Abstract: Wave break forest, which is important for preventing disasters from ocean, is a key component of shelterbelt forests systems in coastal area. In this paper, the photosynthetic characteristics of Hibiscus hamabo and Myrica cerifera were determined under different seawater stress simulating tidal waterlogging. The results showed that, with the seawater stress increasing, the maximum photosynthesis rate (P_max) decreased gradually, while the light compensate point (LCP) increased, the apparent quanta yield (AQY) decreased first and then increased in the 7^th, 21^th day, and then increased in the 42^th, 70^th day, and the dark respiration (R_d) increased, but the value of W8 treatment (waterlogging 8 h with 45 cm depth) was lower than the rest treatments in the 42^th, 70^th day for H.hamabo. The P_max, AQY both increased, and LCP, Rd both decreased for M.cerifera, and significant differences were found between W6 (waterlogging 6 h with 35 cm depth), W8 treatments and the rest treatments for each photosynthetic characteristic in the 42^th, 70^th day. Overall, H.hamabo showed better photosynthetic adaptability than M.cerifera in the 7^th, 21^th day, while this advantage disappeared in the 42^th, 70^th day.

Key words: Hibiscus hamabo, Myrica cerifera, photosynthetic characteristics, tidal waterlogging