Response of Soybean and Weeds to Various Weed Management Practices

Aims: Soybean (Glycine max L.) is highly susceptible to weed competition during its early growth stages, which can cause significant yield losses if not managed properly. Therefore, a field experiment was conducted to evaluate the effectiveness of different weed management practices, including chemical (Pendimethalin, Metribuzin, Imazethapyr, and their combinations) and manual (one-hand and two-hand weeding), on soybean yield, growth attributes, weed density, and weed biomass. Study Design: This experiment was laid out in a randomized complete block design with three replications. Place and Duration of Study: This study was conducted over two consecutive years of 2022/23 and 2023/24 at the Grain Legumes Research Program (GLRP), Khajura, Banke, Nepal. Methodology: The experiment consisted of eight weed management treatments viz., Pendimethalin, Pendimethalin and Imazethapyr, Metribuzin, Metribuzin and Imazethapyr, Imazethapyr, One hand weeding, Two hand weeding and Unweeded. Results: Results demonstrated that weed management significantly influenced key yield components, i.e, days to flowering, number of pods per plant and 100-seed weight. Among treatments, two-hand weeding produced the highest grain yield (1841 kg ha⁻¹), followed by one-hand weeding (1709 kg ha⁻¹), while the lowest yield was recorded in the unweeded control (746 kg ha⁻¹). The combination of Pendimethalin+Imazethapyr was the most effective chemical treatment in suppressing weed dry biomass (19.7 g/0.5 m²) and improving yield-related traits. Although manual weeding effectively reduced weed competition and maximized yield, it was less efficient in reducing total weed biomass compared to integrated chemical treatments at the earlier stage of crop growth. Conclusion: The study concludes that the combination of Pendimethalin and Imazethapyr, offers a sustainable and effective strategy for improving soybean productivity by minimizing weed competition and biomass under field conditions.