Weed management in aerobic rice systems under varying establishment methods

ARTICLE IN PRESS

0261-2194/$ - se

doi:10.1016/j.cr

�CorrespondE-mail addr

anraojaya@hot1Present add

University, Itha2Present addr

033, India.

Crop Protection 27 (2008) 660–671

www.elsevier.com/locate/cropro

Weed management in aerobic rice systems under varyingestablishment methods

Samar Singha, J.K. Ladhab,�,1, R.K. Guptaa, Lav Bhushana, A.N. Raob,2

aRice–Wheat Consortium for the Indo-Gangetic Plains, CIMMYT-India, CG Block, NASC Complex, DPS Marg, New Delhi 110 012, IndiabInternational Rice Research Institute (IRRI), India Office, 1st Floor, CG Block, NASC Complex, DPS Marg, New Delhi 110 012, India

Received 24 September 2007; accepted 25 September 2007

Abstract

Aerobic rice systems, wherein the crop is established via direct-seeding in non-puddled, non-flooded fields, are among the most

promising approaches for saving water and labour. However, aerobic systems are subject to much higher weed pressure than

conventionally puddled transplanted rice (CPTR). Experiments were conducted for 2 years to develop effective and economical methods

for managing weeds in aerobic rice grown by direct-seeding or transplanting on flat land or furrow-irrigated raised-bed systems (FIRBS).

Total weed dry weight and weed density were lower with CPTR and highest with aerobic direct-seeded rice on a FIRBS (ADSB),

followed by aerobic direct-seeded rice (ADSR). In terms of weight grassy weed constituted 78–96% of total weed weight in all systems of

rice establishment. Loss of grain yield of rice due to weed competition ranged from 38% to 92%, being the highest in ADSB. Both weed

density and dry weight were negatively correlated with rice grain yield. ADSR treatment produced yield and net economic returns similar

to CPTR treatment when weeds were controlled. Pretilachlor with safener at 500 g a.i. ha�1 applied 3 days after sowing (DAS)/ days after

transplanting (DAT) followed by chlorimuron+metsulfuron at 4 g a.i. ha�1 applied 21DAS/DAT followed by hand-weeding at 35DAS/

DAT could effectively control all the weeds. The next best treatment was cyhalofop-butyl at 120 g a.i. ha�1 applied 14DAS/DAT

followed by chlorimuron+metsulfuron at 4 g a.i. ha�1 applied 21DAS/DAT followed by hand-weeding at 35DAS/DAT. The ADSR

was as effective as conventionally puddle-transplanted rice in attaining higher rice grain yield and net returns when weeds were kept

under control.

r 2007 Elsevier Ltd. All rights reserved.

Keywords: Chlorimuron+metsulfuron; Cyhalofop-butyl; Pretilachlor with safener; Aerobic rice; Oryza sativa L.; Establishment methods; Economic weed

management

1. Introduction

The rice–wheat system, occupying 24 million hectares ofproductive area in South Asia and China, is important forfood security of the region (Ladha et al., 2003). The annualproductivity of the rice–wheat system in the Indo-GangeticPlains (IGP) is low (3–5Mgha�1) compared with theclimatic yield potential of the region (12–19.3Mgha�1)

e front matter r 2007 Elsevier Ltd. All rights reserved.

opro.2007.09.012

ing author. Tel.: +9111 25843802; fax: +91 11 25841801.

esses: [email protected] (J.K. Ladha),

mail.com (A.N. Rao).

ress: Department of Crop and Soil Sciences, Cornell

ca, NY 14853, USA.

ess: Plot 1294A, Road 63A, Jubilee Hills, Hyderabad 500

(Aggarwal et al., 2000; Pathak et al., 2003). In high-productivity zones of the IGP, the rice–wheat system isstressed due to production fatigue as evidenced bydeclining soil organic matter content, low fertilizer useand diminishing rates of factor productivity (Dwivediet al., 2003; Ladha et al., 2003). Transplanting in puddledsoils (wet tillage), with continuous flooding, is the mostcommon method of rice crop establishment. Transplantedrice requires a large amount of water and labour. Duringpeak periods of transplanting, labour also becomes veryscarce. Puddling also affects soil health due to thedispersion of soil particles, soil becoming compact andmaking tillage operations difficult requiring more energy insucceeding crops such as wheat (Singh et al., 2002).Fujisaka et al. (1994), on the basis of a diagnostic survey

www.elsevier.com/locate/cropro

dx.doi.org/10.1016/j.cropro.2007.09.012

mailto:[email protected]

mailto:[email protected]

ARTICLE IN PRESSS. Singh et al. / Crop Protection 27 (2008) 660–671 661

conducted in several rice–wheat areas in South Asia,observed low wheat yields in a rice–wheat system, mainlydue to deterioration in soil structure and the developmentof subsurface hardpans. Hobbs et al. (2002) described theemerging issues of sustainability of rice–wheat systems andstressed the need to improve water-use efficiency, soilstructure and weed management against the backdrop ofincreasing labour and water scarcity. An alternative topuddling and transplanting of rice could be aerobic direct-seeding because it requires less water, labour and capitalinput. The direct-seeded crop also matures earlier (7–10days) than the transplanted crop, thus allowing timelyplanting of the succeeding wheat crop (Giri, 1998; Singhet al., 2006).

Irrigated ‘‘aerobic rice’’ is a new system being developedfor lowland areas with water shortage and for favourableupland areas with access to supplementary irrigation(Tuong and Bouman, 2003; Belder et al., 2005). Aerobicrice systems, wherein the crop is established via direct-seeding in non-puddled, non-flooded fields, are among themost promising approaches for saving water (Wang et al.,2002; Tuong and Bouman, 2003; Bhushan et al., 2007).Aerobic rice systems can reduce water application by 44%relative to conventionally transplanted systems, by redu-cing percolation, seepage and evaporative losses, whilemaintaining yield at an acceptable level (6Mgha�1) (Wanget al., 2002; Bouman et al., 2005). However, aerobicsystems are subject to much higher weed pressure thanconventional puddled transplanting systems (Rao et al.,2007; Balasubramanian and Hill, 2002) in which weeds aresuppressed by standing water and by transplanted riceseedlings, which have a ‘‘head start’’ over germinatingweed seedlings (Moody, 1983). Aerobic soil dry-tillage andalternate wetting and drying conditions, on the other hand,are conducive to the germination and growth of weedscausing grain yield losses of 50–91% (Elliot et al., 1984;Fujisaka et al., 1993; Rao et al., 2007). Thus, weeds are themost severe constraints to aerobic rice production andtimely weed management is crucial to increasing theproductivity of aerobic rice (Rao et al., 2007).

