Effects of different weed management practices on growth and yield of direct-seeded spring rice in Jhapa, Nepal

A field experiment was conducted during the spring season of 2019 to determine the effects of various weed management practices on weed dynamics and productivity of wet direct-seeded spring rice at Baniyani, Jhapa. The experiment was laid out in a Randomized complete block design (RCBD) with five treatments and four replications. The treatments consisted of Pretilachlor 50% EC (dose: 900 ml a.i. ha−1) as a pre-emergence herbicide, Bispyribac sodium 10% SC (dose: 240 ml a.i. ha−1) as a post-emergence herbicide, hand weeding (at 30 DAS and 60 DAS), weed-free (weeding at every 15 days interval) and weedy check as control. The rice variety used in the experiment was Hardinath-1. The plot treated with Bispyribac sodium recorded a significantly higher number of effective tillers per meter square and grains per panicle at 90 DAS while it recorded the lowest weed density (9.17 weeds m−2) at 60 DAS. Sedges were dominant as compared to broadleaf and grasses. Sterility percentage and 1000-grain weight were not affected by various weed management techniques. Bispyibac sodium was found statistically superior in terms of grain yield (6.97 tons ha−1), straw yield (7.78 tons ha−1) and harvest index (47.29%). The experiment concluded that there was a reduction in yield by 67.9 percent due to the presence of weed as compared to weed-free. The economic analysis revealed that the post-emergence herbicide Bispyribac sodium was beneficial as compared to other weed management practices in terms of gross returns, net returns and BC ratio.