Weed competition is one of the most important yield-limiting factors in lowland transplanted rice, and labour-intensive manual weeding is increasingly uneconomical and impractical. This study evaluated the effects of integrated weed management (IWM) treatments, with emphasis on herbicide-based options, on grain yield, straw yield and economic returns in transplanted lowland rice under Chhattisgarh plains conditions. A field experiment was conducted during the kharif season of 2022 at BTC CARS, Bilaspur (C.G.), using a randomized block design with ten weed management treatments and three replications. Treatments included pre- and post-emergence herbicides (pyrazosulfuron-ethyl, bispyribac-sodium, chlorimuron-ethyl + metsulfuron-methyl), either alone or in combination with mechanical or manual weeding, along with weed-free and weedy-check controls.
The weed-free treatment recorded the highest grain yield (57.79 q ha⁻¹) and straw yield (66.50 q ha⁻¹), but at the highest cost of cultivation due to multiple hand weedings. Among herbicidal treatments, chlorimuron-ethyl 10% WP + metsulfuron-methyl 10% WP @ 0.06 g a.i. ha⁻¹ at 20 days after transplanting (DAT) + mechanical weeding at 20 and 40 DAT achieved grain yield of 56.12 q ha⁻¹, straw yield of 62.45 q ha⁻¹, net return of ₹114,080 ha⁻¹, and the highest benefit-cost (B:C) ratio (2.35). The weedy check recorded only 18.32 q ha⁻¹ grain yield and negative net returns, reflecting severe economic loss without weed control. Herbicide-only or herbicide + single mechanical weeding treatments produced intermediate yields and returns.
Results indicate that herbicide-based IWM can deliver yield levels comparable to weed-free plots while substantially reducing labour cost and improving profitability. The combination of chlorimuron-ethyl + metsulfuron-methyl with mechanical weeding emerges as an economically superior strategy for transplanted lowland rice in labour-scarce environments. These findings support a shift from purely manual weed control towards cost-effective, herbicide-integrated systems to sustain rice productivity and farm profitability.