Studies in northern Australia (Garside et al., 1992) andIndonesia (Van Cooten and Borrell, 1999) found that ricecan be successfully rotated with upland crops usingsaturated soil culture on permanent raised beds. Advan-tages identified with this system of rice production undersaturated soil culture on permanent beds include water,nitrogen and phosphorus economies, energy savings,greater timeliness of field operations and a reduction insoil compaction (Borrell and Garside, 2005). Farmers’ andresearchers’ trials in the IGP suggest irrigation watersavings of 12–60% for direct-seeded or transplanted rice onflat or raised beds, but with some yield penalty (Guptaet al., 2000). As the bed is often under aerobic conditions,growth of weeds, especially grasses, is promoted, posing aproblem in the raised-bed system (Singh et al., 2006).

Most upland and aerobic rice growers in Asia mechani-cally weed their crops two or three times per season,

investing up to 190 person days ha�1 in hand-weeding(Roder, 2001). The labour requirement for weeding is amajor impediment to the adoption of water-saving aerobicrice, and to increasing the productivity of aerobic rice-based cropping systems. Herbicides are considered to be analternative/supplement to hand-weeding (Singh et al.,2006). Both pre-emergence and post-emergence herbicidescan be used in aerobic rice fields, and they are effective, ifproperly used (De Datta and Baltazar, 1996; Singh et al.,2006). Chemical weed control on puddled flat lands wasgood but in case of transplanted rice on beds 1–2 hand-weedings were required, which increased to 3–4 in direct-seeded rice on beds (Kukal et al., 2005).Information on weeds and weed management in aerobic

rice cultivated on flat land and on raised beds, by eithertransplanting or direct-seeding, is scarce. Since the conceptof aerobic rice is new (Tuong and Bouman, 2003; Belder etal., 2005), growing rice under aerobic conditions on raisedbeds or on flat land would require suitable, effective andeconomical weed-control methods. Development of newimproved herbicides for aerobic dry-seeded rice is alsoneeded (Gupta et al., 2003). The present experiment wasconducted to develop effective and economical methods formanaging weeds in aerobic rice grown by direct-seeding ortransplanting on flat land or furrow-irrigated raised-bedsystems (FIRBS) and comparing it with conventionalflooded puddled transplanted rice.

2. Materials and methods

2.1. Experimental site

The field experiment was conducted for 2 years (2002and 2003) at the experimental farm of the Sardar VallabBhai Patel University of Agriculture and Technology,Modipuram, Meerut, Uttar Pradesh, India (29140N and771460E, at an elevation of 237m above mean sea level).The climate of Modipuram is broadly classified as semi-arid subtropical, characterized by very hot summers andcold winters. The hottest months are May and June, whenthe maximum temperature reaches 45–46 1C, whereasduring December and January, the coldest months of theyear, the minimum temperature often goes below 5 1C. Theaverage annual rainfall is 863mm, 75–80% of which isreceived through the northwest monsoon during July–September. The experimental soil was silty loam in texturewith particle density 2.65Mgm�3, mean weight diameter ofsoil aggregates 0.71mm indicating a poorly developed soilstructure, mainly because the soil reclaimed recently wasalkaline (sodic) in nature. The soil (0–15 cm) retained 18%and 7% moisture (mass basis) at 30 and 1500 kPa suction,respectively, with plant-available water capacity of 11%.The soil reaction was alkaline, with very low salt content.The surface soil (0–15 cm) had 0.83% total carbon, 0.088%total N, 25mgkg�1 Olsen’s P and 0.314meq 100 g�1 1NNH4OAC-extractable K. DTPA-extractable Zn, Cu, Feand Mn were in the high range in the surface soil layer.

ARTICLE IN PRESSS. Singh et al. / Crop Protection 27 (2008) 660–671662

2.2. Experimental design and treatments

The experiment was arranged in a split-plot design withthree replications. The four treatments (see Table 1)assigned to the main plot were (a) aerobic direct-seededrice on FIRBS (ADSB), (b) aerobic direct-seeded rice onflat land (ADSR), (c) aerobic transplanted rice on FIRBS(ATPB) and (d) conventionally puddled transplanted rice(CPTR). The rice was direct-seeded at 40 kg ha�1 at 20-cmrow spacing using a tractor-drawn zero-till seed machine-cum-fertilizer drill in zero-till conditions for direct-seededrice on flat land. The size of subplots was 10m� 5.4m.Five weed-control treatments (see Table 1) were assigned tothe subplots: (a) weedy; (b) weed-free; (c) cyhalofop-butyl(at 120 g a.i. ha�1 applied 14DAS/DAT) followed by 2,4-D(ester) (at 500 g a.i. ha�1 applied 21DAS/DAT) followed byhand-weeding at 35DAS/DAT (referred as cyhalofop-butyl/2,4-D/HW); (d) cyhalofop-butyl (at 120 g a.i. ha�1

applied 14DAS/DAT) followed by chlorimuron+metsul-furon (at 4 g a.i. ha�1 applied 21DAS/DAT) followed byhand-weeding at 35DAS/DAT (referred as cyhalofop-butyl/chlorimuron+metsulfuron/HW) and (e) pretilachlorwith safener (at 500 g a.i. of pretilachlor ha�1 applied3DAS/DAT) followed by chlorimuron+metsulfuron (at4 g a.i. ha�1 applied 21DAS/DAT) followed by hand-weeding at 35DAS/DAT (referred as pretilachlor/chlor-imuron+metsulfuron/HW). Herbicides were applied usinga knapsack sprayer with a flat fan nozzle and water as acarrier at 300 l ha�1. For the weed-free subplot treatment,six hand-weedings were done to maintain a weed-freesituation. In the weedy control, no weeding was done.

2.3. Experimental details and measurements

Rice (cv. NDR 359, a medium-long-duration variety)was planted in June and harvested in October in each year.For ADSB and ATPB main-plot treatments, land wasprepared with two ploughings with a disc harrow and oneplanking. After preparation of the field, beds 37 cm widewith a furrow of 30 cm were formed with the help of atractor-drawn bed planter (Bhushan et al., 2007). In ADSBtreatment, seed at 30 kg ha�1 was direct-seeded in two rowsat 25-cm spacing using a tractor-drawn bed planter. Aftergermination of rice, all plots were submerged for a week.Later, irrigation was applied to maintain soil saturation fora month, which was followed by irrigation at an interval of4–5 days. In the ATPB treatment, manual transplantingwas done at one seedling per hill in two rows at 20-cmspacing with 12 cm for plant-to-plant spacing. For direct-seeded rice on flat land (ADSR) in the main-plot treatment,the pre-seeding herbicide glyphosate was applied 2 daysbefore seeding in zero-till conditions to kill alreadygerminated weeds and seeding (40 kg ha�1) was done onflat land using a tractor-mounted zero-till seed-cum-fertilizer drill keeping 25 cm of distance between rows.Irrigation was applied after seeding. Soil saturation wasmaintained for a month and later irrigation was given at an

interval of 4–5 days. The land preparation for the CPTRmain plot treatment consisted of one dry ploughingfollowed by irrigation and two harrowings to puddle thesoil under wet conditions. Two rice seedlings per hill weretransplanted at 20 cm� 20 cm spacing after puddling.Nitrogen was applied at 150 kg ha�1 in three equal splits

as basal, at 20DAT/42DAS and at 45DAT/65DAS.Phosphorus at 60 kg ha�1 as P2O5 in the case of direct-seeded rice on flat land and in raised beds was applied witha zero-till drill (ZT) during seeding. For transplanted rice,it was broadcast at the time of transplanting. Potash at60 kg ha�1 as K2O and zinc at 25 kg ha�1 as ZnSO4

were broadcast in all plots uniformly before rice sowing/transplanting.Weed density and weed dry weight were measured at 30,

