Simplified overwintering covers improve spring tea yield and quality by buffering the canopy microenvironment in northern tea plantations

Tea plants in northern production regions are exposed to low temperature, drought, and strong irradiance during winter, which constrain safe overwintering and spring tea production. This study compared the effects of simplified overwintering cover treatments, followed by light pruning (LP) or no light pruning (NLP) after cover removal, on the canopy microenvironment, winter injury, physiological responses, spring tea yield, and tea quality. The results indicated that appropriate mulching could stabilize the temperature and humidity environment of the canopy, reduce diurnal temperature variation, and mitigate overwintering damage, with T8 (HDPE woven fabric + crop straw) demonstrating the best overall performance. The activities of superoxide dismutase (SOD) and catalase (CAT) in T8 were approximately 190 U·mg −1 protein and 30 U·g −1 fresh weight, respectively. Malondialdehyde (MDA) content was approximately 23% lower than that under the uncovered T1, and Fv/Fm was highest. These responses indicated less oxidative injury and greater photosystem stability. The T8-NLP also provided the best overall production performance and sensory quality, with higher free amino acid, theanine, and water extract contents, and a lower phenol-to-amino acid ratio. In contrast, although light pruning after cover removal increased bud density, it generally reduced one-hundred-bud weight and overall quality potential. An exploratory structural equation model (SEM) showed that the observed associations were consistent with the proposed sequence in which canopy microenvironmental buffering was associated with reduced winter injury, improved physiological recovery, and subsequent variation in spring tea yield and quality. These findings provide a technical basis for overwintering management in mature Huangshan‑population tea plantations in northern tea‑growing regions such as Shandong Province.