higher temperature (June) were comparable with those maturing and harvested in April
(Hassan, 2000). Qadir et al. (2006) reported that in autumn, Hysun-33 produced
significantly highest oil contents (49.65%), as compared to Award (44.66%) and there
were significant differences observed for fatty acid composition.
Different locations had also had significant bearing upon oil quality. Irujo and
Aguirrezabel (2007) reported that at low latitude locations, sunflower oil with high
nutritious value and oxidative stability at low latitude compensated for relatively low
yields, whereas high-linoleic acid oil production was compatible with high yield
potentials at higher latitudes. Differences between hybrids for oil and protein content and
their fatty acid profiles have also been documented elsewhere (Monoth et al., 2000;
Andrei et al., 2002). A negative correlation between the 1000-achene weight and oil
concentration was reported by Diepenbrock et al. (2001). Resultantly, the effects of
planting geometry on the 1000-achene weight may have some effects on oil
concentration. This different response to row orientation and row spacing may be due to
“dilution” effect associated with the higher 1000-achene implying that accumulation of
higher total weight per achene had a contradictory bearing on oil concentration.
2.6. ROW SPACING AND PLANT DENSITY
The utilization of light can be affected by row spacing (Flenet et al., 1996), water
and nutrients (Gubbles and Dwdio, 1988) and ultimately the growth and achene yield of
sunflower can be modified. The optimum achene yield might be obtained when intra- and
inter- row spacing is about the same at any given plant density (Metz et al., 1984). Effect
of plant density on achene yield depends on the cultivar (Blamey et al., 1997) and its
environment (Prunty, 1981). The achene yield increased to a maximum with increasing
plant density and remained constant at even higher plant densities under favorable
conditions (Wade and Foreman, 1988).
Optimum yields in sunflowers were recorded across a wide range of plant
densities (Villalobos et al., 1994; Andrade, 1995). Numerous factors as temperature, soil
fertility, water availability, and genotypes are responsible for optimization of plant
densities in sunflowers (Diepenbrock et al., 2001). Stear et al. (1986) observed that stem
and shoot dry weights remained more in plants at high than at low population densities
throughout the growing season. Dry matter and nitrogen accumulation rates after floret
initiation decreased in all organs in dense populations.
21
Wahba et al. (1990) indicated that decreasing planting density from 8 to 5 plants
m-2 approximately doubled the yield of seeds. Zaffaroni and Schneiter (1991) determined
the effect of different row arrangements and plant populations (35000, 50000 and 65000
plants ha-1) on yield components, and agronomic traits of a semi-dwarf and standard
height sunflower hybrid. The direct response of plant population was masked by the
negative effect of seeds per head and seed weight, resulting in a low coefficient of
correlation. Individual achene weight decreased at higher plant densities, but the amount
of oil per seed was little affected so that potential yields under irrigated environments
could be achieved by growing short-cycle cultivars at high plant density (Villalobos et al.,
1994). Days to 50% flowering and days to maturity were not influenced by varying plant
populations, while increasing population enhanced plant height and suppressed head
diameter significantly (Ahmad and Quresh, 2000).
Barros et al., (2004) concluded that both the number of seeds per head and the
mean seed weight decreased significantly with increasing plant population. An increasing
plant density significantly decreased the seeds per head and mean seed weight.
Nonetheless, the number of seeds per unit area only increased up to the medium plant
density (3.5 plants m-2). Leaf area duration increased at the highest density (4.6 plants m-
2) than lowest (1.7 plants m-2). Higher plant populations produced lighter seeds, thinner
stems, taller plants and more yield than lesser plant density (Beg et al., 2007).
Different reports described the influence of planting density on sunflower achene
oil content and yield. Oil yield per plant was decreased by increasing plant density, while
the oil %, seed dry weight was not affected by population (Stear et al., 1986).
Diepenbrock et al. (2001) stated that the lowest oil concentration (44%) was found at
wider row spacing (100 cm) as compared to narrow spacing (75 cm) where oil (45.6%)
was achieved. Opposite to this, Gubbles and Dedio (1990) observed non-significant effect
of row spacing on oil concentration. Diepenbrock et al. (2001) found negative correlation
between 1000-achene weight and oil concentration of achene. Consequently, the effects
of planting pattern on the 1000-achene weight may account for some of their effects on
oil concentration.
Inter-plant competition for water, nutrient, and light can be reduced with
narrowing row spacing. Decreasing row spacing increases radiation interception and dry
matter accumulation (Shibles and Weber, 1966) and reduces the threshold values of leaf
area index that is sufficient enough to intercept 95% of the incident radiation only due to
increase in the light extinction co-efficient (Flenet et al., 1996). Compact rows also
22
minimize the evaporative water loss from the ground surface (Yao and Shaw, 1985),
inhibit weed growth (Forcella et al., 1992; Nawaz et al., 2001) and improve uptake of
nutrients from the rhizosphere (Stickler, 1964). Narrow rows had a positive influence on
amount of intercepted radiation and grain yield. (Andrade et al., 2002). Highest
interception of radiation was at flowering was observed in long season hybrids in wide
rows so that there was no evident of positive grain yield response to narrow rows. Greater
interception of radiation in narrow rows was attributed to greater LAIs (Board and
Harvile (1992).
Wide row plantations intercepted less radiation than their narrow row
counterparts; likewise radiation interception by short season hybrid (Zenit) was lower
than its long-season counterparts (Calvino et al., 2004). Yield response to narrow rows
was significant only for short-season hybrid; there was no increase in yield of long season
hybrids. Yield improvements in narrow rows were associated with higher number of
grains m-2, while reduced grain weight was held responsible for yield reductions.
2.7. CANOPY DEVELOPMENT, LIGHT INTERCEPTION AND RADIATION
USE EFFICIENCY
Being integral entities in plant enzymatic structures and reserve proteins in grain,
both sulphur and nitrogen are identified as essential nutrients for plants (Tabe et al.,
2002). Extent of dry matter accumulation and its partitioning within the plant are
important determinants of crop yields (Werf, 1996). Rate and extent of dry matter
accumulation by the crop depends ability of the crop canopy to intercept incident photo
synthetically active radiation (IPAR) and the efficiency with which this radiation can be
converted into new biomass i.e. radiation use efficiency (Sinclair and Muchow, 1999).
Enough evidence is documented to establish that one or both of physiological
mechanisms for biomass production may be altered by genotype, temperature or water
availability (Calderini et al., 1999; Anderade et al., 1993; Jamieson et al., 1995).
Deficiency of nitrogen or phosphorus may affect both interception of incoming
photosynthetically active radiation and radiation use efficiency (Caviglia and Sadras,
2000; Rodriguez et al., 2000). Canopy architecture is primary determinant of the light
extinction coefficient (K), and hence is less influenced than LAI in crops grown under
nutritional deficiency (Hasegawa and Horrie, 1996).
23
Since an environmental stress can cause rapid change in the expansion of leaves
than the photosynthetic capacity of the crop (Fitter and Hay, 2002), the crop grown under
N and S deficiency exhibits a reduction in leaf area index and intercepted photo
synthetically active radiation. Net CO2 assimilation affects the utilization efficiency of
radiation (Loomis & Amthor, 1999) and this process (CO2 assimilation) depends upon
availability of N, because it increases the Rubisco content in leaves (Sinclair and Horie,
1989). An increased S supply also increases leaf photosynthesis (Terry, 1976). Therefore,
radiation use efficiency might also increase with increase in N and S supply, but in a
lower order than LAI and IPAR. The application of nitrogen significantly improved
interception of PAR (Khaliq, 2004) and radiation utilization efficiency of sunflower crop
sown in irrigated areas.
A directional and pre imputable resource is light (Schwinning and Weiner ;1998).
Weiner and Fishman (1994) suggested that plant height is very important in determining
radiation interception and, hence, the success of individuals primarily depends on plant
height in crowded crop stands. Fully intercepted available light required for a crop
however, may be optimized by row width and plant densities (Ball et al., 2000). With the
selection of hybrids of desired maturity, the duration of light interception by the crop may
also be managed (Purcell et al., 2002). Light interception (LI), leaf area index (LAI), and
light interception efficiency (LIE) vary greatly at different developmental stages (Board
and Harvile, 1992). Among these parameters rapid leaf area index and higher LAIs during
vegetative and early reproductive development were the leading features liable for better
light interception in contracted rows and were identified as selection criteria for cultivar-
genotype performance in narrow-row culture at late planting.
A plateau of sunflower yield was observed when 85% threshold of radiation
interception at flowering stage was achieved (Mercau et al., 2001). The crops may not be
able to achieve full interception of radiation due to many reasons e.g. very early sowing,
selection of hybrids of short growing cycle and/or short stature, defoliation, and reduction
in leaf expansion (Sadras et al., 2000), and other factors, as water or nutrient deficits at
vegetative stages (Alessi et al., 1997; Trapani and Hall., 1996; Sadras and Trapani, 1999).
Ferreira and Abreu (2001) reported that leaf number, canopy light extinction coefficient
and the radiation use efficiency did not vary in sunflower at the densities of 11.4 (D1) and
4 (D2) plants m-2 while crop dry matter production and solar radiation interception were
smaller in D2 than in D1 owing to greater leaf area index in D1 (Ferreira and Abreu, 2001).
24
Lower density (D2) resulted in an increase in leaf area and aboveground dry matter per
plant.
Accumulated intercepted radiation during grain filling period of crop significantly
influenced the biomass production and harvest index, and both of these depended on the
duration of grain filling and green leaf area (Vega and Hall, 2002). Bangge et al. (1997)
also concluded that dry matter accumulation was greatly affected by accumulated
intercepted radiation rather than by radiation use efficiency. Weight per seed and oil
concentration in sunflower could be badly affected as a result of decrease in intercepted
photosynthetically active radiation (PAR) for the period of seed filling (Aguirrezabal et
al., 2003). Schneiter and Miller (1981) also recorded that weight per seed was strongly
linked with intercepted photosynthetically active radiation from the closing stages of
flowering to maturity stage of the crop. (Schneiter and Miller, 1981).
2.8 OIL YIELD AND ITS COMPOSITION IN SUNFLOWER SEEDS
One advantage of the sunflower oil is its higher degree of oxidative stability than
oils low in oleic acid (Fullner et al., 1967), which is desirable for frying purposes,
refining and, storage. From the nutritional point of view, a diet rich in monounsaturated
fatty acids has been suggested to reduce cholesterol in blood plasma (Delpanque, 2000),
and thus decreasing the risk of heart disease(Grundy, 1986). In particular, the fatty acid
composition is known to differ between cultivars and with environmental conditions
(Connor and Sadras, 1992). Oleic acid content is essentially influenced by temperature
during seed development. Each one degree C increase in temperature leads to about 2 %
increase in oleic acid. A strong negative correlation exists between oleic and linoleic acid.
A low oleic phenotype would essentially be high linoleic one (Demurin et al.,2000)
Genotype and temperature during oil formation exert the major effect on the proportions
of oleic and linoleic acids, whereas the effect of N supply is small and depends on time of
N application (Steer and Sailor (1990). Negative influence of nitrogen on oleic acid was
reported Khaliq (2004) while linoleic acid and palmitic acid concentration increased
gradually with increasing levels of nitrogen. Munir et al (2007) studied the impact of
integrated crop manuring and nitrogen application on quality of spring planted sunflower.
Maximum protein content(16.75%) and linoleic acid in oil(49.72%) were recorded in the
treatment of 50-75-50 NPK kg ha-1and minimum protein contents(11.46%) and linoleic
acid (43.45%) were found in the treatments where no fertilizer was applied, while
25
opposite response(40.50% oleic and 47.71% linoleic acid) was seen ,where 100-75-50
NPK kg ha-1 was applied. These results are in line with those of Ghani et al;(2000),
Nangundappa et al;(2001). Field trials were conducted on oilseed rape by Momoh et
al;(2004) at the agronomy experimental site of Zhejiang University and the results
revealed that increasing levels of nitrogen application (225 kg ha-1 ) enhanced the
composition of palmitic and linolic acids by (9.0% and 5.5%) respectively and the
difference of other fatty acid contents among various N levels was non significant.
Present day sunflowers hybrids are identified as either oil type or confectionery
type. Oil type is characterized with small seeds, relatively high oil of variable fatty acid
composition, and is utilized as high-quality edible oil for human consumption, or for
biodiesel production (Arkansas Biofuel Enterprises, 2007; National Sunflower
Association, 2009). The confectionery type has large, striped hull seeds, and is used either
for confectionery or birdseed (National Sunflower Association, 2009).The saturated fatty
acid (FA) content of sunflower oil is considered moderate (130 g kg-1) with the principal
saturated FA being palmitic (16:0) and stearic (18:1) acids. However, a further reduction
to 60 to 80 g kg-1 saturated FA would increase consumer acceptance of sunflower oil
benefit the sunflower industry. (USDA, 1992).
The concentration of FA in various sunflower hybrids is important with respect to
its final uses and market price (Warner et al., 2003; Burton et al., 2004; National
Sunflower Association, 2009). In general, sunflower oil contains both saturated and
unsaturated FA, either mono or polyunsaturated. Unsaturated FA comprise approximately
900 g kg−1 of the oil and include oleic acid (18:1, or 18-carbon FA with one double bond)
and linoleic acid (18:2). Saturated FA such as palmitic acid (16:0) and stearic acid (18:0)
may constitute another 70 to 110 g kg−1 of the oil (Steer and Seiler, 1990; Friedt et al.,
1994; Pierson, 1994; Skoric et al., 2008). Other saturated FA of sunflower oil are minor
constituents and include arachidic (20:0), behenic (22:0), and lignoceric (24:0).
Consumption of oils with high concentration of unsaturated FA has been found to
have a positive effect on human health (Jing et al., 1997; Krajcovicova-Kudlackova et al.,
1997; Hu et al., 2001). Increased consumption of saturated FA leads to higher
concentrations of total and LDL cholesterol in humans, which in turn significantly
increases risks of heart attack and stroke, America's number one and number three killers
(American Heart Association, 2009). Hence, it is important to reveal agricultural factors
that may reduce or increase the concentration of TSFA (combined concentration of
palmitic, stearic, arachidic, behenic, and lignoceric) of sunflower. Studies by Vick et al.
26
(2004) have shown that environment plays a significant role in the relative proportion of
TSFA in sunflower grown in the northern plains. However, to date there are no reports on
the effects of agronomic or environmental factors that could be used to reduce the TSFA
of sunflower grown in the southeastern United States.
Furthermore, starting in the 1970s, breeders have been developing sunflower
cultivars and hybrids with high concentrations of monounsaturated FA and decreased
TSFA (Soldatov, 1976; Hardin, 1998; Kleingartner, 2002; Vick et al., 2003; Burton et al.,
2004; Vick et al., 2007; Skoric et al., 2008). Many selection and breeding efforts
throughout the world produced sunflower hybrids with increased monounsaturated FA
composition; however, some of these hybrids had reduced oil content relative to the
traditional sunflower cultivars and hybrids. Agricultural factors that may increase oil
content of sunflower are definitely of interest to producers, due to the fact that current
sunflower prices at crushing plants are determined based on oil content (National
Sunflower Association, 2009).
This review suggests that for realizing good harvest of sunflower hybrids, it is
needed that requirements for S nutrition be determined properly and more specifically
under different N application rates. Similarly the growth analysis of sunflower hybrids
belonging to different maturity groups under varying planting densities are to be
quantified in terms of intercepted radiation under local environments. This will help
optimize the development of packages of production practices that suit to different
growers.
27
CHAPTER-III
MATERIALS AND METHODS
3.1. SITE AND SOIL
The studies were conducted to examine the influence of sulphur and nitrogen
application on autumn planted sunflower, and response of sunflower hybrids of different
maturity periods to varying plant population. Both the experiments were conducted for
two consecutive years i.e. 2006 and 2007.The experimental site was agronomic research
farm, located at University of Agriculture Faisalabad. The investigational vicinity was
somewhat homogeneous, and hence, a combined soil fragment from 30 cm depth was
taken prior to initiating the research trial in fields during both the years. Experimental soil
was sandy loam. Physico-chemical characteristics of the soil are presented in Table 3.1.
Table 3.1. Pre-sowing physico-chemical soil analysis.
Determination Unit Value
2006 2007
A Physical Analysis
Sand % 66.6 64.5
Silt % 16.6 18.5
Clay % 16.8 17
Textural class Sandy loam
B Chemical Analysis
pH 7.8 8.0
EC dS m-1 1.32 1.40
Organic matter % 0.75 0.78
Total nitrogen % 0.045 0.047
Available phosphorus ppm 9.00 9.10
Available potassium ppm 140 145
Available sulphur ppm 9.00 9.10
28
3.1.1 Mechanical analysis:
Textural class of the soil was examined by Bouyoucos hydrometer method and the
international triangle was used to determine the soil textural class (Moodie et al., 1959).
3.1.2. Chemical analysis:
Analysis of the soil was carried out to record the chemical characteristics by following
standard procedures ( Homer and Pratt ,1961).
3.1.2.1. pH of saturated soil paste:
About 250 g of soil was saturated with distilled water. The paste was allowed to
stand for 1 h and pH was recorded by pH meter (Kent Eil 7015) with glass electrode
using buffer of 4 and 9 pH as standards (Method 21a).
3.1.2.2. Electrical conductivity of saturated soil extracts (ECe):
Saturated soil extract was taken by using vacuum pump (Method 3a) and its
electrical conductivity was measured using digital conductivity meter (Model Jenway
4070).
3.1.2.3. Organic matter:
One gram of soil sample was mixed with 10 ml 1 N potassium dichromate
solution and 20 ml concentrated H2SO4 (commercial). To this, 150 ml of distilled water
and 25 ml of 0.5 N FeSO4 solutions were added and the excess was titrated with 0.1 N
potassium permanganate solutions to pink end point (Moodie et al., 1959).
3.1.2.4 Total nitrogen:
Nitrogen was determined by Gunning and Hibbard’s method of H2SO4 digestion
and distillation of NH3 into 4% H3BO4 by macro Kjeldahl apparatus (Jackson, 1962).
3.1.2.5. Available phosphorus:
Phosphorus was determined by taking 5 g soil and 10 ml N NaHCO3 solution
adjusted at pH 8.5. Five milliliter of clear filtrate was taken in 25 ml volumetric flask and
potassium tartrate and sulphuric acid were added. Color intensity was measured on
spectrophotometer at 880 nm (Watanade and Olsen, 1965).
3.1.2.6 Available sulphur:
Available sulphur (SO4) was determined following the procedure of Beardsley and
Lancaster (1960).
29
3.2 METROLOGICAL DATA:
Climatic data as temperature, rainfall, humidity, and net radiation for the both
cropping seasons were collected from the metrological station located at University of
Agriculture, Faisalabad. Weather summary for the growing years i.e 2006-07 is exhibited
in Fig. 3.1.
a.
Tem
pera
ture
(C
)
Weeks of the month
b.
Tem
pera
ture
(C
)
Weeks of the month
R.H
. (%
), R
ainf
all (
mm
)
Fig. 3.1. Meteorological data during year (a) 2006 (b) 2007.
30
3.3. EXPERIMENTAL DETAILS
A set of two experiments was conducted to study the influence of varying levels
of sulphur and nitrogen nutrition on autumn planted hybrid sunflower in Experiment I,
and to quantify the developmental and agronomic traits of three sunflower hybrids when
sown in different planting densities under varying row spacing (Experiment II). Both the
studies were carried out for two years (2006 and 2007). The crop was planted on 15th.of
August during year 2006 and on 16th August during 2007. Experimental details for both
the studies are given as under.
3.3.1. Experiment 1: Response of agro-physiological traits of autumn planted sunflower grown under varying sulphur-nitrogen nutrition
In this experiment four levels of each sulphur and nitrogen fertilizers were tested
as per following treatments.
Treatments:
A. Sulphur (kg ha-1):
S1 = 0 (control)
S2 = 40
S3 = 80
S4 = 120
B. Nitrogen (kg ha-1):
N1 = control
N2 = 100
N3 = 140
N4 = 180
The experiment was laid out in randomized complete block design with factorial
arrangement and replicated thrice. Net plot size was 4.5 m x 7.0 m.
31
3.3.2 Experiment II: Radiation interception, radiation use efficiency and productivity of different genotypes of sunflower under varying row spacing/planting densities
In this experiment, three sunflower hybrids owing to different maturity groups
were grown at different row spacing. The treatments were as under:
A. Hybrids (main plots):
H1 = FH-331 (early maturing)
H2 = SF-187 (medium maturing)
H3 = Hysun-33 (late maturing)
B. Row spacing (sub plots):
S1= 45 cm apart rows (98765 plants ha-1)
S2= 60 cm apart rows (74074 plants ha-1)
S3 = 75 cm apart rows (59259 plants ha-1)
Three sunflower hybrids were selected on the basis of their maturity as noted in
the parenthesis with respective hybrids. SF-187 (medium maturing) hybrid is on US
origin, while Hysun-33 (late maturing) is Australian origin. FH-331 (early maturing) is
locally developed hybrid. Seeds of all the hybrids were purchased from local
representatives of the companies marketing these hybrids in the country. The experiment
was laid down in randomized complete block design with split plot arrangement and
replicated three times. Six rows of each hybrid were sown at row spacing of 45 cm
(98765 plants ha-1), 60 cm (74074 plants ha-1) and 75 cm (59259 plants ha-1) with a
uniform plant to plant distance of 22.5 cm in all row spacing.
3.3.3 CROP HUSBANDRY
For the preparation of seed bed, pre-soaking irrigation of 10 cm was applied. For
the achievement of excellent germination of sunflower seed, soil was cultivated 4 times
with tractor mounted cultivator each followed by planking. Dibbler was used for seed
placement of the seeds at proper depth in the field. At 4-leaf stage extra plants were
uprooted to maintain plant to plant distance of 22.5 cm.. In Experiment I, fertilizer dose
of P2O5 and K2O was applied at 100 and 60 kg ha-1, respectively in the form of di-
ammonium phosphate and murate of potash. Sulphur and nitrogen were applied in the
form of urea and gypsum (20% S) as per treatment. For experiment II, recommended dose
of NPK (140-100-60 kg ha-1) was applied. and plant population was maintained as per
32
treatments. In each case, half of N and all phosphorus, potash and sulphur were applied at
sowing, while remaining nitrogen was applied with 2nd irrigation. A uniform and
recommended production package for sunflower crop was applied for all the treatments.
3.4. DATA RECORDED
Data on various growth, developmental, agronomic and yield traits were recorded
in due course of studies to quantify the response of sunflower to different treatments. The
detailed procedures are given as under.
3.4.1. Agronomic and yield related traits:
Following agronomic and yield traits were observed during both the years.
1. Number of plants at maturity (m-2)
2. Plant height at maturity (cm)
3. Stem diameter (cm)
4. Head diameter (cm)
5. Number of achenes per head
6. 1000-achene weight (g)
7. Achene yield (kg ha-1)
8. Oil yield (kg ha-1)
9. Stover yield (kg ha-1)
10. Harvest index (%)
The procedures adopted for recording data on various agronomic and yield
related parameters are described as under:
a. Number of plants per plot at maturity:
Total numbers of plants was counted at harvest in each plot and are reported m-2
basis.
b. Plant height (cm):
Ten randomly selected plants were selected from each plot and their height was
measured with tape was averaged to represent plant height.
c. Stem diameter (cm):
At final harvesting, vernier caliper was used to determine stem diameter of ten
randomly selected plants at base, middle and top of each stem and then was averaged to
compute stem diameter in cm.
33
d. Head diameter (cm):
Diameter of 10 randomly selected heads were measured in cm with the help of a
measuring tape and then averaged.
e. Number of achenes per head:
After manual threshing, the heads of 10 randomly chosen plants were separated
and accounted for total achenes in these heads.
f. 1000-achene weight (g):
From the seed lot of every plot five samples, each of 1000-achenes were randomly
selected and then recorded their weight and mean 1000-achene weight was computed.
g. Achene yield (kg ha-1):
Central two rows from each experimental unit were harvested at physiological
maturity and the heads were separated from stalks. Then achene yield was recorded after
sun-drying and then with manual threshing of the crop. The random achene samples were
taken from each plot to determine the Achene-moisture contents were recorded with a
moisture meter and then 10% moisture content was adjusted for presentation of final
achene yield in kg ha-1.
h. Oil yield (kg ha-1):
Oil content (%) determined for each experimental unit was multiplied with achene yield
of respective plot to compute the oil yield on ha basis.
i. Stalk yield (kg ha-1):
Two central rows leaving the border from both sides were selected and then weighed all the stalks for recording of the stalk yield.
j. Harvest index (%)
Harvest index was computed as the ratio of achene yield to biological yield and
calculated as follows.
Harvest index (%) = (Achene yield/biological yield) x 100
3.4.2. GROWTH AND DEVELOPMENT:
Data were recorded to compute the following parameters.
1. Leaf area index (LAI)
2. Leaf area duration (days)
3. Crop growth rate (g m-2 day-1)
4. Mean net assimilation rate (g m-2 day-1)
34
5. Light interception (MJm-2)
6. Radiation use efficiency (g MJ-1)
3.4.2.1. Sampling:
Plant sampling was done fortnightly starting from 30 days after sowing and total five
harvests were made. After leaving appropriate borders, five plants representing each plot
were clipped from ground surface, and leaves, stem and head (when appeared) were
separated and their fresh weights recorded. After this, samples were oven dried to a
constant dry weight at 75 °C. The procedure for computing various attributes are
described below.
3.4.2.2. Leaf area index (LAI):
From above sampling (Section 3.4.2.1) leaves were separated, fresh weight
recorded at each sampling and a sub-sample of 20 g was used to measure leaf area by a
leaf area meter (DT Area Meter, model MK2). Total leaf area was computed after making
calculations of total leaf dry weight/s. Leaf area index (LAI) was calculated by using the
formula given by Watson (1947).
LAI = Leaf area/land area 3.4.2.3. Leaf area duration (days):
LAD (leaf area duration) was measured by using the formulae suggested by Hunt
(1978) as under:
LAD = (LAI1 + LAI2) x (t2-t1)/2, where, LAI1 and LAI2 are leaf area indices at
times t2 and t1, respectively.
3.4.2.4. Crop growth rate (g m-2 day-1):
Total dry weight of periodic samples was used to estimate crop growth rate as
proposed by Hunt (1978).
CGR = (W2-W1)/(t2-t1), where W1 and W1 are total dry weight per unit land area (g m-2) at time t1 and t2,respectively.
3.4.2.5. Net assimilation rate (g m-2 day-1):
Net assimilation rate was determined by using the formula given by Hunt (1978).
NAR = TDM/ LAD where TDM is total dry matter, and LAD is seasonal leaf area duration.
35
3.4.2.6. Light interception (MJm-2):
The fraction of radiation intercepted (Fi) by the green leaf area of the crop was
calculated for each plot using the exponential attenuation equation as suggested by
Monteith and Elston (1983).
Fi = 1-exp (-K x LAI) MJ m-2
where K is an extinction coefficient for total solar radiation. The K value of 0.75 was
used for sunflower (Lemeur, 1973). Values of Fi were multiplied with daily incident PAR
(Si) during the season to determine the amount of intercepted PAR (Sa).
Sa = Fi x Si Mj m-2
The amount of total PAR intercepted by the crop was calculated by multiplying Fi with
0.5 PAR of incident radiation (Szeiez, 1974).
3.4.2.7. Radiation use efficiency (g MJ-1):
Radiation use efficiency for TDM (RUE TDM) and grain yield (RUEGY) were
calculated as the ratio of total biomass and grain yield to cumulative intercepted PAR
(∑Sa).
RUETDM = TDM/∑Sa gMJ-1
RUEGY = Grain Yield/∑Sa gMJ-1
3.4.3. Achene oil quality traits:
Chemical analyses of achenes were carried out for determining the following
quality parameters.
1. Oil content (%)
2. Protein content (%)
3. Fatty acid profile
3.4.3.1 Achene oil content (%)
Achene oil content was determined by Soxhlet Fat Extraction method (AOAC,
1990).
3.4.3.2. Achene protein content (%):
Nitrogen in achenes was determined according to Kjeldahl method (Bremner,
1964) and then protein percentage was worked out as under:
Crude protein percentage=percent nitrogen multiplied by 6.25
3.4.3.3. Achene fatty acid profile (%):
Fatty acids were identified by Shamadzo Gas Liquid Chromatograph(GLC).
36
3.4.4 Nutrient uptake pattern (kg ha-1):
Leaf, stem and head at physiological maturity were analyzed chemically to
determine N, P K and S content for computing nutrient uptake by the crop under varying
growing conditions.
1. Nitrogen uptake in plant (kg ha-1)
2. Phosphorus uptake in plant (kg ha-1)
3. Potash uptake in plant (kg ha-1)
4. Sulphur uptake in plant (kg ha-1)
3.4.4.1 Sample preparation:
Oven dried plant samples of leave; stem and head were ground with an electric
grinder and then stored in clean dry plastic bags for further processing. The procedures
adopted for determination of the nutrients are summarized as under.
3.4.4.2. Nitrogen uptake (kg ha-1):
The nitrogen concentration (%) in leaves, stem and head were recorded separately by
micro Kjeldahl method (AOAC, 1990). The nitrogen uptake was then, calculated by
multiplying its concentration with dry matter of each of the leave, stem and head and then
total nitrogen uptake (kg ha-1) was computed.
3.4.4.3. Phosphorus uptake (kg ha-1):
Spectrophotometer was used to record the phosphorus concentration. The standard
curve was formed to determine phosphorus concentration (%) of each fraction of the plant
and then it was converted into plant uptake by multiplying it with dry weight of each part
(leave, stem and head). Finally, total phosphorus uptake (kg ha-1) was computed from
these parts.
3.4.4.4. Potassium uptake (kg ha-1):
Potassium was determined by flame photometer (Janway PEP-7).The
concentration of every plant part was multiplied with dry weight of respective fraction to
determine potassium uptake (kg ha-1). By adding uptake from all the three parts (leave,
head and stem), total potassium uptake was calculated.
3.4.4.5. Determination of sulphur uptake (kg ha-1):
A common procedure followed wet ashing (diacid digestion) of the plant parts
was practiced and the sulphate content in the digested material was determined by barium
sulphate turbidimetric method.
37
3.5. STATISTICAL ANALYSIS:
Data collected were statistically analyzed by using the Fisher’s analysis of
variance technique (Steel et al., 1997) and LSD test at 5% probability was used to
compare the difference/s among treatment’s means. Regression analysis was done to
estimate the existence of relationship between various traits and to quantify the same.
38
CHAPTER-IV
RESULTS AND DISCUSSION
4.1. Experiment 1: Response of agro physiological traits of autumn planted
sunflower (Helianthus annuus L.) grown under varying sulphur-nitrogen nutrition.
4.1.1. Agronomic and yield related traits
4.1.1.1. Number of plants m-2
Plant population per unit area provides basis for yield comparisons under variable
management systems. Number of plants at the time of harvest (Table 4.1) indicated that
different levels of sulphur and nitrogen fertilization did not alter plant population at
harvest during both years of experimentation. On an average plant population ranged
from 5.80 to 5.84 plants m-2.
