STUDY ON THE MANUAL, CHEMICAL, CULTURAL AND INTEGRATED WEED MANAGEMENTS IN SOYBEAN

Abstract

During Rabi season, a field experiment was conducted at Sher-e-Bangla Agricultural University, Dhaka from December 2021 to April 2022 to study the manual, chemical, cultural, and integrated weed managements in soybean (Glycine max L.). The experiment was laid out in randomized complete block design (RCBD) with twelve weed management treatments such as no weeding (Control), two hand weeding (15 and 30 DAS), pre-emergence herbicide (Herbilin 33% EC @ 400 ml ha -1 ), post-emergence herbicide, (Irish @ 1200 ml ha -1 ), pre + post-emergence herbicide, pre-emergence + 1 hand weeding {40 days after sowing (DAS)}, Post-emergence + 1 hand weeding (40 DAS), pre + post-emergence + 1 hand weeding (40 DAS), straw mulching, intercrop with red amaranth (Amaranthus dubius), intercrop with maize (Zea mays), and weed-free. The experimental result showed among seven different weed species found, Cyperus rotundus was the most prevalent weed, with the highest weed density (128.67 and 123 m ) and relative weed emergence (38.79 and 43.16 %) in the weedy check plot at 60 and 90 DAS, followed by Echinochloa colona and Cynodon dactylon. In comparison, the dominance of Heliotropium indicum and Alternanthera philoxeroides was the lowest among all weed species in the weedy check plot at 60 and 90 DAS. In case of different weed management treatments, the treatment Pre + Post-emergence + 1 hand weeding (40 DAS) showed the highest pod length (4.16 cm) and seeds pod -1 (3.89), while the weed free treatment resulted with the highest 1000 seed weight (111.00 g), seed yield (1.86 t ha ), stover yield (2.16 t ha -1 ), biological yield (4.03 t ha -1 ), harvest index (46.35 %). However, the highest benefit-cost ratio (2.85) was obtained under post-emergence herbicide (Irish @ 1200 ml ha -1 ) treatment. Therefore, applying post-emergence herbicide (Irish @ 1200 ml ha -1 ) will be the best weed management practice for profitable soybean cultivation. -1 -2