Effect of spacing and weed management practices on yield parameters and yield of direct-seeded rice

Field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Thiruchirappalli, Tamil Nadu during the rabi season of 2022-23 to evaluate the effect of spacing and weed management practices of yield parameters and yield of direct seeded rice (DSR) under sodic soil using three levels of spacing and seven weed management strategies.

The main plots were spacing of 20 × 15 cm, 20 × 20 cm and 25 × 25 cm. Sub-plot consisted of weed management practices in DSR viz., pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + bispyribac sodium 25 g ha^-1 at 20 DAS, pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + cono weeding at 20 DAS + hand weeding (HW) at 40 DAS, pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + cono weeding at 20 DAS and 40 DAS, pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + bispyribac sodium at 25 g ha^-1 at 20 DAS + cono weeding at 40 DAS, pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + bispyribac sodium at 25 g ha^-1 at 20 DAS + HW at 40 DAS, hand weeding at 20 and 40 DAS and unweeded control. The field experiment was laid out in split plot design with three replications.

The results indicated that lower total weed density (40.39 no. m^-2), dry weight of weeds (85.52 g m^-2) and higher WCE (77.5%) were registered under 20 × 15 cm which was on par with spacing of 20 × 20 cm. The higher number of productive tillers m^-2 (389), number of grains panicle^-1 (192), number filled grains panicle^-1 (187), grain yield (4546 kg ha^-1) and straw yield (6714 kg ha^-1) were observed under spacing of 20 × 20 cm. Application of pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + bispyribac sodium 25 g ha^-1 at 20 DAS + cono weeding at 40 DAS possessed the lowest total weed density (7.67 no. m^-2), dry weight of weeds (12.63 g m^-2), higher WCE (97.0) at 45 DAS and significantly improved the yield parameters and yields compared to unweeded control. The highest grain and straw yields were recorded from interaction between 20 × 20 cm and pyrazosulfuron ethyl 20 g ha^-1 at 3 DAS + bispyribac sodium 25 g ha^-1 at 20 DAS + cono weeding at 40 DAS.