Different combinations of sulphur and nitrogen fertilizers also showed non
significant influence of plant population at harvest (Table 4.1).
Uniform plant population at harvest under all treatment combinations may be
attributed to an even germination that is characteristic of present-day sunflower hybrids.
These findings are in confirmatory to the results of Saleem and Malik (2004) and Iqbal
(2008) who reported that fertilizer application did not influence final plant population of
sunflower. Uniform plant population at harvest under all treatment combinations may be
attributed to an even germination that is characteristic of present-day sunflower hybrids.
4.1.1.2 Plant height at maturity (cm)
Data regarding plant height as influenced by various treatments at maturity are
presented in Table 4.2.Sulphur application did not influence plant height of sunflower
significantly (P≤0.05) at maturity during both the years in these studies (Table 4.2).
However, there was an increasing trend with addition of sulphur over control. On an
average, plant height was 153.08 cm in plots without S as compared with 158.92 cm tall
plants recorded with 120 kg ha-1 S. Budhar et al. (2003) also reported non-significant
influence of sulphur application on plant height of sunflower, while Reddy and Singh
(1996) and Sing et al. (2000) stated that increasing levels of sulphur significantly
increased the plant height in sunflower.
39
Table 4.1. Influence of sulphur and nitrogen nutrition on plant population (m-2)
of sunflower.
Treatments 2006 2007 Mean
Sulphur levels (S)
S1= Control 5.87 5.88 5.88
S2= 40 kg ha-1 5.83 5.86 5.85
S3= 80 kg ha-1 5.85 5.85 5.85
S4= 120 kg ha-1 5.88 5.84 5.86
LSD at 5% NS NS
Nitrogen levels (N)
N1= Control 5.88 5.86 5.87
N 2= 100 kg ha-1 5.86 5.83 5.85
N 3= 140 kg ha-1 5.85 5.89 5.87
N 4= 180 kg ha-1 5.85 5.85 5.85
LSD at 5% NS NS
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
40
Table 4.2. Influence of sulphur and nitrogen nutrition on plant height (cm) of
Sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 157.55 151.08 153.08
S2= 40 159.94 154.72 157.33
S3= 80 162.93 155.62 159.28
S4= 120 161.92 155.91 158.92
LSD at 5% NS NS
Nitrogen (kg ha-1)
N1= Control 129.50 c 128.07 d 128.79
N 2= 100 161.33 b 153.44 c 157.39
N 3= 140 173.00 a 163.62 b 168.31
N 4= 180 178.00 a 172.19 a 175.10
LSD at 5% 5.24 7.04
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
41
Increasing levels of nitrogen enhanced plant height significantly (P≤0.05) over
control during both the years (Table 4.2). On an average, application of 100 kg ha-1 N
increased plant height by 22% while the increase was 31% for 140 kg ha-1 N over control.
Plant height did not increase further to significant extent with additional N application
during 2006 but increased significantly during 2007. Malik et al. (2004) and Ozer et al.
(2004) also observed increase in plant height with higher N doses, while Herdem (1999)
and Killi (2004) indicated non-significant impact of N application on plant height of
sunflower. Nitrogen plays a significant role in vegetative growth and development of
sunflower plant, and the positive response of plant height to N application has been
reported by Poonia (2002), Arif et al. (2003) and Akhtar (2004).
A non-significant interaction between sulphur and nitrogen fertilization was
observed during both the years, which showed that positive response of plant height to
nitrogen nutrition was not dependent on sulphur application.
4.1.1.3 Stem diameter (cm)
Stem diameter increased significantly with sulphur application only at medium
(80 kg ha-1) level during both the years of experimentation (Table 4.3). Response to S
application at low level (40 kg ha-1) was non-significant. Similarly stem diameter also
could not increase beyond medium S application level during both the years. On an
average, S application increased stem diameter by 6-8 percent over control.
Nitrogen application significantly increased stem diameter of sunflower (Table
4.3). On an average 28, 38 and 37 percent increase in stem diameter was recorded with
the application of N at 100, 140 and 180 kg ha-1, respectively. In fact, stem diameter did
not increase significantly (P≤0.05) beyond 140 kg ha-1 N during both years.
Different combinations of S and N fertilizer had a significant (P≤0.05) influence
on stem diameter of sunflower only during 2007 (Table 4.3). The thickest stems were
recorded with the application of ≥80 kg ha-1 S and ≥140 kg ha-1 N. The increase in stem
thickness with the increasing levels of nitrogen was also reported by Akhtar (2004) and
Khaliq (2004) who noted the maximum stem diameter with 150 and 200 kg ha-1 nitrogen
application, respectively. Iqbal (2008) also reported increase in stem girth as a
consequence of nitrogen application.
42
Table 4.3. Influence of sulphur and nitrogen nutrition on stem diameter (cm) of
sunflower
Treatments 2006 2007 Mean Sulphur (kg ha-1)
S1= Control 1.69 b 1.65 b 1.67
S2= 40 1.72 b 1.69 b 1.70
S3= 80 1.79 a 1.75 a 1.77
S4= 120 1.82 a 1.78 a 1.80
LSD at 5% 0.05 0.02
Nitrogen (kg ha-1)
N1= Control 1.40 c 1.37 c 1.38
N 2= 100 1.78 b 1.75 b 1.76
N 3= 140 1.92 a 1.89 a 1.90
N 4= 180 1.91 a 1.88 a 1.89
LSD at 5% 0.05 0.02
Interaction (S x N) NS
S1N1 1.35 1.32 i 1.34
S1N2 1.70 1.66 g 1.68
S1N3 1.87 1.83 cde 1.85
S1N4 1.83 1.80 def 1.82
S2N1 1.38 1.35 hi 1.37
S2N2 1.75 1.72 fg 1.77
S2N3 1.88 1.85 bcde 1.87
S2N4 1.87 1.84 bcde 1.86
S3N1 1.47 1.43 h 1.45
S3N2 1.78 1.75 efg 1.77
S3N3 1.95 1.92 abc 1.94
S3N4 1.94 1.91 abc 1.93
S4N1 1.41 1.37 hi 1.39
S4N2 1.89 1.86 abcd 1.88
S4N3 1.97 1.94 ab 1.96
S4N4 1.99 1.96 a 1.98
LSD at 5% NS 0.09
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
43
4.1.1.4 Head diameter (cm)
Among different components, head diameter is of prime importance for yield
determination. Production potential of sunflower crop is determined by its head size.
Volume of the sunflower head contributes considerable share in final achene yield as it
influences both the number and weight of achenes.
Sulphur application significantly (P≤0.05) influenced the head diameter during
both the years (Table 4.4). During both the years head diameters increased initially with
sulphur application up to 80 kg ha-1 S but exhibited a declining trend with further increase
in S levels. On an average, head diameter increased by 6, 13 and 10 percent over control
with application of 40, 80 and 120 kg ha-1 sulphur, respectively.
Larger heads harvested with S application were associated with more number of
grains thus giving more yield (Hassan et al., 2007). In contrary, less number of grains
developed on smaller heads would not have faced any competition for assimilates thus
produced heavier individual grain weight. Singh (2000), Bhaghat et al. (2005) and Hassan
et al. (2007) also reported increasing trend of sunflower head diameters with increasing
sulphur fertilization.
Nitrogen application also increased head diameter of sunflower in these studies
during both the years (Table 4.4). However, the response was non significant beyond 140
kg ha-1 N during both the years. Application of 100, 140 and 180 kg ha-1 N recorded 51,
62 and 63 percent increase in head diameter, respectively over control during both the
years. On an average head diameter ranged from 10.98 cm to 17.91 cm. comparatively
smaller heads were produced during 2007.
Interactive effect of different combinations of sulphur and nitrogen nutrition was
significant only during 2007. Highest head diameter (18.73 cm) was produced with the
combination of sulphur and nitrogen at the rate of 80 kg ha-1and 140 kg ha-1 respectively.
Head diameters produced with the application of sulphur and nitrogen at 80 kg ha-1 each
were statistically at par with the former combination. The crop grown without sulphur and
nitrogen nutrition failed to achieve remarkable size of head and that was the minimum
size of head (9.34 cm). Overall, head diameter was in the range 9.36 cm to 18.73 cm.
There was a optimistic association between number of achene per head and head diameter
(cm) of the sunflower crop (Fig 4.1) and the common regression accounted for 95%
(95.34-94.83) of the variation in number of achenes per head owing to head diameter.
44
Table: 4.4. Influence of sulphur and nitrogen nutrition on head diameter (cm) of
sunflower hybrid.
Treatments 2006 2007 mean
Sulphur (kg ha-1)
S1= Control 14.68 c 14.78 b 14.73
S2= 40 15.94 b 15.31 b 15.63
S3= 80 16.92 a 16.32 a 16.62
S4= 120 16.46 ab 16.08 a 16.27
LSD at 5% 0.56 0.54
Nitrogen (kg ha-1)
N1= Control 11.25 c 10.71 c 10,98
N 2= 100 16.75 b 16.32 b 16.54
N 3= 140 17.94 a 17.70 a 17.82
N 4= 180 18.05 a 17.76 a 17.91
LSD at 5% 0.56 0.54
Interaction (S x N) NS
S1N1 9.50 9.43 i 9.47
S1N2 15.61 15.25 f 15.43
S1N3 16.79 17.12 cde 16.96
S1N4 16.82 17.34 cd 17.08
S2N1 11.00 9.97 hi 10.49
S2N2 16.57 16.10 ef 16.34
S2N3 18.00 17.29 cd 17.65
S2N4 18.18 17.87 abc 18.03
S3N1 12.00 10.60 h 11.30
S3N2 17.83 17.45 bcd 17.64
S3N3 18.83 18.73 a 18.78
S3N4 19.00 18.50 ab 18.75
S4N1 12.51 12.83 g 12.67
S4N2 16.99 16.48 de 16.74
S4N3 18.13 17.68 abc 17.91
S4N4 18.21 17.33 cd 17.77
LSD at 5% NS 1.08
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
45
4.1.1.5. Number of achenes per head
Number of achenes per head has a direct bearing on final achene yield of
sunflower. Data (Table 4.5) showed that sulphur fertilization during 2006 did not
influence number of achenes per head. However, during 2007, S application increased the
number of achenes by 3% over control and the difference between lower S levels being
non-significant over control. Budhar et al. (2003) observed significant influence of
sulphur application on number of achenes in sunflower. The results of Bhaghat et al.
(2005) also supported the findings of present work. Larger heads harvested with S
application were associated with more number of grains thus giving more yield (Hassan
et al., 2007). In contrary, less number of grains developed on smaller heads would not
have faced any competition for assimilates thus produced heavier individual grain weight.
Data (Table 4.5) exhibited that number of achenes per head was positively
influenced by nitrogen application during both the years. During both the years,
application of 140 and 180 kg ha-1 N recorded highest and similar (P≤0.05) number of
achenes per head. On an average, N fertilization @at 100, 140 and 180 kg ha-1, increased
number of achenes by 20, 27 and 28 percent over control, respectively. Crop grown
without N developed very low number of achenes per head (615).
Different combinations of S and N did not vary significantly (P≤0.05) for number
of achenes per head during both years of experimentation in present studies. (Table 4.5).
Quantity of achenes per head is also optimistically linked with head size and
ultimately contributing towards final grain yield. Privileged grain yields designed for
greater N treatments are connected by means of higher grain number (Zubillaga et al.,
2002). There was an optimistic association between number of achenes per head and head
diameter of the sunflower crop (Fig 4.2) and the common regression accounted for 95%
(95.34-94.83) of the variation in number of achenes per head owing to head diameter.
Number of achenes per head was also positive associated with oil yield of sunflower (Fig.
4.3), and regression accounted for 86% (90-82) of the variation in oil yield of sunflower
owing to difference/s in number of achenes produced under various treatments in these
studies.
46
N
umbe
r of
ach
ene
per
head
y = 25.137x + 362.61
R2 = 0.9534
0
100
200
300
400
500
600
700
800
900
0 5 10 15 20
y = 21.425x + 362.41
R2 = 0.9483
0
100
200
300
400
500
600
700
800
900
0 5 10 15 20
Head diameter
Head diameter (cm)
Fig. 4.1. Relationship between number of achene per head and head diameter (cm) a) 2006, b) 2007
a
(b)
47
A
chen
e yi
eld(
kg h
a -1
)
y = 224.08x - 1279.9
R2 = 0.9223
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20
y = 229.25x - 1385.3
R2 = 0.9232
500
1000
1500
2000
2500
3000
3500
5 10 15 20
Head diameter
Head diameter (cm)
Fig. 4.2. Relationship between achene yield and head diameter (cm) a) 2006, b) 2007
(a)
(b)
48
Table 4.5. Influence of sulphur and nitrogen nutrition on number of achenes
head-1 of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 752 685 b 718
S2= 40 767 695 ab 731
S3= 80 772 701 ab 737
S4= 120 769 708 a 739
LSD at 5% NS 17.95
Nitrogen (kg ha-1)
N1= Control 640 c 590 c 615
N 2= 100 774 b 697 b 736
N 3= 140 818 a 748 a 783
N 4= 180 827 a 753 a 790
LSD at 5% 30.25 17.95
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
49
4.1.1.6. 1000 achene weight (g) Weight of individual achenes expresses the magnitude of achene development is
one of the most important determinants of seed yield and seed quality. Application of
sulphur significantly (P≤0.05) influenced 1000-achene weight of sunflower during both
the years (Table 4.6). Heaviest 1000-achenes (53.94 g) were produced with sulphur
application at 80 kg ha-1, which was 20.48% more than that (44.77 g) without sulphur
fertilization. Further enhancement in sulphur dose up to 120 kg ha-1 resulted in non-
significant (P≤0.05) increase in 1000-achene weight. On an average, 1000-achene weight
increased by 10, 21 and 16 percent over control with the application of 40, 80 and 120 kg
ha-1 S, respectively. Several authors (Singh et al., 2000; Poonia, 2000; Nasreen and Haq,
2002; Khan et al., 2003; Bhagat et al., 2005; Hassan et al., 2007) have reported
encouraging response of achene weight to sulphur application in sunflowers.
Nitrogen application also had a constructive behavior for 1000-achene weight
during both the years (Table 4.6). During 2006, maximum 1000-achene weight (55.89 g)
was recorded with application of 180 kg ha-1 nitrogen which was 48.52% higher than
control (no nitrogen). Nitrogen at 140 kg ha-1 exhibited similar achene weight as former
treatment. Similar trend was observed during 2007. On an average, application of 100,
140 and 180 kg ha-1 N increased 1000-achene weight by 29, 47 and 50 percent,
respectively over control. Several other authors (Ahmad et al., 2005; Ozer et al., 2004;
Poonia, 2000) observed a progressive and reliable raise in achene weight with addition in
N dose up to 160 kg ha-1.
Different combinations of sulphur and nitrogen exhibited significantly different
achene weight only during 2007 (Table 4.6) Maximum (60.53 g) 1000-achene weight was
recorded for 140 kg ha-1 nitrogen and 80 kg ha-1 sulphur. This treatment was statistically
at par with 1000-achene weights of 60.02 and 57.60 g recorded with application of
sulphur and nitrogen application at 80, 40 and 180 kg ha-1, respectively. The significant
interactive effect of sulphur and nitrogen nutrition on test weight of sunflower was also
reported by Sing (2000) and Sofi et al., (2004). 1000-achene weight was positively
associated with oil yield of sunflower (Fig. 4.4), and regression accounted for 93% (90-
96) of the variation in oil yield of sunflower owing to difference/s in achene weight
recorded under various treatments in these studies.
50
Table 4.6. Influence of sulphur and nitrogen nutrition on 1000-achene weight (g)
of sunflower.
Treatments 2006 2007 mean Sulphur (kg ha-1) S1= Control 44.77c 42.55 c 43.66 S2= 40 48.44 b 47.55 b 48 S3= 80 53.94 a 51.88 a 52.91 S4= 120 52.26 a 48.95 b 50.61
LSD at 5% 2.15 1.98
Nitrogen (kg ha-1) N1= Control 37.63 c 36.43 c 37.03
N 2= 100 49.54 b 46.15 b 47.85
N 3= 140 55.37 a 53.47 a 54.42
N 4= 180 55.89 a 54.88 a 55.39
LSD at 5% 2.15 1.98
Interaction (S x N) NS
S1N1 32.07 30.75 i 31.41
S1N2 43.40 42.40 g 42.90
S1N3 50.44 47.47 ef 48.96
S1N4 53.17 49.57 de 51.37
S2N1 37.97 37.23 h 37.60
S2N2 47.92 43.97 fg 45.95
S2N3 52.71 51.40 cde 52.06
S2N4 55.17 57.60 ab 56.39
S3N1 40.93 37.73 h 39.33
S3N2 54.02 49.23 de 51.63
S3N3 60.11 60.53 a 60.32
S3N4 60.71 60.02 a 60.36
S4N1 39.53 40.00 gh 39.77
S4N2 52.80 49.00 de 50.90
S4N3 58.22 54.47 bc 56.35
S4N4 58.51 52.33 cd 55.42
LSD at 5% NS 3.97 Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
51
4.1.1.7. Stover yield (kg ha-1) Increasing levels of sulphur application enhanced the stover yield (Table 4.7)
during both the years that could reach level of significance (P≤0.05) only during 2007.
Sulphur application at 40 kg ha-1 increased stover yield by only 3 % over control that was
13% with application of 80 kg ha-1 S. A further increase in S level did not enhance stover
yield significantly over the former treatment. Poonia et al. (2000) and Khan et al. (2002)
have also reported improvement in stover yield of sunflower with increase in sulphur
application rates.
Application of nitrogen significantly improved stover yield (Table 4.7) during
both the years of experimentation. Highest stover yield (7981-8358 kg ha-1) was recorded
with the application of 180 kg ha-1 N during both years. On an average, application of
100, 140 and 180 kg ha-1 enhanced stover yield by 47, 64 and 87 percent, respectively
over control. Different combinations of sulphur and nitrogen did not influence stover
yield significantly (P≤0.05) during both the years (Table 4.7) depicting an independent
response of both the nutrients in terms of vegetative growth.
4.1.1.8 Achene yield (kg ha-1)
Final achene yield is the function of combined effect of all the yield components
under the influence of particular set of environmental conditions. Application of sulphur
enhanced achene yield significantly (P≤0.05) during both years of experimentation (Table
4.8). During 2006, maximum achene yield (2620 kg ha-1) was recorded with application
of 80 kg ha-1 S and declined thereafter. Although the trend was same during 2007 but the
decline was non-significant (P≤0.05). On average, achene yield increases of 25, 39 and 32
percent were observed with application of 40, 80 and 120 kg ha-1 S, respectively over
control. Doubling sulphur application over 40 kg ha-1 enhanced achene yield by 12% but
declined by 5% when S level was doubled further. Lega and Giri (1999), Sarkar et al.
(1999) and Hitsuda et al. (2005) also reported positive impact of sulphur fertilization on
achene yield of sunflower.
Nitrogen application also enhanced achene yield significantly (P≤0.05) over
control and a yield plateau was achieved with application of 140 kg ha-1 during both the
years (Table 4.8). Application of 100 kg ha-1 enhanced achene yield by 88% over control
that was 126% when N application was increased by 40 kg ha-1. Achene yield was
increased by 134% over control with application of 180 kg ha-1 N (Table 4.8).
52
Table 4.7. Influence of sulphur and nitrogen nutrition on stover yield (kg ha-1) of
sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 6539 5876 b 6207
S2= 40 6665 6073 b 6369
S3= 80 7000 6631 a 6816
S4= 120 6789 6598 a 6694
LSD at 5% NS 408
Nitrogen (kg ha-1)
N1= Control 4585 d 4128 a 4357
N 2= 100 6651 c 6175 c 6413
N 3= 140 7400 b 6893 b 7147
N 4= 180 8358 a 7981 a 8170
LSD at 5% 388 408
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
53
Table 4.8. Influence of sulphur and nitrogen nutrition on achene yield (kg ha-1)
of sunflower.
Treatments 2006 2007 mean
Sulphur (kg ha-1)
S1= Control 1804 d 1833 c 1819
S2= 40 2322 c 2217 b 2270
S3= 80 2620 a 2425 a 2523
S4= 120 2474 b 2311 ab 2393
LSD at 5% 96.43 119.46
Nitrogen (kg ha-1)
N1= Control 1320 c 1087 c 1204
N 2= 100 2321 b 2202 b 2262
N 3= 140 2750 a 2696 a 2723
N 4= 180 2830 a 2800 a 2815
LSD at 5% 96.43 119.46
Interaction (S x N)
S1N1 838 i 767 j 803
S1N2 1683 j 1732 h 1708
S1N3 2133 f 2250 fg 2192
S1N4 2517 e 2583 de 2550
S2N1 1300 h 1133 i 1217
S2N2 2288 f 2117 g 2203
S2N3 2800 cd 2700 cde 2750
S2N4 2900 bc 2917 abc 2909
S3N1 1580 g 1250 i 1415
S3N2 2667 de 2483 ef 2575
S3N3 3167 a 3000 a 3084
S3N4 3069 ab 2967 ab 3018
S4N1 1517 g 1200 i 1359
S4N2 2647 de 2477 ef 2562
S4N3 2900 bc 2833 abc 2867
S4N4 2833 cd 2733 bcd 2783
LSD at 5% 192.87 239 Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
54
Zubillaga et al. (2002) recorded maximum achene yield with application of 150
kg ha-1 nitrogen while Arif et al. (2003) and Ozer et al. (2004) also recorded substantial
increase in achene yield with N application. Vegetative and generative growth of plant.
reduces during N deficiency and premature senescence also occurs, consequently
decreasing yield (Narwal and Malik, 1985; Khokani et al., 1993; Legha and Giri, 1999
and Tomar et al., 1999).
Increase in achene yield can be attributed to improvement in light interception
(Table 4.14 ) and improved leaf area indices (Table4.10) resulting in better crop growth
rates (Table 4.12 ) recorded with higher doses of nitrogen. Increase in nitrogen
availability resulted in higher achene yield was closely related to the improvement in
yield components such as head diameter (Tomer (1997), Sadiq et al (2000), number of
achenes/head (Zubillaga et al.2002) and 1000 seed weight (Hocking et al.(1987), Mahal
et al.(1998), Georgio et al(1990), and Killi (2004).
Interactive effect of different combinations of S and N was significant (P≤0.05) in
enhancing achene yield of sunflower (Table 4.8). During both the years, highest achene
yield (3084-3018 kg ha-1) was recorded with the application of S and N at 80 and 140 kg
ha-1. Similar (P≤0.05) achene yield levels were recorded with lower S application (40 kg
ha-1) but when N application rates was increased upto 180 kg ha-1 showing that S and N
levels interacted to increase the efficiency of these nutrients in terms of achene yield.
There was a positive and linear relationship between head diameter and achene
yield during 2006 and 2007 (Fig 4.2) and regression accounted for 92% of the variance in
yield. Achene yield was also positively related to the number of achenes per head (Fig
4.3) and 1000-achene weight (Fig 4.4) and regression accounted for 89.62 and 95.04%
variance in achene yield, respectively. Such close association between the yield
contributing parameters under discussion and achene yield was also reported by
Cantagallo et al. (1997), Mercau et al. (2001), Khaliq (2004) and Hussain (2008).
55
Ach
ene
yiel
d(kg
ha
-1)
y = 224.08x - 1279.9
R2 = 0.9223
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20
y = 229.25x - 1385.3
R2 = 0.9232
500
1000
1500
2000
2500
3000
3500
5 10 15 20
Head diameter
Head diameter (cm)
Fig. 4.3. Relationship between achene yield and head diameter (cm) a) 2006, b) 2007
(b)
a
56
A
chen
e yi
eld
(Kg
ha-1
)
y = 8.3771x - 4101.3
R2 = 0.8542
100
600
1100
1600
2100
2600
3100
3600
300 400 500 600 700 800 900
y = 10.504x - 5126
R2 = 0.9381
500
1000
1500
2000
2500
3000
3500
500 550 600 650 700 750 800
Number of achene per head
Fig. 4.4. Relationship between achene yield and number of achene per head a)
2006, b) 2007
(a)
(b)
57
A
chen
e yi
eld
(Kg
ha-1
)
y = 79.826x - 1674.5
R2 = 0.9675
0
500
1000
1500
2000
2500
3000
3500
0 20 40 60 80
y = 83.907x - 1808.6
R2 = 0.933
50
550
1050
1550
2050
2550
3050
3550
20 30 40 50 60 70
1000-grain weight
Fig. 4.5. Relationship between achene yield and 1000-achene weight a) 2006, b) 2007
(a)
(b)
58
4.1.1.9. Harvest index (%)
Harvest index (HI) indicates the balanced distribution of assimilates into
economic yield. Sulphur nutrition had a significant (P≤0.05) and positive bearing on
harvest index (Table 4.9). Highest HIs (27.0-26.3) were recorded with application of 80
kg ha-1 S during 2006 and 2007, respectively and had a decreasing trend with increasing S
level further. On an average, sulphur dose of 40 and 80 kg ha-1 improved HI by 18 and 21
percent, respectively over control.
Nitrogen application also improved harvest index significantly (P≤0.05) over
control during both the years of experimentation (Table 4.9). Harvest index increased
initially with N application so that maximum values (27-28 %) were recorded with 140 kg
ha-1 N and declined by about 7 % with increasing N to 180 kg ha-1. On an average, N
application at 100 and 140 kg ha-1 improved HI by 21 and 28 percent. The decrease in
harvest index with the higher nitrogen application might be due to changing the stability
between vegetative and reproductive growth towards unnecessary vegetative growth, and
hence, in reduced achene yields (Fara et al., 1981; Hocking et al., 1987).
Data (Table 4.9) revealed that different combinations of S and N had an
interactive effect on harvest index during both years. Although highest HI values were
recorded with application of 80 and 140 kg ha-1 S and N, respectively but these were at
par (P≤0.05) with those recorded with increasing S level to 120 kg ha-1 with a
concomitant decrease in N to 100 kg ha-1. Similarly, increase/decrease in level of either S
or N compensated equilaterally to achieve similar level of harvest indices in these studies.
4.1. 2.Growth
4.1.2.1 Leaf area index
Sulphur application enhanced development of leaf area indices (LAI) during both
the years (Fig. 4.5). LAI did not vary significantly (P≤0.05) amongst different levels of S
at 30 days after sowing (DAS) that started getting significant with the advancement in
developmental stage and became prominent at 60 DAS. Highest LAIs (4.22-4.28) were
recorded with application of 80 and 120 kg ha-1 S during 2006. However, during 2007,
maximum LAI was recorded with application of 80 kg ha-1 S and declined thereafter with
higher level of S (Table 4.10). Application of 40, 80 and 120 kg ha-1 S improved LAI by
5 and 10 percent, respectively during both years of experimentation.
59
Table 4.9. Influence of sulphur and nitrogen nutrition on harvest index (%) of sunflower.
Treatments 2006 2007 mean
Sulphur (kg ha-1)
S1= Control 21.07 c 22.95 c 22.01 S2= 40 25.58 b 26.36 a 25.97 S3= 80 27.00 a 26.29 a 26.65
S4= 120 26.60 ab 25.45 b 26.03
LSD at 5% 1.13 0.75
Nitrogen (kg ha-1) N1= Control 22.18 c 20.79 c 21.49
N 2= 100 25.73 b 26.21 b 25.97
N 3= 140 27.02 a 28.08 a 27.55
N 4= 180 25.32 b 25.98 b 25.65
LSD at 5% 1.13 0.75
Interaction (S x N)
S1N1 17.28 h 18.09 h 17.69
S1N2 20.53 g 22.09 fg 21.31
S1N3 22.75 fg 25.87 e 24.31
S1N4 23.70 ef 25.75 e 24.73
S2N1 22.99 f 23.08 f 23.93
S2N2 25.89 cde 26.87 cde 26.38
S2N3 27.85 abc 29.07 ab 28.46
S2N4 25.59 de 26.42 de 26.01
S3N1 23.89 ef 21.37 g 22.63
S3N2 28.02 abc 27.93 bc 27.98
S3N3 29.48 a 29.71 a 29.60
S3N4 26.58 bcd 26.15 e 26.37
S4N1 24.55 def 20.62 g 22.59
S4N2 28.47 ab 27.95 bc 27.71
S4N3 27.98 abc 27.65 bcd 27.82
S4N4 25.40 de 25.59 e 25.50
LSD at 5% 2.26 1.50
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
60
During 2007, maximum value for leaf area index (4.21) was recorded with 80 kg
ha-1 S application and was 16.62% higher over control. LAI declined after 75 DAS in
treatments during both the years.
Sing et al. (2000) reported that increasing sulphur levels from zero to 45 kg ha-1
enhanced the leaf area index significantly over control. Ahmad and Abdin (2000) also
supported the positive effect of sulphur on leaf area. The increase in LAI might be
credited to the contribution of sulphur in the synthesis of chlorophyll and being the
component of amino acids- cystin, cystein and methionine (Marschnar, 1995).
Nitrogen application recorded significantly (P≤0.05) different leaf area indices
throughout crop growth period during both the years (Fig. 4.6). In contrary to S,
significant differences amongst different N levels were depicted at earlier stage and were
also more pronounced than those recorded for S. Highest LAI values (4.96) were
recorded with application of 180 kg ha-1 N during both the years (Table 4.10). On an
average, 54, 77 and 89 percent higher LAIs were recorded with application of 100, 140
and 180 kg ha-1 N, respectively over control. The increase in LAI was sharper from 0 to
100 kg ha-1 N and became less steeper for next level (140 kg ha-1) and ultimately achieved
a plateau for 180 kg ha-1 N. LAI declined steadily after 75 DAS during both the years
achieving almost similar (P≤0.05) values at 90 DAS for all N-applied plots. However,
LAI in control plots declined only to slight extent (Fig.4.6 ). Different combinations of S
and N did not reflect significant differences for LAI during both the years of
experimentation (Table 4.10).
The correlation analysis showed a strong and positive association of the leaf area
index with number of achenes per head (Fig 4.7), 1000-achene weight (Fig 4.8), crop
growth rate (Fig 4.9) and achene yield (Fig 4.10). The common regression accounted for
95.73% (96.32-95.13%) variation in number of achenes per head and 89.43% (92.73-
86.13%) variance in 1000-achene weight. While regression accounted for 98.33% (98.95-
97.84%) variation in crop growth rate and 92.37% (90.01-94.74%) for variance in achene
yield owing to differences in LAI.
