Response of Rice (Oryza sativa L.) to Weed Management Methods in the Lower Gangetic Plain Zone

Abstract

Background: In India, rice covers largest area under cultivation. Among the biotic stresses weeds pose serious threat to rice if not controlled in its critical crop-weed competition period, reducing yield by 50%, in case of transplanted rice. The experiment was carried out to evaluate effectiveness of different herbicides and its combination with mechanical weed control methods in checking weed population in transplanted rice so as to maintain sustained production. Methods: The experiment was carried out in lower Gangetic plain zone during kharif season of 2018. It was laid out in randomized block design with seven treatments replicated thrice. The treatments were pretilachlor 50% EC@ 1500 ml ha-1 (0-4 DAT), butachlor 50% EC @ 4000 ml ha-1 (0-4 DAT), bispyribac Na 10% SC @ 200 ml ha-1 (Post-emergence), Sesbania intercrop @ 25 kg ha-1 up to 30 DAT followed by mechanical incorporation followed by 1 hand weeding @ 50 DAT, pretilachlor 50% EC @ 1500 ml ha-1 (0-4 DAT) followed by bispyribac Na 10% SC @ 2000 ml ha-1 (25 DAT), two hand weedings at 25 DAT and 50 DAT and untreated control. Result: Cyperus rotundus, Cyperus difformis, Alternanthera philoxeroides, Ludwigia octovalvis, Echinochloa colona, Fimbristyslis sp. were the dominating weed species as per experimental findings. Among all treatments two hand weedings at 25 DAT and 50 DAT significantly reduced the total weed density (no.m-2) while total weed biomass (g m-2) as was found to be lowest in treatment of pretilachlor 50% EC @ 1500 ml ha-1 (0-4 DAT) followed by bispyribac Na 10% SC @ 2000 ml ha-1 (25 DAT). Highest growth characteristics in rice was observed in treatment of two hand weedings at 25 DAT and 50 DAT. Pre- emergence and post-emergence application of pretilachlor and bispyribac sodium, respectively, was successful in achieving highest yield attributes, yield (4.12 t ha-1) and economic return (Rs. 47438 ha-1).