Response of Shoot Growth to Ecological Factors Highlights a Synergistic Relationship Between Yield and Catechin Accumulation in Tea Plant (Camellia sinensis L.)

Ecological factors directly influence the growth and metabolism of tea plants (Camellia sinensis L.), and unfavorable environmental conditions cause abiotic stress to them. Abiotic stress causes damage to reliable, high-quality, and safe tea production, yet the optimal ecological conditions for enhancing both yield and quality remain unclear. To investigate the response patterns of shoot growth to ecological factors and its relationship with catechin accumulation, this study conducted the cultivation of tea plants with a precise modulation of both individual and combined ecological parameters. Under 30 °C and 90% air humidity, specific combinations of light intensity and substrate relative humidity (“250 µmol·m−2·s−1 + 65%” or “350 µmol·m−2·s−1 + 70%”) significantly enhanced growth and yield. A significant correlation between shoot growth and catechin accumulation was observed, and mathematical models further revealed a synergistic response between shoot growth capacity and total catechin content to ecological factors. Furthermore, co-expression analysis indicated that catechin biosynthesis-related genes exhibited coordinated expression with key growth-related genes, including CsTCP, CsErf, and CsXth. In conclusion, these findings identify optimal ecological conditions to mitigate abiotic stress and reveal a synergistic relationship between catechin biosynthesis and shoot growth, providing an ecological basis for balancing yield and quality in tea production.