Bio-efficacy of different herbicides for weed control in direct-seeded rice

Field experiment was conducted during Kharif 2009 and 2010 to study the bio-efficacy of different herbicides in direct-seeded rice. Weed control treatments comprised of pendimethalin 0.75 kg, butachlor 1.50 kg, thiobencarb 1.50 kg, anilofos 0.375 kg, pretilachlor 0.75 kg, oxadiargyl 0.09 kg and pyrazosulfuron ethyl 0.015 kg/ha as pre-emergence and with sequential application of bispyribac 0.025 kg/ha at 30 DAS; two hand weedings and unweeded control. Significantly lower number of grass weeds was observed with application of pendimethalin as compared with other pre-emergence herbicides. Sequential application of pendimethalin and bispyribac recorded the lowest weed biomass and 100% weed control efficiency. Crop dry matter accumulation, number of tillers, and effective tillers were significantly higher in sequential use of pre-and post-emergence herbicides, resulting in more grain yield and net returns. The maximum grain yield was recorded in two hand weedings, which was at par with follow-up application of bispyribac after pendimethalin, butachlor, thiobencarb and oxadiargyl.