Influence of spacing and weed management practices on the growth characters, nutrient removal of weeds and nutrient uptake of direct seeded rice

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).

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.

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.