Abstract:The responses of important physiological and biochemical parameters in Myricaria laxiflora were studied by simulated flooding. The results showed that M. laxiflora underwent dormancy during summer whether flooding or not. The contents of total soluble sugar and sucrose, and peroxidase (POD) activity increased under flooding, which had no significant difference with control. After summer flooding stress released, plants recovered growth quickly. The contents of total soluble sugar and sucrose, activities of POD and polyphenol oxidase (PPO) decreased to the normal level, which also had no significant difference between flooding and control. Transpiration rate and photosynthesis rate of submerged plants were higher markedly than those of control. It was concluded that the dormancy and the changes in physiological and biochemistry of M. laxiflora were an active adaptation to summer flooding.