61
Lea
f ar
ea in
dex
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
30 45 60 75 90
S1 S2 S3 S4
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
30 45 60 75 90
S1 S2 S3 S4
Days after sowing
Fig. 4.6. Pattern of leaf area index with time as influenced by sulphur nutrition during (a) 2006 and (b) 2007 ±SD
S1= Control, S2= 40 kg ha-1, S3= 80 kg ha-1, S4= 120 kg ha-1
(a) 2006
(b) 2007
62
Lea
f ar
ea in
dex
0.0
1.0
2.0
3.0
4.0
5.0
6.0
30 45 60 75 90
N1 N2 N3 N4
0.0
1.0
2.0
3.0
4.0
5.0
6.0
30 45 60 75 90
N1 N2 N3 N4
Days after sowing
Fig. 4.7: Pattern of leaf area index with time as influenced by nitrogen
nutrition during (a) 2006 and (b) 2007 ±SD N1= Control, N2= 100 kg ha-1, N3= 140 kg ha-1, N4= 180 kg ha-1
(a) 2006
(b) 2007
63
Table 4.10. Influence of sulphur and nitrogen nutrition on leaf area index (75
DAS) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 4.03 b 3.61 d 3.82
S2= 40 4.09 b 3.95 c 4.02
S3= 80 4.22 a 4.21 a 4.22
S4= 120 4.28 a 4.10 b 4.19
LSD at 5% 0.11 0.10
Nitrogen (kg ha-1)
N1= Control 2.87 d 2.36 d 2.62
N 2= 100 4.13 c 3.94 c 4.04
N 3= 140 4.67 b 4.60 b 4.64
N 4= 180 4.96 a 4.96 a 4.96
LSD at 5% 0.11 0.10
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
64
N
umbe
r of
ach
ene
per
head
y = 141.39x + 379.74
R2 = 0.9632
400
450500
550600
650
700750
800850
900
0.00 1.00 2.00 3.00 4.00
y = 114.66x + 409.33
R2 = 0.9513
400
450
500
550
600
650
700
750
800
850
0 1 2 3 4
Leaf area index
Fig. 4.8. Relationship between number of achene per head and leaf area
index a) 2006, b) 2007
(a)
(b)
b
65
1000
-gra
in w
eigh
t (g)
y = 15.494x + 7.661
R2 = 0.9273
0
10
20
30
40
50
60
70
0 1 2 3 4
y = 13.62x + 13.543
R2 = 0.8613
0
10
20
30
40
50
60
70
0 1 2 3 4
Leaf area index
Fig. 4.9. Relationship between 1000-grain weight and leaf area index a) 2006, b) 2007
(a)
(b)
66
Cro
p gr
owth
rat
e (g
m-2
d-1
)
y = 7.258x - 7.3411
R2 = 0.9895
0
2
4
6
8
10
12
14
16
18
0 1 2 3 4
y = 6.3594x - 4.1038
R2 = 0.9784
0
24
6
810
12
1416
18
0 1 2 3 4
Leaf area index
Fig. 4.10 Relationship between crop growth rate and leaf area index a) 2006, b) 2007
(a)
(b)
67
A
chen
e yi
eld
(kg
ha-1
)
y = 1238.8x - 1068.4
R2 = 0.9001
0
500
1000
1500
2000
2500
3000
3500
0 1 2 3 4
y = 1240.9x - 918.47
R2 = 0.9474
0
500
1000
1500
2000
2500
3000
3500
0 1 2 3 4
Leaf area index
Fig. 4.11 Relationship between achene yield (kg ha-1) and leaf area index a) 2006, b) 2007
(a)
(b)
68
4.1.2.2 Leaf area duration
Sulphur nutrition enhanced leaf area duration (LAD) over control and the pattern
was same during both years of experimentation (Table 4.11). During 2006 highest and
similar LAD were recorded with application of 80 and 120 kg ha-1 S while during 2007
significantly lower LAD was recorded with later dose of S. On an average, S application
at 40, 80 and 120 kg ha-1 enhanced LAD by 7, 12 and 10 percent, respectively over
control. Comparatively lesser LAD was recorded during 2007 and might be attributed to
higher rains (Fig. 3.1) and hence higher soil moisture available for better leaf area
development (Fig. 4.5) throughout the season.
Nitrogen application significantly (P≤0.05) increased the leaf area duration over
control plots and maximum LAD (210.65-193.10 d) was recorded with 180 kg ha-1
nitrogen during both years. Similar patterns of LAD increase were recorded for different
N levels. On an average, application of 100, 140 and 180 kg ha-1 N gave an LAD
advantage of 48, 47 and 75 percent, respectively over control. Khaliq (2004) and Iqbal
(2008) also concluded that nitrogen application improved leaf area duration of sunflower.
Different combinations of S and N had a non significant impact on LAD in present
studies during both the years (Table 4.11).
4.1.2.3 Crop growth rate
Periodic data at fortnight interval (Fig. 4.11 & 4.12) revealed that crop growth rate
(CGR) of sunflower crop progressively increased and achieved maximum value (21.21 g
m-2 d-1) at 75 DAS and declined sharply thereafter; reaching a value of 6.63 g m-2 d-1 at 90
DAS during 2006. Similar trend was observed during 2007 for this hybrid. Pattern of crop
growth rate as influenced by sulphur and nitrogen nutrition has been illustrated in figures
4.11 and 4.12 respectively. Sulphur application improved seasonal crop growth over
control during both years of experimentation (Table 4.12) however, the differences
amongst different S levels remained non-significant (P≤0.05). On an average, sulphur
application at 40, 80 and 120 kg ha-1 improved seasonal crop growth rate by 9, 13 and 12
percent over control. Crop growth rates were in the range of 11.21 to 12.70 g m-2 d-1.
Mean seasonal crop growth was significantly influenced by nitrogen application
rates during both years (Table 4.12). Mean crop growth rate improved with each
incremental level of N. During both the years nitrogen applied at 180 kg ha-1 recorded
highest CGR (16.11-15.54 g m-2 day-1) that was , on average, 7.40% more than that
(15.00 g m-2 day-1) recorded with the application of 140 kg ha-1 nitrogen.
69
Table 4.11. Influence of sulphur and nitrogen nutrition on leaf area duration
(days) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 168.38 c 147.64 c 158.01
S2= 40 176.00 b 162.27 b 169.14
S3= 80 183.11 a 171.15 a 177.13
S4= 120 182.23 a 164.04 b 173.14
LSD at 5% 5.43 6.89
Nitrogen (kg ha-1)
N1= Control 123.62 d 107.50 d 115.56
N 2= 100 175.78 c 166.40 c 171.09
N 3= 140 199.67 b 178.11 b 188.89
N 4= 180 210.65 a 193.10 a 201.88
LSD at 5% 5.43 6.89
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
70
Cro
p gr
owth
rat
e (g
m-1
d-1
)
0
5
10
15
20
25
45 60 75 90
S1 S2 S3 S4
0
5
10
15
20
25
45 60 75 90
S1 S2 S3 S4
Days after sowing
Fig. 4.11: Pattern of crop growth rate with time as influenced by sulphur nutrition during (a) 2006 and (b) 2007 ±SD S1= Control, S2= 40 kg ha-1, S3= 80 kg ha-1, S4= 120 kg ha-1
(a) 2006
(b) 2007
71
Cro
p gr
owth
rat
e (g
m-1
d-1
)
0
5
10
15
20
25
30
45 60 75 90
N1 N2 N3 N4
0
5
10
15
20
25
30
45 60 75 90
N1 N2 N3 N4
Days after sowing Fig. 4.12: Pattern of crop growth rate with time as influenced by nitrogen nutrition during (a) 2006 and (b) 2007 ±SD N1= Control, N2= 100 kg ha-1, N3= 140 kg ha-1, N4= 180 kg ha-1
(a) 2006
(b) 2007
72
Table 4.12. Influence of sulphur and nitrogen nutrition on seasonal crop growth
rate (g m-2 d-1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 11.70 b 10.72 b 11.21
S2= 40 12.42 ab 11.91 a 12.17
S3= 80 13.00 a 12.40 a 12.70
S4= 120 12.58 a 12.41 a 12.50
LSD at 5% 0.88 0.78
Nitrogen (kg ha-1)
N1= Control 6.37 d 6.28 d 6.33
N 2= 100 12.21 c 11.51 c 11.86
N 3= 140 15.00 b 14.12 b 14.56
N 4= 180 16.11 a 15.54 a 15.83
LSD at 5% 0.88 0.78
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
73
Sunflower crop grown without nitrogen fertilization exhibited lowest mean CGR
(6.37 g m-2 day-1) that was 135.47% and 91.67% lower, when crop was sown with 140
and 100 kg ha-1 nitrogen rate respectively. Approving results were recorded by Khaliq
(2004) who concluded that nitrogen rate of 200 kg ha-1 presented highest mean crop
growth rate in sunflower crop.
Non significant differences were recorded regarding interactive effect of sulphur
and nitrogen on mean CGR of sunflower crop during both years. Different combinations
of these nutrients gave mean CGR in the range between 5.92 and 15.58 g m-2 day-1.
There was a positive and linear relationship between crop growth rate and achene
yield (Fig 4.13) during both the years of study and regression accounted for 91% (86.64-
94.70%) variation in achene yield.
4.1.2.4 Net assimilation rate
. Sulphur application exhibited a non-significant (P≤0.05) effect on net
assimilation rate of sunflower during both years of experimentation (Table 4.13).
Nitrogen application significantly increased NAR over control during both the years so
that highest and similar NAR values (5.07-5.01 g m-2 d-1) were recorded for 180 and 140
kg ha-1 N over control. On an average, N rates of 100, 140 and 180 kg ha-1 improved
NAR by 19, 32 and 33 percent, respectively over control. Shabeer (2009) reported similar
range of NAR (4.75-4.5 g m-2 d-1) for sunflowers grown under similar environments
Different combinations of S and N also depicted non-significant differences for
NAR in these studies (Table 4.13).
4.1.2.5 Cumulative light interception
Sulphur application enhanced amount of intercepted radiation significantly
(P≤0.05) during both years of study (Table 4.14). During both the years, highest and
similar cumulative intercepted radiation was observed with the application of 80 and 120
kg ha-1 S which was about 5% higher over control. Application of 40 kg ha-1 S enhanced
cumulative radiation interception only by 3% over control. The enhancement in
cumulative light interception was expected because of improvement in LAI (Table 4.10)
with increasing sulphur application rates which concomitantly is associated with increase
in intercepted photosynthetically active radiation (Olsen et al., 2000). ). Higher
interception of radiation was recorded during 2006 that might be attributed to better
climatic conditions conducive for development of higher intercepting surfaces of crop
canopy (Fig. 4.5).
74
A
chen
e yi
eld(
kg
ha-1
)
y = 166.58x + 235.65
R2 = 0.8664
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20
y = 192.96x - 91.932
R2 = 0.947
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20
Crop growth rate
crop growth rate (g m-2 d-1) Fig. 4.13. Relationship between achene yield and crop growth rate (g m-2 d-1) a)
2006, b) 2007
(a)
(b)
75
Table 4.13. Influence of sulphur and nitrogen nutrition on net assimilation rate (g m-
2 d-1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 4.66 4.74 4.68
S2= 40 4.52 4.76 4.64
S3= 80 4.55 4.63 4.59
S4= 120 4.1 4.85 4.48
LSD at 5% NS NS
Nitrogen (kg ha-1)
N1= Control 3.58 c 4.06 c 3.82
N 2= 100 4.56 b 4.56 b 4.56
N 3= 140 4.86 a 5.16 a 5.01
N 4= 180 4.93 a 5.20 a 5.07
LSD at 5% 0.28 0.30
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
76
Nitrogen application resulted in better cumulative radiation interception during
both the years in these studies (Table 4.14). Maximum light interception (536.14-503.22
MJ m-2) was recorded with 180 kg ha-1 nitrogen application during both years which was
24 and 20 percent higher than respective control values during 2006 and 2007.Nitrogen
application at 100 and 140 kg ha-1 recorded radiation interception of 489.58 and 510.76
MJ m-2, respectively which was 14.98 and 19.96 percent more than control. Higher mean
values during 2006 were recorded owing to higher extent of leaf expansion.
Cumulative PAR interception during whole growing season by maize, sunflower and
soybean recorded was 820, 700 and 720 M. J m-2 (Andrade, 1995). Improvement in
radiation interception as a consequence of nitrogen fertilization has been reported in many
of previous studies. Hall et al. (1995) reported that total cumulated intercepted radiation
by sunflower crop increased by 6% (from 928 to 971 MJ m-2), with increasing nitrogen
from zero to 50 kg ha-1. Positive impact of nitrogen application on radiation interception
has been reported by Khaliq (2004) under similar environments. Fernando and Miralles
(2008) reported 20 and 7% increase in intercepted photosynthetic active radiation in
wheat crop with nitrogen and sulphur addition, respectively.
Different combinations of S and N recorded significantly (P≤0.05) different
radiation interception values only during 2007 (Table 4.14). A critical perusal of data
revealed that application of higher N rates (180 kg ha-1) without sulphur application
recorded as high levels of radiation interception as was recorded with application of 140
kg ha-1 N in combination with 40, 80 and/or 120 kg ha-1 S. It may not be impertinent to
mention that N had a predominating role in canopy development that is crucial in
radiation interception. So where the critical threshold levels of LAIs were achieved with
ample N in the absence of S, the later did not contribute much towards radiation
interception.
There was a optimistic and linear association between cumulative intercepted
PAR and LAI (Fig 4.14) and regression accounted for 96.36% (96.76-95.97 %) of
variance in PAR owing to differences in LAI. There also existed a similar relationship
between cumulative radiation interception and achene yield (Fig 4.15) and regression
accounted for 93.56% (91.79-95.34 %) variance in achene yield.
77
Table 4.14. Influence of sulphur and nitrogen nutrition on cumulative radiation
interception (M.J.m-2) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 480.84 c 460.94 c 370.89
S2= 40 499.10 b 473.28 b 486.19
S3= 80 507.64 a 478.96 ab 493.30
S4= 120 508.48 a 482.32 a 495.40
LSD at 5% 8.42 7.31
Nitrogen (kg ha-1)
N1= Control 431.96 d 419.58 d 425.77
N 2= 100 501.92 c 477.25 c 489.58
N 3= 140 526.04 b 495.47 b 510.76
N 4= 180 536.14 a 503.22 a 519.68
LSD at 5% 8.42 7.31
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
78
C
umul
ativ
e in
terc
epte
d ra
diat
ion
(MJ
m-2
)
y = 79.836x + 281.61
R2 = 0.9676
300
350
400
450
500
550
600
1.0 1.5 2.0 2.5 3.0 3.5
y = 59.33x + 324.95
R2 = 0.9597
200
250
300
350
400
450
500
550
0 1 2 3 4
Leaf area index
Fig. 4.14. Relationship between cumulative intercepted radiation (MJ
m-2)and leaf area index a) 2006, b) 2007
(a)
(b)
79
A
chen
e yi
eld
Kg
ha-1
)
y = 15.414x - 5386.7
R2 = 0.9179
100
600
1100
1600
2100
2600
3100
3600
300 350 400 450 500 550 600
y = 3.2843x - 1131.1
R2 = 0.9534
100
150
200
250
300
350
400
450
500
550
600
300 350 400 450 500 550
Cumulated intercepted radiation
Cumulative intercepted radiation (MJ m-2)
Fig. 4.15. Relationship between achene yield (kg ha-1) and cumulative intercepted radiation (MJ m-2) a) 2006, b) 2007
(a)
(b)
80
.4.1.2.6 Radiation use efficiency (TDM)
Translation of intercepted photosynthetically active radiation into new biomass is
termed as radiation use efficiency (Sinnclair and Muchow, 1999) and help measure net
carbon assimilation of a crop. Sulphur application exhibited significant (P≤0.05)
influence on RUE(TDM) only during 2007 (Table 4.15). Application of sulphur enhanced
RUE(TDM) by 8-10 percent over control, while the differences amongst different sulphur
levels were non-significant. On an average, RUE(TDM) was 1.653 g MJ-1. Fernando and
Miralles (2008) recorded increase in RUE of wheat crop with increasing rates of sulphur
nutrition that might be attributed to increase in photosynthesis with increased sulphur
application (Terry, 1976).
Nitrogen application had a significant (P≤0.05) influence on RUE(TDM) during both
years (Table4.15 ). Application of increasing levels of nitrogen improved RUE(TDM) upto
140 kg ha-1 N during 2006 with a non significant increase with 180 kg ha-1 N. However,
during 2007, RUE(TDM) increased steadily with each incremental level of N so that highest
(1.995 g MJ-1) was recorded with the application of 180 kg ha-1 N. On an average,
application of 100, 140 and 180 kg ha-1 N improved the RUE(TDM) by 55, 79 and 91
percent, respectively over control (Table 4.15).
Hall et al. (1995) also concluded that nitrogen supply influenced RUE of
sunflower and it increased from 1.01 g MJ-1 to 1.18 g MJ-1 with the increase in nitrogen
rate from zero to 50 kg ha-1. The values of RUE for sunflower in the study under
discussion are in confirmatory to those reported by Kiniry et al. (1989), Khaliq (2004)
and Iqbal (2008). The values of RUE for sunflower as reported by Connor et al. (1985),
Cox and Jolliff (1986) and Champan et al. (1993) for above ground dry matter were 1.75,
2.79, and 1.05 g MJ-1, respectively. Sinclair and Horie, (1989)reported that nitrogen
increased Rubisco activity in leaves and resulted an improvement in radiation use
efficiency (RUE),which is reliant on net CO2 assimilation(Loomis and Amthor, 1999).
Different combinations of N and S did not influence RUE (TDM) in these studies.
(Table 4.15)
81
Table 4.15. Influence of sulphur and nitrogen nutrition on radiation use efficiency TDM (g M.J -1) of sunflower
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 1.567 1.509 b 1.538
S2= 40 1.601 1.632 a 1.617
S3= 80 1.640 1.667 a 1.654
S4= 120 1.593 1.661 a 1.627
LSD at 5% NS 0.108
Nitrogen (kg ha-1)
N1= Control 1.023 1.035 d 1.029
N 2= 100 1.594 1.588 c 1.591
N 3= 140 1.844 1.850 b 1.847
N 4= 180 1.939 1.995 a 1.967
LSD at 5% 0.108 0.108
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5% probability level; NS = Non-significant
82
4.1.2.7 Radiation use efficiency (grain)
Sulphur application influenced RUE grain significantly (P≤0.05) during both
years of experimentation (Table 4.16). During 2006, maximum radiation use efficiency
for grain (0.51 g MJ-1) was recorded when sunflower crop was fertilized with 80 kg ha-1
sulphur. It was 11.35% higher than that recorded for 40 kg ha-1 sulphur, and was 39%
higher over control. Similar trend was observed during 2007. On an average, application
of 40, 80 and 120 kg ha-1 S improved RUE for grain by 22, 34 and 26 percent,
respectively over control.
Radiation use efficiency for grain under study was markedly influenced with
different nitrogen levels during both years (Table 4.16). Increasing levels of N enhanced
RUE for grain that did not increase significantly (P≤0.05) beyond 140 kg ha-1 N during
both years of experimentation. Application of N @ 100, 140 and 180 kg ha-1, improved
RUEgrain by 64, 86 and 92 percent, respectively over control (Table 4.16). Almost similar
values of radiation use efficiency for grain (achene) were reported earlier by Iqbal (2008)
under similar environmental conditions.
Non-significant (P≤0.05) interaction between sulphur and nitrogen nutrition for
RUEgrain was recorded during both years of experimentation in present studies (Table
4.16).
4.1.3 Quality parameters
4.1.3.1 Achene protein contents (%)
Data (Table 4.17) revealed that sulphur application improved achene-protein
content during both the years. During 2006, maximum and similar (P≤0.05) achene-
protein (21.66-21.21 %) was recorded with the application of 80 and 120 kg ha-1 sulphur,
while a minimum (16.09%) was observed in control plots. Similar trend was observed
during 2007. Increase in achene-protein contents with sulphur application is in
confirmatory to previous reports of Bhagat et al. (2005) and Sreenamannarayana et al.
(1998) who concluded that sulphur nutrition had a positive bearing on achene-protein
content. Poonia (2003) also recorded an increase in protein contents of sunflower in
response to sulphur application.
Application of nitrogen significantly (P≤0.05) enhanced achene-protein content
during both the years (Table 4.17). The maximum protein concentration (22.87-23.07-%)
was recorded with application of 180 kg ha-1 during 2006 and 2007. Achene-protein
improved with application of all N levels over control in these studies. When averaged
83
Table 4.16. Influence of sulphur and nitrogen nutrition on radiation use efficiency
grain (g M.J -1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 0.366 c 0.388 c 0.377
S2= 40 0.458 b 0.461 b 0.460
S3= 80 0.510 a 0.498 a 0.504
S4= 120 0.480 a 0.473 ab 0.423
LSD at 5% 0.026 0.026
Nitrogen (kg ha-1)
N1= Control 0.306 a 0.258 0.282
N 2= 100 0.462 b 0.462 0.462
N 3= 140 0.522 a 0.525 0.524
N 4= 180 0.525 a 0.558 0.542
LSD at 5% 0.026 0.026
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
84
Table 4.17. Influence of sulphur and nitrogen nutrition on achene protein
contents (%) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 16.22 c 16.09 d 16.16
S2= 40 19.03 b 19.35 c 19.19
S3= 80 21.44 a 21.66 a 21.55
S4= 120 21.20 a 21.21 b 21.21
LSD at 5% 0.30 0.24
Nitrogen (kg ha-1)
N1= Control 14.41 d 14.27 d 14.34
N 2= 100 18.72 c 18.84 c 18.78
N 3= 140 21.88 b 22.12 b 22.00
N 4= 180 22.87 a 23.07 a 22.97
LSD at 5% 0.30 0.24
Interaction (S x N)
S1N1 11.60 j 11.12 l 11.36
S1N2 15.55 h 15.41 j 15.48
S1N3 18.25 g 18.35 h 18.30
S1N4 19.46 f 19.46 g 19.46
S2N1 14.02 l 14.23 k 14.35
S2N2 18.50 g 18.67 h 18.59
S2N3 21.12 d 21.72 e 21.42
S2N4 22.50 c 22.79 d 22.65
S3N1 16.11 h 16.11 i 16.11
S3N2 20.65 de 20.86 f 20.76
S3N3 24.23 ab 24.40 bc 24.32
S3N4 24.75 a 25.25 a 25.00
S4N1 15.90 h 15.63 j 15.77
S4N2 20.18 e 20.42 f 20.30
S4N3 23.93 b 24.03 c 23.98
S4N4 24.77 a 24.77 b 24.77
LSD at 5% 0.59 0.47 Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
85
across years, N rates of 100, 140 and 180 kg ha-1 improved achene-protein percentage by
31, 53 and 60 percent, respectively over control. Previous findings of Malhi and Leach
(2000), Khaliq (2004), Kuchar (2005) and Ahmad (2007) also supported the results under
discussion.
Different combinations of S and N had a significant (P≤0.05) influence on achene-
protein content and the trend was same during both the years (Table 4.17). Application of
80 kg ha-1 S with 140 and/or 180 kg ha-1 N recorded as good achene-protein content as
was recorded with application of 120 kg ha-1 S in combination with 180 kg ha-1 N (Table
4.17). Lower achene-protein content was recorded with highest levels of either of the
nutrients under study in present investigations, revealing that there was a strong
interactive effect of both S and N in improving achene-protein content in sunflowers.
4.1.3.2. Achene oil content (%)
Quality of sunflower seed is determined from its oil content. Data (Table 4.18)
indicated a significantly (P≤0.05) positive influence of sulphur application so that highest
achene-oil content (44.17-44.04 percent) was recorded during two years of study with the
application of 120 kg ha-1 S. Sunflower grown without S application exhibited 38.38%
achene-oil content, while application of 40, 80 and 120 kg ha-1 S improved achene-oil
content by 6, 13 and 15 percent, respectively over control.
The higher oil contents recorded with increasing sulphur levels is in line with the
results obtained by Ahmad et al.(1999). Poonia (2003) reported significant influence of
sulphur application on sunflower oil contents. The increasing trend of oil concentration
with sulphur application in present studies is in line with the findings of (Hassan et al.
(2007) who concluded that different levels of sulphur (0, 10, 15, 20 kg ha-1) improved the
oil contents of the autumn planted sunflower from 38.1 to 45.1 %. Baghat et al. (2005)
recorded highest oil contents (41.72%) with 40 kg ha-1 sulphur.
Nitrogen application had a negative (P≤0.05) bearing on oil contents (Table 4.18) so that
lowest achene-oil content (39.82-39.77 percent) was noted with application of 180 kg ha-1
N during both years of experimentation. Sunflower crop grown without nitrogen
application exhibited highest achene-oil content (43.81 and 43.56 percent) during 2006
and 2007, respectively. On an average application of 100, 140 and 180 kg ha-1 N recorded
2.8, 7.3 and 9.9 percent reduction in achene-oil content, respectively over control. Several
authors (Schneiter et al., 2002; Ali et al., 2004; Ozer et al., 2004; Al-Thabet, 2006) have
reported negative influence of N on seed oil concentration. Concentration of protein in the
86
kernels as recorded by Ivanov and Stoyanova (1978) ranged from 17 to 36%, while
Khaliq (2004) recorded comparatively lower achene protein concentration that ranged
from 12 to 16% under similar environments. The significant negative relationship
between seed oil content and high nitrogen fertilization could be probably attributed to
the sugar translocation effecting oil synthesis (Salisbury & Ross, 1994). Kutcher et al.
(2005) attributed such negative relationship to the diluting effect of higher seed yield at
higher N application and the opposite relationship between protein and oil content.
Different combinations of S and N exhibited non-significant (P≤0.05) influence
on achene-oil content of sunflowers grown during both the years (Table 4.18).
4.1.3.3 Oil yield (kg ha-1)
The ultimate objective in oilseed crop production is the oil yield, which is a
product of achene yield and achene oil contents in case of sunflower. Data (Table 4.19)
indicated that oil yield of sunflower increased with S fertilization and maximum (1139-
1041 kg ha-1) was recorded with the application of S @ 80 Kg ha-1 during 2006 and
2007, respectively. A further increase in S level did not bring a significant (P≤0.05)
increase in oil yield. On an average, S application at 40, 80 and 100 kg ha-1 resulted in 33,
58 and 52 percent increase in oil yield, respectively over control. The effect of sulphur
application on the oil yield which is a product of oil contents and achene yield was also
studied by Poonia (2003) and Bhaghat (2005) and they recorded positive and significant
effect.
Nitrogen application also exhibited significant (P≤0.05) improvement in oil yield
of sunflower during both years of experimentation (Table 4.19). Highest oil yield (1136
kg ha-1) was recorded with application of 140 kg ha-1 N during 2006 that reached to
highest value (1115 kg ha-1) with further increased level (180 kg ha-1) of N during 2007.
Two years average data indicated the oil yield increased by 83, 110 and 111 percent with
N dose of 100, 140 and 180 kg ha-1 N, respectively over no nitrogen treatment...
Different combinations of S and N exhibited a non significant (P≤0.05) difference
in oil yield during both the years (Table 4.19).
There was positive relationship between achene yield and oil yield (Fig 4.16) and
regression accounted for 96 % variance in oil yield of sunflower.
87
Table 4.18. Influence of sulphur and nitrogen nutrition on achene oil contents (%)
of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 38.58 c 38.18 d 38.38
S2= 40 40.95 b 40.64 c 40.80
S3= 80 43.70 a 43.23 b 43.47
S4= 120 44.17 a 44.01 a 44.09
LSD at 5% 1.35 0.73
Nitrogen (kg ha-1)
N1= Control 43.81 a 43.56 a 43.70
N 2= 100 42.79 a 42.25 b 42.52
N 3= 140 40.97 b 40.49 c 40.73
N 4= 180 39.82 b 39.72 d 39.77
LSD at 5% 1.35 0.73
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
88
Table 4.19. Influence of sulphur and nitrogen nutrition on achene oil yield (kg ha-1)
of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 686.90 c 689.20 c 688.05
S2= 40 940.20 b 888.90 b 914.55
S3= 80 1139.20 a 1040.86 a 1090.03
S4= 120 1083.86 a 1008.00 a 1045.93
LSD at 5% 62.93 70.19
Nitrogen (kg ha-1)
N1= Control 584.40 c 477.70 c 531.05
N 2= 100 1001.70 b 936.70 b 969.20
N 3= 140 1135.81 a 1097.90 a 1116.86
N 4= 180 1128.29 a 1114.60 a 1121.45
LSD at 5% 62.93 70.19
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
89
O
il y
ield
(kg
ha-1
)
y = 0.4122x + 12.291
R2 = 0.9529
0
200
400
600
800
1000
1200
1400
1600
0 1000 2000 3000 4000
y = 0.4008x + 26.519
R2 = 0.9601
0
200
400
600
800
1000
1200
1400
0 500 1000 1500 2000 2500 3000 3500
Achene yield
Achene yield (kg ha-1) Fig. 4.16 Relationship between oil yield (kg ha-1) and achene yield (kg ha-
1)a) 2006, b) 2007
(a)
(b)
90
4.1.3.4 Fatty acid profile
Relative proportion of different fatty acids in edible oil, determines the superiority
of that oil and the oil that possesses higher percentage of poly-unsaturated fatty acids for
lowering cholesterol level in human body is considered of good quality (Cunnae ;1995).
Utilization of oils having larger proportion of un-saturated fatty acids has been found to
have constructive consequences on human health (Jing et al., 1997; Hu et al., 2001).
Some of the important fatty acids present in sunflower achene oil are discussed in this
portion.
4.1.3.4.1 Oleic acid concentration (%)
Concentration of oleic acid (18:1) in achene oil of sunflower varied significantly
(P≤0.05) under different sulphur levels (Table 4.20). During first year, maximum oleic
acid concentration (12.14%) was recorded when crop was grown without sulphur
application and it decreased progressively with increasing levels of sulphur so that
minimum oleic acid concentration (10%) was exhibited with the application of sulphur
@120 kg ha-1.Similar trend was recorded during 2007 but oleic acid concentration did not
vary amongst different S levels to significant (P≤0.05) extent. Manaf and Hassan (2006)
and Ahmad and Abidin (2000) recorded inconsistent response of oleic acid to sulphur
levels. These results are contradictory to the findings of Misra et al. (2002).
Application of nitrogen had a significantly (P≤0.05) negative influence on oleic
acid (18:1) (mono-unsaturated fatty acid) concentration (Table 4.20) during both the years
of experimentation. During 2006, sunflower grown without nitrogen application exhibited
maximum (17.25%) oleic acid concentration in achene oil and minimum (7.35%) was
recorded for 180 kg ha-1 nitrogen fertilization. Increasing nitrogen levels from 100 to 140
kg ha-1 resulted in significant (P≤0.05) decrease (28.38%) in concentration of oleic acid in
achene oil. It was further decreased by 12.65% with the highest level (180 kg ha-1) of
nitrogen application. Almost similar trend was recorded for 2007.
Khaliq (2004) and Iqbal (2008) also reported negative impact of nitrogen on oleic
acid contents of sunflower under similar environmental conditions. These results are also
in line with finding of Ahmad and Abdin (2000).
Interactive effects of nitrogen and sulphur application on the oleic acid concentration
were found to be non significant (P≤0.05) during both the years of study.
