Integrated weed management in dry-seeded irrigated rice (Oryza sativa)

Abstract

A field experiment was conducted during rainy seasons of 2006 and 2007 on clay-loam soil at Jabalpur, Madhya Pradesh to find out the effect of tillage (zero and conventional), time of sowing (before and after monsoon) and weed-control measures (integration of hand weeding and Sesbania with herbicides and rotational use of her- bicides) on weeds, yield, nutrient uptake and economics of dry-seeded irrigated rice ( Oryza sativa L.). The major weeds associated with dry-seeded rice were: Echinochloa colona (31.5%), Phyllanthus spp. (26.5%), Commelina communis (17.8%), Cyperus ir ia (9.9%), Alter nanthera sessilis (5.9%), Dinebra retrolexa (5.1%), Physalis minima (1.8%) and Caesulia axillaris (1.2%). Zero tillage significantly reduced the total population and dry matter of weeds compared with conventional tillage, but the difference in yield was not significant. Dry seeding before monsoon re- sulted in lower grain yield due to higher population and dry matter of weeds. Infestation of weeds reduced the grain yield of dry-seeded rice by 60% compared with hand-weeding twice and removed 10.99 kg N, 2.78 kg P and 7.22 kg K/ha. The maximum rice yield (3.41 t/ha) was obtained from 2 hand-weeding. Integration of pendimethalin 1.0 kg/ha or pretilachlor 0.75 kg/ha with 1 hand-weeding at 30 days after sowing or sequential application of pre-emer- gence herbicides followed by post-emergence application of 2, 4-D (0.5 kg/ha) and fenoxaprop (0.07 kg/ha), being on a par with each other, proved quite effective against weeds and gave significantly higher grain yields and ben- efits than weedy check.