60 and 120DAS/DAT. Weed density was recorded with thehelp of a quadrate (0.5m� 0.5m) placed randomly at twospots in each plot. Weeds were cut at ground level, washedwith tap water, sun dried, oven dried at 70 1C for 48 h andthen weighed. The data on actual number of weeds weretransformed by angular transformation for statisticalanalyses. Grain yield was taken from a 6-m2 area in thecentre of each plot and expressed in Mgha�1 at 14%moisture. The statistical analysis of the data was doneusing IRRISTAT Windows Version 4.1. Unless indicatedotherwise, differences were considered significant only atPp0.05.

3. Results and discussion

The major weeds associated with rice include grassesDactyloctenium aegyptium (L.) Willd., Echinochloa crus-galli

(L.) Beauv., Echinochloa colona (L.) Link and Leptochloa

chinensis (L.) Nees, and broadleaf weeds Commelina

benghalensis L., Caesulia axillaris Roxb., Eclipta prostrata

(L.) L., Euphorbia hirta L., Portulaca oleracea L., Trianthema

portulacastrum L. and Lindernia sp.The total weed dry weight (Table 1) and total weed

density (Table 2) were lower with CPTR at all stages ofcrop growth in both years. It is reported that the greatestweed pressure and crop–weed competition occur in uplandand aerobic rice and least in transplanted irrigated andrainfed lowland rice (De Datta and Baltazar, 1996; Moody,1996; Rao et al., 2007). During both years, the proportionof grassy weed dry weight was higher (78–96% of totalweed dry weight in 2002 and 82–89% in 2003) than forother weeds in all systems of rice establishment. Grassespersist in all of the principal crops and are a major causefor concern (Mortimer and Riches, 2001). The proportionof mean grassy weed dry weight (Table 3) in ADSB(93–96% of total weed biomass) and ADSR (92–96% oftotal weed biomass) was higher than that recorded withATPB (78–93% of total weed biomass) and CPTR(82–93% of total weed biomass) systems of rice establish-ment during 2002. The ADSB treatment resulted in thehighest total weed dry weight at all stages of crop growthduring both years. The next highest weed dry weight was

ARTIC

LEIN

PRES

S

Table 1

Impact of varying methods of rice establishment and weed control treatments on total weed dry weight (gm�2)

Weed control method (W)a Method of rice establishment (T)b

ADSB ADSR ATPB CPTR Mean

30DAS 60DAS 120DAS 30DAS 60DAS 120DAS 30DAT 60DAT 120DAT 30DAT 60DAT 120DAT 30DAS/DAT 60DAS/DAT 120DAS/DAT

Year 2002

Cyhalofop/2,4-D/HW 16.1 107.9 184.3 10.6 60.3 145.1 4.2 19.2 43.0 2.7 11.6 19.5 8.4 49.8 98.0

Cyhalofop/chlorimuron+metsulfuron/HW 16.2 89.3 190.3 9.9 57.1 137.6 4.9 18.7 37.8 2.2 11.5 15.9 8.3 44.2 95.4

Pretilachlor/chlorimuron+metsulfuron/HW 8.8 73.9 143.2 3.8 36.7 87.5 1.8 9.3 25.0 1.3 4.8 13.0 4.0 31.2 67.2

Weedy treatment 27.3 270.6 441.0 17.3 153.7 285.4 6.7 111.8 256.7 4.7 70.6 152.7 14.0 151.7 283.9

Mean 13.8 108.4 191.9 8.4 61.7 131.2 3.6 31.9 72.6 2.2 19.8 40.3

LSD (p ¼ 0.05) for comparison:

Of two T means at each W 2.8 27.1 27.9

Of two W means at each T 2.5 25.3 25.3

T means 1.7 15.1 16.4

W means 1.2 12.6 12.7

Year 2003

Cyhalofop/2,4-D/HW 19.0 91.6 140.5 13.9 78.1 150.6 13.1 62.3 108.5 6.2 34.4 57.6 13.0 66.6 114.3



Weedy treatment 34.1 263.3 348.8 27.8 202.1 285.6 24.3 136.8 224.5 12.0 81.7 130.4 24.6 171.0 247.3

Mean 17.7 99.1 144.5 12.5 79.1 130.3 12.0 57.3 100.4 5.6 30.5 52.8




T means 1.77 16.0 13.3

W means 1.67 14.4 15.1

aCyhalofop/2,4-D/HW ¼ cyhalofop (at 120 g a.i. ha�1 applied 14DAS/DAT) followed by 2,4-D (at 500 g a.i. ha�1 applied 21DAS/DAT) followed by hand-weeding at 35DAS/DAT, cyhalofop/

chlorimuron+metsulfuron/HW ¼ cyhalofop (at 120 g a.i. ha�1 applied 14DAS/DAT) followed by chlorimuron+metsulfuron (at 4 g a.i. ha�1 applied 21DAS/DAT) followed by hand-weeding at

35DAS/DAT, pretilachlor/chlorimuron+metsulfuron/HW ¼ pretilachlor with safener (at 500 g a.i. ha�1 applied 3DAS/DAT) followed by chlorimuron+metsulfuron (at 4 g a.i. ha�1 applied 21DAS/

DAT) followed by hand-weeding at 35DAS/DAT.bADSB ¼ aerobic direct-seeded rice on furrow-irrigated raised-bed system (FIRBS); ADSR ¼ aerobic direct-seeded rice; ATPB ¼ aerobic transplanted rice on FIRBS; CPTR ¼ conventionally

puddled transplanted rice; DAS ¼ days after seeding; DAT ¼ days after transplanting.

S.

