Herbicide combinations for weed control in direct-seeded rice

A field experiment was conducted during Kharif season of 2018-19 at Agriculture Research Farm, Bihar Agriculture University, Sabour, Bhagalpur to assess the bioefficacy of different herbicides and their combinations for weed control as well as their relative influence on profitability in direct dry-seeded rice cultivation. The minimum weed index (1.69%) was recorded under herbicidal treatment T5 (Pyrazosulfuron @ 25 g a.i. ha-1 PE fb Bispyribac sodium @ 20 g a.i. ha-1 + Pyrazosulfuron @ 20 g a.i. ha-1 POE) whereas, the maximum weed index (36.39%) was recorded under T2 (Pendimethalin @ 1000 g a.i. ha-1 PE). Among different herbicidal treatments, the maximum weed control efficiency was recorded under T5 (Pyrazosulfuron @ 25 g a.i. ha-1 PE fb Bispyribac sodium @ 20 g a.i. ha-1 + Pyrazosulfuron @ 20 g a.i. ha-1 POE) treatment at 45 and 60 days after sowing, the minimum weed control efficiency (69.00%) was observed in treatment T2 (Pendimethalin @ 1000 g a.i. ha-1 PE). Maximum net return (Rs. 62401 ha-1) and benefit: cost ratio (1.95) were obtained from the treatment T5 (Pyrazosulfuron @ 25 g a.i.ha-1 PE fbBispyribac sodium @ 20 g a.i. ha-1 + Pyrazosulfuron @ 20 g a.i. ha-1 POE). T10 (Hand weeding) treatment though significantly reduced weeds dry weight and improved the grain yield and gave less benefit: cost ratio owing to higher cost of farm labour.