Chemical management of non-grassy weeds in direct-seeded rice

摘要

Field experiments were conducted during Rabi 2011-12, Kharif 2012 and Rabi 2012-13 to evaluate the bioefficacy of carfentrazone-ethyl at 20 and 25 g/ha on 15-20 DAS with 2,4-D Na salt 800 g/ha on 20-25 DAS, weed free situation and un-weeded check as treatments in randomized block design replicated four times. Fimbristylis miliacea, Cyperus dijformis, Cyperus iria, Schenoplectus pungens were the major sedges and Monochoria vaginalis, Ludwigiaperennis and Sphenoclea zeylanica were the dominant broadleaved weed species. Application of carfentrazone-ethyl 20 g/ha on 15-20 DAS proved effective in controlling sedges and broad-leaved weeds in direct-seeded rice. Carfentrazone-ethyl 40 DF 20 g/ha recorded higher grain yield (3.68 t/ha) with weed control efficiency of 90.7% and weed index of 9.5. It was comparable with 2,4-D Na salt 800 g/ha (3.65 t/ha) with weed control efficiency of 96.7% and weed index of 10.5. There was 72% reduction in grain yield due to the infestation of non-grassy weeds in direct-seeded rice. Weed free situation recorded the highest grain yield (4.07 t/ha) but its B: C ratio was lower than carfentrazone-ethyl 20 g/ha and 2,4-D Na salt 800 g/ha. Carfentrazone-ethyl, both at 20 and 25 g/ha did not exhibit any phytotoxic effect in rice plant.