DETERMINING GAMMA RADIATION DOSE FOR INDUCED MUTATION IN MAIZE(ZEA MAYS)
By Chilembo LeonardComp: 11004517
SUPERVISORS : DR. K. MUNYINDADR. L. TEMBO
INTRODUCTIONMaize (Zea mays L.) Maize is the most
significant cereal crop and staple food for more than 1.2 billion people in Sub-Saharan Africa (SSA) and Latin America (Vivek et al., 2005)
However, maize yield is low due to biotic and abiotic stresses on the crop
Creation of genetic variation through induced mutation from which desired mutants can be selected proves to provide great success in plant breeding programmes (Ahloowalia, 2004).
STATEMENT OF THE PROBLEM
Low maize yield is an increasing challenge in ensuring food security. This calls for breeding methods such as induced mutation to generate maize genotypes with desired traits such as drought, low soil fertility, disease and pest resistance (Parr et al., 2005).
JUSTIFICATION OF THE STUDY
Induced mutation is a significant tool for creating genetic variations among the maize genotypes (Wani and Anis, 2008).
Variations enables the selection of desired traits such as drought and low fertility tolerance to solve the problem of low maize yields (Ashraf, 2009).
OBJECTIVE
To determine the optimum gamma radiation dose for induced mutation in maize for producing desirable traits.
RESEARCH HYPOTHESIS Gamma irradiation produces mutation
derived maize lines with desirable traits (drought, high nutrient use efficiencies)
MATERIALS AND METHODSThe materials used in the study were five
genotypes: GV 635, ZARICZH 122, ZARICZH 1021, ZARICZH 131002 and ZARICZH 131008
Got from Zambia Agricultural Research Institute (ZARI) provided by the department of plant science.
MATERIALS AND METHODS CONT’D
The genotypes were irradiated at four different doses (0, 150, 300, 450 and 600 Gy)
Irradiated seeds were then planted in pots in the greenhouse
MATERIALS AND METHODS CONT’D
Planting was done on 23rd January 2016 and
The experiment was carried out for a period of 30 days.
Parameters measured
Plant germination was recorded 7 days after planting
Plant height, Leaf length, leaf width and chlorophyll content were all measured 30
days after plantingLeaf area (L × W × A ); A=0.75 (Pearce, 1975)
EXPERIMENTAL DESIGN
• Complete Randomized Design (CRD)• Two factors:– Gamma radiation dose (Gy)– maize genotypes
• 5 treatments which are gamma radiation doses (0, 150, 300, 450 and 600 Gy).
• 4 replications of radiation dose. • Data analyzed by GenSat18
RESULTS
Genotypic Mean Squares for measured Parameters evaluated across Gamma ray doses (Gy)
Source of D.f Germ Plant height Leaf length leaf Area Chlorophyll Variation MS MS MS MS MS
Genotype 4 7.534 ** 370.163 *** 144.940*** 669.3*** 59.91ns
Dose 4 9.403** 221.828 *** 180.174*** 1246.0*** 37.14ns
Genotype×Dose 16 8.851*** 139.4ns 0.11 29ns 28.638ns 42.19ns
Residual 70 2.208 3.231 6.730 106.3 25.51 CV% 16.5 4.5 4.2 16.3 15.6KEY*,**,***, Significant at P=0.1, P=0.05 & P=0.001 respectively , ns=Non significant, MS=Mean Square, DF=Degree of Freedom.
Fig 1: Effects of gamma radiation dose on plant height
015
030
045
060
0 015
030
045
060
0 015
030
045
060
0 015
030
045
060
0 015
030
045
060
0
GV 635 ZARICZH 1021 ZARICZH 122 ZARICZH 131002 ZARICZH 131008
0
10
20
30
40
50
60
GENOTYPE AND RADIATION DOSE
Plan
t gro
wth
(cm
)
Fig 2: % Reduction in plant height
150 Gy 300 Gy 450 Gy 600 Gy0
5
10
15
20
25
30
% Reduction
Gamma radiation dose
Plan
t hei
ght (
cm)
Fig 3: Effects of gamma radiation dose on leaf length
015
030
045
060
0 015
030
045
060
0 015
030
045
060
0 015
030
045
060
0 015
030
045
060
0
GV 635 ZARICZH 1021 ZARICZH 122 ZARICZH 131002
ZARICZH 131008
05
1015202530354045
GENOTYPE AND RADIATION DOSE
Leaf
leng
th (c
m
Fig 4: % Reduction in leaf length
150 Gy 300 Gy 450 Gy 600 Gy05
101520253035
% Reduction
Gamma radiation dose
Leaf
leng
th (c
m)
Fig 5: Effects of gamma radiation dose on leaf area0
150
300
450
600 0
150
300
450
600 0
150
300
450
600 0
150
300
450
600 0
150
300
450
600
GV 635 ZARICZH 1021 ZARICZH 122 ZARICZH 131002 ZARICZH 131008
0
10
20
30
40
50
60
70
80
90
GENOTYPE AND RADIATION DOSE
leaf
are
a (c
m²)
Fig 6: % Reduction in leaf area
150 Gy 300 Gy 450 Gy 600 Gy0
10
20
30
40
50
60
% Reduction
Gamma radiation dose
Aver
age
leaf
are
a (c
m²)
DISCUSSIONAt 0 Gy all the genotypes showed normal growth
but had some stimulating growth at 150 GyThis is because the stimulatory effect is attributed
to the production of growth hormone, kinetin, which forms hormonal balance
Hormonal balance is formed due to increasing number of cells to overcome stress factors such as frequency of chromosomal damage with increasing fluctuations of light intensity and temperature because of gamma radiation (Chung and J.S. Kim, 2007).
CONCLUSION
The optimum gamma radiation dose found for irradiating maize genotypes was 450 Gy
This is because radiation dose of 450 Gy caused a percentage reduction growth in the parameters measured of more than 20%
A dose causing percentage reduction of 20 and above is considered optimum, where maximum mutation is produced with minimal damage to the plant (Kangarasu S, 2014).
RECOMENDATION
Since the optimal gamma irradiation dose was determined, growing maize plants irradiated at 450 Gy to maturity to observe yield and other characteristics should be done.
References• Ahloowalia (2004). Global impact of mutation-derived varieties. Euphytica 135:187-204.
• Ashraf M (2009). Changes in antioxidant enzymes and some key metabolites in some genetically diverse cultivars of radish (Raphanus sativus L.). Environ. Exp. Bot., 67: 395-402
• Chung and J.S. Kim, 2007. Effects of markers. African Journal of Biotechnology, gamma irradiation on morphological changes and 8(19): 4824-4829. biological responses in plants. Micron, 38: 553-564
• Kangarasu S (2014). Determination of Lethal Dose for Gamma Rays and Ethyl Methane Sulphonate Induced Mutagenesis In Cassava (Manihot Esculenta Crantz). Department of Plant Genetic Resources, Centre for Plant Breeding and Genetics, Tamil Nadua Agricultural University, Coimbatore.
• Parry et al., (2007). Prospects for increasing photosynthesis by overcoming the limitations of Rubisco. Journal of Agricultural Science 145, 31–43.
• Pearce et al., (1975). Maize plant physiology. Iowa State University Press, Ames, IA. USA
• Vivek et al., (2005). Characterization of maize germplasm grown in eastern and southern Africa: Results of the 2004 regional trials coordinated by CIMMYT. Harare, Zimbabwe. CIMMYT. 68pp.
THANK YOU!!
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