Optimizing tea plantation through rapeseed intercropping: ecological and pest-resistant benefits

Intercropping in tea plantations offers multiple ecological and agronomic benefits, directly impacting tea yield and profitability. While most studies on intercropping focus on summer and autumn seasons, the ecological impacts of intercropping during spring remain underexplored. Building on initial findings that tea-rapeseed ( Brassica napus L.) intercropping reduced pest damage in spring, this study explored its broader ecological effects on tea plantations and tea plant development. Results indicated that tea-rapeseed intercropping reduced young shoot damage by Apolygus lucorum by 44.04 %, facilitated by enhanced soil-microbe interactions, modified spectral ecology, and activated defense pathways in tea plants during the profuse flowering period of rapeseed. Specifically, intercropping increased C and N availability in tea rhizosphere soil, boosting organic matter and nitrogen content in the shared ecological zone. This improvement was accompanied by a significant increase in the abundance of nitrogen- and phosphorus-cycling microbial taxa, such as Methylomirabilota , Armatimonadota , and Entotheonellaeota . Moreover, rapeseed intercropping altered canopy reflectance, increasing red-edge and near-infrared spectraand boosting NDVI by 5.97 %. GC-MS analysis revealed upregulated flavonoid biosynthesis and ABC transporters, leading to higher levels of antioxidants and defense compounds in tea shoots. Concurrently, predator populations (spiders, ladybirds, and hoverflies), increased by 5–7 times from rapeseed flowering to pod stages. These findings highlight the ecological and agronomic benefits of tea-rapeseed intercropping in spring, providing a foundation for sustainable tea plantation management and pest control strategies. • Tea-rapeseed intercropping reduced pest damage by 44.04 % in early spring. • Tea canopy reflectance increased in red-edge and near-infrared spectra. • Optimizes rhizosphere microbial communities, enriching key nutrient-cycling taxa. • Key metabolites in tea shoots boosted antioxidants and resistant compounds.