Abstract: With tea plant cultivar ‘Zhongcha 108’ as the test material, the effects of spraying EBR with different concentrations (0.10, 0.30, 0.50mg·L^-1) on the chlorophyll content, stomatal aperture, photosynthetic gas exchange parameters and related gene expression of tea leaves were studied. The results show that spraying 0.10 and 0.30mg·L^-1 EBR on leaves significantly increased the chlorophyll content of tea leaves on the first day after treatment. Compared with the control condition, chlorophyll content increased by 38.89% and 22.22%, respectively. On the third and fifth days after treatment, the stomatal aperture of tea leaves treated with 0.10 and 0.30mg·L^-1 EBR increased significantly. On the first and fifth days after treatment, spraying EBR significantly increased the net photosynthetic rate of tea leaves. At the same time, EBR treatment could significantly up-regulate the expressions of genes involved in BR biosynthesis, chlorophyll biosynthesis, and carbon assimilation. These results indicate that exogenous EBR increased the chlorophyll content and stomata aperture of tea leaves by regulating the expression of related genes, which ultimately promoted the photosynthetic rate of tea plants.

Key words: tea plant, 24-epibrassinolide, chlorophyll, photosynthetic characteristics, gene expression