91
Table 4.20. Influence of sulphur and nitrogen nutrition on oleic acid
concentration (%) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 12.14 a 11.80 a 11.97
S2= 40 11.00 b 10.50 b 10.75
S3= 80 10.38 bc 10.13 b 10.26
S4= 120 10.00 c 10.00 b 10
LSD at 5% 0.67 0.69
Nitrogen (kg ha-1)
N1= Control 17.25 a 16.17 a 16.71
N 2= 100 10.63 b 10.54 b 10.59
N 3= 140 8.28 c 8.24 c 8.26
N 4= 180 7.35 d 7.48 d 7.42
LSD at 5% 0.67 0.69
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
92
4.1.3.4. 2. Linoleic acid concentration (%)
Sulphur application had a significant (P≤0.05) bearing on linoleic acid (18:2)
concentration in sunflower achene oil only during 2006 (Table 4.21). However, the
differences amongst sulphur levels were non-significant. On an average, sulphur
application at 40, 80 and 120 kg ha-1 improved linoleic content by 2.3, 3 and 3.5 percent,
respectively over control. This increasing trend in linoleic acid concentration with sulphur
application is in line with the findings of Misra et al. (2002), while Ahmad and Abidin
(2002) reported contradictory results in brassica species. During both the years, linoleic
acid concentration varied significantly (P≤0.05) under different levels of nitrogen
application as compared with control (Table 4.21). It increased gradually with increasing
levels of nitrogen so that application of 140 and 180 kg ha-1 N recorded highest and
similar (P≤0.05) values of 80.5 and 81.4 percent during both years. The minimum
(72.01%) linoleic acid concentration was realized without nitrogen application, while
application of 100, 140 and 180 kg ha-1 N improved it by 7, 12 and 13 percent,
respectively over the former treatment (control). These results are in line with those
reported by Steer and Sailor (1990), Khaliq (2004).
Different combinations of S and N recorded a significant (P≤0.05) influence on
linoleic acid concentration in achene-oil of sunflower only during 2006 (Table 4.21).
Highest concentrations of this fatty acid were recorded where either both S or N or any
one of these was used at its higher application rate. For example, combination
of S and N at 0+180, 40+140, 40+180 kg ha-1 recorded as high concentration as was
realized with combined application of 120+80, 120+180, 80+180, 80+140 kg ha-1 of S
and N, respectively (Table 4.21). This implied that the maximum concentration of linoleic
acid was developed in achene-oil when either of these nutrients touched its so called
saturation level, and that it was not dependent on any specific one used in present studies.
4.1.3.4.3. Palmitic Acid concentration (%)
Data (Table 4.22) revealed that sulphur application did not influence the palmitic
acid (16:1) concentration to significant extent (P≤0.05) during both the years. Palmitic
acid concentration was in the range of 4.96 to 5.20%.
Palmitic acid concentration increased significantly (P≤0.05) with the application of
nitrogen over control during both years (Table 4.22). During 2006, maximum
concentration (6.19%) was recorded by the application of 180 kg ha-1 nitrogen. It was
followed by 5.94% and 5.72% with 140 and 100 kg ha-1 N and the difference between
93
these being non-significant (P≤0.05). Average of two year data revealed that palmitic acid
concentration improved by 11, 15 and 20 percent with application of 100, 140 and 180 kg
ha-1 N, respectively over control. The increase in palmitic acid concentration with
increasing nitrogen levels confirms the findings of Steer and Seiler (1990) and Khaliq
(2004).
A non-significant (P≤0.05) difference among combinations of various sulphur and
nitrogen levels was recorded for both years of experimentation (Table 4.22)
4.1.3.4.4. Stearic acid (%)
Stearic acid is categorized as saturated fatty acid, and is an undesirable oil quality
characteristic. The perusal of the analyzed data (Table 4.23) revealed that neither sulphur,
nor nitrogen nutrition influenced the concentration of stearic acid during 2006 & 2007 to
significant (P≤0.05) level over control. Non-significant effect of nitrogen application on
stearic acid concentration of sunflower was also recorded by Iqbal (2008) under similar
climatic conditions. Valtcho et al. (2009) reported a decrease in stearic acid concentration
in sunflower when it was fertilized with 0 and 64 kg ha-1 N as compared to 134 and 202
kg ha-1 N application. Valchovski (2002) also reported similar results for N application.
Different combinations of S and N also had a non-significant (P≤0.05) influence
on stearic acid concentration in sunflower achene-oil (Table 4.23).
94
Table 4.21. Influence of sulphur and nitrogen nutrition on linoleic acid
concentration (%) of sunflower achene oil.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 76.17 b 76.58 76.38
S2= 40 78.06 a 78.21 78.14
S3= 80 78.55 a 78.92 78.74
S4= 120 79.14 a 79.06 79.10
LSD at 5% 1.70 NS
Nitrogen (kg ha-1)
N1= Control 72.07 c 71.81 c 71.94
N 2= 100 78.40 b 78.58 b 78.49
N 3= 140 80.39 a 80.63 ab 80.51
N 4= 180 81.05 a 81.75 a 81.40
LSD at 5% 1.70 2.19
Interaction (S x N) NS
S1N1 72.32 g 70.07 71.32
S1N2 76.18 f 75.71 75.95
S1N3 79.17 cd 78.73 78.95
S1N4 80.42 abc 80.15 80.28
S2N1 76.35 ef 71.00 73.68
S2N2 79.30 bcd 78.90 79.10
S2N3 80.43 abc 80.67 80.55
S2N4 81.11 a 81.67 81.39
S3N1 77.99 de 72.33 75.16
S3N2 80.05 abc 79.00 79.53
S3N3 80.85 abc 81.21 81.03
S3N4 81.03 a 81.67 81.35
S4N1 76.24 f 74.89 75.57
S4N2 79.69 abc 80.00 79.85
S4N3 80.97 ab 80.93 80.95
S4N4 81.00 ab 80.73 80.87
LSD at 5% 1.72 NS Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
95
Table 4.22. Influence of sulphur and nitrogen nutrition on palmatic acid
concentration (%) of sunflower achene oil.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 5.77 4.60 5.19
S2= 40 5.76 4.63 5.20
S3= 80 5.76 4.61 4.96
S4= 120 5.78 4.62 5.20
LSD at 5% NS NS
Nitrogen (kg ha-1)
N1= Control 5.22 c 4.07 4.65
N 2= 100 5.75 b 4.59 5.17
N 3= 140 5.94 b 4.79 5.37
N 4= 180 6.19 a 5.01 5.60
LSD at 5% 0.24 NS
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
.
96
Table 4.23. Influence of sulphur and nitrogen nutrition on stearic acid concentration
(%) of sunflower achene oil.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 4.81 3.81 4.31
S2= 40 4.83 3.84 4.34
S3= 80 4.85 3.86 4.36
S4= 120 4.86 3.87 4.37
LSD at 5% NS NS
Nitrogen (kg ha-1)
N1= Control 4.83 3.84 4.34
N 2= 100 4.83 3.85 4.34
N 3= 140 4.84 3.85 4.35
N 4= 180 4.85 3.83 4.34
LSD at 5% NS NS
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
97
4.1.4 Nutrient uptake
Information on nutrient uptake of the crop is crucial in determining the fertilizer
use efficiency, and also helpful in devising fertilizer management strategies for achieving
yield targets in a crop. Following section discusses the nutrient uptake by sunflower
grown on various S and N nutrition.
4.1.4.1 Nitrogen uptake (kg ha-1)
Sulphur application increased nitrogen uptake significantly (P≤0.05) during both
the years (Table 4.24). During 2006, maximum and similar (P≤0.05) nitrogen uptake
(105.9 and 102.7 kg ha-1) was recorded with 120 and 80 kg ha-1 sulphur fertilization,
respectively. Application of sulphur at 40 kg ha-1 recorded 92.6 kg ha-1 N uptake by the
crop. Similar pattern for N uptake was observed during 2007, but was in lesser quantity
than the previous year that might be attributed to due to more rain, and higher soil
moisture regimes during periods of active growth in that year (Fig. 3.1). Application of N
uptake was improved by 13 % when S rate was increased from 40 to 80 kg ha-1, and
increased slightly (by only 2%) when S application was further increased to 120 kg ha-1.
Data (Table 4.24) revealed that nitrogen application significantly (P≤0.05)
enhanced N uptake by the crop. During 2006, highest N uptake (140 kg ha-1) was
recorded with application of 180 kg ha-1 N. It was 12% higher than that recorded for 140
kg ha-1 N application and 59% higher than that recorded for plots fertilized at 100 kg ha-1
N. Almost similar trend for N uptake in response to nitrogen application was recorded
during 2007. Crop grown without N fertilization recorded only 27 kg ha-1 N.
The significant difference for removal of nutrients by sunflower is dependent on
yield produced by the crop and positive regression accounted for (90-94%) for the years
2006 and 2007 (Fig 4.17) Angelova and Christov (2003) observed that variation in achene
yield from 500 to 3500 kg ha-1 resulted in an increase in N uptake from 8.8 to 197.4 kg
ha-1. Almost same trend of yield and nutrient uptake was recorded in present studies.
Different combinations of S and N fertilizer exhibited a significant (P≤0.05) influence on
N uptake by the crop during both years of experimentation (Table 4.24). A careful perusal
of data indicated that application of higher levels (140, 180 kg ha-1) of nitrogen resulted in
increased N uptake in combination with either lower (40 kg ha-1) or higher (120 kg ha-1)
levels of sulphur application.
98
Table 4.24. Influence of sulphur and nitrogen nutrition on total nitrogen uptake
(kg ha-1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 78.07 c 71.43 c 74.75
S2= 40 92.63 b 88.25 b 90.44
S3= 80 102.69 a 101.83 a 102.26
S4= 120 105.87 a 101.96 a 103.85
LSD at 5% 6.90 6.83
Nitrogen (kg ha-1)
N1= Control 26.93 d 26.39 d 26.66
N 2= 100 87.98 c 83.44 c 85.71
N 3= 140 124.33 b 117.94 b 121.14
N 4= 180 140.02 a 135.69 a 137.86
LSD at 5% 6.90 6.83
Interaction (S x N)
S1N1 21.40 f 21.56 g 21.48
S1N2 72.23 e 64.13 f 68.18
S1N3 98.14 d 89.82 e 93.98
S1N4 120.50 c 110.21 c 115.36
S2N1 26.20 f 27.94 g 27.07
S2N2 86.56 d 83.58 e 85.07
S2N3 117.60 c 107.60 cd 112.6
S2N4 140.15 b 133.89 b 137.02
S3N1 29.94 f 27.52 g 28.73
S3N2 98.53 d 94.18 de 96.36
S3N3 140.25 b 133.07 be 136.66
S3N4 154.74 a 152.53 a 153.64
S4N1 30.18 f 28.56 g 29.37
S4N2 94.58 d 91.87 e 93.23
S4N3 141.31 ab 141.26 ab 141.29
S4N4 144.69 ab 146.14 ab 145.42
LSD at 5% 13.81 13.66
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
99
A
chen
e yi
eld
(Kg
ha-1
)
y = 14.37x + 942.76
R2 = 0.9049
0
500
1000
1500
2000
2500
3000
3500
0 50 100 150 200
y = 15.818x + 759.09
R2 = 0.9377
0
500
1000
1500
2000
2500
3000
3500
0 50 100 150 200
Nitrogen uptake
Nitrogen uptake (Kg ha-1 Fig. 4.17. Relationship between achene yield (Kg ha-1)and nitrogen uptake a)
2006, b) 2007
(a)
(b)
100
Application of only 40 kg ha-1 S exhibited a fairly good N uptake only when accompanied
by a higher level (180 kg ha-1) of nitrogen. On the other hand, crop grown without S
fertilization in combination with 140 kg ha-1 N also failed to achieve fairly good N uptake
levels suggesting a synergistic effect of both nutrients in enhancing N uptake in
sunflowers.
Fig (4.17) revealed that there was a positive correlation between achene yield and
nitrogen uptake by sunflower crop during both the years and regression accounted for
(90-94 %) variance in achene yield.
4.1.4.2 Phosphorus uptake (kg ha-1)
Sulphur application had a pronounced (P≤0.05) effect on total P uptake by
sunflower crop during both years of experimentation (Table 4.25). Increasing levels of S
up to 80 kg ha-1 resulted in corresponding increase in P uptake that did not increase
further with next level of S in these studies. Similar trend was observed for both the years
for P uptake, so that application of 40, 80 and 120 kg ha-1 S improved total P uptake by
13, 23 and 20 percent, respectively over control.
Agarwal et al. (2000) recorded an increase in phosphorus uptake with sulphur
application at the rate of 40 kg ha-1. Nasreen and Haq (2002) reported synergistic effect of
sulphur on P uptake and recorded an increase in P uptake upto 35 kg ha-1 with increasing
level of sulphur application upto 80 kg ha-1 in sunflower crop. Sing and Chaudhuri (1996)
recorded similar results in groundnut. Singh and Singh(2007) also recorded positive
response of P uptake by linseed with increasing sulphur application rate.
Increasing levels of nitrogen fertilization significantly (P≤0.05) enhanced total P
uptake in sunflower during both years of experimentation (Table 4.25). During 2006,
highest phosphorus uptake (50.40 kg ha-1) was recorded in the plots where nitrogen was
applied at 180 kg ha-1, and it was 197.97% higher than that recorded for control plots
(16.78 kg ha-1 P). Increasing nitrogen application from 100 to 140 kg ha-1 improved
nitrogen uptake from 34.64 to 45.42 kg ha-1 which was 10.96% lower than that obtained
with the highest dose of nitrogen in present studies. Almost similar trend was observed
during 2007.
Different combinations of S and N exhibited a non-significant (P≤0.05) influence
on total P uptake in sunflower during both years of experimentation (Table 4. 25).
Regarding relationship between phosphorus uptake and achene yield (Fig.4.18),
there was a optimistic correlation and regression accounted for (87-93%) for two years of
study.
101
Table 4.23. Influence of sulphur and nitrogen nutrition on total phosphorus uptake
(kg ha-1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1) 33.21 c 30.51 c 31.86
S1= Control 36.60 b 35.07 b 35.84
S2= 40 39.93 a 38.31 a 39.12
S3= 80 39.49 ab 37.10 ab 38.30
S4= 120 6.83 2.60
LSD at 5%
Nitrogen (kg ha-1) 16.78 d 16.48 d 16.63
N1= Control 34.64 c 32.78 c 33.71
N 2= 100 45.42 b 42.97 b 44.20
N 3= 140 50.40 a 48.76 a 49.58
N 4= 180 6.83 2.60
LSD at 5% 6.83 2.60
Interaction (S x N) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
102
A
chen
e yi
eld
(Kg
ha-1
)
y = 48.481x + 520.81
R2 = 0.8764
0
500
1000
1500
2000
2500
3000
3500
0 10 20 30 40 50 60
y = 54.564x + 273.15
R2 = 0.9319
0
500
1000
1500
2000
2500
3000
3500
0 10 20 30 40 50 60
Phosphorus uptake
Phosphorus uptake(Kg ha-1) Fig. 4.18. Relationship between achene yield (Kg ha-1)and phosphorus uptake(Kg
ha-1) a) 2006, b) 2007
(b)
103
4.1.4.3 Potassium uptake (kg ha-1)
Sulphur fertilization showed significant (P≤0.05) influence on total K uptake by
the crop during both the years (Table 4.26). Application of 120 kg ha-1 S resulted in
highest total K uptake 135-129 kg ha-1) during two years of study. However, a lower dose
of S (80 kg ha-1) exhibited similar (P≤0.05) level of total K uptake. Crop grown with
application of 40 kg ha-1 S exhibited 30 % higher K uptake as against 89-92 kg ha-1
recorded for control plots. Similar pattern of K uptake was observed during 2007.
Data (Table 4.26) revealed that nitrogen application resulted in significant
(P≤0.05) increase in total K uptake by sunflower during both the years. Highest K uptake
(159-164 kg ha-1) was recorded with application of 180 kg ha-1 N. It was followed by
145.15, 116.20 and 60.32 kg ha-1 total potash recorded with nitrogen application at 140,
100 and 0 kg ha-1, respectively. Similar trend of increase in phosphorus uptake with
increasing dose of nitrogen was recorded during 2007.
Interaction between sulphur and nitrogen fertilization during year 2006 was non-
significant. During 2007, combined effect of nitrogen and sulphur was synergistic and
this positive response was also reported by Nasreen and Haq (2002). Maximum (191 kg
ha-1 potash was taken by the sunflower crop when it was fertilized with sulphur and
nitrogen applied at 120 and 180 kg ha -1 .It was statistically similar to that produced with
sulphur and nitrogen at the rate of 80 and 120 kg ha-1. Data (Table 4.26) revealed that
total potash uptake ranged between 46.11 and 190.68 kg ha-1 under varying combinations
of N and S fertilization.
Achene yield in these experiments was optimistically associated with potash
uptake and regression accounted for 86 and 92 % variation in yield owing to P uptake
(Fig. 4.19).
4.1.4.4 Sulphur uptake (kg ha-1)
Application of sulphur enhanced S-uptake significantly (P≤0.05) over control
(Table 4.27) and the differences were also significant amongst the S levels used. On an
average, S application at 40, 80 and 120 kg ha-1 improved S-uptake by 29, 54 and 69
percent over control, respectively. S-uptake with 80 kg ha-1 S was about double than that
recorded with 40 kg-1 S but 10% less than that recorded with application of 120 kg ha-1 S.
Bhagat et al. (2005) also recorded significant increase in total sulphur uptake by the
sunflower crop with increase in sulphur application.
S-uptake was also improved significantly (P≤0.05) with nitrogen nutrition during
both the years of experimentation (Table 4.27). Application of 100, 140 and 180 kg ha-1 N
104
Table 4.26. Influence of sulphur and nitrogen nutrition on total potash uptake (kg
ha-1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 92.46 c 85.01 c 88.74
S2= 40 120.65 b 115.81 b 118.23
S3= 80 134.66 a 129.15 a 131.91
S4= 120 138.05 a 136.62 a 137.34
LSD at 5% 8.16 8.28
Nitrogen (kg ha-1)
N1= Control 60.32 d 59.16 d 59.74
N 2= 100 116.20 c 110.36 c 113.28
N 3= 140 145.15 b 137.65 b 141.40
N 4= 180 164.14 a 159.42 a 161.78
LSD at 5% 8.16 8.28
Interaction (S x N) NS
S1N1 46.48 46.11 46.30
S1N2 82.59 78.52 g 80.56
S1N3 101.20 99.36 f 100.28
S1N4 118.15 116.07 e 117.11
S2N1 60.44 63.44 gh 61.94
S2N2 108.52 113.35 ef 110.94
S2N3 128.87 133.44 d 131.16
S2N4 147.59 153.02 c 150.31
S3N1 57.22 60.31 hi 58.77
S3N2 120.02 124.31 de 122.17
S3N3 148.45 153.65 c 151.05
S3N4 166.04 177.91 ab 171.98
S4N1 62.05 66.77 gh 64.41
S4N2 127.11 124.88 de 126.00
S4N3 162.62 164.13 bc 163.38
S4N4 188.27 190.68 a 189.48
LSD at 5% NS 16.65
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
105
A
chen
e yi
eld
(Kg
ha-1
)
y = 15.052x + 477.07
R2 = 0.9228
0
500
1000
1500
2000
2500
3000
3500
0 50 100 150 200
y = 15.537x + 384.04
R2 = 0.8672
0
500
1000
1500
2000
2500
3000
3500
4000
0 50 100 150 200 250
Potassium uptake
Potash uptake (Kg ha-1)
Fig. 4.19. Relationship between achene yield (Kg ha-1) and potash uptake (Kg ha-1) a) 2006, b) 2007
(a)
(b)
106
Application of 100, 140 and 180 kg ha-1 N improved S-uptake by 118, 192 and 232
percent over control. Average data depicted 35 % higher S-uptake with application of 140
kg ha-1 N than that recorded with application of 100 kg ha-1 that declined to 13% with
application of 180 kg ha-1 N.
Different combinations of S and N application rates had a significant (P≤0.05)
bearing upon S-uptake during both the years of experimentation (Table 4.27). Increase in
S-uptake became more pronounced with increasing rates of N application. However, the
differences got narrow at higher N rates. Similarly, S-uptake improved with application of
S fertilization but the improvement was again associated with the nitrogen nutrition of the
crop as the response to S application was poor where N was not applied.
Data depicted a significant and positive correlation between achene yield and S-
uptake (Fig. 4.20). Regression accounted for 89 % variance in yield owing to S-uptake
and 80 to 85 kg ha-1of yield was associated with each kg ha-1 S taken up by the crop.
4.1.5 Economic Analysis 4.1.5.1 Benefit cost ratio
Growing sunflower was generally profitable according to almost all the treatments
except where no sulphur and nitrogen was applied in the sense of providing a positive net
income at a reasonable ratio between income and expenditure (Table i). Highest achene
yield 3084 kg ha-1 was recorded where sulphur was applied at the rate of 80 kg ha-1for
along with 140 kg ha-1 nitrogen. Computation of benefit cost ratio (BCR) revealed that
the highest BCR 2.38 was also pertinent to the same treatment. It was closely followed by
the BCR of 2.23 where sulphur was applied at the rate of 80 kg ha-1for along with 120 kg
ha-1 nitrogen with achene yield of 3018 kg ha-1 and a net income of Rs. 35425 ha-1.
Variables benefit cost ratios were computed for all S*N treatments that were also
corresponding to the relative yield performance of the same combination sulphur and
nitrogen. In this study all the treatments had BCR >1 except where no sulphur and
nitrogen was applied indicating that application of sulphur and nitrogen at any rate is
economically viable under these agro-ecological and market conditions of the region,
however for highest yield goals sulphur and nitrogen should be applied at the rate of 80
kg ha-1for along with 140 kg ha-1 nitrogen.
107
Table 4.27. Influence of sulphur and nitrogen nutrition on total sulphur (kg ha-1) of sunflower.
Treatments 2006 2007 Mean
Sulphur (kg ha-1)
S1= Control 13.53 d 12.85 d 13.19
S2= 40 17.41 c 16.54 c 16.98
S3= 80 20.79 b 19.75 b 20.27
S4= 120 22.93 a 21.80 a 22.37
LSD at 5% 1.63 1.60
Nitrogen (kg ha-1)
N1= Control 7.92 d 7.50 d 7.71
N 2= 100 17.30 c 16.45 c 16.88
N 3= 140 23.12 b 22.05 b 22.59
N 4= 180 26.31 a 25.00 a 25.65
LSD at 5% 1.63 1.60
Interaction (S x N)
S1N1 5.45 h 5.18 h 5.32
S1N2 12.26 f 11.65 f 11.96
S1N3 16.49 e 15.67 e 16.08
S1N4 19.92 d 18.92 d 19.42
S2N1 7.84 gh 7.45 gh 7.65
S2N2 15.77 e 15.00 e 15.39
S2N3 20.59 d 19.50 d 20.04
S2N4 25.42 bc 24.15 bc 24.79
S3N1 8.26 gh 7.85 gh 8.06
S3N2 19.01 de 18.05 de 18.53
S3N3 25.79 b 24.50 b 25.15
S3N4 30.08 a 28.80 a 29.44
S4N1 10.13 fg 9.50 fg 9.82
S4N2 22.17 cd 21.05 cd 21.61
S4N3 29.60 a 28.00 a 28.80
S4N4 29.81 a 28.00 a 28.90
LSD at 5% 3.26 3.24
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
108
Ach
ene
yiel
d (K
g ha
-1)
y = 80.924x + 795.04
R2 = 0.893
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20 25 30 35
y = 85.406x + 602.52
R2 = 0.8919
0
500
1000
1500
2000
2500
3000
3500
0 5 10 15 20 25 30 35
Sulphur uptake
Sulphur uptake (kg ha-1)
Fig. 4.20. Relationship between achene yield (kg ha-1) and sulphur uptake (kg ha-1)a) 2006, b) 2007
(a)
(b)
109
Table 4.27a: Benefit cost ratio for Experiment 1 2006-07 S=Sulphur N=Nitrogen
Cost of production (Rs. ha-1)
Cost of fertilizer PK (Rs.
ha-1)
Cost of seed (Rs.
ha-1)
Cost of Sulphur fertilizer (Rs. ha-
1)
Cost of Nitrogenous
fertilizer (Rs. ha-1)
Total expenditure
(Rs. ha-1)
Gross Income (Rs. ha-1)
Net Income (Rs. ha-1)
BCR
S1N1 12800/ 8697/- 1548/- 0 0 23045/- 17063.75 -5981.25 0.74 S1N2 12800/ 8697/- 1548/- 0 2821/ 25866/- 36295 10429.00 1.40 S1N3 12800/ 8697/- 1548/- 0 3952/- 26997/- 46580 19583.00 1.73 S1N4 12800/ 8697/- 1548/- 0 5083/- 28128/- 54187.5 26059.50 1.93 S2N1 12800/ 8697/- 1548/- 289/- 0 23334/- 25861.25 2527.25 1.11 S2N2 12800/ 8697/- 1548/- 289/- 2821/ 26155/- 46813.75 20658.75 1.79 S2N3 12800/ 8697/- 1548/- 289/- 3952/- 27286/- 58437.5 31151.50 2.14 S2N4 12800/ 8697/- 1548/- 289/- 5083/- 28417/- 61816.25 33399.25 2.18 S3N1 12800/ 8697/- 1548/- 579/- 0 23624/- 30068.75 6444.75 1.27 S3N2 12800/ 8697/- 1548/- 579/- 2821/ 26445/- 54718.75 28273.75 2.07 S3N3 12800/ 8697/- 1548/- 579/- 3952/- 27576/- 65535 37959.00 2.38 S3N4 12800/ 8697/- 1548/- 579/- 5083/- 28707/- 64132.5 35425.50 2.23 S4N1 12800/ 8697/- 1548/- 867/- 0 23912/- 28878.75 4966.75 1.21 S4N2 12800/ 8697/- 1548/- 867/- 2821/ 26733/- 54442.5 27709.50 2.04 S4N3 12800/ 8697/- 1548/- 867/- 3952/- 27864/- 60923.75 33059.75 2.19 S4N4 12800/ 8697/- 1548/- 867/- 5083/- 28995/- 59138.75 30143.75 2.04
110
DISCUSSION
Different combinations of sulphur and nitrogen fertilizers showed non-significant
influence on plant population at harvest (Table 4.1) in present studies. Uniform plant
population at harvest under all treatment combinations may be attributed to an even
germination that is characteristic of present-day sunflower hybrids. Saleem and Malik
(2004) and Iqbal (2008) also reported non-significant influence of fertilizer application on
final plant population of sunflower. On an average, application of 100 kg ha-1 N increased
plant height by 22% while the increase was 31% for 140 kg ha-1 N over control (Table
4.2). Positive response of plant height to N application has been reported by Poonia
(2002), Arif et al. (2003) and Akhtar (2004). Malik et al. (2004) and Ozer et al. (2004)
also observed increase in plant height with higher N doses, while Herdem (1999) and
Killi (2004) indicated non-significant impact of N application on plant height of
sunflower.
During both the years head diameters increased initially with sulphur application
up to 80 kg ha-1 S but exhibited a declining trend with further increase in S levels (Table
4.4). Larger heads harvested with S application were associated with more number of
grains thus giving more yields (Hassan et al., 2007). In contrary, less number of grains
developed on smaller heads would not have faced any competition for assimilates thus
produced heavier individual grain weight. Singh (2000), Bhaghat et al. (2005) and Hassan
et al. (2007) also reported increasing trend of sunflower head diameters with increasing
sulphur fertilization. Application of 100, 140 and 180 kg ha-1 N recorded 51, 62 and 63
percent increase in head diameter, respectively over control during both the years. Ozer
(2004) recorded maximum (20.73 cm) head diameter with 120 kg ha-1 nitrogen
application. Malik et al. (2004) and Khaliq (2004) also reported positive influence of N
application on sunflower head diameters, while Singh (2007) noted decrease in head
diameter by increasing nitrogen from 80 to 120 kg ha-1. The crop grown without sulphur
and nitrogen nutrition failed to achieve remarkable size of head and that was the
minimum size of head (9.34 cm). Sulphur fertilization during 2006 did not influence
number of achenes per head. However, during 2007, S application increased the number
of achenes by 3% over control and the difference between lower S levels being non-
significant over control (Table 4.5). Budhar et al. (2003) and Bhaghat et al. (2007)
observed significant influence of sulphur application on number of achenes in sunflower.
During both the years, application of 140 and 180 kg ha-1 N recorded highest and similar
111
(P≤0.05) number of achenes per head. The establishment of grain number around seed
formation stage is dependent on the translocation of assimilates to some extent (Andrade
1995). Nawaz et al. (2003), Khaliq (2004), Al-Thabet (2006) and Singh (2007) concluded
that increase in nitrogen application not only increased head size, but also enhanced the
number of achenes per head and ultimately better yield of sunflower. There was an
optimistic association between number of achenes per head and head diameter of the
sunflower crop (Fig 4.2). Number of achenes per head was also positively associated with
oil yield of sunflower in these studies (Fig. 4.3).
Heaviest 1000-achenes (53.94 g) were produced with sulphur application at 80 kg
ha-1, which was 20.48% more than that (44.77 g) without sulphur fertilization (Table 4.6).
Several authors (Singh et al., 2000; Poonia, 2000; Nasreen and Haq, 2002; Khan et al.,
2003; Bhagat et al., 2005; Hassan et al., 2007) have reported encouraging response of
achene weight to sulphur application in sunflowers. Maximum 1000-achene weight
(55.89 g) was recorded with application of 180 kg ha-1 nitrogen which was 48.52% higher
than control (no nitrogen). Several other authors (Ahmad et al., 2005; Ozer et al., 2004;
Poonia, 2000) observed a progressive and reliable raise in achene weight with addition in
N dose up to 160 kg ha-1. The significant interactive effect of sulphur and nitrogen
nutrition on test weight of sunflower was also reported by Singh (2000) and Sofi et al.,
(2004). 1000-achene weight was positively associated with oil yield of sunflower (Fig.
4.4), and regression accounted for 93% (90-96) of the variation in oil yield of sunflower
owing to difference/s in achene weight recorded under various treatments in these studies.
Final achene yield is the function of combined effect of all the yield components under
the influence of particular set of environmental conditions. Application of sulphur
enhanced achene yield significantly (P≤0.05) during both years of experimentation (Table
4.8). Doubling sulphur application over 40 kg ha-1 enhanced achene yield by 12% but
declined by 5% when S level was doubled further. Lega and Giri (1999), Sarkar et al.
(1999) and Hitsuda et al. (2005) also reported positive impact of sulphur fertilization on
achene yield of sunflower. Yield response trend of sunflower to sulphur application in
present studies is similar to that reported by Khan et al. (2003) who concluded that
sulphur dose of 50 kg ha-1 was superior in terms of producing high yield of fresh dry
matter, fresh disc weight, 1000 seed weight and total seed yield of sunflower. Application
of sulphur above 50 kg ha-1 reduced yield components and final seed yield, suggesting a
classical yield response curve. Nitrogen application also enhanced achene yield
significantly (P≤0.05) over control and a yield plateau was achieved with application of
112
140 kg ha-1 during both the years (Table 4.8). Application of 100 kg ha-1 enhanced achene
yield by 88% over control that was 126% when N application was increased by 40 kg ha-
1. Achene yield was increased by 134% over control with application of 180 kg ha-1 N
(Table 4.8). Zubillaga et al. (2002) recorded maximum achene yield with application of
150 kg ha-1 nitrogen while Arif et al. (2003) and Ozer et al. (2004) also recorded
substantial increase in achene yield with N application. Vegetative and generative growth
of plant reduces during N deficiency and premature senescence also occurs, consequently
decreasing yield (Narwal and Malik, 1985; Khokani et al., 1993; Legha and Giri, 1999
and Tomar et al., 1999).
