Abstract: The present study investigated the effects of exogenous 24epibrassinolide （EBR） on gas exchange， chlorophyll fluorescence parameters， lipid peroxidation （MDA content） and antioxidant enzymes activities in tea （Camellia sinensis cv. Longjing 43） leaves under heat stress. Results showed that foliar application of EBR could significantly increase Pn， Gs， Vc，max， Jmax and Fv/Fm in tea leaves under heat stress. Moreover， EBR remarkably increased activities of APX， CAT， SOD and POD， but decreased MDA content in tea leaves following heat stress. These results suggest that exogenous EBR mitigates heat stressinduced photosynthetic inhibitions in tea leaves， mainly by eliminating the nonstomatal limitations and promoting the photosynthetic carbon reaction. Furthermore， EBR strengthened the antioxidant system effectively to scavenge harmful levels of reactive oxygen species and thus alleviated heat stress in tea plant.

Key words: Camellia sinensis L., heat stress, EBR, photosynthetic characteristics, antioxidant enzymes