Sin

gh

eta

l./

Cro

pP

rotectio

n2

7(

20

08

)6

60

–6

71

663

ARTIC

LEIN

PRES

STable 2

Impact of varying methods of rice establishment and weed control treatments on total weed density (numberm�2)



30DAS 60DAS 120DAS 30DAS 60DAS 120DAS 30DAT 60DAT 120DAT 30DAT 60DAT 120DAT 30DAS/

DAT

60DAS/

DAT

120DAS/

DAT

Year 2002

Cyhalofop/2,4-D/HW 183 133 120 111 92 93 138 102 93 61 46 37 123 93 85

(13.5) (11.6) (11.0) (10.5) (9.6) (9.7) (11.8) (10.1) (9.7) (7.8) (6.8) (6.2) (10.9) (9.5) (9.1)

Cyhalofop/chlorimuron+metsulfuron/HW 171 127 113 101 81 83 129 89 83 61 45 29 116 85 76

(13.1) (11.3) (10.7) (10.1) (9.0) (9.1) (11.4) (9.5) (9.1) (7.8) (6.8) (5.4) (10.6) (9.1) (8.5)

Pretilachlor/chlorimuron+metsulfuron/

HW

115 110 99 57 67 55 44 52 55 22 19 16 60 62 59

(10.8) (10.5) (10.0) (7.6) (8.2) (7.5) (6.7) (7.2) (7.5) (4.8) (4.4) (4.1) (7.5) (7.6) (7.4)

Weedy treatment 314 392 368 196 243 252 224 301 252 135 179 191 217 279 273

(17.7) (19.8) (19.2) (14.0) (15.6) (15.9) (15.5) (17.4) (15.9) (11.7) (13.1) (13.9) (14.6) (16.5) (16.4)

Mean 157 152 140 93 97 97 107 109 97 56 58 55

(11.2) (10.8) (10.4) (8.7) (8.7) (8.6) (9.2) (9.0) (8.6) (6.6) (6.5) (6.1)

LSD (p ¼ 0.05) for comparison:c



T means 1.7 0.8 0.7

W means 1.2 0.7 0.4

Year 2003

Cyhalofop/2,4-D/HW 125 150 111 85 149 147 79 103 80 48 59 57 84 115 99

(11.2) (12.3) (10.6) (9.3) (12.2) (12.1) (8.9) (10.2) (9.0) (7.0) (7.7) (7.6) (9.1) (10.6) (9.8)


(10.6) (12.1) (9.5) (9.0) (11.7) (10.8) (8.5) (9.7) (8.0) (6.4) (7.4) (6.6) (8.6) (10.2) (8.7)


HW

80 112 74 57 79 69 39 79 49 17 28 23 48 74 54

(9.0) (12.6) (8.6) (7.5) (8.9) (8.3) (6.3) (8.9) (7.1) (4.3) (5.4) (4.8) (6.8) (8.4) (7.2)

Weedy treatment 286 373 305 233 299 264 167 222 184 96 112 92 196 251 211

(16.9) (19.3) (17.5) (15.3) (17.3) (16.2) (13.1) (14.9) (13.6) (9.8) (10.6) (9.6) (13.8) (15.5) (14.2)

Mean 120 156 116 91 133 119 71 100 75 40 50 43

(9.4) (11.1) (9.4) (8.4) (10.2) (9.7) (7.5) (8.9) (7.7) (5.7) (6.4) (5.9)




T means 0.83 0.62 0.56

W means 0.65 0.63 0.61

aAs in Table 1.bADSB ¼ aerobic direct-seeded rice on furrow-irrigated raised-bed system (FIRBS); ADSR ¼ aerobic direct-seeded rice; ATPB ¼ aerobic transplanted rice on FIRBS; CPTR ¼ conventionally

puddled transplanted rice; DAS ¼ days after seeding; DAT ¼ days after transplanting.cCalculated using transformed values given in parentheses.

S.

Sin

gh

eta

l./

Cro

pP

rotectio

n2

7(

20

08

)6

60

–6

71

664

ARTIC

LEIN

PRES

S

Table 3

Impact of varying methods of rice establishment and weed control treatments on grassy weed dry weight (gm�2)



30DAS 60DAS 120DAS 30DAS 60DAS 120DAS 30DAT 60DAT 120DAT 30DAT 60DAT 120DAT 30DAS/DAT 60DAS/DAT 120DAS/DAT

Year 2002

Cyhalofop/2,4-D/HW 15.2 105.0 176.3 10.2 57.9 137.3 3.8 17.4 38.8 2.3 10.6 16.1 7.9 47.7 92.2



Weedy treatment 24.9 262.2 420.4 15.4 147.2 272.0 4.9 104.8 240.2 3.6 66.1 141.8 12.2 145.1 268.6

Mean 12.8 105.1 183.4 7.7 59.1 124.7 2.8 29.7 67.2 1.8 18.5 36.3




T means 1.5 15.4 16.6

W means 1.2 13.0 13.1

Year 2003

Cyhalofop/2,4-D/HW 15.8 79.3 124.9 11.8 69.0 131.0 11.5 56.1 96.4 5.3 30.5 50.5 11.1 58.7 100.7



Weedy treatment 27.8 229.7 303.9 22.8 171.8 247.6 20.9 119.9 197.5 9.8 75.2 119.0 20.3 149.2 217.0

Mean 14.7 86.8 128.0 10.4 68.5 114.1 10.1 51.0 89.0 4.6 27.0 47.0




T means 1.5 15.6 11.1

W means 1.6 13.4 14.4


puddled transplanted rice; DAS ¼ days after seeding; DAT ¼ days after transplanting.

S.

Sin

gh

eta

l./

Cro

pP

rotectio

n2

7(

20

08

)6

60

–6

71

665

ARTIC

LEIN

PRES

STable 4

Impact of varying methods of rice establishment and weed control treatments on grass weed density (numberm�2)



30DAS 60DAS 120DAS 30DAS 60DAS 120DAS 30DAT 60DAT 120DAT 30DAT 60DAT 120DAT 30DAS/

DAT

60DAS/

DAT

120DAS/

DAT

Year 2002

Cyhalofop/2,4-D/HW 155 110 90 97 75 74 124 85 71 54 37 31 108 77 66

(12.4) (10.5) (9.5) (9.9) (8.6) (8.6) (11.1) (9.2) (8.5) (7.4) (6.1) (5.6) (10.2) (8.6) (8.1)


(12.8) (10.6) (9.8) (9.7) (8.2) (8.5) (11.0) (8.8) (8.2) (7.4) (6.2) (5.0) (10.2) (8.4) (7.9)


HW

76 85 75 29 49 43 18 39 50 4 8 9 32 45 45

(8.8) (9.2) (8.7) (5.5) (7.1) (6.6) (4.3) (6.3) (7.2) (2.2) (3.0) (3.2) (5.2) (6.4) (6.4)

Weedy treatment 252 320 291 161 195 191 174 245 231 109 143 138 174 226 213

(15.8) (17.8) (17.1) (12.7) (13.9) (13.8) (13.2) (15.6) (15.2) (10.5) (12.0) (11.8) (13.0) (14.8) (14.5)

Mean 129 125 110 76 77 76 87 89 84 44 45 40

(10.2) (9.8) (9.2) (7.8) (7.8) (7.7) (8.1) (8.2) (9.1) (5.7) (5.7) (5.3)




