Effect of herbicides on weeds, rhizospheric microorganisms, tea green leaf yield and nutrient uptake in tea plantation

Field experiment was conducted in the Tarai region of Jalpaiguri, West Bengal, India during 2021 and 2022 to evaluate the effect of post-emergence herbicides on weeds, non-target soil organisms, nutrient dynamics and productivity of tea (var. TV-25) under natural weed infestations in tea a garden. The experimental treatments were comprised of: post-emergence application (PoE) of five doses of 2-methyl-4-chlorophenoxyacetic acid (MCPA): 0.5, 0.8, 1.0, 1.25 and 1.5 kg/ha; 2,4-D Sodium salt 1.0 kg/ha PoE and untreated control. A randomized complete block design replicated thrice was used. MCPA 1.50 kg/ha PoE was most effective against broad-leaved weeds, achieving higher weed control efficiency (> 85%) and producing the highest total tea green leaf yield. No phytotoxicity was observed on mature tea leaves due to any of the herbicidal treatment. Although transient reductions in rhizospheric micro-flora (total bacteria, fungi, and actinomycetes) were detected after herbicide application, microbial communities recovered over time, indicating no persistent adverse effects due to herbicides tested. Maximum nutrients uptake and soil available nutrients were recorded with higher dose of MCPA. MCPA at 1.5 kg/ha was observed as the best substitute for others post-emergent herbicide to manage broad-leaved weeds in tea garden.