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

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 herbicides) 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 iria (9.9%), Alternanthera 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 resulted 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-emergence 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 benefits than weedy check.