Optimizing Planting Geometry and Weed Management for Improved Yield of Boro Rice (cv. Jirashail)

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University to evaluate the effects of planting geometry and integrated weed management on weed infestation and grain yield of Jirashail rice during the boro season. Four spacings (20cm ×15 cm, 20cm × 20 cm, 25cm × 15 cm, 25cm × 20 cm) and five weed control methods (unweeded control; two hand weedings at 25 and 50 days after transplanting (DAT); pre-emergence herbicide + one hand weeding at 50 DAT; early post-emergence herbicide + one hand weeding at 50 DAT; and a combination of pre- and early post-emergence herbicides) were organized in a randomized complete block design (RCBD) with three replications. The lowest weed density occurred at the closest spacing (20cm × 15cm), while the widest spacing (25cm × 20cm) had the highest. Weed infestation was most severe in unweeded plots, whereas combined herbicide application (pre- and early post-emergence) provided the best suppression. The greatest weed growth was observed at 25cm × 20cm under unweeded conditions; maximum suppression occurred at 20cm × 15cm with both herbicides at 20 and 40 DAT. Grain yield was highest at 20cm × 20 cm which was at par with 25cm × 20cm. Weed control, yield, and profitability were achieved using 20cm × 20cm spacing with combined herbicides.