T means 1.7 0.8 0.7

W means 1.2 0.7 0.4

Year 2003

Cyhalofop/2,4-D/HW 80 79 56 53 83 61 51 66 42 29 39 32 53 66 48

(9.0) (8.9) (7.5) (7.3) (9.1) (7.9) (7.2) (8.1) (6.6) (5.5) (6.3) (5.7) (7.3) (8.1) (6.9)


(9.0) (9.0) (7.3) (7.5) (8.6) (7.7) (7.1) (7.5) (6.0) (5.1) (5.5) (5.0) (7.2) (7.7) (6.5)


HW

56 61 43 24 32 59 21 40 27 7 5 24 27 35 26

(7.5) (7.9) (6.6) (5.0) (5.7) (5.5) (4.6) (6.4) (5.2) (2.7) (2.5) (5.0) (5.0) (5.6) (5.0)

Weedy treatment 146 194 169 112 147 128 99 130 109 56 77 55 103 137 115

(12.1) (13.9) (13.0) (10.6) (12.1) (11.3) (10.0) (11.4) (10.5) (7.5) (8.8) (7.4) (10.1) (11.6) (10.6)

Mean 72 83 64 49 67 55 44 58 43 23 30 24

(7.7) (8.1) (7.1) (6.3) (7.3) (6.7) (6.0) (6.9) (5.9) (4.4) (4.8) (5.0)




T means 0.52 0.25 0.38

W means 0.53 0.46 0.55


puddled transplanted rice;DAS ¼ days after seeding; DAT ¼ days after transplanting.cCalculated using transformed values given in parentheses.

S.

Sin

gh

eta

l./

Cro

pP

rotectio

n2

7(

20

08

)6

60

–6

71

666


observed with aerobic direct-seeded rice (ADSR). Incontrast, Meisner et al. (2005) reported fewer weeds inrice with permanent raised beds. Promotion of the growthof grassy weeds in the raised-bed system was reported byCabangon and Tuong (2005). In 2002, the proportion ofgrassy weed density ranged from 73% to 79% of total weeddensity in CPTR, whereas in other systems of planting riceit ranged from 78% to 82% (Table 4). In 2003, suchvariation among establishment methods was not observedand the proportion of grassy weeds ranged from 46% to60% of the total weed density under different establish-ment methods.

During both years, pretilachlor/chlorimuron+metsul-furon/HW treatment resulted in significantly lower meantotal weed dry weight than other chemical weed controltreatments (Table 1). Pretilachlor/chlorimuron+metsul-furon/HW treatment resulted in a 68%, 73% and 67%reduction in weed dry weight at 30, 60 and 120DAS/DAT,respectively, in 2002 and 57%, 78% and 69% reduction in2003. The weed dry weight with cyhalofop-butyl/chlor-imuron+metsulfuron/HW and cyhalofop-butyl/2,4-D/HW treatments did not differ among each other. Cyhalo-fop-butyl was reported to be effective on Echinochloa

species (Barotti et al., 1998) and other grasses (Buendia

Table 5

Correlation between weed density and dry weight at different days after seedi

Weed parameter Days after seeding G

2

Total weed dry weight (gm�2) 30 �

60 �

90 �

Grassy weed weight (gm�2) 30 �

60 �

90 �

Broadleaf weed weight (gm�2) 30 �

60 �

90 �

Sedge weed weight (gm�2) 30 �

60 �

90 �

Total weed density (numberm�2) 30 �

60 �

90 �

Grassy weed density (numberm�2) 30 �

60 �

90 �

Broadleaf weed density (numberm�2) 30 �

60 �

90 �

Sedge weed density (numberm�2) 30 �

60 �

90 �

�Significant at the 5% level.

et al., 1998) that were predominant in the trials. With allmethods of rice establishment, the reduction in total weeddry weight and grassy weed dry weight was higher at60DAS/DAT and the efficacy of all the chemicals at120DAS/DAT was lower than that recorded at 60DAS/DAT. The reduction in efficacy at 120DAT was lowestwith CPTR. Irrespective of the stage of crop growth andtype of weed group, a significant negative correlation ofweed density and weed dry weight with rice grain and strawyield was observed (Table 5), indicating the need forminimizing weed density and dry weight to attain optimalrice grain yield.The highest rice grain yield was recorded with the CPTR

method of establishment during both years (Table 6). Thegrain yield of ADSR was lower than that of CPTR asreported by Singh et al. (2001). However, under weed-freesituations, the grain yield under these two methods ofestablishment did not differ significantly, suggesting thatsimilar yield potential is achievable. Reddy and Panda(1988) suggested that direct-seeded rice performed betterthan a transplanted crop, while Mitchell et al. (2004)indicated that direct-seeded rice and transplanted ricewill produce a similar yield for a given environment pro-vided they are grown using good management practices.

ng and rice grain and straw yield

rain yield (Mgha�1) Straw yield (Mgha�1)

002 2003 2002 2003

0.73� �0.88� �0.67� �0.86�

0.89� �0.94� �0.84� �0.92�

0.89� �0.92� �0.82� �0.91�

0.69� �0.87� �0.63� �0.85�

0.88� �0.94� �0.83� �0.92�

0.89� �0.92� �0.82� �0.91�

0.80� �0.87� �0.76� �0.85�

0.94� �0.95� �0.89� �0.90�

0.92� �0.94� �0.87� �0.92�

0.58� �0.46� �0.56� �0.48�

0.75� �0.75� �0.71� �0.73�

0.75� �0.69� �0.70� �0.70�

0.84� �0.93� �0.81� �0.90�

0.94� �0.92� �0.91� �0.90�

0.96� �0.90� �0.92� �0.89�

0.80� �0.89� �0.78� �0.88�

0.93� 00.92� �0.90� �0.91�

0.92� �0.83� �0.88� �0.82�

0.84� �0.94� �0.84� �0.91�

0.95� �0.91� �0.93� �0.88�

0.92� �0.95� �0.87� �0.92�

0.74� �0.83� �0.71� �0.79�

0.85� �0.81� �0.80� �0.77�

0.96� �0.96� �0.93� �0.71�

ARTICLE IN PRESS

Table 6

Impact of varying methods of rice establishment and weed control treatments on rice grain and straw yield (Mgha�1)



Grain

yield

Straw

yield

Grain

yield

Straw

yield

Grain

yield

Straw

yield

Grain

yield

Straw

yield

Grain

yield

Straw

yield

Year 2002:

