Integrated Herbicide-Based Weed Management Practices for Improving Growth, Yield Attributes and Crop Safety in Groundnut (Arachis hypogaea L.) under Rice–Groundnut Cropping System

Abstract

Integration of pre-emergence herbicides with post-emergence herbicides or manual weeding is widely regarded as an effective strategy for season-long weed control. Post-emergence herbicides such as imazethapyr and quizalofop-p-ethyl have shown promising results in controlling broad-leaved and grassy weeds during the critical stages of crop growth. The present study aimed to evaluate the effectiveness of different herbicide combinations and integrated weed management practices for improving weed control and crop productivity in groundnut. A field experiment was conducted during rabi–summer 2016–17 at the Agricultural Research Station, Kumta, Karnataka, to evaluate the effects of different weed management practices on growth parameters, yield attributes, and crop phytotoxicity of groundnut (Arachis hypogaea L.) under a rice–groundnut cropping system. The experiment was laid out in a randomized complete block design with nine weed management treatments and three replications. Observations on plant height, number of branches per plant, dry matter production, and crop phytotoxicity were recorded at different growth stages. The weed-free treatment recorded significantly higher plant height, number of branches, and dry matter accumulation, which were statistically at par with pre-emergence application of pendimethalin @ 1.5 kg ha⁻¹ followed by one hand weeding at 25 days after sowing (DAS), and pendimethalin @ 1.5 kg ha⁻¹ followed by post-emergence imazethapyr @ 75 g ha⁻¹ at 20–30 DAS. The unweeded control recorded the lowest values for all growth parameters due to severe crop–weed competition. Visual phytotoxicity ratings revealed no severe or persistent injury to the groundnut crop under any herbicide treatment, and initial mild symptoms disappeared within 21–28 days after application. The harvest index was significantly influenced by weed management treatments. The highest harvest index (0.29) was recorded in the weed-free check, which was statistically at par with pendimethalin followed by hand weeding (0.29) and pendimethalin followed by imazethapyr (0.28), while the lowest harvest index (0.25) was recorded in the unweeded check. Overall, integrated weed management practices involving pre-emergence application of pendimethalin followed by hand weeding or post-emergence herbicides significantly improved yield and yield attributes compared with the unweeded condition. It is concluded that integrated weed management combining pre-emergence herbicide application with manual or post-emergence weed control is an effective and crop-safe approach for enhancing the productivity of groundnut under rice-fallow conditions.