Influence of Spacing and Weed Management Practices on the Growth Characters, Nutrient Removal of Weeds and Nutrient Uptake of Direct Seeded Rice

Background: The field experiment was conducted at the Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli, Tamil Nadu during rabi, 2022-2023 to study the influence of spacing and weed management practices on growth characters, nutrient removal by weeds and nutrient uptake of direct seeded rice (DSR). Methods: The field experiment was laid out in split plot design with three replications. The main plots were spacing of 20 × 15 cm, 20 × 20 cm and 25 × 25 cm. Sub plots were assigned with weed management practices viz., pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE, Pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Cono weeding on 20 DAS + hand weeding (HW) on 40 DAS, Pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Cono weeding on 20 DAS and 40 DAS, Pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE + Cono weeding on 40 DAS, Pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE + Hand weeding on 40 DAS, Hand weeding at 20 and 40 DAS and unweeded control. Result: The results indicated that the highest growth attributes, higher nutrient uptake of nitrogen, phosphorous and potassium under DSR and were significantly improved by spacing 20 × 20 cm along with pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE + Cono weeding on 40 DAS. This was on par with pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE + Hand weeding on 40 DAS and hand weeding on 20 and 40 DAS. Similarly lower nutrient removal by weeds were registered under 20 × 15 cm spacing along with pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE + cono weeding on 40 DAS. The interaction of spacing 20 × 20 cm and pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS as PE + Bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS as PoE + Cono weeding on 40 DAS significantly increased the growth attributes such as plant height, dry matter production and total numbers of tillers and significantly lowered the nutrient removal by weeds.