Cyhalofop/2,4-D/HW 4.99 4.83 6.12 6.21 5.79 5.29 6.63 5.74 5.88 5.52

Cyhalofop/chlorimuron+metsulfuron/

HW

4.92 4.91 6.20 6.37 5.92 5.32 6.66 5.75 5.92 5.58


HW

5.39 5.29 6.47 6.69 6.16 5.41 6.79 5.87 6.21 5.81

Weed-free treatment 5.82 5.43 6.75 6.90 6.73 5.79 6.82 5.82 6.53 5.98

Weedy treatment 0.48 1.45 0.8 2.28 2.12 2.85 2.90 3.41 1.57 2.50

Mean 4.32 4.38 5.27 5.69 5.34 4.93 5.93 5.32 5.22 5.08


Of two T means at each W 0.32 0.25

Of two W means at each T 0.31 0.28

T means 0.16 0.18

W means 0.16 0.12

Year 2003

Cyhalofop/2,4-D/HW 4.39 4.47 5.19 4.62 5.08 4.72 5.84 5.78 5.13 4.90

Cyhalofop/chlorimuron+metsulfuron/

HW

4.42 4.75 5.21 5.17 5.14 4.86 5.89 5.63 5.16 5.10


HW

4.53 4.72 5.44 4.96 5.25 5.03 5.99 5.95 5.30 5.16

Weed-free treatment 5.03 4.89 5.70 5.91 5.66 5.05 6.08 6.12 5.61 5.49

Weedy treatment 1.10 1.57 1.50 2.62 2.54 2.73 3.80 3.57 2.24 2.62

Mean 3.89 4.05 4.61 4.65 4.73 4.48 5.52 5.41


Of two T means at each W 0.48 0.77

Of two W means at each T 0.60 0.74

T means 0.43 0.29

W means 0.24 0.38

aAs in Table 1.bADSB ¼ aerobic direct-seeded rice on furrow-irrigated raised-bed system (FIRBS); ADSR ¼ aerobic direct-seeded rice; ATPB ¼ aerobic transplanted

rice on FIRBS; CPTR ¼ conventionally puddled transplanted rice.

S. Singh et al. / Crop Protection 27 (2008) 660–671668

The mean grain yield of aerobic dry-seeded rice on flat beds(ADSR) and ATPB did not differ. The least mean grainyield was recorded with ADSB. Many on-farm and on-station trials in the IGP have also observed similar orhigher yields for transplanted rice and slightly lower yieldswith direct-seeded rice on beds (Humphreys et al., 2004).Choudhury et al. (2007) reported that rice yields on raisedbeds that were kept around field capacity were 32–42%lower than under flooded transplanted conditions. Beecheret al. (2006) attributed the reduced grain yield from all bedtreatments to the wide furrows that were not planted withrice and opined that, until an effective herbicide andmethod of weed control are found, there is little scope forsaving water while maintaining yield through the use ofbeds. Across establishment methods, 38–92% of grain yieldwas lost where weeds were not controlled. Yield losses dueto uncontrolled weeds were highest with ADSB (92% in2002 and 78% in 2003) and ADSR (88% in 2002 and 74%in 2003) and lowest with CPTR (58% in 2002 and 38% in

2003). Among weed-control treatments, mean grain yielddata indicated that cyhalofop-butyl/chlorimuron+metsul-furon/HW and pretilachlor/chlorimuron+metsulfuron/HW treatments were similar to that of the weed-freecontrol in realizing higher yields during 2003. However,during 2002, the weed-free control treatment was superiorto all weed-control treatments. Pretilachlor/chlorimur-on+metsulfuron/HW application resulted in significantlyhigher grain yield than other herbicide combinations testedin 2002. Interactions between method of rice establishmentand weed control treatments were also significant duringboth years. Under CPTR, rice grain and straw yield withall weed control treatments were on par with each otherand were superior to that of the weedy check treatment.The grain yield with pretilachlor/chlorimuron+metsulfur-on/HW treatment was similar to that of the weed-freecontrol during both years. Pretilachlor/chlorimuron+met-sulfuron/HW treatment yielded higher in ADSB thanwith other chemical treatments only in 2002. The grain

ARTICLE IN PRESS

Table 7

Net income (US$) as affected by varying methods of rice establishment and weed control



2002 2003 2002 2003 2002 2003 2002 2003 2002 2003

Cyhalofop/2,4-D/HW 73 73 159 159 119 119 193 193 136 136

Cyhalofop/chlorimuron+metsulfuron/HW 127 67 284 165 211 117 281 188 226 134

Pretilachlor/chlorimuron+metsulfuron/HW 177 74 306 183 230 119 292 196 251 143

Weed-free treatment 172 77 307 180 271 142 303 213 263 153

Weedy treatment �339 �265 �304 �221 �186 �136 �110 �3 �235 �156

Mean 42 5 150 93 129 72 192 157

LSD (p ¼ 0.05)

For comparing two sub plot-means (W) at same main plot (T) 44.28 57.65

For two main plot (T) means comparison 27.09 51.19

For two subplot (W) means comparison 22.14 28.83

aCyhalofop/2,4-D/HW ¼ cyhalofop (at 120 g a.i. ha�1 applied 14DAS/DAT) followed by 2,4-D (at 500 g a.i. ha�1 applied 21DAS/DAT) followed by

hand-weeding at 35DAS/DAT, cyhalofop/chlorimuron+metsulfuron/HW ¼ cyhalofop (at 120 g a.i. ha�1 applied 14DAS/DAT) followed by

chlorimuron+metsulfuron (at 4 g a.i. ha�1 applied 21DAS/DAT) followed by hand-weeding at 35DAS/DAT, pretilachlor/chlorimuron+metsulfuron/

HW ¼ pretilachlor with safener (at 500 g a.i. ha�1 applied 3DAS/DAT) followed by chlorimuron+metsulfuron (at 4 g a.i. ha�1 applied 21DAS/DAT)

followed by hand-weeding at 35DAS/DAT.bADSB ¼ aerobic direct-seeded rice on furrow-irrigated raised-bed system (FIRBS); ADSR ¼ aerobic direct-seeded rice; ATPB ¼ aerobic transplanted

rice on FIRBS; CPTR ¼ conventionally puddled transplanted rice.

S. Singh et al. / Crop Protection 27 (2008) 660–671 669

yield in ADSR with pretilachlor/chlorimuron+metsulfur-on/HW and cyhalofop-butyl/chlorimuron+metsulfuron/HW treatments did not differ and was significantly higherthan with the weedy check and cyhalofop-butyl/2,4-D/HWtreatment.

Net returns of ADSR and CPTR treatments (Table 7)did not differ under weed-free situations, as direct sowingresulted in substantial savings in production costs (Singhet al., 2001). Among the herbicide treatments, pretilachlor/chlorimuron+metsulfuron/HW treatment was superior inattaining higher net returns that are similar to those ofweed-free situations under all methods of rice establish-ment. The treatment with cyhalofop-butyl/2,4-D/HW gavelower net income than with other herbicide combinations.Cyhalofop-butyl/chlorimuron+metsulfuron/HW recordednet returns comparable with those of pretilachlor/chlor-imuron+metsulfuron/HW treatment. Thus, it can beinferred that ADSR was as effective as CPTR in attaininghigher rice grain yield and net returns when weedswere kept under control. Weed-free (six hand-weedings)equivalent weed control could be obtained with pretila-chlor with safener (at 500 g a.i. ha�1 applied 3DAS/DAT)followed by chlorimuron+metsulfuron (at 4 g a.i. ha�1

applied 21DAS/DAT) followed by hand-weeding at35DAS/DAT, irrespective of the method of rice establish-ment. The next best treatment in attaining effective weedcontrol was cyhalofop-butyl (at 120 g a.i. ha�1 applied14DAS/DAT) followed by chlorimuron+metsulfuron(at 4 g a.i. ha�1 applied 21DAS/DAT) followed by hand-weeding at 35DAS/DAT. It is concluded that the ADSRwas as effective as conventionally puddle transplanted ricein attaining higher rice grain yield and net returns when

weeds were kept under control using these identifiedeffective weed management treatments.

