Aerobic direct-seeded rice, Bispyribac-Na, Nitrogen levels, Pyrazosulfuron, Rice, Sequential herbicides application, Weed management

Aerobic direct-seeded rice (DSR) is a resource-efficient alternative to puddled transplanted rice but its adoption is influenced by weed infestation and nitrogen (N) management factors. A field experiment was conducted in Kharif 2020 at Kumarganj, Ayodhya, Uttar Pradesh (U.P.), India using a split-plot design with three replications. The objective of this study was to assess the impact of weed management and nitrogen (N) levels on weeds growth and aerobic DSR productivity. The main plots comprised of three N levels, viz. 100%, 125%, and 150% of the recommended dose (RDN), while sub-plots included five weed management options: pre-emergence application (PE) of pyrazosulfuron 25 g/ha; sequential application of pyrazosulfuron 25 g/ha PE followed by (fb) post-emergence application (PoE) of bispyribac-Na 25 g/ha; hand weeding twice at 20 and 40 days after seeding (DAS); weed-free, and unweeded check. 150% RDN significantly reduced weed density and dry biomass (by 27.76%) and improved rice plant height, dry matter, yield attributes, and DSR grain yield (by 14.18%) over 100% RDN. Maximum grain and straw yield were recorded with 150% RDN with hand weeding twice. However, the highest net return and benefit cost ratio (B:C)  were recorded with 150% RDN and sequential application of pyrazosulfuron 25 g/ha PE fb bispyribac-Na 25 g/ha PoE.