Increase in achene yield can be attributed to improvement in light interception
(Table 4.14 ) and improved leaf area indices (Table4.10) resulting in better crop growth
rates (Table 4.12 ) recorded with higher doses of nitrogen. Increase in nitrogen
availability resulted in higher achene yield was closely related to the improvement in
yield components such as head diameter (Tomer (1997), Sadiq et al (2000), number of
achenes/head (Zubillaga et al.2002) and 1000 seed weight (Hocking et al.(1987), Mahal
et al.(1998), Georgio et al(1990), and Killi (2004). Sulphur nutrition had a significant
(P≤0.05) and positive bearing on harvest index (Table 4.9). Highest HIs (27.0-26.3) were
recorded with application of 80 kg ha-1 S during 2006 and 2007, respectively and had a
decreasing trend with increasing S level further. On an average, sulphur dose of 40 and 80
kg ha-1 improved HI by 18 and 21 percent, respectively over control. Harvest index
increased initially with N application so that maximum values (27-28 %) were recorded
with 140 kg ha-1 N and declined by about 7 % with increasing N to 180 kg ha-1. Decrease
in harvest index with the higher nitrogen application might be due to change in stability
between vegetative and reproductive growth towards unnecessary vegetative growth, and
hence, in reduced achene yields (Fara et al., 1981; Hocking et al., 1987).
Sulphur application enhanced development of leaf area indices (LAI) during both
the years (Fig. 4.5). LAI did not vary significantly (P≤0.05) amongst different levels of S
at 30 days after sowing (DAS) that started getting significant with the advancement in
developmental stage and became prominent at 60 DAS. Sing et al. (2000) reported that
increasing sulphur levels from zero to 45 kg ha-1 enhanced the leaf area index
significantly over control. Ahmad and Abdin (2000) also supported the positive effect of
sulphur on leaf area. Nitrogen application recorded significantly (P≤0.05) different leaf
area indices throughout crop growth period during both the years (Fig. 4.6). In contrary to
S, significant differences amongst different N levels were depicted at earlier stage and
113
were also more pronounced than those recorded for S. The increase in LAI was sharper
from 0 to 100 kg ha-1 N and became less steeper for next level (140 kg ha-1) and
ultimately achieved a plateau for 180 kg ha-1 N. LAI declined steadily after 75 DAS
during both the years achieving almost similar (P≤0.05) values at 90 DAS for all N-
applied plots. However, LAI in control plots declined only to slight extent (Fig.4.6).
Improvement in leaf area index with adequate supply of nitrogen has been recorded by
Fredeen et al. (1991). Photosynthetic activity and chlorophyll contents of sunflower plant
enhanced under adequate supply of N (160 kg ha-1) and improved leaf area as compared
with no nitrogen application (Ozer et al., 2004). Toth et al. (2002) attributed this
improvement to increase in chlorophyll content and Rubisco activity in sunflower crop.
Several authors (Hocking and Steer, 1983b&1989; Radin and Boyer, 1982; Blanchet et
al., 1987) have reported that shortage of N through the early vegetative stage may
decrease the number of leaves and limit their increase, and thus insufficient nitrogen
resulted in slower leaf area index. Singh et al. (2005) also reported that LAI and dry
matter production was enhanced as a result of N application (from 30 to 60 Kg ha-1). The
results of present studies also confirm these findings. The correlation analysis showed a
strong and positive association of the leaf area index with number of achenes per head
(Fig 4.7), 1000-achene weight (Fig 4.8), crop growth rate (Fig 4.9) and achene yield (Fig
4.10).
Sulphur nutrition enhanced leaf area duration (LAD) over control and the pattern
was same during both years of experimentation (Table 4.11). Comparatively lesser LAD
was recorded during 2007 and might be attributed to higher rains (Fig. 3.1) and hence
higher soil moisture available for better leaf area development (Fig. 4.5) throughout the
season. Nitrogen application significantly (P≤0.05) increased the leaf area duration over
control plots and maximum LAD (210.65-193.10 d) was recorded with 180 kg ha-1
nitrogen during both years. Khaliq (2004) and Iqbal (2008) also concluded that nitrogen
application improved leaf area duration of sunflower. Different combinations of S and N
had a non significant impact on LAD in present studies during both the years (Table
4.11). Periodic data at fortnight interval (Fig. 4.11 & 4.12) revealed that crop growth rate
(CGR) of sunflower crop progressively increased and achieved maximum value (21.21 g
m-2 d-1) at 75 DAS and declined sharply thereafter; reaching a value of 6.63 g m-2 d-1 at 90
DAS during 2006. Similar trend was observed during 2007 for this hybrid. Pattern of crop
growth rate as influenced by sulphur and nitrogen nutrition has been illustrated in figures
4.11 and 4.12 respectively. Sulphur application improved seasonal crop growth over
114
control during both years of experimentation (Table 4.12). Mean crop growth rate
improved with each incremental level of N. Sunflower crop grown without nitrogen
fertilization exhibited lowest mean CGR (6.37 g m-2 day-1) that was 135.47% and 91.67%
lower, when crop was sown with 140 and 100 kg ha-1 nitrogen rate respectively.
Approving results were recorded by Khaliq (2004) who concluded that nitrogen rate of
200 kg ha-1 presented highest mean crop growth rate in sunflower crop. There was a
positive and linear relationship between crop growth rate and achene yield (Fig 4.13)
during both the years of study and regression accounted for 91% (86.64-94.70%)
variation in achene yield.
Sulphur application exhibited a non-significant (P≤0.05) effect on net assimilation
rate of sunflower during both years of experimentation (Table 4.13). Nitrogen application
significantly increased NAR over control during both the years so that highest and similar
NAR values (5.07-5.01 g m-2 d-1) were recorded for 180 and 140 kg ha-1 N over control.
On an average, N rates of 100, 140 and 180 kg ha-1 improved NAR by 19, 32 and 33
percent, respectively over control. Shabeer (2009) reported similar range of NAR (4.75-
4.5 g m-2 d-1) for sunflowers grown under similar environments.
The total amount of incident photosynthetically active radiation received during
2006 and 2007 was 695 and 681 MJ m-2, respectively. Sulphur application enhanced
amount of intercepted radiation significantly (P≤0.05) during both years of study (Table
4.14). The enhancement in cumulative light interception was expected because of
improvement in LAI (Table 4.10) with increasing sulphur application rates which
concomitantly is associated with increase in intercepted photosynthetically active
radiation (Olsen et al., 2000). Maximum light interception (536.14-503.22 MJ m-2) was
recorded with 180 kg ha-1 nitrogen application during both years which was 24 and 20
percent higher than respective control values during 2006 and 2007. Cumulative PAR
interception during whole growing season by maize, sunflower and soybean recorded was
820, 700 and 720 M. J m-2 (Andrade, 1995). Improvement in radiation interception as a
consequence of nitrogen fertilization has been reported in many of previous studies. Hall
et al. (1995) reported that total cumulated intercepted radiation by sunflower crop
increased by 6% (from 928 to 971 MJ m-2), with increasing nitrogen from zero to 50 kg
ha-1. Positive impact of nitrogen application on radiation interception has been reported
by Khaliq (2004) under similar environments. Fernando and Miralles (2008) reported 20
and 7% increase in intercepted photosynthetic active radiation in wheat crop with
nitrogen and sulphur addition, respectively.
115
Hocking and Steer (1989) stated that N deficiency during early growth stages of
sunflower may reduce the leaf score and restricts their expansion, consequently reduction
in LAI and light interception may occur. An environmental stress has more pronounced
effect on foliar expansion than photosynthetic capacity of the crop (Fitter and Hay, 2002),
therefore, the crop grown under nitrogen and sulphur deficiency is expected to experience
decrease in LAI and intercepted photosynthetically active radiation. Kiniry et al. (2004)
also concluded that nitrogen deficiency reduced LAI of sunflower crop which is typically
associated with concomitant decrease in intercepted photosynthetically active radiation.
There was a optimistic and linear association between cumulative intercepted PAR and
LAI (Fig 4.14).
Translation of intercepted photosynthetically active radiation into new biomass is
termed as radiation use efficiency (Sinnclair and Muchow, 1999) and help measure net
carbon assimilation of a crop. Application of sulphur enhanced RUE(TDM) by 8-10 percent
over control, while the differences amongst different sulphur levels were non-significant.
Fernando and Miralles (2008) recorded increase in RUE of wheat crop with increasing
rates of sulphur nutrition that might be attributed to increase in photosynthesis with
increased sulphur application (Terry, 1976). Application of increasing levels of nitrogen
improved RUE(TDM) upto 140 kg ha-1 N during 2006 with a non significant increase with
180 kg ha-1 N (Table4.15 ). Hall et al. (1995) concluded that nitrogen supply influenced
RUE of sunflower and it increased from 1.01 g MJ-1 to 1.18 g MJ-1 with the increase in
nitrogen rate from zero to 50 kg ha-1. The values of RUE for sunflower in the study under
discussion are in confirmatory to those reported by Kiniry et al. (1989), Khaliq (2004)
and Iqbal (2008). The values of RUE for sunflower as reported by Connor et al. (1985),
Cox and Jolliff (1986) and Champan et al. (1993) for above ground dry matter were 1.75,
2.79, and 1.05 g MJ-1, respectively. Sinclair and Horie, (1989) reported that nitrogen
increased Rubisco activity in leaves and resulted an improvement in radiation use
efficiency (RUE), which is reliant on net CO2 assimilation (Loomis and Amthor, 1999).
Variation in leaf photosynthetic capability coupled by means of the translocation of N
from green leaves to grain (Sinclair and Horie, 1989), and rise in crop respiratory mass
for each constituent of leaf area (Whitfield et al., 1989) might be conscientious for
difference in RUE under varying nitrogen application rates. Different combinations of N
and S did not influence RUE (TDM) in these studies (Table 4.15).
Maximum and similar (P≤0.05) achene-protein (21.66-21.21 %) was recorded with the
application of 80 and 120 kg ha-1 sulphur, while a minimum (16.09%) was observed in
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control plots (Table 4.17). Increase in achene-protein contents with sulphur application is
in confirmatory to previous reports of Bhagat et al. (2005) and Sreenamannarayana et al.
(1998) who concluded that sulphur nutrition had a positive bearing on achene-protein
content. Poonia (2003) also recorded an increase in protein contents of sunflower in
response to sulphur application. Sulphur being an integral part of S-containing amino
acids, viz. cystein, cystine and methionine, also improved protein as well as oil synthesis
in (Tisdale et al., 1985) enhanced protein as well as oil synthesis in seeds. Sexton et al.
(1998) also supported the significant influence of sulphur on seed protein contents by
stating that protein quality of soybean seed could be enhanced by increasing the
concentration of S- containing amino acids. Maximum protein concentration (22.87-
23.07-%) was recorded with application of 180 kg ha-1 during 2006 and 2007. Achene-
protein improved with application of all N levels over control in these studies. Findings of
Malhi and Leach (2000), Khaliq (2004), Kuchar (2005) and Ahmad (2007) also supported
the results under discussion. Abundant supply of nitrogen enhances protein precursors
that are rich in N and there is strong tendency of photosynthates to be utilized for protein
formation and lesser of these are available for fat synthesis (Holmes, 1980). The inter-
relationships of the regulation of NO3- and SO4
2- assimilation might be an effective reason
to enhance net protein synthesis (Reuveny et al., 1980). The metabolic coupling between
N and sulphur has been reported by other authors(Blagrove et al., 1976; Randall et al.,
1979; Sexton et al., 1998),who found that relative sulphur-rich seed protein decreased in
crop raised with ample N but limited sulphur supply, and vice versa. Sofi et al. (2004)
reported similar findings while Ahmad et al. (2007) reported non-significant interactive
effect of sulphur and nitrogen on protein contents of canola. Fazli et al. (2008) concluded
that combined application of S and N enhanced the uptake and assimilation of nitrate,
thereby increased total nitrogen contents and finally resulted in an improvement in protein
contents.
Highest achene-oil content (44.17-44.04 percent) was recorded during two years
of study with the application of 120 kg ha-1 S (Table 4.18). Sunflower grown without S
application exhibited 38.38% achene-oil content, while application of 40, 80 and 120 kg
ha-1 S improved achene-oil content by 6, 13 and 15 percent, respectively over control.
The higher oil contents recorded with increasing sulphur levels is in line with the results
obtained by Ahmad et al.(1999). Poonia (2003) reported significant influence of sulphur
application on sunflower oil contents. Hassan et al. (2007) concluded that different levels
of sulphur (0, 10, 15, 20 kg ha-1) improved oil contents of the autumn planted sunflower
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from 38.1 to 45.1 %. Baghat et al. (2005) recorded highest oil contents (41.72%) with 40
kg ha-1 sulphur. Lowest achene-oil content (39.82-39.77 percent) was noted with
application of 180 kg ha-1 N. Relationship between the level of N application and seed oil
content has usually been shown to be inversely correlated (Xie and Zhou, 2003). Several
authors (Schneiter et al., 2002; Ali et al., 2004; Ozer et al., 2004; Al-Thabet, 2006) have
reported negative influence of nitrogen on seed oil concentration. Concentration of
protein in the kernels as recorded by Ivanov and Stoyanova (1978) ranged from 17 to
36%, while Khaliq (2004) recorded comparatively lower achene protein concentration
that ranged from 12 to 16% under similar environments. The significant negative
relationship between seed oil content and high nitrogen fertilization could be probably
attributed to the sugar translocation effecting oil synthesis (Salisbury & Ross, 1994).
Kutcher et al. (2005) attributed such negative relationship to the diluting effect of higher
seed yield at higher N application and the opposite relationship between protein and oil
content.
Oil yield of sunflower increased with S fertilization and maximum (1139-1041 kg
ha-1) was recorded with the application of S @ 80 Kg ha-1 during 2006 and 2007,
respectively (Table 4.19). The effect of sulphur application on the oil yield which is a
product of oil contents and achene yield was also studied by Poonia (2003) and Bhaghat
(2005) and they recorded positive and significant effect. Highest oil yield (1136 kg ha-1)
was recorded with application of 140 kg ha-1 N during 2006 that reached to highest value
(1115 kg ha-1) with further increased level (180 kg ha-1) of N during 2007.
Relative proportion of different fatty acids in edible oil, determines the superiority
of that oil and the oil that possesses higher percentage of poly-unsaturated fatty acids for
lowering cholesterol level in human body is considered of good quality (Cunnae ;1995).
Utilization of oils having larger proportion of un-saturated fatty acids has been found to
have constructive consequences on human health (Jing et al., 1997; Hu et al., 2001).
Some of the important fatty acids present in sunflower achene oil are discussed in this
portion. Concentration of oleic acid (18:1) in achene oil of sunflower varied significantly
(P≤0.05) under different sulphur levels (Table 4.20). Manaf and Hassan (2006) and
Ahmad and Abidin (2000) recorded inconsistent response of oleic acid to sulphur levels.
These results are contradictory to the findings of Misra et al. (2002). Application of
nitrogen had a significantly (P≤0.05) negative influence on oleic acid (18:1) (mono-
unsaturated fatty acid) concentration (Table 4.20). Khaliq (2004) and Iqbal (2008) also
reported negative impact of nitrogen on oleic acid contents of sunflower under similar
118
environmental conditions. These results are also in line with finding of Ahmad and Abdin
(2000). Application of sulphur and nitrogen increased the percentage of poly unsaturated
fatty acid (linoleic) and decreased mono unsaturated fatty acid (oleic) and hence
improved the quality of sunflower oil. Such inverse relationship between
monounsaturated (oleic acid) and polyunsaturated (linoleic acid) in sunflower has been
reported by Flageella et al. (2002).and Roberson (1981). While, Manaf and -Hasan (2006)
listed inconsistent differences for oleic acid and linoleic acid in Brassica. Moreover, there
is a strong negative association between oleic and linoleic acid so that a phenotype low in
oleic would definitely be high in linoleic one (Demurin et al., 2000). Sulphur application
had a significant (P≤0.05) bearing on linoleic acid (18:2) concentration in sunflower
achene oil only during 2006 (Table 4.21). However, the differences amongst sulphur
levels were non-significant. Increasing trend in linoleic acid concentration with sulphur
application in present studies is in line with the findings of Misra et al. (2002), while
Ahmad and Abidin (2002) reported contradictory results.
Data (Table 4.22) revealed that sulphur application did not influence the palmitic
acid (16:1) concentration to significant extent (P≤0.05) during both the years. Palmitic
acid concentration was in the range of 4.96 to 5.20%. Palmitic acid concentration
increased significantly (P≤0.05) with the application of nitrogen. The increase in palmitic
acid concentration with increasing nitrogen levels confirms the findings of Steer and
Seiler (1990) and Khaliq (2004). Momoh et al. (2004) also support the positive influence
of nitrogen application on palmitic acid concentration. However, Valtcho et al. (2009)
recorded that nitrogen rates within different planting dates of same hybrids had little or no
effect on palmitic acid concentration.
Sulphur application increased nitrogen uptake significantly (P≤0.05) during both
the years (Table 4.24). Application of N uptake was improved by 13 % when S rate was
increased from 40 to 80 kg ha-1, and increased slightly (by only 2%) when S application
was further increased to 120 kg ha-1. Bhaghat et al. (2005) observed an increase in
nitrogen uptake with sulphur application in sunflower crop that might be attributed to
synergistic effect of sulphur and nitrogen. Khandkar (1991), Sreemannarayana et al.
(1989) and Mrinalini et al. (1998) reported similar results that confirm the findings of
present work. Nitrogen application significantly (P≤0.05) enhanced N uptake by the crop.
Jackson (2000) reported that nitrogen application increased N contents in sunflower plant
and seed. Zubillaga et al. (2002) recorded an increase in N uptake up to 138 kg ha-1 with
increasing nitrogen fertilization up to 138 kg ha-1. Singh et al. (2005) reported a
119
significant increase in total biomass and total nitrogen uptake by sunflower with
increasing nitrogen rate up to 90 kg ha-1. Combined effect of sulphur and nitrogen in
increasing total nitrogen uptake was also reported by Nabi et al.(1995) and Fazli et al.
(2008) who attributed this increase to the increase in nitrate reductase activity, that
regulate NO3-N into the amino acids. The increase in total nitrogen (kg ha-1) by rapeseed
and mustard with the combined effect of nitrogen and sulphur has also been reported by
other workers (Brown et al., 2000; Ahmad et al., 2001; Abdin et al., 2001). Fig (4.17)
revealed that there was a positive correlation between achene yield and nitrogen uptake
by sunflower crop during both the years and regression accounted for (90-94 %) variance
in achene yield.
Sulphur application had a pronounced (P≤0.05) effect on total P uptake by
sunflower crop during both years of experimentation (Table 4.25). Increasing levels of S
up to 80 kg ha-1 resulted in corresponding increase in P uptake that did not increase
further with next level of S in these studies. Agarwal et al. (2000) recorded an increase in
phosphorus uptake with sulphur application at the rate of 40 kg ha-1. Nasreen and Haq
(2002) reported synergistic effect of sulphur on P uptake and recorded an increase in P
uptake upto 35 kg ha-1 with increasing level of sulphur application upto 80 kg ha-1 in
sunflower crop. Sing and Chaudhuri (1996) recorded similar results in groundnut. Singh
and Singh (2007) also recorded positive response of P uptake by linseed with increasing
sulphur application rate. Increasing levels of nitrogen fertilization significantly (P≤0.05)
enhanced total P uptake in sunflower (Table 4.25). Sreemannarayana et al. (1998)
recorded an increase in phosphorus uptake by sunflower with an increase in nitrogen
application (from zero to 100 kg ha-1). The significant increase in P2O5 uptake (2.4 to 78
kg ha-1) with enhancement in achene yield from 500 to 3500 kg ha-1 in sunflower crop
was reported by (Angelova and Christov, 2003).
Sulphur fertilization showed significant (P≤0.05) influence on total K uptake by
the crop during both the years (Table 4.26). Application of 120 kg ha-1 S resulted in
highest total K uptake 135-129 kg ha-1) during two years of study. However, a lower dose
of S (80 kg ha-1) exhibited similar (P≤0.05) level of total K uptake. Sreemannarayana et
al. (1998) recorded an increase in potash uptake by sunflower with an increase in sulphur
application (from zero to 60 kg ha-1). Increase in potash uptake by sunflowers with
increasing sulphur application levels was also recorded by Nasreen and Haq (2002), while
Singh and Chaudhary (1996) reported similar results for groundnuts. Nitrogen application
120
resulted in significant (P≤0.05) increase in total K uptake by sunflower during both the
years.
Application of sulphur enhanced S-uptake significantly (P≤0.05) over control
(Table 4.27) and the differences were also significant amongst the S levels used. Bhagat
et al. (2005) also recorded significant increase in total sulphur uptake by the sunflower
crop with increase in sulphur application. Screemannarayana et al. (1998) and Mrinalini
et al. (1998) confirmed the positive response of sulphur uptake with application of
sulphur nutrition. S-uptake was also improved significantly (P≤0.05) with nitrogen
nutrition (Table 4.27).
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4.2: Experiment II: Radiation interception, radiation use efficiency and productivity of different genotypes of sunflower under varying row spacing/planting densities
4.2.1. Agronomic Traits
4.2.1.1. Number of plants m-2
A good crop stand per unit area established by optimum plant population leads to
higher crop yield of sunflower. As regards hybrids of different maturity groups under
study, there was a non-significant (P≤0.05) difference among the hybrids (Table 4.28)
during both the years. This might be attributed to uniform germination and seedling
establishment of the three hybrids as well as absence of lodging in any of the hybrids used
in these studies. Saleem (2004) and Iqbal (2008) also recorded non-significant differences
in final number of plants per unit area for various sunflower hybrids.
Plant population at harvest varied significantly (P≤0.05) with change in row
spacing (Table4.28) during both years of study. At a constant plant to plant distance of
22.5 cm used in these experiments, widening the row spacing from 45 to 60 cm resulted
in 33% decrease in plan density that declined further by 24% when the crop was sown at
75 cm row spacing (Table 4.28). The change in number of plants m-2 was also recorded
by Iqbal (2008) with variation in row to row distance.
The interaction among hybrids and row spacing was found to be non-significant
during both the years depicting that plant density varied owing to row spacing
irrespective of hybrids used.
4.2.1.2 Number of days taken to maturity (d)
As regards hybrids of different maturity groups under study, there was a
significant (P≤0.05) difference among the hybrids (Table 4.29). During both the years,
Hysun-33 took 102 days to reach its maturity and statistically was different with rest of
the hybrids (SF-187 and FH-331) which were statistically at par with each other (Table
4.29). Steer and Hocking (1987) reported that there were small differences in time taken
from sowing to maturity among short stature (early maturity) and taller (late maturity)
hybrids. Johnson and Schneiter (1998) reported hybrids representing the greatest
available diversity for maturity and plant height The differential response of sunflower
hybrids regarding time taken to maturity may attributed to variable genetic character for
the respective hybrids to this trait. Iqbal (2008) also recorded significant difference
among the hybrids for time taken to maturity.
122
Table 4.28 Influence of different row spacing on number of plants m-2 of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 7.58 7.57 7.58
H2= SF-187 7.54 7.59 7.57
H3= Hysun-33 7.59 7.58 7.59
LSD at 5% NS NS
Row spacing (S)
S1= 45 cm 9.63 a 9.63 a 9.63
S 2= 60 cm 7.26 b 7.24 b 7.25
S 3= 75 cm 5.84 c 5.86 c 5.85
LSD at 5% 0.03 0.06
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
123
Table 4.29. Influence of different row spacing on number of days taken to
maturity (days) of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 91.67b 91.00b 92
H2= SF-187 95.44b 94.89b 94
H3= Hysun-33 102.10 a 101.19 a 102
LSD at 5% 4.19 4.71
Row spacing (S)
S1= 45 cm 96.78 96.78 96
S 2= 60 cm 95.67 94.56 95
S 3= 75 cm 96.6 95.67 96
LSD at 5% N.S N.S
Interaction (H x S) N.S N.S
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
124
Sunflower crop sown at varying row spacing did not effect the time taken to
maturity and results depicted in Table 4.29 showed non- significant (P≤0.05) difference
for the time taken to maturity among different planting densities.
4.2.1.3 Plant height
Plant height is a function of both genetic constitution of a plant and the
environmental conditions under which it is grown. Differences in plant height among
different hybrids were significant (P≤0.05) during both the years. During both the years,
tallest plants (176 and 180 cm) were produced by Hysun-33 and plant height of this
hybrid was 28% higher than that of SF-187 and FH-331. SF-187 (141 cm) and FH-331
(140 cm) were statistically at par with each other (Table 4.30). The differential response
of sunflower hybrids regarding plant height may attributed to variable genetic potential
for the respective hybrids to this trait.Johnson and Schneiter (1998) reported hybrids
representing the greatest available diversity for maturity and plant height.
Varying row spacing (plant population) had a significant (P≤0.05) effect on plant
height during both years of experimentation (Table 4.30) and tallest plants (157.67 cm)
were produced when crop was sown in 45 cm apart rows (98765 plants ha-1) and shortest
plants (149.44 cm) were recorded in 75 cm row spacing (59259 plants ha-1), the later was
statistically at par with the plants grown at 60 cm apart.
Higher plant populations produced taller plants and more yield than lesser plant density
(Beg et al., 2007).These results are in agreement with the findings of Sedghi et al. (2008)
and Iqbal (2008), and opposite to those of Van Deynze et al. (1992).
4.2.1.4. Stem diameter
Different hybrids showed significant (P≤0.05) differences in stem diameters during 2006
only (Table4.31). SF-187 and Hysun-33 produced the thickest and similar stems as
compared with FH-331 (1.67 cm). In the year 2007, non significant results were found
regarding stem diameter that ranged from 1.71 to 1.77 cm. The significant differences for
stem diameter between the hybrids have also been reported by Ozer (2004), while the
non-significant differences regarding stem girth among the hybrids were reported by
Tunio et al. (1999.
Widening the row spacing increased the stem diameter significantly during both
the years of investigation (Table 4.31). On an average, minimum (1.67 cm) stem diameter
was recorded when the crop was sown at 45 cm apart row spacing that improved by 5%
and 11% when the crop was sown at 60 and 75 cm apart rows, respectively.
125
Table 4.30. Influence of different row spacing on plant height (cm) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 139.60 b 141.11 b 140.36
H2= SF-187 140.70 b 137.67 b 139.19
H3= Hysun-33 180 a 176.33 a 178.17
LSD at 5% 3.43 6.69
Row spacing (S)
S1= 45 cm 157.70 a 156.67 a 157.19
S 2= 60 cm 153.10 ab 151.22 ab 152.16
S 3= 75 cm 149.40 b 147.22 b 148.31
LSD at 5% 5.36 5.46
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
126
Table 4.31. Influence of different row spacing on stem diameter (cm) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 1.67 b 1.70 1.69
H2= SF-187 1.88 a 1.77 1.83
H3= Hysun-33 1.79 ab 1.76 1.78
LSD at 5% 0.14 NS
Row spacing (S)
S1= 45 cm 1.68 b 1.66 b 1.67
S 2= 60 cm 1.76 b 1.75 ab 1.76
S 3= 75 cm 1.90 a 1.82 a 1.86
LSD at 5% 0.10 0.11
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
127
Higher plant populations produced thinner stems, more yield than lesser plant
density (Beg et al., 2007).An increasing trend in stem diameter with decreasing plant
population was however, reported by Ekin et al. (2005), Al-Thabat (2006) and Sedghi et
al. (2008). Different combinations of hybrids and row spacing depicted a non-significant
influence on stem diameters of the used hybrids in these studies (Table 4.31) during both
the years of experimentation.
4.2.1.5 Head diameter
Head diameter contributes substantially to achene yield of sunflower because of its
contribution towards number of achenes per head and achene size. Different sunflower
hybrids produced heads that varied significantly (P≤0.05) in diameter (Table 4.32).
During both the years, SF-87 recorded maximum (18.57-18.14 cm) head diameter and
was followed by Hysun-33 (16.86-16.65 cm) and FH-331(16.10-15.87 cm). SF-187
recorded head diameter that was 15 % larger than that of FH-331 and 5 % larger than that
of Hysun-33. Variation in head size of hybrids of different genetic background was also
reported by Tunio et al. (1999), Reddy et al. (2002), Khaliq (2004) and Iqbal (2008).
Row spacing also significantly affected head diameter and similar trend for both
years was recorded (Table 4.32). On an average, maximum head diameter (18.02 cm) was
recorded for sunflower planted on 75 cm apart rows. Narrowing the row spacing from 75
to 45 cm resulted in 14% decrease in head diameter. Increasing row spacing from 45 to
60 cm produced 9% larger heads and further increase in row spacing (75 cm) further
increased head diameter by 4%.
Different sunflower hybrids planted on variable row spacing depicted significantly
(P≤0.05) different head diameters during both years of experimentation (Table 4.32). SF-
187 recorded the largest head diameter when planted at all row spacings. It was followed
by FH-331 at 45 cm row spacing and Hysun-33 at 60 and 75 cm apart rows. Head
diameter of FH-331 improved to greater extent when row spacing increased from 45 to 60
cm and did not improve with further widening of row spacing. Similarly, head size of SF-
187 showed lesser flexibility to changing row spacing. On the other hand, head diameter
of Hysun-33 showed greatest flexibility to varying row spacing especially when it was
increased from 45 to 60 cm (14.70 vs. 17.5 cm head diameter) that did not improve
anymore by further widening the row spacing.
128
Table 4.32. Influence of different row spacing on head diameter (cm) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 16.10 c 15.87 c 15.99
H2= SF-187 18.57 a 18.14 a 18.36
H3= Hysun-33 16.86 b 16.65 b 16.76
LSD at 5% 0.55 0.60
Row spacing (S)
S1= 45 cm 15.83 c 15.76 c 15.80
S 2= 60 cm 17.49 b 17.08 b 17.29
S 3= 75 cm 18.22 a 17.82 a 18.02
LSD at 5% 0.69 0.46
Interaction (H x S)
H1S1 15.13 ef 15.00 f 15.07
H1S2 16.27 de 15.80 e 16.04
H1S3 16.90 cd 16.80 d 16.85
H2S1 17.77 bc 17.43 bcd 17.60
H2S2 18.40 ab 18.20 ab 18.30
H2S3 19.55 a 18.78 a 19.17
H3S1 14.58 f 14.83 f 14.71
H3S2 17.80 bc 17.25 cd 17.53
H3S3 18.20 b 17.87 bc 18.04
LSD at 5% 0.39 0.80
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
129
Variation in head size of hybrids of different genetic background was also
reported by Tunio et al. (1999), Reddy et al. (2002), Khaliq (2004) and Iqbal (2008).