References

Aggarwal, P.K., Talukdar, K.K., Mall, R.K., 2000. Potential yields of the

rice–wheat system in the Indo-Gangetic plains of India. Rice–Wheat

Consortium Paper Series 10. Rice–Wheat Consortium for the Indo-

Gangetic Plains, New Delhi, India, and Indian Agricultural Research

Institute, New Delhi, India, 11pp.

Balasubramanian, V., Hill, J.E., 2002. Direct seeding of rice in Asia:

emerging issues and strategic research needs for the 21st century. In:

Pandey, S., Mortimer, M., Wade, L., Tuong, T.P., Lopez, K., Hardy,

B. (Eds.), Direct Seeding: Research Strategies and Opportunities.

International Rice Research Institute, Los Banos, Philippines,

pp. 15–39.

Barotti, R., Carone, A., Dallavalle, N., Gallizia, A., 1998. Cyhalofop-

butyl (DE-537), a new graminicide for the post emergence control of

Echinochloa spp. in paddy rice. In: Proceedings of the Giornate

Fitopatologiche, Scicli e Ragusa, Italy, 3–7 May 1998, pp. 321–326.

Beecher, H.G., Dunn, B.W., Thompson, J.A., Humphreys, E., Mathews,

S.K., Timsina, J., 2006. Effect of raised beds, irrigation and nitrogen

management on growth, water use and yield of rice in south-eastern

Australia. Aust. J. Exp. Agric. 46, 1363–1372.

Belder, P., Bouman, B.A.M., Spiertz, J.H.J., Peng, S., Castaneda, A.R.,

Visperas, R.M., 2005. Crop performance, nitrogen and water use in

flooded and aerobic rice. Plant Soil 273, 167–182.

Bhushan, L., Ladha, J.K., Gupta, R.K., Singh, S., Tirol-Padre, A.,

Saharawat, Y.S., Gathala, M., Pathak, H., 2007. Saving of water and

labor in rice–wheat system with no-tillage and direct seeding

technologies. Agron. J. 99, 1288–1296.

Borrell, A., Garside, A., 2005. Early work on permanent raised beds in

tropical and subtropical Australia focusing on the development of rice

based cropping system. Paper presented at the ACIAR Workshop on

‘‘Permanent Bed Planting Systems,’’ Griffith, NSW, Australia. March

1–3, 2005, 20pp.

ARTICLE IN PRESSS. Singh et al. / Crop Protection 27 (2008) 660–671670

Bouman, B.A.M., Peng, S., Castaneda, A.R., Visperas, R.M., 2005. Yield

and water use of tropical aerobic rice systems. Agric. Water Manage.

74, 87–105.

Buendia, J., Barotti, R., Fullick, K., Thompson, A., Velilla, J., Maillet, J.,

1998. Cyhalofop, a new post-emergence herbicide for grass control in

rice. In: Comptes rendus 6eme symposium Mediterranean EWRS,

Montpellier, France, 13–15 May 1998, pp. 361–368.

Cabangon, R.J., Tuong, T.P., 2005. Effect of water regime on grain

yield, water input and water productivity of rice grown on raised

beds. Paper presented at the ACIAR Workshop on ‘‘Permanent

Bed Planting Systems,’’ Griffith, NSW, Australia. March 1–3, 2005,

20pp.

Choudhury, B.U., Bouman, B.A.M., Singh, A.K., 2007. Yield and

productivity of rice–wheat on raised beds at New Delhi, India. Field

Crops Res. 100, 229–239.

De Datta, S.K., Baltazar, A.M., 1996. Weed control technology as a

component of rice production systems. In: Auld, B.A., Kim, K.U.

(Eds.), Weed Management in Rice. FAO Plant Production and

Protection Paper 139, FAO, Rome, pp. 27–52.

Dwivedi, B.S., Shukla, A.K., Singh, V.K., Yadav, R.L., 2003. Improving

nitrogen and phosphorous use efficiencies through inclusion of forage

cowpea in the rice–wheat systems in the Indo-Gangetic plains of India.

Field Crops Res. 84, 399–418.

Elliot, P.C., Navarez, D.C., Estario, D.B., Moody, K., 1984. Determining

suitable weed control practices for dry-seeded rice. Philipp. J. Weed

Sci. 11, 70–82.

Fujisaka, S., Moody, K., Ingram, K., 1993. A descriptive study of farming

practices for dry seeded rainfed lowland rice in India, Indonesia and

Myanmar. Agric. Ecosyst. Environ. 45, 115–128.

Fujisaka, S., Harrington, L., Hobbs, P.R., 1994. Rice–wheat in South

Asia: systems and long-term priorities established through diagnostic

research. Agric. Syst. 46, 169–187.

Garside, A.L., Borrell, A.K., Ockerby, S.E., Dowling, A.J., McPhee, J.E.,

Braunack, M.V., 1992. An irrigated rice based cropping system for

tropical Australia. In: Hutchinson, K.J., Vickery, P.J. (Eds.).

Proceedings of Sixth Australian Society of Agronomy Conference.

The University of New England, Armidale, Australia and The

Australian Society of Agronomy, Melbourne, pp. 259–261.

Giri, G.S., 1998. Effect of rice and wheat establishment techniques

on wheat grain yield. In: Hobbs, P.R., Bhandari, R. (Eds.),

Proceedings of Rice–Wheat Research End of Project Workshop,

India, pp. 65–68.

Gupta, R.K., Hobbs, P.R., Salim, M., Malik, R.K., Verma, M.R.,

Pokharel, T.P.,Thakur, T.C., Tripathi, J., 2000. Research and

extension issues for farm level impact on the productivity of the

rice–wheat systems in the Indo-Gangetic plains of India and Pakistan.

In: Rice–Wheat Consortium Traveling Seminar Report Series 1,

Facilitation Unit. Rice–Wheat Consortium for the Indo-Gangetic

Plains, IARI Campus, Pusa, New Delhi, pp. 10–11.

Gupta, R.K., Naresh, R.K., Hobbs, P.R., Jiaguo, Z., Ladha, J.K., 2003.

