Mixed weed flora management by bispyribac-sodium in transplanted rice
2013
Kumar, Suresh | Rana, S.S. | Chander, Navell | Ramesh,
Different doses of bispyribac-sodium 20, 25 and 30 g/ha were evaluated against mixed weed flora in transplanted rice under mid-hill conditions of Himachal Pradesh during 2010 and 2011. Major associated weeds were Echinochloa colona (31.1%) and Commelina benghalensis (7.3%) among grasses, Cyperus iria (26.9%) and Scripus (9.3%) among sedges and Ammania baccifera (8.8%) among broad-leaved weeds. Bispyribac-sodium 20–30 g/ha effectively controlled E. colona. Cyhalofop-butyl/butachlor fb metsulfuron-methyl was comparable to bispyribac-sodium in controlling C. benghalensis. Bispyribac-sodium brought about significant reduction in the count of Cyperus sp. up to 60 days after transplanting (DAT). Bispyribac-sodium 30 g/ha behaving statistically similar with bispyribac-sodium 20 and 25 g/ha resulted in significantly lower total weed count and total weed dry weight. There was no phytotoxicity of bispyribac- sodium on rice and no residual toxicity on succeeding crop of wheat. Bispyribac-sodium, farmer's practice, cyhalofop-butyl fb metsulfuron-methyl and cyhalofop-butyl fb 2,4-D were comparable in influencing rice grain yield. Rice grain yield was positively associated with plant height, panicle length, effective tillers and spikelets/panicle and was negatively associated with weed count and weed biomass. With one weed per m²increase up to harvest, grain yield of rice was expected to decrease by 15.3 kg/ha. Bispyribac-sodium at 30 kg/ha was the best in terms of net returns due to weed management. Cyhalofop-butyl fb metsulfuron- methyl gave the highest net profit/rupee invested. Herbicide efficiency index (HEI) was highest and weed index was lowest under bispyribac-sodium 30 g/ha. Weed management index (WMI) and agronomic management index (AMI) were highest under cyhalofop-butyl fb metsulfuron-methyl.
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