Taking Kandelia obovata forest as the research object, through periodical replenishment experiment, the improvement of physicochemical properties of the sediments and the plant physiological indicators were used to ascertain the repair effect of water supplemnet on K. obovata. The main results were as follows. 1) The water content, pH, salinity, total nitrogen and organic matter content of sediments in the hydration group were higher than those in the control group, indicating that water supplement improved the nutrient conditions and salinity of the sediment. 2) Water supplementation significantly increased net photosynthetic rate, water use efficiency, and chlorophyll a content (P<0.05), while decreased intercellular CO2 concentration, indicating that water replenishment effectively improved the photosynthesis status and promoted the absorption and transformation of light energy for K. obovata. 3) The maximum fluorescence efficiency (Fv/Fm) of the photosystem II (PS II) in the control group was significantly lower than 0.8 (common threshold), indicating that the degraded K. obovata forest was in the photoinhibitory state, while Fv/Fm was significantly increased after water supplementation (P<0.01), approaching 0.8, indicating a significant improvement in plant health status. 4) Water supplementation improved the photochemical efficiency of the PS II reaction center of K. obovate and significantly improved the imbalance of the excitation energy distribution between the two-optical systems. Moreover, water supplementation also effectively reduced the heat dissipation of the antenna pigments and made the distribution of light energy tend to be efficient, thus increasing the foliar photochemical utilization efficiency. In summary, periodic replenishment is an effective method for the rehabilitation of land-based degraded mangroves.