Row spacing also significantly affected head diameter and similar trend for both years
was recorded (Table 4.32). On an average, maximum head diameter (18.02 cm) was
recorded for sunflower planted on 75 cm apart rows. Narrowing the row spacing from 75
to 45 cm resulted in 14% decrease in head diameter. Increasing row spacing from 45 to
60 cm produced 9% larger heads and further increase in row spacing (75 cm) further
increased head diameter by 4%.
Plants planted at higher plant populations produced lighter seeds, thinner stems,
taller plants and more yield than lesser plant density (Beg et al., 2007).
Different sunflower hybrids planted on variable row spacing depicted significantly
(P≤0.05) different head diameters during both years of experimentation (Table 4.32). SF-
187 recorded the largest head diameter when planted at all row spacings. It was followed
by FH-331 at 45 cm row spacing and Hysun-33 at 60 and 75 cm apart rows. Head
diameter of FH-331 improved to greater extent when row spacing increased from 45 to 60
cm and did not improve with further widening of row spacing. Similarly, head size of SF-
187 showed lesser flexibility to changing row spacing. On the other hand, head diameter
of Hysun-33 showed greatest flexibility to varying row spacing especially when it was
increased from 45 to 60 cm (14.70 vs. 17.5 cm head diameter) that did not improve
anymore by further widening the row spacing.
4.2.1.6 Number of achenes per head
Number of achenes per head differed significantly (P≤0.05) among the three
hybrids during both years of experimentation (Table 4.33). During both the years, FH-331
and SF-187 recorded similar number of achenes per head (657 vs. 678) that was out
yielded by those of Hysun-33 with 789 achenes per head. Hysun-33 recorded 16 and 20
percent higher number of achenes per head than SF-187 and HS-331, respectively.Several
other authors (Ahmad et al. 1997, Saleem and Malik, 2004 and Iqbal (2008) have
reported such significant differences among various hybrids.
Row spacing also had a significant (P≤0.05) bearing upon number of achenes per
head. During 2006, widening the rows from 45 cm to 75 cm, improved achenes per head
by about 12% that was only 8% when rows were widened upto 60 cm and the difference
between 60 and 75 cm was non-significant (P≤0.05). During 2007, the crop that was
130
Table 4.33. Influence of different row spacing on number of achenes head-1 of
diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 655.69 b 657.67 b 657
H2= SF-187 673.80 b 682.68 b 678
H3= Hysun-33 793.80 a 783.33 a 789
LSD at 5% 28.54 26.63
Row spacing (S)
S1= 45 cm 664.09 b 657.83 c 661
S 2= 60 cm 718.20 a 710.78 b 714
S 3= 75 cm 741.00 a 754.83 a 748
LSD at 5% 28.90 27.02
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
131
planted at 75 cm apart rows recorded maximum number of achenes. Narrowing the width
between rows had an oppressive effect on the number of achenes per head and it declined
by 6% and 15% at time when row spacing was decreased to 60 and 45 cm. respectively.
Different sunflower hybrids sown at varying plant spacing showed non-significant
(P≤0.05) differences in number of achenes per head in these studies, during both years of
experimentation. (Table 4.33) Diepenbrock et al. (2001) reported that number of achenes
per head was reduced with decreasing row spacing from 50 to 75 cm, but the quantity of
achenes m-2 increased significantly with decreasing row spacing. These results suggested
that number of achenes per head increased with increasing head size. Nawaz et al. (2001)
also confirmed that number of achenes per head and 1000-achene weight was greater with
the plants sown in wider rows.
4.2.1.7 Number of achenes m-2
Although number of achenes per head gives an insight into the ability of individual plants
towards yield formation but in field crops it is more common to look for management
options where more number of achenes are harvested per unit area. During 2006, FH-331
and SF-187 produced similar (P≤0.05) number of achenes m-2 that were, however, 20 and
17 percent higher than the former hybrids, respectively (Table 4.34). During 2007, the
difference between FH-331 and SF-187 was significant with 4% higher achenes recorded
for later hybrid and Hysun-33 again out yielded both the former hybrids in producing
higher achenes.
Differential response of hybrids to produce achenes per unit area might be
attributed to their genetic variability. Diepenbrock et al. (2001) reported that number of
achenes per head was reduced with decreasing row spacing from 50 to 75 cm, but the
quantity of achenes m-2 increased significantly with decreasing row spacing.
Different row spacing (plant population) had a significant influence on number of
achenes m-2 produced during both years of study (Table 4.34). Narrowing row spacing
(increasing plant population) had a positive bearing on the number of achenes m-2. Crop
planted on 75 cm apart rows recorded lowest number of achenes m-2 that was improved
by 19 and 45% when row spacing was narrowed down to 60 and 45 cm, respectively.
Increase in achenes per unit area was attributed primarily to higher planting density
(Table 4.34), and hence more achenes per unit areas in crop sown at narrow row spacing
132
Table 4.34. Influence of different row spacing on number of achenes m-2 of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 4934 b 4935 c 4935
H2= SF-187 5074 b 5126 b 5100
H3= Hysun-33 5914 a 5849 a 5882
LSD at 5% 205.20 173.7
Row spacing (S)
S1= 45 cm 6390 a 6338 a 6364
S 2= 60 cm 5209 b 5244 b 5227
S 3= 75 cm 4323 c 4428 c 4376
LSD at 5% 215.4 227
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
133
as compared with wider row plantation. .Diepenbrock et al. (2001) also reported that
achene number m-2 increased significantly with increasing planting density from 40,000
to 120,000 plants ha-1. Borous et al. (2004) and Calvino et al. (2004) also reported more
achenes per unit area owing to higher planting densities in sunflowers.
Different combinations of sunflower hybrids and row spacing had a non
significant (P≤0.05) influence on number of achenes per m-2 (Table 4.34) revealing that
achenes per unit area increased with narrowing row spacing irrespective of the hybrid.
4.2.1.8 1000-achene weight
Extent of development of achenes under any agronomic practice or of various
hybrids is evaluated on basis of 1000-achene weight, which plays a leading role in yield
formation of sunflower. Achene weight of the three hybrids varied significantly (P≤0.05)
and during both the years of experimentation, FH-31 produced the lightest achenes (Table
4.35). SF-187 recorded maximum achene weight that was 13, and 8 percent higher than
that recorded for FH-331 and Hysun-33, respectively. Although Hysun-33 produced more
number of achenes per head (Table 4.33) than SF-187 but the later had higher head
diameter (Table 4.30) as compared with Hysun-33 implying better development of fewer
achenes in wider head spacing in SF-187. Differential response of sunflower hybrids to
1000-achene weight was also reported by Ahmad et al. (1997), Behrooznia et al. (1999).
Khaliq (2004) and Ekin et al. (2005) reported similar results.
Row spacing (plant population) had also significant (P≤0.05) effect on 1000-
achene weight of sunflower (Table 4.35) during both years of experimentation. On an
average maximum 1000-achene weight (57 g) was recorded when the crop was sown at
75 cm apart row spacing. Achene weight was reduced by 11 and 33 % when row spacing
was decreased to 60 and 45 cm, respectively.
Different combinations of sunflower hybrids and row spacing influenced achene
weight to significant (P≤0.05) level only during 2006. Although achene weight was
improved with reducing planting density (widening row spacing) in all the hybrids but the
response was different. Achene weight of Hysun-33 was improved by 32% when row
spacing was increased from 45 to 60 cm while further improvement was only 8% when
row spacing was increased to 75 cm. In contrary to this, the achene weight of FH-331
improved by only 13% when row spacing was increased from 45 to 60 cm that was 23%
for SF-187. Highest improvement in achene weight was also recorded for the later hybrid
when row spacing was increased from 60 to 75 cm.
134
Table 4.35. Influence of different row spacing on 1000-achene (g) weight of
diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 47.86 c 46.82 c 47.34
H2= SF-187 54.06 a 52.57 a 53.32
H3= Hysun-33 50.06 b 48.67 b 49.37
LSD at 5% 1.23 1.08
Row spacing (S)
S1= 45 cm 42.76 c 42.18 c 42.47
S 2= 60 cm 51.95 b 49.88 b 50.92
S 3= 75 cm 57.28 a 55.99 a 56.64
LSD at 5% 1.72 3.30
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
135
4.2.1.9 Achene yield (kg ha-1)
Achene yield (Table 4.36) of hybrids under study differed significantly (P≤0.05)
during both the years. During 2006, Hysun-33 and SF-187 recorded highest and similar
achene yield (2856 and 2588 kg ha-1) that were 24 and 12 percent higher than that
recorded for FH-331. During 2007, Hysun-33 out yielded both the hybrids by recoding
2741 kg ha-1 achene yield that was 21% higher than achene yield of FH-331 (2256 kg ha-
1) and 9% higher than SF-187 (2519 kg ha-1). Studies have shown that hybrids vary in
their potential to perform under variable environments and yields are different even under
similar conditions. Andrade et al. (2002) reported differential response of Zenit (short
season) and Ramcull (long season) hybrids to yield.
Row spacing significantly influenced achene yield of hybrid sunflower during
both the years of study (Table 4.36). Crop planted in 45 and 60 cm apart rows recorded
highest and similar achene yield during 2006 than that planted in 75 cm apart rows.
However, during 2007, the wider row plantation (75 cm) recorded as good achene yield
as was recorded with 60 cm wide row plantation. The later row distance in turn recorded
achene yield that was similar to that recorded for crop planted at 45 cm apart rows. On an
average, increasing row spacing from 45 cm to 60 and 75 cm reduced achene yield by 4
and 12 percent, respectively, and the difference between later two being 12%.
The response of hybrids to varying row spacing (Table 4.36) was significantly
different (P≤0.05) in terms of achene yield. Achene yield of FH-331 decreased by 14%
when row to row distance was increased from 45 to 60 cm and the reduction was by 23%
when it was increased to 75 cm. SF-187 also recorded decrease in achene yield by
increasing row spacing but the magnitude of decrease was almost 50% than that recorded
for preceding hybrid. In contrary to both of these hybrids, Hysun-33 exhibited increase in
yield by 10% when row distance was increased from 45 to 60 cm that was only 1% when
row distance was widened to 75 cm. However, the achene yield was similar (P≤0.05) at
the three row spacing in this hybrid.
Andrade et al. (2002) reported that the response of Zenit (short season) and
Ramcull (long season) hybrids was encouraging to contracted rows in expressions of
proportionate raise in light interception and achene yield of the sunflower hybrids.
Maximum radiation interception at blossoming in spacious rows was achieved with the
extended season hybrid (Ramcull), and rejection to positive response of achene yield to
contracted rows was experienced, that is contrary to observations of Zaffaroni and
Schneiter (1991).
136
Table 4.36. Influence of different row spacing on achene yield (kg ha-1) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 2311 b 2256 c 2284
H2= SF-187 2588 a 2519 b 2554
H3= Hysun-33 2856 a 2741 a 2799
LSD at 5% 272 217
Row spacing (S)
S1= 45 cm 2722 a 2630 a 2676
S 2= 60 cm 2628 a 2524 ab 2576
S 3= 75 cm 2405 b 2362 b 2384
LSD at 5% 187 166
Interaction (H x S)
H1S1 2633 bc 2533 bcd 2583
H1S2 2267 de 2233 de 2250
H1S3 2033 e 2000 e 2017
H2S1 2783 ab 2740 ab 2762
H2S2 2583 bcd 2450 bcd 2517
H2S3 2398 cd 2367 cd 2383
H3S1 2750 ab 2617 abc 2684
H3S2 3033 a 2888 a 2961
H3S3 2783 ab 2717 ab 2750
LSD at 5% 324 287
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
137
4.2.1.10 Stover yield (kg ha-1)
The three hybrids produced significantly different (P≤0.05) stover yield during
both the years (Table 4.37). Highest stover yield during both the years (8030-7579 kg ha-
1) was recorded for Hysun-33 that was, on an average, 24% higher than stover yield of
FH-331 and 14% higher than that recorded for SF-331. This differential behavior of
varying maturing hybrids was due to inherited capacity of each hybrid. Higher stover
yields of the hybrids are attributed to their respective plant heights which contribute a
large towards stover of sunflower crop. Khaliq (2004) also reported variable stover yield
of sunflower hybrids with different morphological characters.
During 2006, maximum (7621 kg ha-1) stover yield (Table 4.37) was produced
when the sunflower was sown at 45 cm apart rows (98765 plants ha-1). Increasing row
spacing from 45 to 60 cm, resulted in 9% decrease in stover yield that was further
decreased by 7% when crop was planted in 75 cm spaced rows. Almost similar trend of
increasing stover yield with increasing plant population was realized during second year
of experimentation. More stover yield in narrow row plantations was due to taller plants
(Table 4.30) recorded at narrow row spacing.
The three hybrids grown in variable row distances showed a non-significant (P≤0.05)
difference in stover yield during both years of experimentation (Table 4.37).
4.2.1.11. Harvest index (%)
A harvest index (H.I) show the ratio of economic yield to biological yield and is
indicative of the proportionate translocation of assimilates into economic yield. Data
(Table 4.38) exhibited that harvest indices of the three hybrids in present studies did not
vary to significant (P≤0.05) level. Harvest indices were in range of 25.98 to 27.41
percent. Miralles et al. (1997) also reported the non-significant differences in H.Is of
various sunflower hybrids, while Saleem (2004) and Iqbal (2008) reported that H.Is of
different sunflower hybrids varied significantly. Non significant differences in hybrids of
different plant heights might be attributed to concomitant higher achene yields
(Table4.36) associated with taller (long duration) plants thereby resulting in non-
significant H.Is.
Varying row spacing also depicted non-significant (P≤0.05) differences in HIs in
these studies (Table 4.38). Steer et al. (1986) and Diepenbroke et al. (2001) reported that
increasing plant population resulted in decline in H.I. This decrease might be due to more
stover yield (Table 4.37) produced in narrow row spacing (increased plant population).
138
Table 4.37. Influence of different row spacing on stover yield (kg ha-1) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 6117 c 6444 b 6281
H2= SF-187 7028 b 6646 b 6837
H3= Hysun-33 8030 a 7579 a 7805
LSD at 5% 558 660
Row spacing (S)
S1= 45 cm 7621 a 7466 a 7544
S 2= 60 cm 6991 b 6854 ab 6923
S 3= 75 cm 6563 b 6349 b 6456
LSD at 5% 553 710
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
139
Table 4.38. Influence of different row spacing on harvest Index (%) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 27.41 25.98 26.70
H2= SF-187 26.96 27.53 27.25
H3= Hysun-33 26.35 26.67 26.51
LSD at 5% NS NS
Row spacing (S)
S1= 45 cm 26.52 26.16 26.34
S 2= 60 cm 27.34 26.93 27.14
S 3= 75 cm 26.85 27.08 26.96
LSD at 5% NS NS
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
140
4.2.2 Growth
4.2.2.1. Leaf area index
Patterns of development of leaf area index (LAI) are presented in Fig.4.21a&b.
During both the years, leaf area index increased slowly in the beginning of crop season
and crop started fast accumulation of LAI at 45 days after sowing that reached to its
maximum value at 75 days after sowing and started declining thereafter. The differences
amongst the hybrids remained non-significant (P≤0.05) upto 60 days after sowing beyond
which the difference/s in LAIs were more evident. The highest values of LAIs were
reached at flowering stage. Long season hybrid Hysun-33 exhibited highest LAI (5.10),
followed by SF-187 (4.49), which was statistically at par with FH-331 (4.32). Zaffaroni
and Schneiter (1991) reported that semi dwarf and medium stature sunflower hybrids
grown at different row arrangements had non-significant differences in leaf area index
(LAI).
The differences in LAI of sunflowers planted at different row spacing were
significant (P≤0.05) throughout the growing season (Fig.4.22a&b.). During 2006, highest
LAI (5.20) was recorded for the crop sown at 60 cm apart rows that declined to 4.50 and
4.32 for 45 and 75 cm apart rows, respectively. During 2007, maximum LAI (5.01) was
observed when the crop was sown at 45 cm apart row spacing and was statistically at par
with that of the crop planted at 60 cm apart rows, while the lowest (4.46) was recorded at
75 cm apart rows. Similar patterns of LAI for these row spacing were recorded during the
second year. Time of achieving maximum leaf area indices corresponded to their
flowering times in respective row spacing. Zaffaroni and Schneiter (1991) reported that
semi dwarf and medium stature sunflower hybrids grown at different row arrangements
had non-significant differences regarding leaf area index (LAI).
An optimistic and compareable association was observed between LAI and achene
yield of sunflower (Fig. 4.20) and the regression accounted for 77% variance in achene
yield owing to difference in LAIs
141
Lea
f ar
ea in
dex
0
1
2
3
4
5
6
30 45 60 75 90
FH 331 SF 187 Hysun 33
0
1
2
3
4
5
6
30 45 60 75 90
FH 331 SF 187 Hysun 33
Days after sowing
Fig. 4.21: Patterns of leaf area index with time: comparison of different sunflower hybrids during (a) 2006 and (b) 2007 ±SD
(a) 2006
(b) 2007
142
Lea
f ar
ea in
dex
0
1
2
3
4
5
6
30 45 60 75 90
45 cm 60 cm 75 cm
0
1
2
3
4
5
6
30 45 60 75 90
45 cm 60 cm 75 cm
Days after sowing
Fig. 4.22: Patterns of leaf area index with time: comparison of different row spacing during (a) 2006 and (b) 2007
(a) 2006
(b) 2007
143
4.2.2.2 Crop growth rate
Periodic data at fortnight intervals (Fig. 4. 23a&b) revealed that crop growth rate
(CGR) of Hysun-33 progressively increased and achieved maximum value (21.21 g m-2 d-
1) at 75 DAS and declined sharply thereafter; reaching a value of 6.63 g m-2 d-1 at 90 DAS
during 2006. Similar trend was observed during 2007 for this hybrid. Early maturing
hybrid FH-331 recorded maximum CGR (19.30 g m-2 d-1) at 60 DAS that declined
slightly (16.75 g m2 d-1) at 75 DAS and reached lower level (1.85 g m-2 d-1) at 90 DAS.
Almost the same trend was exhibited by SF-187 and the maximum (20.45 g m-2 d-1) and
the minimum (3.81 g m-2 d-1) CGRs were recorded at 60 and 90 DAS, respectively.
During 2007, SF-187 showed slight increase (19.89 to 20.10 g m-2 d-1) in CGR from 60 to
75 DAS and then reached to its minimum (2.47 g m-2 d-1) level at 90 DAS, while FH-331
recorded the similar trend during both years.
Regarding row spacing, crop planted at 45 cm apart rows showed maximum CGR
throughout the growing season as compared to plants grown at 60 and 75 cm apart rows
for both the years.(Fig.4. 24a&b)
Apart from periodic crop growth rates, there were significant differences observed
for hybrids in their mean seasonal crop growth rates (Table4.39). Highest mean seasonal
crop growth rate (14.10-15.67 g m-2 d-1) was recorded for Hysun-33 during both the years
that was followed by SF-187 (12.45-13.81 g m-2 d-1) with the lowest values (10.99-12.04
g m-2 d-1) observed for FH-33. On an average, Hysun-33 exhibited 30 and 13 % higher
seasonal crop growth rate than FH-331 and SF-187, respectively Widening the row
spacing (decreasing plant population) resulted in decrease in mean seasonal crop growth
rate during both the years (Table 4.39). Seasonal crop growth rate was decreased by 8%
when row distance was increased from 45 cm to 60 and declined further up to 24% at 75
cm apart rows of sunflowers.
A non significant interaction between hybrids of different stature under discussion
(Table 4.39) was also in line with the findings of Zaffaroni and Schneiter (1991),who
reported that semi dwarf and medium stature sunflower hybrids grown at different row
arrangements had non-significant differences in relative growth rate
An optimistic and significant association was observed between leaf area index
and crop growth rate of sunflower (Fig. 4. 25) and the regression accounted for 89-94%
variance in crop growth rate owing to differences in leaf area indices.
144
Cro
p gr
owth
rat
e (g
m-1
d-1
)
0
5
10
15
20
25
30
45 60 75 90
FH 331 SF 187 Hysun 33
0
5
10
15
20
25
30
45 60 75 90
FH 331 SF 187 Hysun 33
Days after sowing
Fig. 4.23: Pattern of crop growth rate with time: comparison of different sunflower hybrids during (a) 2006 and (b) 2007 ±SD
(a) 2006
(b) 2007
145
Cro
p gr
owth
rat
e (g
m-1
d-1
)
0
5
10
15
20
25
30
45 60 75 90
45 cm 60 cm 75 cm
0
5
10
15
20
25
45 60 75 90
45 cm 60 cm 75 cm
Days after sowing Fig. 4.24: Pattern of crop growth rate with time: comparison of different row spacing during (a) 2006 and (b) 2007 ±SD
(a) 2006
(b) 2007
146
Table. 4.39 Influence of different row spacing on seasonal crop growth rate (g m-2
day -1) of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 12.04 c 10.99 c 12.29
H2= SF-187 13.81 b 12.45 b 14.15
H3= Hysun-33 15.67 a 14.10 a 16.02
LSD at 5% 0.65 0.41
Row spacing (S)
S1= 45 cm 15.32 a 13.60 a 15.54
S 2= 60 cm 14.15 b 12.65 b 14.38
S 3= 75 cm 12.55 c 11.29 c 12.55
LSD at 5% 0.45 0.40
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
147
C
rop
grow
th r
ate
(g m
-2 d
-1)
y = 6.002x - 4.4111
R2 = 0.9404
0
2
4
6
8
10
12
14
16
0 1 2 3 4
y = 8.8081x - 11.491
R2 = 0.8926
0
2
4
6
8
10
12
14
16
18
20
1 2 3 4
Leaf area index
Fig. 4.25. Relationship between crop growth rate (g m-2 d-1) and leaf area index a) 2006, b) 2007
(a)
(b)
148
4.2.2.3 Net assimilation rate
Net assimilation rate (NAR) is the net gain of photosynthetic assimilates per unit
of assimilatory surface and time. Data on NAR (Table 4.40) revealed that seasonal NAR
differed significantly (P≤0.05) for different hybrids. Maximum and similar NAR were
observed for Hysun-33 and SF-187 (4.98 vs. 4.88 g m-2 d-1) as compared with FH-187
(4.47 g m-2 d-1) during both the years. On an average, SF-187 and Hysun-33 recorded 9
and 11 percent higher seasonal net assimilation rate, respectively than FH-331. Zaffaroni
and Schneiter (1991) reported that semi dwarf and medium stature sunflower hybrids
grown at different row arrangements had non-significant differences net assimilation rate
(NAR).
Regarding row spacing, there was significant (P≤0.05) decrease in net assimilation
rate with widening the row spacing (increase in plant population). Maximum mean NAR
(5.00 g m-2 d-1) was recorded when the crop was grown at row spacing of 45 cm and it
was 10% higher than that recorded for crop planted in 75 cm apart rows. The three
hybrids sown at varying row spacing exhibited similar (P≤0.05) responses in terms of
mean net assimilation rate (Table4.40).
4.2.2.4. Dry matter accumulation
The patterns of total dry matter (TDM) accumulation in different hybrids
throughout the crop growth period during both the years of experimentation are presented
in Fig 4.26. Three hybrids accumulated total dry matter to similar extent until 45 days
after sowing after which the differences among Hysun-33, SF-187 and FH-331 became
significant (P≤0.05) till harvest and the differences grew to the maximum at 90 DAS.
Hysun-33, SF-187 and FH-331 produced 1004,890 and 783 g m-2 TDM during 2006 and
the corresponding values for the year 2007 were 909,807 and 719 g m-2 (Table 4.41). On
an average, Hysun-33 recorded 12% more TDM than SF187 that was also 27% higher
than that observed for FH-331.The higher TDM production by Hysun-33 may be
attributed to its higher plant height as compared with rest of the hybrids (Table4.41).
Lower biomass production by the short duration hybrid (FH-331) might be due to low
quantity of radiation potentially available over the crop growth duration. Miralles et al.
(1997), Angadi and Entz (2001) and Khaliq (2004) also recorded significant differences
for TDM production by hybrids of different stature. Seasonal accumulation of total dry
matter was, in general, slow until 45 DAS in all the planting densities (Fig 4.27) and
subsequent increase in TDM was sharper and it reached to its maximum at 90 DAS.
Significant differences were recorded for TDM among varying row spacing (Table4.41).
149
Table 4.40. Influence of different row spacing on net assimilation rate (g m-2 day-1)
of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 4.71 b 4.22 b 4.47
H2= SF-187 5.06 a 4.69 a 4.88
H3= Hysun-33 5.07 a 4.88 a 4.98
LSD at 5% 0.21 0.24
Row spacing (S)
S1= 45 cm 5.15 a 4.84 a 5.00
S 2= 60 cm 4.98 b 4.66 b 4.82
S 3= 75 cm 4.69 c 4.29 c 4.49
LSD at 5% 0.17 0.14
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS= Non-significant
150
Tot
al d
ry m
atte
r (g
m-1
)
0
200
400
600
800
1000
1200
30 45 60 75 90
FH 331 SF 187 Hysun 33
0100
200300
400500600
700800
9001000
30 45 60 75 90
FH 331 SF 187 Hysun 33
Days after sowing
Fig. 4.26: Pattern of total dry matter accumulation with time: comparison of different sunflower hybrids during (a) 2006 and (b) 2007 ±SD
(a) 2006
(b) 2007
151
Tot
al d
ry m
atte
r (g
m-1
)
0
200
400
600
800
1000
1200
30 45 60 75 90
45 cm 60 cm 75 cm
0
100
200
300
400
500
600
700
800
900
1000
30 45 60 75 90
45 cm 60 cm 75 cm
Days after sowing
Fig. 4.27: Patterns of total dry matter with time: comparison of different row spacing during (a) 2006 and (b) 2007 ±SD
(a) 2006
(b) 2007
152
Table 4.41 Influence of different row spacing on total dry matter (g m-2) of diverse
sunflower hybrids.
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significance
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 783 c 719 c 751
H2= SF-187 890 b 807 b 848
H3= Hysun-33 1004 a 909 a 956
LSD at 5% 40.98 25.76
Row spacing (S)
S1= 45 cm 987 a 884 a 935
S 2= 60 cm 912. b 820 b 866
S 3= 75 cm 778 c 732 c 755
LSD at 5% 25 23.71
Interaction (H x S)
H1S1 882d 794 d 838
H1S2 783 e 715 e 749
H1S3 684 f 648 f 660
H2S1 972 c 883 c 928
H2S2 903 d 813 d 858
H2S3 795 e 727 e 762
H3S1 1107 a 973 a 1040
H3S2 1050 b 932 b 991
H3S3 855 d 820 d 837
LSD at 5% 44.57 41.07
153
A
chen
e yi
eld
(kg
ha-1
)
y = 2.602x + 472.6
R2 = 0.8056
0
500
1000
1500
2000
2500
3000
3500
0 200 400 600 800 1000 1200
y = 1.6889x + 997.69
R2 = 0.6718
0500
1000150020002500
30003500
200 400 600 800 1000 1200
Total dry weight
Total dry weight (kg ha-1) Fig. 4.28 Relationship between achene yield (kg ha-1)and dry weight (g m-2)
a) 2006, b) 2007
(a)
(b)
154
Increase in row spacing resulted in decrease in TDM production during both the
years of experimentation. On an average highest TDM (935.52 g m-2) was produced when
the sunflower crop was sown at 45 cm apart rows. TDM decreased by 8 and 24 % when
row distance was increased to 60 and 75 cm, respectively.
Hall et al.(1995) recorded an increase in total biomass yield of sunflower from
794 to 906 g m-2 by increasing plant population from 2.4 to 4.8 plants m-2.Ferreira and
Abreu (2001) also reported similar findings regarding total dry mater production under
varying planting densities.
Different sunflower hybrids planted at varying row spacing recorded significant
(P≤0.05) differences in total dry mater production during both the years of
experimentation (Table 4.41). Total dry matter production in all the hybrids decreased as
row to row spacing was increased but the pattern of decrease was quite different in the
three hybrids. Widening row spacing from 45 to 60 cm (decreasing planting density)
decreased TDM in FH-331, SF-187 and Hysun-33 by 11, 8 and 5 percent, respectively
which was reduced further by 12, 11 and 15 percent when row spacing was increased up
to 75 cm.Data depicted a significant and positive correlation between achene yield and
total dry weight (Fig. 4.28). Regression accounted for 74 % variance in yield owing to
differences in TDM. Such positive and significant correlation between TDM and
sunflower achene yield has also been reported by Pathak(1974) and Zaffaroni and
Schneiter (1991).
4.2.2.5. Leaf area duration
Differences in maximum leaf area indices may not explain precisely the variation in
total dry matter and achene yield in response to agronomic treatments. Therefore,
sometimes leaf area duration (LAD) accounts for differences in yield in response to
different treatments. LAD expresses the number of days that a square meter of leaf
surface covered a square meter of ground. At any particular moment e.g. pace of
establishment, extent and rate of regression, all the settings of photosynthesizing system
are taken into account by LAD (Miralles et al., 1997). To observe the significance of
photosynthetic vicinity throughout growth (appearance to maturity) LAD was estimated
(Table 4.42) There were significant differences among the hybrids under study during
both the years. Hysun-33 showed maximum (205.54 d) LAD that was 3 and 10 % higher
than that observed for SF-187 and FH-331, respectively. Hysun-33, which has longer
155
Table 4.42. Influence of different row spacing on leaf area duration (days) of
diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 185.22 c 176.22 c 180.68
H2= SF-187 189.44 b 184.00 b 186.68
H3= Hysun-33 205.33 a 205.78 a 205.54
LSD at 5% 1.95 7.12
Row spacing (S)
S1= 45 cm 203.78 a 197.56 a 200.67
S 2= 60 cm 195.00 b 189.56 b 192.28
S 3= 75 cm 181.22 c 178.89 c 180.05
LSD at 5% 5.11 3.50
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
156
growth period (Table 4.29) than the other two hybrids, stood out for its maximum LAD
(205.54 d) due to the highest maximum LAI (Fig.4.21), which also coincides with
thehighest values of TDM (Table 4.41 ).Miralles et al. (1997) and Khaliq (2004) also
recorded similar results for LAD of sunflower hybrids of varying maturity and
morphophysiological traits.
There was significant difference in LAD when sunflower was sown at different
row spacing (planting density). Maximum LAD was recorded when the crop was sown at
45 cm apart rows and progressively decreased with widening row spacing (Table4.42).
On an average, LAD decreased by 4 and 11 percent when row spacing was increased
from 45 to 60 and 75 cm, respectively. This decrease in LAD for the sunflower crop sown
in wider rows (low planting density) might be attributed to relatively lower LAIs (leaf
area per unit of land area). Khaliq (2004) reported similar ranges of LADs for sunflowers
grown under similar set of environmental conditions.Different sunflower hybrids
recorded similar (P≤0.05) leaf area durations when planted under varying row spacing
during both years of experimentation (Table 4.42)
4.2.2.6 Cumulative radiation interception
Leaf area index and canopy architecture determine the extent to which a crop can
intercept photosynthetically active radiation which, in turn is instrumental in determining
crop biomass accumulation and its partitioning within the plant (Van der Werf, 1996).
