INFLUENCE OF HERBICIDES ON GROWTH, YIELD AND CONTROLLING WEEDS IN DIRECT-SEEDED AUS RICE

Abstract

A field experiment was carried out at the Agronomy field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, from March to August 2022, to investigate the efficiency of herbicides against weeds and influence on growth, yield and yield contributing parameters of direct-seeded rice aus rice of Bangladesh. The experiment consisted of 13 treatments viz., Unweeded (control), partial weeding (two-hand weeding at 20 and 40 Days After Sowing), weedfree,

Butachlor (25 kg ha -1 ), Pendamethyline (2 L ha ii -1 ), Pretilachlor (1 L ha ), BispyribacSodium (25 g ha -1 ), Butachlor (25 kg ha -1 ) + Bispyribac-Sodium (25 g ha -1 ), Pendamethyline (2 L ha 1 -1 ) + Bispyribac-Sodium (150 g ha -1 -1 ), Pretilachlor 6% + Pyrazosulfuron- ethyl 0.15% (2 kg ha ), Pretilachlor 30% + Pyrazosulfuron- ethyl 0.75% (2 kg ha -1 ), Acitachlor 14% + Bensulfuron methyl 4% (3 kg ha -1 ), 2, 4-D Amine (2.24 L ha -1 ). The test rice variety was BRRIdhan 98. The experiment was laid out in a randomized complete block design having 3 replications. Seeds were sown directly on 29 March 2022. Seventeen weed species infested the experimental field belonging to 10 families, where the most dominating were broadleaf and grass weed species. Among the weeds, Digitaria ischaemum was the most dominant weed at 20, 40, and 60 DAS, followed by Physalis heterophylla and Digitaria sanguinalis. The sequential application of Pendimethalin and Bispyribac-Sodium herbicides treated plots recorded minimum weed density m -2 (0.0, 2.33, and 4.00) and weed dry weight (0.00, 0.57, and 1.25 g) at 20, 40, and 60 DAS, respectively. The highest weed control efficiency (100, 88.46 and 80.66 %) at 20,40 and 60 DAS among all herbicidal treatments and also the highest weed control index (97.31 and 99.16%, respectively) at 60 and 90 DAS. Among the weed management practices weed-free and partial weeding notably reduced the weed counts, higher growth and yield attributes and grain yields. It was statistically at par with applying Pendamethyline (2 L ha -1 ) followed by Bispyribac-Sodium (25 g ha -1 ), which ultimately gave the highest grain yield was obtained from weed free treatment followed by partial weeding. But from economic view of point, partial weeding and Pendimethalin + Bispyribac-sodium showed almost similar benefit-cost ratio.Therefore, Pendamethyline (2 L ha -1 ) and Bispyribac-Sodium (25 g ha -1 ) were found as the best broadspectrum effective herbicides to manage the various weed flora in direct-seeded aus rice.