Effect of weed management practices on yield and yield attributes of wet direct seeded rice under lowland ecosystem of Assam

Field experiment was conducted at Agricultural Farm of the Regional Rainfed Lowland Rice Research Institute, Gerua, Assam during early ahu (summer) season of 2015 and 2016 to study the influence of different weed management practices on yield and yield attributes of wet direct seeded rice sown through drum seeder. The dominant weed flora in the experimental field consisted of sedges Cyperus difformis L., Scirpus incurvatus Roxb., grasses Leptochloa chinensis L., Echinochloa glabrescens, Echinochloa colona L. and broad-leaved weed Ludwigia adscendes L. The composition of grasses, sedges and broad-leaved weeds in weedy check plot at 60 DAS was 15.1, 71.5 and 13.4%, respectively. There was 37.3% reduction in the grain yield of rice due to competition with weeds in the weedy plots. All the weed control treatments significantly reduced weed population, dry matter and increased grain yield of rice compared to weedy check. Hand weeding twice recorded grain yield of 5.64 t ha-1 resulting in 54.5% increase over weedy check. Mechanical weeding followed by one hand weeding recorded reduction in grain yield of 9.2% over hand weeding twice. Application of flucetosulfuron at 25 g ha-1 (5.42 t ha-1), bispyribac sodium at 30 g ha-1 (5.40 t ha-1), azimsulfuron at 35 g ha-1(5.38 t ha-1) and bensulfuron methyl+pretilachlor at 60+600 g ha-1 recorded grain yield on par with the hand weeding twice. Tank mix application of azimsulfuron+bispyribac sodium recorded 2.2% and 1.9% only, increase in grain yield over its single application.