Data presented in Table 4.43 reflects the effect of hybrids of varying maturity
groups sown in different row spacing on accumulated radiation interception (AIR).
During both the years Hysun-33 recorded highest values for AIR (517.6-527.7 MJm-2)
and was followed by SF-187 (505.3-5138 MJm-2). On an average, AIR by Hysun-33 was
4% higher than that recorded for FH-331 and 2% higher than that for SF-187. Dosio et al.
(2000) reported variation in photosynthetically active radiation intercepted by two
genetically different hybrids (Dekalb and NKT). Khaliq (2004) and Iqbal (2008) reported
similar findings for radiation interception by hybrids of varying maturity under similar
environmental conditions.
Row spacing and planting density may be used as a management tool to optimize
the time required for a crop to fully intercept available light (Ball et al., 2000). Increasing
row spacing (decreased planting density) exhibited an antagonistic influence of radiation
interception during both years of experimentation (Table 4.45). Maximum radiation
interception (527 MJ m-2) was the outcome of sunflower planted at 45 row spacing and it
157
Table 4.43. Influence of different row spacing on cumulative radiation interception
(M.J.m-2) (cm) of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 502.8 c 497.6 c 500.2
H2= SF-187 513.80 b 505.3 b 509.55
H3= Hysun-33 527.70 a 517.6 a 522.65
LSD at 5% 2.92 4.13
Row spacing (S)
S1= 45 cm 527 a 517.8 a 522.4
S 2= 60 cm 514.2 b 506 b 510.1
S 3= 75 cm 503.10 c 496.70 c 499.9
LSD at 5% 4.54 4.13
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
158
Cum
ulat
ive
inte
rcep
ted
radi
atio
n (M
J m
-2)
y = 51.953x + 368.27
R2 = 0.8959
400
420
440
460
480
500
520
540
560
0 1 2 3 4
y = 0.0177x - 6.0856
R2 = 0.9577
2.00
2.20
2.40
2.60
2.80
3.00
3.20
3.40
480 490 500 510 520 530
Leaf area index
Fig. 4.29. Relationship between cumulative intercepted radiation (MJ m-2) and leaf area index a) 2006, b) 2007
(a)
(b)
159
A
chen
e yi
eld
(kg
ha-1
)
y = 18.179x - 6772.6
R2 = 0.794
0
500
1000
1500
2000
2500
3000
3500
450 470 490 510 530 550
y = 18.722x - 6983.7
R2 = 0.7499
0
500
1000
1500
2000
2500
3000
3500
420 440 460 480 500 520 540
Cumulative intercepted radiation
Fig. 4.30. Relationship between achene yield (kg ha-1)and cumulated intercepted radiation (MJ m-2)a) 2006, b) 2007
was 4.75% higher of the crop grown at 75 cm row distance. Andrade et al. (2002) also
recorded an increase in light interception by the sunflower crop sown with reduced row
spacing (higher planting density).
All the hybrids under study exhibited similar (P≤0.05) levels of radiation interception
when planted under varying row spacing (Table 4.43).
There was a positive and linear relationship between LAI and cumulative
radiation interception (Fig. 4.29) and regression accounted for 89-96 % variance during
both years of study. The dependence of fractional intercepted radiation on leaf area index
(a)
(b)
160
was also recorded by Ferreira and Abreu (2001). A positive and linear relationship was
also observed between cumulative light interception and achene yield of sunflowers (Fig.
4.30) and regression accounted for 74-79 % of variance in achene yield owing to
accumulated intercepted radiation by the crop. Such positive response was also reported
by Ferreira and Abreu (2001).
4.2.2.7 Radiation utilization efficiency (RUETDM)
Extent of dry matter accumulation and its partitioning within the plant are
important determinants of crop yields (Werf, 1996). Rate and extent of dry matter
accumulation by the crop depends on ability of the crop canopy to intercept incident
photosynthetically active radiation (IPAR) and the efficiency with which this radiation
can be converted into new biomass i.e. radiation use efficiency (Sinclair and Muchow,
1999).. Radiation use efficiency is a conservative quantity (Monteith and Elson, 1983).
The perusal of data realized that the hybrids differed significantly (P≤0.05) in radiation
use efficiency for TDM (Table 4.44). Hysun-33 utilized radiation more efficiently (1.98-
1.94 g MJ-1) for total dry matter accumulation, which was, 22% greater than the early
maturing hybrid (FH-331) and 9% higher than the mid season hybrid (SF-187)..
Decreasing plant population (increasing row spacing) showed a depressing effect
on radiation use efficiency on unit area basis. (Table 4.44). Maximum radiation utilization
(1.92 g MJ-1) for TDM buildup was observed for the crop sown at narrow (45 cm) row
spacing. Increasing the row spacing from 45 to 60 cm recorded 5% decrease in RUETDM
and further widening the row spacing from 60 to 75 cm further experienced a 12%
decrease in RUETDM.
The interactive influence of hybrids and row spacing on RUETDM was significant
(P≤0.05) only during 2007 wherein Hysun-33 planted in 45 and 60 cm apart rows
recorded the highest RUE that declined significantly when row spacing was increased to
75 cm. Minimum RUETDM (1.40 g M.J-1) was realized by FH-331 planted at row spacing
of 75 cm. Khaliq (2004) and Iqbal (2008) also reported similar findings for sunflower in
the same environmental conditions.
161
Table 4.44. Influence of different row spacing on radiation use efficiency (tdm) (gMJ-
1) of diverse sunflower hybrids.
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 1.65 c 1.57 c 1.61
H2= SF-187 1.81 b 1.76 b 1.79
H3= Hysun-33 1.98 a 1.94 a 1.96
LSD at 5% 0.06 0.09
Row spacing (S)
S1= 45 cm 1.93 a 1.90 a 1.92
S 2= 60 cm 1.83 b 1.80 b 1.82
S 3= 75 cm 1.67 c 1.56 c 1.62
LSD at 5% 0.06 0.05
Interaction (H x S)
H1S1 1.78 1.73 cd 1.76
H1S2 1.66 1.58 f 1.62
H1S3 1.51 1.40 g 1.46
H2S1 1.93 1.88 b 1.91
H2S2 1.82 1.79 c 1.81
H2S3 1.67 1.61 ef 1.64
H3S1 2.08 2.11 a 2.10
H3S2 2.02 2.03 a 2.02
H3S3 1.83 1.68 c 1.75
LSD at 5% NS 0.08
162
4.2.2.8. Radiation use efficiency for grain (RUEGrain)
Table 4.45 showed that radiation use efficiency for grain yield (RUEGrain) varied
significantly (P≤0.05) among different sunflower hybrids for both the years. During 2006,
Hysun-33 and SF-187 recorded maximum and similar (P≤0.05) RUEGrain (0.54 and 0.50 g
MJ-1) as against the minimum (0.46 g MJ-1) recorded for FH-331. The later hybrid was
also at par with SF-187. Similar trend was observed during 2007, except that FH-331 had
lowest RUEGrain in this year. On an average, Hysun-33 recorded 17 and 9 percent higher
RUEGrain as compared with FH-331 and SF-187, respectively.
Sunflowers planted at variable row spacing exhibited non-significant (P≤0.05)
differences for RUEGrain during both years of experimentation (Table 4.45).
Different sunflower hybrids exhibited differential response towards RUEGrain
when planted at variable row spacing (Table 4.46). Both FH-331 and SF-187 observed a
decline (18 and 9 %, respectively) in RUEGrain with widening the rows from distance of
45 cm to 60 cm. In contrary, Hysun-33 exhibited a 12% gain in RUEGrain for same
increase in row spacing. By further widening the rows from 60 to 75 cm, decline in
RUEGrain resulted in all the hybrids under study. Again, when RUEGrain was compared for
45 and 75 cm spaced planting, FH-331 and SF-187 showed a decline of 18 and 9 percent,
respectively while Hysun-33 recorded a gain of 6%.
An optimistic and noteworthy association was experienced between (RUEGrain)
and achene yield of sunflower (Fig. 4.31) and the regression accounted for 98% variance
in achene yield owing to difference in radiation use efficiency.
4.2.3 Quality Characteristics
4.2.3.1 Achene oil content
Achene oil contents differed significantly ,when diverse hybrids were studied
(Table4.46). During first year, maximum and comparable (P≤0.05) achene-oil content
(42.89-42.56 %) was recorded for hybrids Hysun-33 and FH-331. Comparatively lower
(by 6%) achene-oil content was observed for SF-187. Same tendency was observed
during second year, with oil content being relatively on upper side in this year.
Ahmad and Hassan,(2000) reported that oil contents in sunflower hybrids
maturing and harvested at higher temperature (June) were comparable with those
maturing and harvested in April (Hassan, 2000). Higher achene-oil content in late
maturing hybrid is in agreement with previous findings (Dubbelde, 1989; .El-Hinnaway
et al., 1981) who reported increase in oil contents of sunflower with increase in maturity.
163
Table 4.45. Influence of different row spacing on radiation use efficiencygrain
(gMJ-1) of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 0.46 b 0.45 b 0.46
H2= SF-187 0.50 ab 0.50 a 0.5
H3= Hysun-33 0.54 a 0.53 a 0.54
LSD at 5% 0.059 0.041
Row spacing (S)
S1= 45 cm 0.52 0.50 0.51
S 2= 60 cm 0.51 0.49 0.5
S 3= 75 cm 0.48 0.47 0.47
LSD at 5% NS NS
Interaction (H x S)
H1S1 0.51 bc 0.50 bc 0.5
H1S2 0.45 cd 0.45 cd 0.45
H1S3 0.42 d 0.41 d 0.41
H2S1 0.53 ab 0.53 ab 0.53
H2S2 0.50 bc 0.49 bc 0.49
H2S3 0.48 bc 0.48 bc 0.48
H3S1 0.51 bc 0.50 abc 0.5
H3S2 0.57 a 0.56 a 0.56
H3S3 0.54 ab 0.53 ab 0.53
LSD at 5% 0.018 0.056
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
164
Ach
ene
yiel
d (k
g ha
-1)
y = 6367.4x - 606.05
R2 = 0.9806
0
500
1000
1500
2000
2500
3000
3500
0.0 0.2 0.4 0.6 0.8
y = 6126.5x - 518.57
R2 = 0.9807
0
500
1000
1500
2000
2500
3000
3500
0.0 0.1 0.2 0.3 0.4 0.5 0.6
RUEgrain
Fig. 4.31. Relationship between achene yield (kg ha-1)and radiation use efficiency (RUEGrain) a) 2006, b) 2007
(a)
(b)
165
Varying row spacing (different planting densities) had significant (P≤0.05)
influence on the oil content of sunflower during 2006&2007(Table 4.46). Sunflower
grown in narrow rows exhibited more achene-oil content than that sown in wider rows.
Maximum oil content (43.22%) was gained, when the crop was sown at 45 cm row
spacing. It was followed by the crop sown at row spacing of 60 and 75 cm apart rows
with achene-oil content of 41.78 % and 40.78 % (Table 4.46). Stear et al. (1986) stated
that oil yield per plant was reduced by rising plant density; while the percentage of oil in
seed was not exaggerated by dense population.
Different hybrids grown under varying row spacing exhibited similar response
with reference to their achene-oil concentration (Table 4.46)
4.2.3.2 Oil yield (kg ha-1)
The ultimate objective in oilseed crop production is the oil yield, which is a
product of achene yield and achene oil contents in case of sunflower. Sunflower has been
rightly named as an oil-crop owing to its higher oil harvested per unit area. Data (Table
4.47) indicated that oil yield of sunflower hybrids differed significantly (P≤0.05) during
both years. Hysun-33 recorded highest oil yield (1214 kg ha-1) that was 13% more than
oil yield of SF-187 (1062 kg ha-1) and 24% higher than that of FH-331 (922 kg ha-1).
Comparably higher oil yield in Hysun-33 may be explained by its higher achene yield
(Table 4.36) and achene-oil content (Table 4.46) in this hybrid as compared with the other
hybrids.
Although oil yield of sunflower planted in varying row spacing differed
significantly (P≤0.05) during 2006 but the magnitude of such differences was not as high
as was observed for those recorded in hybrids. Similar oil yield was recorded in crop
planted in 45 and 60 cm rows. The later row spacing also yielded similar oil as was
recorded for crop sown in 75 cm row. In contrary to this, the sunflowers planted in
varying row spacing exhibited non-significant (P≤0.05) differences during 2007.
Regarding interaction between hybrids and row spacing (Table 4.47), it was found
to be non-significant during 2006 and significant differences (P≤0.05) were recorded for
the year 2007.The combination of Hysun-33 and 60 cm row spacing produced the highest
(1265 Kg ha-1) oil yield and was statistically at par with the oil yield (1216 Kg ha-1)
produced by the same hybrid sown at 75 cm apart rows. On the other hand, remaining
both hybrids (SF-187 and FH-331) exhibited significantly higher oil yields on narrow (45
and 60 cm) row spacing as compared to wider (75 cm) row spacing. The lowest oil yield
166
Table 4.46. Influence of different row spacing on achene oil contents (%) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 42.56 a 42.78 ab 42.67
H2= SF-187 40.33 b 41.24 b 40.79
H3= Hysun-33 42.89 a 43.69 43.29
LSD at 5% 1.33 1.73
Row spacing (S)
S1= 45 cm 43.22 a 44.06 a 43.64
S 2= 60 cm 41.78 b 42.24 b 42.01
S 3= 75 cm 40.78 b 41.41 b 41.10
LSD at 5% 1.37 0.98
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
167
Table 4.47. Influence of different row spacing on oil yield (kg ha-1) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 924 c 919 c 922
H2= SF-187 1066 b 1058 b 1062
H3= Hysun-33 1228 a 1200 a 1214
LSD at 5% 133 114.4
Row spacing (S)
S1= 45 cm 1105 a 1087 1096
S 2= 60 cm 1092 ab 1069 1081
S 3= 75 cm 1021 b 1021 1021
LSD at 5% 83 NS
Interaction (H x S) NS
H1S1 1132
1008 cd 1070
H1S2 1060
914 de 962
H1S3 1005
836 e 921
H2S1 1156
1133 bc 1145
H2S2 1304
1028 cd 1166
H2S3 1223
1012 cd 1118
H3S1 1027
1120 bc 1074
H3S2 910
1265 a 1088
H3S3 834
1216 ab
LSD at 5% NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
168
(836 kg ha-1) was recorded by the hybrid FH-331 sown at the row spacing of 45 cm.
4.2.3.3 Achene protein content
Achene protein content varied significantly among the different hybrids (Table
4.48). SF-187 had highest achene protein content (20.97%) as compared with the lowest
(19.03%) for Hysun-33. The local hybrid FH-331 accumulated as high protein (20.13%)
as was recorded for SF-187. During 2007, FH-331 and SF-187 recorded similar (P≤0.05)
achene-protein concentration. Opposite trend of oil and protein content in different
hybrids may be the explanation for this lesser amount of protein in Hysun-33 hybrid. The
inverse relationship between oil and protein concentration in seed has also been recorded
by Goffner et al. (988) and Singh et al. (1988) and the major cause of this inverse
relationship is the continuing deposition of oil, which has diluting effects on protein in
such hybrids.
The significant differences in protein contents of diverse sunflower hybrids have
also been reported by Khaliq (2004), Saleem (2004) and Iqbal (2008).
Widening the row spacing (increasing plant population) affected the protein
contents negatively during both years (Table 4.48). During 2006, highest protein content
(22.28%) was registered with the crop sown in wider (75 cm) rows. Corresponding values
for crop planted at 60 and 45 cm wide rows were 21.25% and 20.68%, respectively
(Table4.48). Similar trend was observed during 2007. Means of two years revealed 3 and
8 percent increase in achene-protein when row spacing was increased from 45 to 60 and
75 cm, respectively.Non-significant (P≤0.05) differences were recorded in achene-protein
concentration under varying row spacing during both the years of experimentation (Table
4.48) indicating similar response of hybrids to varying plant density.
4.2.3.4 Fatty acid profile
4.2.3.4.1. Palmitic acid concentration (%)
Data (Table 4.49) revealed that palmitic acid concentration did not vary
significantly (P≤0.05) for FH-331 and SF-187 (5.67 vs 5.46 %) and was higher than that
recorded for Hysun-33 (4.90%). On an average FH-331 and SF-187 recorded 14 and 4
percent higher palmitic acid concentration than Hysun-33.
The supporting results were achieved by Ahmad (1999) and Khaliq (2004) who
conducted the experiment under similar environmental conditions. Contrary to this,
Saleem (2004), Cecarmi et al. (2004) and Iqbal (2004) reported non-significant
differences among various hybrids for their palmitic acid concentration in the achene-oil.
169
Table 4.48. Influence of different row spacing on protein contents (%) of diverse
sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 21.02 a 20.13 a 20.58
H2= SF-187 22.61 a 20.97 a 21.79
H3= Hysun-33 20.59 b 19.03 b 19.81
LSD at 5% 0.84 0.86
Row spacing (S)
S1= 45 cm 20.68 a 19.34 c 20.01
S 2= 60 cm 21.25 b 19.96 b 20.61
S 3= 75 cm 22.28 a 20.83 a 21.55
LSD at 5% 0.73 0.43
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
170
Table 4.49. Influence of different row spacing on palmitic acid concentration (%)
of oil of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 5.94 a 5.41 a 5.68
H2= SF-187 5.79 a 5.13 a 5.46
H3= Hysun-33 5.38 b 4.42 b 4.90
LSD at 5% 0.18 0.33
Row spacing (S)
S1= 45 cm 5.63 4.93 5.28
S 2= 60 cm 5.73 5.01 5.37
S 3= 75 cm 5.76 5.01 5.39
LSD at 5% NS NS
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
171
Qadir et al. (2006) reported that in autumn, Hysun-33 produced significantly highest oil
contents (49.65%), as compared to Award (44.66%) and there were significant
differences observed for fatty acid composition.
Varying row spacing had non-significant (P≤0.05) bearing upon palmitic acid
concentration in achene-oil of sunflowers during both years of experimentation (Table
4.49).Non-significant differences (P≤0.05) were also observed for palmitic acid
concentration in achene-oil of different hybrids planted at varying row spacing (Table
4.49).
4.2.3.4.2. Stearic acid concentration (%)
Stearic acid is categorized as saturated fatty acid, and is an undesirable oil quality
characteristic. The perusal of data (Table 4.50) revealed that different hybrids showed
significant (P≤0.05) difference for the stearic acid concentration in sunflower oil during
both year of experimentation. Hysun-33 recorded highest (3.97%) stearic acid
concentration as compared with FH-331(3.67%) and SF-187 (3.61%) which revealed
non-significant difference between them. Ahmad (1999) and Iqbal (2008) reported non-
significant differences among various hybrids, while the results recorded by Khaliq
(2004) are in line with the differential behavior of diverse sunflower hybrids under
discussion.
Sunflower crop sown at different row spacing (plant density) showed non-
significant (P≤0.05) effect on stearic acid concentration of its achene-oil (Table4.50).
Similarly interaction between hybrids and row spacing was found to be non-significant
during both years of study.
4.2.3.4.3 Oleic acid concentration (%)
Concentration of oleic acid (18:1) in achene oil of sunflower varied significantly
(P≤0.05) among hybrids (Table 4.51) and was in order of Hysun-33>FH-331>Sf-187
during both years of experimentation. On an average Hysun-33 recorded highest
(10.70%) oleic acid concentration that was 7% and 22% higher than that exhibited by FH-
331 (9.96%) and SF187 (8.80%), respectively. Skoric et al. (1978), Ahmad et al. (1999)
and Khaliq (2004) also reported variation in oleic acid concentration of oil of different
sunflower hybrids.
Sunflowers planted at variable row spacing exhibited non-significant (P≤0.05)
differences for oleic acid concentration during both years of experimentation (Table
4.51).
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Table 4.50. Influence of different row spacing on stearic acid concentration (%) of
oil of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 3.72 b 3.63 b 3.67
H2= SF-187 3.65 b 3.57 b 3.61
H3= Hysun-33 3.94 a 4.01 a 3.97
LSD at 5% 0.12 0.10
Row spacing (S)
S1= 45 cm 3.74 3.57 3.65
S 2= 60 cm 3.79 4.01 3.90
S 3= 75 cm 3.77 3.63 3.70
LSD at 5% NS NS
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
173
Table 4.51. Influence of different row spacing on oleic acid concentration (%) of
oil of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 10.08 b 9.84 b 9.96
H2= SF-187 8.89 c 8.71 c 8.80
H3= Hysun-33 10.82 a 10.58 a 10.70
LSD at 5% 0.38 0.39
Row spacing (S)
S1= 45 cm 9.84 9.61 9.73
S 2= 60 cm 9.94 9.72 9.83
S 3= 75 cm 10.02 9.79 9.91
LSD at 5% NS NS
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
174
Interactive effects of hybrids and different row spacing on the oleic acid concentration
were also found to be non significant (P≤0.05) during both the years of study.
4.2.3.4. 4. Linoleic acid concentration (%)
During both the years, linoleic acid concentration did not vary significantly
(P≤0.05) among different hybrids (Table 4.52). Ahmad et al. (1997), Saleem (2004) and
Iqbal (2008) also recorded non-significant differences among hybrids of different
maturity and plant height, while Khaliq (2004) recorded significant differences in linoleic
acid content of various sunflower hybrids.
Different combinations of hybrids and row spacing also showed a non-significant
(P≤0.05) influence on linoleic acid concentration in achene-oil of sunflower during both
years of study (Table 4.52).
175
Table 4.52. Influence of different row spacing on linoleic acid concentration (%)
of diverse sunflower hybrids.
Treatments 2006 2007 Mean
Hybrids (H)
H1= FH-331 79.14 80.00 79.57
H2= SF-187 80.04 81.78 80.91
H3= Hysun-33 77.67 78.67 78.67
LSD at 5% NS NS
Row spacing (S)
S1= 45 cm 78.89 80.11 79.50
S 2= 60 cm 79.19 80.67 79.93
S 3= 75 cm 78.76 79.67 79.22
LSD at 5% NS NS
Interaction (H x S) NS NS
Means having different letters within a column differ significantly from each other at 5%
probability level; NS = Non-significant
176
DISCUSSION
There was a non-significant (P≤0.05) difference in final plant population among
the hybrids (Table 4.28) which might be attributed to uniform germination and seedling
establishment of the three hybrids as well as absence of lodging in any of the hybrids used
in these studies. Saleem (2004) and Iqbal (2008) also recorded non-significant differences
in final number of plants per unit area for various sunflower hybrids. At a constant plant
to plant distance of 22.5 cm used in these experiments, widening the row spacing from 45
to 60 cm resulted in 33% decrease in plan density that declined further by 24% when the
crop was sown at 75 cm row spacing (Table 4.28).Change in the number of plants m-2
was also recorded by Iqbal (2008) with variation in row to row distance. During both the
years, Hysun-33 took 102 days to reach its maturity and was different with rest of the
hybrids (SF-187 and FH-331) which were statistically at par with each other (Table 4.29).
Steer and Hocking (1987) reported that there were small differences in time taken from
sowing to maturity among short stature (early maturity) and taller (late maturity) hybrids.
Johnson and Schneiter (1998) reported hybrids representing the greatest available
diversity for maturity and plant height The differential response of sunflower hybrids
regarding time taken to maturity may attributed to variable genetic character for the
respective hybrids to this trait. Iqbal (2008) also recorded significant difference among
the hybrids for time taken to maturity. Sunflower crop sown at varying row spacing did
not affect the time taken to maturity and results depicted in Table 4.29 showed non-
significant (P≤0.05) difference for the time taken to maturity among different planting
densities.
Varying row spacing (plant population) had a significant (P≤0.05) effect on plant
height (Table 4.30) and tallest plants (157.67 cm) were produced when crop was sown in
45 cm apart rows (98765 plants ha-1) as against the shortest (149.44 cm) recorded in 75
cm row spacing (59259 plants ha-1). These results reflected that plant height increased
with decrease in row spacing (increasing planting density) and vice versa. This may be
attributed to better utilization of light, moisture and more competition within plants into
crop canopy in case of narrow spaced plants as compared to wider spaced plants. Higher
plant populations produced taller plants and more yield than lesser plant density (Beg et
al., 2007). These results are in agreement with the findings of Sedghi et al. (2008) and
Iqbal (2008), and opposite to those of Van Deynze et al. (1992). Inter-plant competition
for radiation and other aerial resources by the plants may be the reason for taller plants at
177
higher plant densities (Gubbel and Dedio, 1988). The maximum existing range for
maturity and plant stature were also recorded by Johnson and Schneiter (1998) who
reported that plant height was inclined by inter hybrid antagonism.
SF-87 recorded maximum (18.57-18.14 cm) head diameter and was followed by
Hysun-33 (16.86-16.65 cm) and FH-331(16.10-15.87 cm) during both the years (Table
4.32). Variation in head size of hybrids of different genetic background was also reported
by Tunio et al. (1999), Reddy et al. (2002), Khaliq (2004) and Iqbal (2008). Narrowing
the row spacing from 75 to 45 cm resulted in 14% decrease in head diameter (Table 4.32).
Increasing row spacing from 45 to 60 cm produced 9% larger heads and a further increase
in row spacing (75 cm) improved head diameter by 4%. Beg et al. (2007) reported that
dense plantations produced lighter seeds, thinner stems, taller plants and more yield than
lesser plant density. Negative effect of increasing plant population on head diameter
recorded in the experiment under study is in agreement with findings of Ahmad and
Quresh (2000), Killi (2004) and Al-Thabat (2006). During both the years, FH-331 and
SF-187 recorded similar number of achenes per head (657 vs. 678) that was out yielded
by those of Hysun-33 with 789 achenes per head (Table 4.33). Hysun-33 recorded 16 and
20 percent higher number of achenes per head than SF-187 and HS-331, respectively.
Albeit higher head diameter of SF-187 (Table 4.33), the number of achenes per head were
more in Hysun-33 that may be attributed to better seed set in the later hybrid. Villalobos
et al. (1994) reported that response to biomass, seed number and yield to variable plant
population depended on hybrids. Several other authors (Ahmad et al. 1997, Saleem and
Malik, 2004 and Iqbal (2008) have reported such differences amongst hybrids. Widening
the rows from 45 to 75 cm, recorded 12% more achenes per head and the advantage was
only 8% when rows were widened upto 60 cm. Diepenbrock et al. (2001) reported that
increasing row spacing from 50 to 75 cm decreased number of achenes per head, but the
quantity of achenes m-2 increased significantly with decreasing row spacing. These results
suggested that number of achenes per head increased with increasing head size. Nawaz et
al. (2001) confirmed that number of achenes per head and 1000-achene weight was
greater with the plants sown in wider rows. There may be grain abortion due to
oppressive influence of shared shading at contracted row spacing and hence reduce
number of achenes per head (Andrade et al., 1993). The reciprocal association of number
of achenes per head for the planting density was recorded by Barros et al. (2004) who
observed that number of achenes per head decreased with increase in planting density.
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In field crops it is more common to look for management options where more
number of achenes is harvested per unit area. During 2006, FH-331 and SF-187 produced
similar (P≤0.05) number of achenes m-2 which was 20 and 17 percent higher than the
former hybrids, respectively (Table 4.34). The difference between FH-331 and SF-187
was non-significant during 2007. Diepenbrock et al. (2001) reported that number of
achenes per head was reduced with decreasing row spacing from 50 to 75 cm, but the
quantity of achenes m-2 increased significantly with decreasing row spacing. Narrowing
row spacing (increasing plant population) had a positive bearing on the number of
achenes m-2. Crop planted on 75 cm apart rows recorded lowest number of achenes m-2
that was improved by 19 and 45% when row spacing was narrowed down to 60 and 45
cm, respectively. Borous et al. (2004) and Calvino et al. (2004) also reported more
achenes per unit area owing to higher planting densities in sunflowers.
Weight of achenes plays a leading role in yield formation of sunflower. FH-331
produced the lightest achenes (Table 4.35) while SF-187 recorded maximum achene
weight that was 13, and 8 percent higher than that recorded for FH-331 and Hysun-33,
respectively. Although Hysun-33 produced more number of achenes per head (Table
4.33) than SF-187 but the later had higher head diameter (Table 4.30) as compared with
Hysun-33 implying better development of fewer achenes in wider head spacing in this
(SF-187) hybrid. Differential response of sunflower hybrids to 1000-achene weight was
also reported by Ahmad et al. (1997), Behrooznia et al. (1999). Khaliq (2004) and Ekin et
al. (2005) reported similar results. The maximum 1000-achene weight (57 g) was
recorded when the crop was sown at 75 cm apart row spacing. Achene weight was
reduced by 11 and 33 % when row spacing was decreased to 60 and 45 cm, respectively.
Reduction in achene weight at narrow row spacing (higher planting densities) might be
attributed to lesser nutritional area available for growth and development of the crop at
higher densities and is supported by the findings of Johnson (2003).
During 2006, Hysun-33 and SF-187 recorded highest and similar achene yield
(2856 and 2588 kg ha-1) that were 24 and 12 percent higher than that recorded for FH-331
(Table 4.36). During 2007, Hysun-33 out yielded both the hybrids by recoding 2741 kg
ha-1 achene yield that was 21% higher than achene yield of FH-331 (2256 kg ha-1) and 9%
higher than SF-187 (2519 kg ha-1). Variation in yield potential amongst hybrids under
variable environments is not uncommon; rather yields might differ even under similar
conditions. Andrade et al. (2002) reported differential response of Zenit (short season)
and Ramcull (long season) hybrids to yield. The significant differences among the
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hybrids of different maturity groups of sunflower were also reported by Khaliq (2004)
and Iqbal (2008) under same set of environmental conditions. In contrast, Tunio et al.
(1999) reported superior yield production by medium stature hybrids due to improved
reproductive development as compared to semi-dwarf varieties. The highest achene yield
of Hysun-33 is the outcome of more number of achenes per head (Table 4.33), higher
light interception (Table 4.43) by the plants as a consequence of prolonged growth
duration (Table 4.29), as well as relatively higher crop growth rate (Table4.39. Crop
planted in 45 and 60 cm apart rows recorded highest and similar achene yield during 2006
than that planted in 75 cm apart rows. However, during 2007, the wider row plantation
(75 cm) recorded as good achene yield as was recorded with 60 cm wide row plantation.
Increasing row spacing from 45 cm to 60 and 75 cm reduced achene yields by 4 and 12
percent, respectively. Jose et al. (2004) suggested that the number of achenes per head
and 1000 achene weight decreased significantly with increment in plant density, but the
number of achenes m-2 and higher mean seed weight were sufficient to compensate the
concomitant decrease. However, the studies by Zaffaroni and Schneiter (1989) gave
inconsistent results for achene yield by increasing row spacing. Diepenbrock et al. (2001)
reported that the yield was consistently higher at 75 cm rather than at 50 cm row spacing.
