Vol. 11, Issue 9 (2022)

Direct seeded rice (DSR) has emerged as a resource conserving alternative to puddled transplanted rice to address emerging scarcity of labour and water and the rising cost of cultivation. However, weeds are biggest biological constraint in DSR significantly reducing the yield and income. The availability of effective weed control options is critical for the success and wide-scale adoption of DSR. A field study was conducted at during the wet seasons of 2020 and 2021, at the Agronomy Research Farm of Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India, to evaluate the efficacy and economics of combination of pre and post-emergence herbicides under resource conserving crop establishment options. The treatments included three establishment methods viz., Dry-DSR, Wet-DSR and puddled transplanted rice (PTR) in main plot and six weed management treatments viz., hand weeding, oxadiargyl @ 90 g ha^-1 as pre-emergence (PE) followed by (fb.) penoxsulam+cyhalofop @ 135 g ha^-1 as post-emergence (PoE), oxadiargyl @ 90 g ha^-1 (PE) fb. triafamone+ethoxysulfuron @ 60 g ha^-1 (PoE), oxadiargyl @ 90 g ha^-1 (PE) fb. bispyribac sodium @ 25 g ha^-1 +fenoxaprop @ 56 g ha^-1 (PoE), brown manuring (DSR) / green manuring (PTR) fb. 2,4-D at 25 DAS/T and unweeded control in subplot. The results demonstrated that weed competition in the unweeded control treatment recorded maximum yield loss in Dry-DSR (82.2%) compared to that of Wet-DSR (56.7%) and PTR (21.9%). Hand weeding resulted in significant reduction in weed density and dry-biomass, but among herbicides, oxadiargyl (PE) fb. penoxsulam+cyhalofop (PoE) significantly reduced the density and Dry weight of weeds with WCE of 94.4%, 93.7% and 91.2% in PTR, Wet-DSR and Dry-DSR, respectively. Though the highest grain yield was recorded with the interaction effect of hand weeding treatment with PTR, Wet-DSR and Dry-DSR with values of 5111, 5064 and 4943 kg ha^-1, respectively, the values were at par with Oxadiargyl (PE) fb. Penoxsulam + Cyhalofop (PoE) when applied in PTR (5055 kg ha^-1), Wet-DSR (4441 kg ha^-1) and DDSR (4926 kg ha^-1). Interaction effect of establishment methods and weed management on net return of rice was found significant, with oxadiargyl (PE) fb. penoxsulam + cyhalofop (PoE), being the most profitable treatment, when applied under Dry-DSR (Rs. 49,342 ha^-1).