Impact of different herbicides and their combinations on production- economics of winter rice in naz of west bengal

Field studies were carried out at Instructional Farm of Bidhan Chandra Krishi Viswavidyalaya, West Bengal during kharif season of 2015 to reveal the effect of cost effective chemical weed management for getting better production of transplanted rice over hand weeding. Among grassy weeds, Cynodon dactylon, Echinochloa colona and Leersia hexandra were most common. Fimbristylis dichotoma, Scirpus validus and Cyperus difformis were the pre-dominant sedges found at the time of observation. The important broadleaf weeds identified in this study were Ammania baccifera, Ipomeoea reptens, Scoparia dulsis, Marsilea quadrifolia etc. Hand weeding twice at 20 & 40 DAT gave best results in reducing both weed density and biomass and ultimately increased the grain (4.53 t ha-1) and straw yield (5.80 t ha-1). However, second highest grain (4.20 t ha-1) and straw yield (5.57 t ha-1) was obtained with Bensulfuron-methyl 0.6% + Pretilachlor 6% as PE + one hand weeding at 40 DAT treatment followed by combined herbicidal treatment (Bensulfuron-methyl 0.6% + Pretilachlor 6% as PE + Bispyribac Sodium 10% SC as POE) giving grain yield 4.17 t ha-1 and straw yield 5.53 t ha-1. Considering the benefit: cost ratio, the highest value (1.92) was obtained with the performance of Bensulfuron-methyl 0.6% + Pretilachlor 6% as PE +Metsulfuron methyl 10% + Chlorimuron-ethyl 10% as POE followed by the application of Bensulfuron-methyl 0.6% + Pretilachlor 6% as PE + Bispyribac Sodium 10% SC as POE (1.90). On the other hand, costly hand weeding (20 & 40 DAT) treatment required the maximum cost of cultivation resulting the B: C ratio 1.85