Intercropping tea plants with selenium-accumulating rapeseed via foliar selenium application: A cultivation practice for promoting tea plant growth and tea quality

The sustainable development of monoculture tea ( Camellia sinensis L) plantations is confronted with multifaceted challenges, such as overusing chemical fertilizer, unstable yields, and declining tea quality. These issues not only impede the long-term productivity of tea but also pose risks to environment. Given these concerns, exploring eco-friendly cultivation strategies is of paramount importance. This study established an innovative cultivation model by integrating intercropping with selenium (Se)-accumulating rapeseed green manure and foliar Se application, aiming to explore its effects and underlying mechanisms on tea plant growth, tea quality, rhizosphere soil environment, and Se biofortification. Physiological and biochemical indicators including chlorophyll, free amino acids, catechins, and selenium-containing speciation in tea leaves were determined, together with key enzyme activities involved in rhizosphere nutrient cycling. The results showed that the integrated system significantly promoted tea plant growth and improved tea quality by increasing chlorophyll and free amino acid contents while decreasing catechin concentrations. Se in tea leaves was predominantly present in bioavailable organic forms such as selenoamino acids, meeting the standard for selenium-enriched tea. Meanwhile, the integrated strategy significantly enhanced the activities of β‑glucosidase, leucine aminopeptidase, and N‑acetyl‑β‑glucosaminidase in rhizosphere soil, and alleviated soil acidification by increasing pH. These results demonstrate that the synergistic mode of green manure intercropping and selenium application effectively facilitates selenium uptake via amino acid transporters, improves rhizosphere nutrient cycling, and coordinates tea growth, quality, and soil health. This integrated approach provides an eco-friendly and sustainable strategy for the production of functional selenium-enriched tea. • Intercropping rape with selenium boosts tea growth, chlorophyll, and soil health. • It increases free amino acids and reduces catechin, improving flavor quality. • The level of Selenoamino acids in tea meets Selenium-enriched standards. • Intercropping rapeseed enhances the activities of enzymes in rhizosphere soil.