Sustainability of post-green revolution agriculture: the rice–wheat

cropping systems of the Indo-Gangetic Plains and China. In: Ladha,

J.K., Hill, J.E., Duxbury, J.M., Gupta, R.K., Buresh, R.J. (Eds.),

Improving the Productivity and Sustainability of Rice–Wheat Systems:

Issues and Impacts. ASA Inc., CSSA Inc., SSSA Inc., ASA Special

Publication no. 65, Madison, WI, USA, pp. 1–25.

Hobbs, P.R., Singh, Y., Giri., G.S., Lauren, J.G., Duxbery, J.M.,

2002. Direct-seeding and reduced tillage options in the rice–wheat

systems of the Indo-Gangetic plains of South Asia. In: Pandey, S.,

Mortimer, M., Wade, L., Tuong, T.P., Hardy, B. (Eds.), Direct-

Seeding in Asian Rice Systems: Strategic Research Issues and

Opportunities. International Rice Research Institute, Philippines,

pp. 201–215.

Humphreys, E., Meisner, C., Gupta, R., Timsina, J., Beecher, H.G., Tang,

Y. L., Singh, Y., Gill, M.A., Masih, L., Zheng, J. G., Thompson, J.A.,

2004. Water saving in rice–wheat systems. In: Proceedings of the

Fourth International Crop Science Congress, 26 September–1 October

2004, Brisbane, Queensland, Australia.

Kukal, S.S., Singh, Y., Humphreys, E., Dhillon, S.S., Singh, B., 2005. Soil

water dynamics and crop performance in rice–wheat on permanent

beds in Indo-Gangetic plains of India. In: The ACIAR Workshop on


1–3, 2005, p. 18.

Ladha, J.K., Dawe, D., Pathak, H., Padre, A.T., Yadav, R.L., Singh, B.,

Singh, Y., Singh, Y., Singh, P., Kundu, A.L., Sakal, R., Ram, N.,

Regmi, A.P., Gami, S.K., Bhandari, L., Amin, R., Yadav, C.R.,

Bhattarai, E.M., Das, S., Aggarwal, H.P., Gupta, R.K., Hobbs, P.R.,

2003. How extensive are yield declines in long term rice–wheat

experiments in Asia. Field Crops Res. 81, 159–180.

Meisner, C.A., Talukdar, H.M., Hossain, I., Gill, M., Mujeeb Rahmen,

H.M., Baksh, E., Justice, S., Sayre, K., 2005. Introduction and

implementing a permanent bed system in the rice–wheat cropping

pattern in Bangladesh and Pakistan. In: The ACIAR Workshop on


1–3, 2005, p. 12.

Mitchell, J., Fukai, S., Basnayake, J., 2004. Grain yield of direct-seeded

and transplanted rice in rainfed lowlands of South East Asia. In: New

Directions for a Diverse Planet. Proceedings of the Fourth Interna-

tional Crop Science Congress, Brisbane, Australia, 26 September–1

October, 2004.

Moody, K., 1983. The status of weed control in Asia. FAO Plant Prot.

Bull. 30, 119–123.

Moody, K., 1996. Weed community dynamics in rice fields. In: Naylor, R.

(Ed.), Herbicides in Asian Rice: Transitions in Weed Management.

Institute for International Studies, Stanford University, Palo Alto,

California, and International Rice Research Institute, Manila,

Philippines, pp. 27–35.

Mortimer, A.M., Riches, C.R., 2001. Current status and future trends in

grass weed occurrence and control worldwide. In: Proceedings of the

International Symposium on The World’s Worst Weeds, Hilton,

Brighton, UK, 12 November 2001, pp. 21–40.

Pathak, H., Ladha, J.K., Aggarwal, P.K., Peng, S., Das, S., Singh, Y.,

Singh, B., Kamra, S.K., Mishra, B., Sastri, A.S.R.A.S., Aggarwal,

H.P.K., Das, D.K., Gupta, R.K., 2003. Climatic potential and on farm

yield trends of rice and wheat in Indo-Gangetic plains. Field Crops

Res. 80, 223–224.

Rao, A.N., Johnson, D.E., Sivaprasad, B., Ladha, J.K., Mortimer, A.M.,

2007. Weed management in direct-seeded rice. Adv. Agron. 93, 153–255.

Reddy, M.D., Panda, M.M., 1988. Effect of methods of stand establish-

ment on grain yield of rice under intermediate deepwater conditions

(15–50 cm). J. Agric. Sci. Cambridge 110, 47–51.

Roder, W., 2001. Slash-and-burn rice systems in the hills of northern Lao

PDR. In: Description, Challenges and Opportunities. IRRI, Los

Banos, Philippines, 201pp.

Singh, S., Bhushan, L., Ladha, J.K., Gupta, R.K., Rao, A.N., Sivaprasad,

B., 2006. Weed management in dry-seeded rice (Oryza sativa)

cultivated on furrow irrigated raised bed planting system. Crop Prot.

25, 487–495.

Singh, Y., Singh, G., Singh, V.P., Singh, R.K., Srivastava, R.S.L., Singh,

P., Mortimer, M., White, J.L., Johnson, D.E., 2001. Direct seeding of

rice in the rice–wheat systems of the Indo-Gangetic plains and the

implications for weed management. In: The Proceedings of BCPC

International Conference ‘‘Weeds, 2001,’’ vols.1 and 2, Brighton, UK,

12–15 November 2001, pp. 187–192.

Singh, Y., Singh, G., Singh, V.P., Singh, R.K., Singh, P., Srivastava,

R.S.I., Saxena, A., Mortimer, M., Johnson, D.E., White, J.L., 2002.

Effect of different establishment methods on rice–wheat and the

implication of weed management in Indo-Gangetic plains. In:

Proceedings of the International Workshop on Herbicide Resistance

Management & Zero Tillage in Rice–Wheat Cropping System, 4–6

March 2002, Department of Agronomy, CCS Haryana Agricultural

University, Hisar, India, pp. 188–192.

Tuong, T.P., Bouman, B.A.M., 2003. Rice production in water scarce

environments. In: Kijne, J.W., Barker, R., Molden, D. (Eds.), Water

Productivity in Agriculture: Limits and Opportunities for Improve-

ment. CABI Publishing, pp. 53–67.


Van Cooten, D.E., Borrell, A.K., 1999. Enhancing food security in semi-

arid eastern Indonesia through permanent raised-bed cropping: a

review. Aust. J. Exp. Agric. 39, 1035–1046.

Wang, H.Q., Bouman, B.A.M., Zhao, D.L., Wang, C., Moya, P.F., 2002.

Aerobic rice in northern China: opportunities and challenges. In:

Bouman, B.A.M., Hengsdijk, H., Hardy, B., Bindraban, P.S., Tuong,

T.P., Ladha, J.K. (Eds.), Proceedings of the International Workshop

on Water-wise Rice Production, 8–11 April 2002, Los Banos,

Philippines. International Rice Research Institute, Los Banos,

Philippines, pp. 143–154.

Weed management in aerobic rice systems under varying establishment methods

Documents

Transcript of Weed management in aerobic rice systems under varying establishment methods