Weed control efficiency and weed index as influenced by weed management practices in machine transplanted rice (Oryza sativa L.)

Field experiment on effect of different weed management practices in machine transplanted rice (Oryza sativa L.) was conducted at ARS, Gangavathi, University of Agricultural Sciences, Raichur, Karnataka during kharif, 2012 and 2013 under irrigated condition in clay soil. Pooled mean indicated that, application of butachlor 50 EC fb passing of power operated low land rice weeder twice at 20 and 30 DAT with hand weeding in intra row space recorded significantly lower grassy weed population and dry weight at 40, 60 DAT and at harvest (1.98, 2.47, 2.97/0.25 m2 and 1.00, 1.20, 1.47 g /0.25 m2, respectively), sedge weed population and dry weight (2.61, 3.21, 3.52 /0.25 m2 and 1.19, 1.48, 1.71 g /0.25 m2, respectively) and broad leaved weed population and dry weight (1.68, 2.10, 2.52 / 0.25 m2 and 0.91, 1.06, 1.28 g /0.25 m2, respectively). Significantly higher WCE (87.53%), lower weed index (3.11 %), grain and straw yield (5160 and 6482 kg ha-1, respectively), gross and net returns (Rs. 92,212 and 50,410 ha-1, respectively), and B:C of 2.22 over unweeded check. Hence, application of butachlor 50 EC fb passing of power operated low land rice weeder at 20 and 30 DAT with hand weeding in intra row space was found to be the best weed control method as it recorded higher B:C. Present conventional manual weeding is which is not advantageous as it is costlier, time consuming and labour may trample and damage rice seedlings. Mechanical weeder and sequential application can overcome the same.