Harvest indices of the three hybrids in present studies did not vary to significant (P≤0.05)
extent (Table 4.38) and were in the range of 25.98 to 27.41 percent. Miralles et al. (1997)
reported non-significant differences in HIs of various sunflower hybrids, while Saleem
(2004) and Iqbal (2008) reported that HIs varied significantly amongst hybrids. Varying
row spacing also depicted non-significant (P≤0.05) differences in HIs in these studies
(Table 4.38). Steer et al. (1986) and Diepenbroke et al. (2001) reported that increasing
plant population resulted in decline in HI. This decrease might be due to more stover
yield (Table 4.37) produced in narrow row spacing (increased plant population).
Patterns of development of leaf area index (LAI) as presented in Fig.4.21a&b.
revealed that during both the years, leaf area index increased slowly in the beginning of
crop season and crop started fast accumulation of LAI at 45 days after sowing and
reached to the maximum at 75 days after sowing, and started declining thereafter. The
differences amongst the hybrids remained non-significant (P≤0.05) upto 60 days after
sowing after which the difference/s in LAIs were more pronounced. Long season hybrid
Hysun-33 exhibited highest LAI (5.10), followed by SF-187 (4.49), which was
statistically at par with FH-331 (4.32). Zaffaroni and Schneiter (1991) reported that semi
dwarf and medium stature sunflower hybrids grown at different row arrangements had
180
non-significant differences in leaf area index (LAI). Miralles et al. (1997) reported that a
longer season hybrid (SH-222) stood out for its maximum LAI and crop growth rate
(CGR) and dry matter than the other hybrids. Differential leaf area indices of hybrids
have also been reported by Saleem and Malik (2004) and Khaliq (2004). Patterns of leaf
area indices for sunflower planted with increasing population were quite opposite to that
for leaf area per plant so that LAI was always greater in plots with higher population than
that of lower planting densities (Ferreira and Abreu, 2001). An optimistic and comparable
association was observed between LAI and achene yield of sunflower (Fig. 4.20).
Periodic data at fortnight intervals (Fig. 4. 23a&b) revealed that crop growth rate
(CGR) of Hysun-33 progressively increased and achieved maximum value (21.21 g m-2 d-
1) at 75 DAS and declined sharply thereafter; reaching a value of 6.63 g m-2 d-1 at 90 DAS
during 2006. Early maturing hybrid FH-331 recorded maximum CGR (19.30 g m-2 d-1) at
60 DAS that declined slightly (16.75 g m2 d-1) at 75 DAS and reached lower level (1.85 g
m-2 d-1) at 90 DAS. Almost the same trend was exhibited by SF-187 and the maximum
(20.45 g m-2 d-1) and the minimum (3.81 g m-2 d-1) CGRs were recorded at 60 and 90
DAS, respectively. Variation in CGR of different hybrids is attributed to their different
maturity periods. The highest CGR in Hysun-33 was due to its higher leaf area index.
Miralles et al. (1997) also reported that a longer season hybrid (SH-222) had the highest
CGR which was the consequence of its higher leaf area index. Crop planted at 45 cm
apart rows showed maximum CGR throughout the growing season as compared to plants
grown at 60 and 75 cm apart rows for both the years.(Fig.4. 24a&b). Widening the row
spacing (decreasing plant population) resulted in decrease in mean seasonal crop growth
rate during both the years (Table 4.39). Seasonal crop growth rate was decreased by 8%
when row distance was increased from 45 cm to 60 and declined further up to 24% at 75
cm apart rows of sunflowers. Decreasing crop growth rates at wider row spacing might be
attributed to lesser dry matter accumulation per unit area by low plant populations at such
row spacing. Seasonal net assimilation rate (NAR) differed significantly (P≤0.05) for
different hybrids (Table 4.40). Maximum and similar NAR were observed for Hysun-33
and SF-187 (4.98 vs. 4.88 g m-2 d-1) as compared with FH-187 (4.47 g m-2 d-1) during
both the years. Zaffaroni and Schneiter (1991) reported that semi dwarf and medium
stature sunflower hybrids grown at different row arrangements had non-significant
differences net assimilation rate (NAR). Maximum mean NAR (5.00 g m-2 d-1) was
recorded when the crop was grown at row spacing of 45 cm and it was 10% higher than
that recorded for crop planted in 75 cm apart rows. The three hybrids sown at varying row
181
spacing exhibited similar (P≤0.05) responses in terms of mean net assimilation rate
(Table4.40).
All hybrids accumulated total dry matter (TDM) to similar extent until 45 days
after sowing after which the differences became significant (P≤0.05) till harvest (Fig
4.26). Hysun-33, SF-187 and FH-331 produced 1004, 890 and 783 g m-2 TDM during
2006 and the corresponding values for the year 2007 were 909,807 and 719 g m-2 (Table
4.41). Hysun-33 recorded 12% more TDM than SF187 which, in turn was 27% higher
than that observed for FH-331. The higher TDM production by Hysun-33 may be
attributed to its higher plant height as compared with rest of the hybrids (Table4.41).
Lower biomass production by the short duration hybrid (FH-331) might be due to low
quantity of radiation potentially available over the crop growth duration. Miralles et al.
(1997), Angadi and Entz (2001) and Khaliq (2004) also recorded significant differences
for TDM production by hybrids of different stature. Fereres et al. (1986) and Schneiter
(1992) attributed the differences for production of TDM by different genotypes to crop
duration and maturity ranking of sunflower. The differences among the hybrids in TDM
yields in these studies were outcome of the shortened crop duration. Values of total
biomass recorded in present studies were similar to other reports (Anderson et al., 1985;
Connor et al., 1985 and Khaliq, 2004).
Leaf area duration (LAD) accounts for differences in yield in response to different
treatments. At any particular moment e.g. pace of establishment, extent and rate of
regression, all the settings of photosynthesizing system are taken into account by LAD
(Miralles et al., 1997). Hysun-33 showed maximum (205.54 d) LAD that was 3 and 10 %
higher than that observed for SF-187 and FH-331, respectively (Table 4.42). Hysun-33
stood out for its maximum LAD due to the highest maximum LAI (Fig.4.21), which also
coincides with the highest values of TDM (Table 4.41 ). Miralles et al. (1997) and Khaliq
(2004) also recorded similar results for LAD of sunflower hybrids of varying maturity
and morphophysiological traits. Maximum LAD was recorded when the crop was sown at
45 cm apart rows and progressively decreased with widening row spacing (Table4.42).
On an average, LAD decreased by 4 and 11 percent when row spacing was increased
from 45 to 60 and 75 cm, respectively. This decrease in LAD for the sunflower crop sown
in wider rows (low planting density) might be attributed to relatively lower LAIs (leaf
area per unit of land area). Khaliq (2004) reported similar ranges of LADs for sunflowers
grown under similar set of environmental conditions.
182
Leaf area index and canopy architecture determine the extent to which a crop can
intercept photosynthetically active radiation which, in turn is instrumental in determining
crop biomass accumulation and its partitioning within the plant (Van der Werf, 1996).
Hysun-33 recorded highest values for accumulated radiation interception (517.6-
527.7 MJ m-2) and was followed by SF-187 (505.3-5138 MJ m-2). Dosio et al. (2000)
reported variation in photosynthetically active radiation intercepted by two genetically
different hybrids (Dekalb and NKT). Calvino et al. (2004) also recorded that light
interception and yield of sunflower were subjected to cultivar features including time to
maturity and plant stature and concluded that short season hybrid (Zenit) consistently
intercepted less radiation than long season hybrid (Sucrofer). Khaliq (2004) and Iqbal
(2008) reported similar findings for radiation interception by hybrids of varying maturity
under similar environmental conditions.
Row spacing and planting density may be used as a management tool to optimize
the time required for a crop to fully intercept available light (Ball et al., 2000). Maximum
radiation interception (527 MJ m-2) was the outcome of sunflower planted at 45 row
spacing and it was 4.75% higher of the crop grown at 75 cm row distance (Table 4.45).
Andrade et al. (2002) also recorded an increase in light interception by the sunflower crop
sown with reduced row spacing (higher planting density). Decreasing row spacing
increases radiation interception and dry matter accumulation (Shibles and Weber, 1966)
and reduces the threshold values of leaf area index that is sufficient enough to intercept
95% of the incident radiation only due to increase in the light extinction co-efficient
(Flenet et al., 1996). Calvino et al. (2003) concluded that sunflower crop sown in narrow
rows intercepted more radiation than that in wider rows. Ferreira and Abreu (2001)
suggested that solar radiation intercepted by sunflower with higher planting density was
greater than lower planting density owing to greater LAI with higher planting density.
Extent of dry matter accumulation and its partitioning within the plant are
important determinants of crop yields (Werf, 1996). Rate and extent of dry matter
accumulation by the crop depends on ability of the crop canopy to intercept incident
photosynthetically active radiation (IPAR) and the efficiency with which this radiation
can be converted into new biomass i.e. radiation use efficiency (Sinclair and Muchow,
1999). Moreover, radiation use efficiency is a conservative quantity (Monteith and Elson,
1983). Hysun-33 utilized radiation more efficiently (1.98-1.94 g MJ-1) for total dry matter
accumulation, which was, 22% greater than the early maturing hybrid (FH-331) and 9%
higher than the mid season hybrid (SF-187). Khaliq (2004) and Iqbal (2008) also
183
reported significant differences for RUE of sunflower hybrids of diverse maturity.
Edward et al. (2005) recorded significant differences in diverse maturity hybrids sown at
different planting densities.
Decreasing plant population (increasing row spacing) showed a depressing effect
on radiation use efficiency on unit area basis (Table 4.44) and the maximum radiation
utilization (1.92 g MJ-1) for TDM buildup was observed for the crop sown at narrow (45
cm) row spacing. Increasing the row spacing from 45 to 60 cm recorded 5% decrease in
RUETDM and further widening the row spacing from 60 to 75 cm further experienced a
12% decrease in RUETDM. The utilization of light can be affected by row spacing (Flenet
et al., 1996). Decrease in radiation use efficiency for TDM production as a consequence
of decreasing planting density has been recorded in rice (Ahmed et al., 2008) and
soybeans (Purcell et al., 2002). In contrary, Ferreira and Abreu (2001) reported that
radiation use efficiency was not affected by plant density in sunflower crop. They further
concluded that RUE(tdm) was associated with LAI and TDM, and increasing planting
density with narrowing row spacing resulted in higher LAI as compared to sunflower
with lower plant density (wider row spacing).
Different sunflower hybrids exhibited differential response towards RUEGrain
when planted at variable row spacing (Table 4.46). Both FH-331 and SF-187 observed a
decline (18 and 9 %, respectively) in RUEGrain with widening the rows from distance of
45 cm to 60 cm. In contrary, Hysun-33 exhibited a 12% gain in RUEGrain for same
increase in row spacing. By further widening the rows from 60 to 75 cm, decline in
RUEGrain resulted in all the hybrids under study. Again, when RUEGrain was compared for
45 and 75 cm spaced planting, FH-331 and SF-187 showed a decline of 18 and 9 percent,
respectively while Hysun-33 recorded a gain of 6%.
Achene oil contents differed significantly, when diverse hybrids were studied
(Table4.46). During first year, maximum and comparable (P≤0.05) achene-oil content
(42.89-42.56 %) was recorded for hybrids Hysun-33 and FH-331. Comparatively lower
(by 6%) achene-oil content was observed for SF-187. Same tendency was observed
during second year, with oil content being relatively on upper side in this year.
Higher achene-oil content in late maturing hybrid is in agreement with previous
findings (Dubbelde, 1989; .El-Hinnaway et al., 1981). Ali et al. (1992), Ahmad (1999),
Monoth et al. (2000), Iqtidar et al. (2000) also reported significance differences in oil
contents of different hybrids. Higher oil content in Hysun-33 also is explained by its
genetic character and less 1000-achene weight (Table 4.35) which leads to higher
184
concentration of oil when determined on weight basis. Villalobos et al. (1994) confirmed
that a low 1000-achene weight was always coupled with a high oil concentration and vice
versa. Bodenkultur et al. (2001) reported negative correspondence between the 1000-
achene weight and oil concentration. However, Ceccarini et al. (2004) recorded non-
significant differences in oil concentration of two different hybrids which might be
explained by environmental factors and/or owing to genetic similarity of the hybrids in
their studies. Sunflower grown in narrow rows exhibited more achene-oil content than
that sown in wider rows (Table 4.46). Maximum oil content (43.22%) was gained, when
the crop was sown at 45 cm row spacing. Stear et al. (1986) stated that oil yield per plant
was reduced by rising plant density; while the percentage of oil in seed was not
exaggerated by dense population. Bodenkultur et al. (2001) stated that the lowest oil
concentration (44%) was found at 100 cm row spacing as compared to 75 cm (45.6%) and
50 cm (46.4%) row spacing. However, Gubbles and Dedio (1990) and Johnson and
Schneitr (1998) observed non-significant effects of row spacing on oil concentration in
sunflowers. Johnson (1998) also established non-significant inter-hybrid competition
(different row spacing) influence on oil contents of sunflower crop.
Sunflower has been rightly named as an oil-crop owing to its higher oil harvested
per unit area. Hysun-33 recorded highest oil yield (1214 kg ha-1) that was 13% more than
oil yield of SF-187 (1062 kg ha-1) and 24% higher than that of FH-331 (922 kg ha-1;
(Table 4.47). Higher oil yield in Hysun-33 may be explained by its higher achene yield
(Table 4.36) and achene-oil content (Table 4.46) as compared with the other hybrids.
Similar oil yield was recorded in crop planted in 45 and 60 cm rows. The later row
spacing also yielded similar oil as was recorded for crop sown in 75 cm row. In contrary
to this, the sunflowers planted in varying row spacing exhibited non-significant (P≤0.05)
differences during 2007.
SF-187 had highest achene protein content (20.97%) as compared with the lowest
(19.03%) for Hysun-33 (Table 4.48). Local hybrid FH-331 accumulated as high protein
(20.13%) as was recorded for SF-187. The inverse relationship between oil and protein
concentration in seed has also been recorded by Goffner et al. (988) and Singh et al.
(1988) and is explained by the continuing deposition of oil, which has diluting effects on
protein in such hybrids.
Palmitic acid concentration did not vary significantly (P≤0.05) for FH-331 and
SF-187 (5.67 vs 5.46 %) and was higher than that recorded for Hysun-33 (4.90%).
Ahmad (1999) and Khaliq (2004) conducted the experiment under similar environmental
185
conditions and reported similar findings. Contrary to this, Saleem (2004), Cecarmi et al.
(2004) and Iqbal (2004) reported non-significant differences among various hybrids for
their palmitic acid concentration in the achene-oil. Qadir et al. (2006) reported that in
autumn, Hysun-33 produced significantly highest oil contents (49.65%), as compared to
Award (44.66%) and there were significant differences observed for fatty acid
composition. Varying row spacing had non-significant (P≤0.05) bearing upon palmitic
acid concentration in achene-oil of sunflowers during both years of experimentation
(Table 4.49).
Different hybrids showed significant (P≤0.05) difference for stearic acid
concentration in sunflower oil (Table 4.50). Hysun-33 recorded highest (3.97%) stearic
acid concentration as compared with FH-331(3.67%) and SF-187 (3.61%) which revealed
non-significant difference between them. Ahmad (1999) and Iqbal (2008) reported non-
significant differences among various hybrids, while the results recorded by Khaliq
(2004) are in line with the differential behavior of diverse sunflower hybrids under
discussion. Sunflower crop sown at different row spacing (plant density) showed non-
significant (P≤0.05) effect on stearic acid concentration of its achene-oil (Table4.50).
Concentration of oleic acid (18:1) in achene oil of sunflower varied significantly
(P≤0.05) among hybrids (Table 4.51) and was in order of Hysun-33>FH-331>Sf-187.
Hysun-33 recorded highest (10.70%) oleic acid concentration that was 7% and 22%
higher than that exhibited by FH-331 (9.96%) and SF187 (8.80%), respectively. Skoric et
al. (1978), Ahmad et al. (1999) and Khaliq (2004) also reported variation in oleic acid
concentration of oil of different sunflower hybrids.
During both the years, linoleic acid concentration did not vary significantly
(P≤0.05) among different hybrids (Table 4.52). Ahmad et al. (1997), Saleem (2004) and
Iqbal (2008) also recorded non-significant differences among hybrids of different
maturity and plant height, while Khaliq (2004) recorded significant differences in linoleic
acid content of various sunflower hybrids.
186
CHAPTER 5
SUMMARY
Two sets of field experiments were conducted during 2006 and 2007 to study the
influence of varying levels of sulphur and nitrogen nutrition on autumn planted hybrid
sunflower (Experiment I), and to study the developmental patterns and quantify
agronomic response of three sunflower hybrids when sown in different planting densities
under varying row spacing (Experiment II). In Experiment-I, sunflower hybrid Hysun-33
was subjected to four sulphur levels (0, 40, 80, 120 kg ha-1), and four nitrogen levels (0,
100, 140, 180 kg ha-1). Treatments were laid out as factorial combination in randomized
complete block design with three replications with a net plot size of 4.5 m x 7.0 m. In
Experiment-II, three sunflower hybrids viz., FH-331 (early maturing), SF-187 (medium
maturing) and Hysun-33 (late maturing) were sown at three row spacing. Six rows of
each hybrid were sown at row spacing of 45 cm (98765 plants ha-1), 60 cm (74074 plants
ha-1) and 75 cm (59259 plants ha-1) with a uniform plant to plant distance of 22.5 cm in
all row spacing. Sowing was done with dibbler at 22.5 cm in both the experiments at the
respective row spacing in both the experiments. Measurements of crop growth, achene
yield and yield components, and environmental variables were made to establish the
causes underlying expected variation in crop yields associated with the varying N and S
nutrition and plant population on hybrids of different morpho-physiological
characteristics. Achenes were analyzed for oil and protein contents, and fatty acid profiles
of the oil were also studied. Results obtained are described in the following sections.
Yield and yield components
Application of sulphur enhanced achene yield significantly and maximum achene
yield was recorded with application of 80 kg ha-1 S.
Achene yield increased by 25, 39 and 32 percent with application of 40, 80 and
120 kg ha-1 S, respectively over control.
Nitrogen application also enhanced achene yield significantly over control and a
yield plateau was achieved with application of 140 kg ha-1 during both the years.
Application of 100 kg ha-1 N enhanced achene yield by 88% over control that was
126% when N application was increased by 40 kg ha-1.
187
Highest achene yield (3084-3018 kg ha-1) was recorded with the application of S
and N at 80 and 140 kg ha-1.
Highest harvest index 29.48% was recorded with the application of 140 kg N and
80 kg S ha-1.
Both sulphur and nitrogen application enhanced head diameter, number of
achenes per head and 1000-achene weight during both years of experimentation.
Hysun-33 recorded 21 to 24 percent higher achene yield than that recorded for
FH-331.
Crop planted in 45 and 60 cm apart rows recorded highest and similar achene
yield during 2006 than that planted in 75 cm apart rows.
Achene yield of FH-331 increased by 14% when row to row distance was
decreased from 60 to 45cm.
SF-187 also recorded increase in achene yield by decreasing row spacing but the
magnitude of increase was almost 50% than that recorded for FH-331. In contrary
to both of these hybrids, Hysun-33 exhibited increase in yield by 10% when row
distance was increased from 45 to 60 cm.
Achene weight of Hysun-33 was improved by 32% when row spacing was
increased from 45 to 60 cm.
Crop planted on 75 cm apart rows recorded lowest number of achenes m-2 that
was improved by 19 and 45% when row spacing was narrowed down to 60 and 45
cm, respectively.
Maximum 1000-achene weight (57 g) was recorded when the crop was sown at 75
cm apart row spacing. Reducing row spacing exhibited a corresponding reduction
in achene weight.
Varying row spacing also depicted non-significant difference in harvest indices.
Growth and growth analysis
Highest LAI was reached at 75 DAS with the application of 180 kg ha-1 N and 80
kg ha-1S. Highest values of LAI were associated with anthesis stage of the crop in
all hybrids.
Harvest indices of the three hybrids in present studies did not vary to significant
level.
Highest LAI (5.20) was recorded for the crop sown at 60 cm apart rows that
declined to 4.50 and 4.32 for 45 and 75 cm apart rows.
188
Both sulphur and nitrogen application enhanced leaf area duration (LAD).
Hysun-33 showed maximum leaf area duration (206 d).
LAD decreased by 4 and 11 percent when row spacing was increased from 45 to
60 and 75 cm, respectively.
Sulphur application at 40, 80 and 120 kg ha-1 improved seasonal crop growth rate
by 9, 13 and 12 percent over control.
Nitrogen at 180 kg ha-1 recorded highest crop growth rate CGR (16.11-15.54 g m-2
day-1).
On an average, Hysun-33 exhibited 30 and 13 % higher seasonal crop growth rate
than FH-331 and SF-187, respectively.
Narrowing the row spacing (increasing plant population) resulted in increase in
mean seasonal crop growth rate during both the years.
Both S and N application improved net assimilation rate. Maximum and similar
NAR were observed for Hysun-33 and SF-187 (4.98 vs. 4.88 g m-2 d-1) as
compared with FH-187 (4.47 g m-2 d-1) during both the years.
Maximum mean NAR (5.00 g m-2 d-1) was recorded when the crop was grown at
row spacing of 45 cm and it was 10% higher than that recorded for crop planted in
75 cm apart rows.
Highest and similar cumulative intercepted radiation was observed with the
application of 80 and 120 kg ha-1 S.
Nitrogen application resulted in better cumulative radiation interception and the
maximum light interception (536.14-503.22 MJ m-2) was recorded with
application of 180 kg ha-1 nitrogen.
Application of sulphur and nitrogen both enhanced radiation use efficiency for
total dry matter (RUETDM) and for grain (RUEgrain).
Hysun-33 recorded highest values for accumulated intercepted radiation (AIR)
that was, on an average, 4% higher than that recorded for FH-331 and 2% higher
than that for SF-187.
Hysun-33 utilized radiation more efficiently (1.98-1.94 g MJ-1) for total dry matter
accumulation, which was, on an average, 22% higher than that observed for early
maturing hybrid (FH-331) and 9% higher than the mid season hybrid (SF-187).
Hysun-33 and SF-187 recorded maximum and similar RUEGrain (0.54 and 0.50 g
MJ-1) as against the minimum (0.46 g MJ-1) recorded for FH-331.
189
Decreasing row spacing (increased planting density) exhibited a positive influence
on radiation interception.
Maximum radiation interception (527 MJ m-2) was the outcome of sunflower
planted at 45 row spacing. Maximum radiation utilization (1.92 g MJ-1) for dry
matter accumulation was recorded for the crop sown at narrow (45 cm) row
spacing and widening the row spacing resulted in decrease in RUETDM.
FH-331 and SF-187 observed a decline (18 and 9 %, respectively) in RUEGrain
when row spacing was increased from 45 to 60 cm. In contrary, Hysun-33
exhibited a 12% gain in RUEGrain for same increase in row spacing.
Nutrient Uptake
Improving sulphur and nitrogen nutrition of sunflower had a positive bearing on
nutrient uptake.
Application of higher levels (140, 180 kg ha-1) of nitrogen resulted in increased N
uptake in combination with either lower (40 kg ha-1) or higher (120 kg ha-1) levels
of sulphur application.
Crop grown without S fertilization in combination with 140 kg ha-1 N failed to
achieve fairly good N uptake levels suggesting a synergistic effect of both
nutrients in enhancing N uptake in sunflowers.
Increasing levels of S and N nutrition resulted in corresponding increase in P and
K uptake.
Oil yield and quality
Application of sulphur and nitrogen improved achene-protein content. Application
of 80 kg ha-1 S with 140 and/or 180 kg ha-1 N recorded as good achene-protein
content as was recorded with application of 120 kg ha-1 S in combination with 180
kg ha-1 N.
SF-187 showed highest achene protein content (20.97%) as compared with the
lowest (19.03%) for Hysun-33.
Sunflower grown without nitrogen application exhibited highest achene-oil
content. Application of 100, 140 and 180 kg ha-1 N recorded 2.8, 7.3 and 9.9
percent reduction in achene-oil content, respectively as compared with non-
fertilized crop.
Maximum and similar achene-oil content (42.89-42.56 %) was recorded for
hybrids Hysun-33 and FH-331.
190
Sunflower grown in narrow rows exhibited more achene-oil content than that
sown in wider rows.
Oil yield of sunflower increased with S fertilization so that 40, 80 and 100 kg ha-1
S resulted in 33, 58 and 52 increase in oil yield, respectively over control.
Oil yield increased by 83, 110 and 111 percent with application of 100, 140 and
180 kg ha-1 N, respectively as compared with no-N plots.
Hysun-33 recorded highest oil yield (1214 kg ha-1) that was 13% higher than oil
yield of SF-187 (1062 kg ha-1) and 24% higher than that of FH-331 (922 kg ha-1).
Row spacing had a significant bearing on oil yield only during 2006 where similar
oil yield was recorded in crop planted in 45 and 60 cm rows. The later row
spacing also yielded similar oil as was recorded for crop sown in 75 cm row.
Sulphur as well as nitrogen application had a depressing effect on concentration of
oleic acid (18:1) in achene oil of sunflower.
Concentration of oleic acid (18:1) was in order of Hysun-33>FH-331>Sf-187 and
the influence of row spacing was non-significant.
Sulphur application improved linoleic acid (18:2) concentration in sunflower
achene oil that also increased gradually with increasing levels of nitrogen. Highest
concentrations of linoleic acid were recorded where either both S or N or any one
of these was used at its higher application rate.
Linoleic acid concentration did not vary significantly (P≤0.05) among different
hybrids and row spacing.
Sulphur application did not influence the palmitic acid (16:1) concentration to
significant extent but application of nitrogen enhanced it and maximum
concentration (6.19%) was recorded by the application of 180 kg ha-1 nitrogen.
FH-331 and SF-187 recorded 14 and 4 percent higher palmitic acid concentration
than Hysun-33 while varying row spacing had non-significant bearing upon it.
Neither sulphur, nor nitrogen nutrition influenced the concentration of stearic acid.
Hysun-33 recorded highest (3.97%) stearic acid concentration as compared with
FH-331(3.67%) and SF-187 (3.61%) and the effect of row spacing (plant density)
was non-significant.
191
CONCLUSION
On the basis of two years results, it is concluded that sunflower hybrid
should be fertilized at rate of 80 kg ha-1 sulphur and 140 kg ha-1 nitrogen
for obtaining high yields and maximum economic return.
Early and mid season hybrid like FH-331 and SF-187 need to be planted at
45 cm row spacing while late season hybrid as Hysun-33 reflected an
increasing trend in yield with 60 cm row spacing in these studies.
Sulphur and nitrogen nutrition improved the nutrient uptake, and hence
improved the growth and developmental traits of sunflower. Both the
nutrients worked in synergism.
Oil yield was improved with improving sulphur and nitrogen nutrition and
quality of oil in terms of unsaturated fatty acids was also improved by
both sulphur and nitrogen nutrition in these studies.
Albeit the negative effects of decreasing row spacing (increased plant
population) on agronomic and growth traits of individual plants of
sunflower, positivity was recorded when computation of achene and oil
yields were made on unit area basis.
192
Future Recommendations
Biochemical basis of variation in growth, and physiology of yield formation
owing to sulphur nutrition need to be investigated under present environments.
Seasonal patterns of radiation interception and utilization under variables
nutritional status and row spacing need to be established for hybrids of varying
maturity.
Energy and/or carbohydrates equivalents of oil and protein under varying row
spacing and nutritional status need to be investigated in detail. This may help fetch
a premium price of the produce.
Intra row spacing with varying inter row spacing should be standardized.
193
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Appendix: 1 Cost of production during 2006-07 for experiment 1 Operation/Input Amount/Frequency Rate Rs. unit-1 Total Expenditure (Rs. ha-
1)Tillage and seedbed preparation Ploughing 2 300 600/- Planking 1 125 125/- Sowing
Bund making 5 men for ¼ day 100 man-1 day-1 125/- Sowing 8 men for 1/2 day 100 man-1 day-1 500/- Plant protection Sprays including labour charges
2 750 1500/-
Watch and ward 1 man for 30 days 100 man-1 day-1 3000/- Irrigation Cleaning of water channel
½ man day 100 man-1 day-1 50/-
Labour charges for 4 irrigations
1 man day 100 man-1 day-1 100/-
Harvesting charges
8 man days 100 man-1 day-1 800/-
Threshing charges
10 man days 100 man-1 day-1 1000/-
Land rent (6 months)
10000 annum-1 5000/-
Sub-total (a) 12800/-
Cost of fertilizer for Experiment I Year Rate of
fertilizers Price per bag(50kg)
Fertilizer expenditure
Total Amount (Rs.)
PK (kg ha-1) DAP, MOP P + K (Rs.) 2006 100 -60 1600/-, 500/- =6956/+1250/- 8206/- 2007 100- 60 1800/-, 550/- =7812/+1375/- 9187/- Average 8697/-
Sub-total (b) 8697/- Cost of Seed for Experiment I
Year Seed rate (kg ha-1)
Price per kg-1 Total cost (Rs.)
2006 8 =350/- =2800/- 2007 8 =370/- =2960/- Average =1548/-
Sub-total (b) =3096/-
218
Cost of Nitrogenous fertilizer for Experiment 1: 2006 Treatments Nitrogen ( Kg ha-1) Urea ( Kg
ha-1) Price per bag of Urea( 50kg)
Fertilizer expenditure (Rs.)
Total Amount (Rs.)
N1 0 0 Rs. 600/- 0 0 N2 100 217 =2604/- 2604/- N3 140 304 =3648/- 3648/- N4 180 391 =4692/- 4692/-
Cost of Nitrogenous fertilizer for Experiment 1 2007 Treatments Nitrogen ( Kg ha-1) Urea ( Kg
ha-1) Price per bag of Urea( 50kg)
Fertilizer expenditure (Rs.)
Total Amount (Rs.)
N1 0 0 Rs. 700/- 0 0 N2 100 217 =3038/- =3038/- N3 140 304 =4256/- =4256/- N4 180 391 =5474/- =5474/-
Cost of Sulphur fertilizer for Experiment 1 2006 Treatments Sulphur ( Kg ha-1) Gypsum (
Kg ha-1) Price per bag of Gypsum ( 50kg)
Fertilizer expenditure (Rs.)
Total Amount (Rs.)
S1 0 0 Rs. 60/- 0 0 S2 40 222 =266/- =266/- S3 80 445 =534/- =534/- S4 120 667 =800/- =800/-
Cost of Sulphur fertilizer for Experiment 1 2007 Treatments Sulphur ( Kg ha-1) Gypsum (
Kg ha-1) Price per bag of Gypsum ( 50kg)
Fertilizer expenditure (Rs.)
Total Amount (Rs.)
S1 0 0 Rs. 70/- 0 0 S2 40 222 =311/- =311/- S3 80 445 =623/- =623/- S4 120 667 =934/- =934/-
