Physiological Response of Three Tree Species Seedlings to Submergence Stress

In order to provide reference for selection of submergence-resistant tree species, seedling physiological changes of Manglietia glauca, Casuarina equisetifolia, and Michelia chapensis were studied under submerged stress environment. Effect of seedling physiological indexes on submergence stress was evaluated by testing contents of chlorophyll, soluble sugar, soluble protein, content of malondialdehyde (MDA) and superoxide dismutase (SOD) activity. With increasing submergence time, the chlorophyll content of M. glauca increased after slight fluctuation, that of C. equisetifolia slightly decreased followed by an increase, whereas it changed a little for M. chapensi. The peak of chlorophyll content in three seedlings was between （1.73±0.02）mg·g^-1 and（2.37±0.02）mg·g^-1; the content of soluble sugar of M. glauca decreased followed by an increase, C. equisetifolia continuously increased and M. chapensis increased gradually at the beginning and then decreased, and their peak was between （3.21±0.14）% and （4.96±0.34）%; the contents of soluble protein of M. glauca rapidly fluctuated, C. equisetifolia fluctuantly decreased, M. chapensis increased and then decreased, with a peak between （17.97±0.83）mg·g^-1 and （28.10±2.16）mg·g^-1; the activity of SOD of M. glauca and M. chapensis gradually decreased, whereas that of C. equisetifolia increased and then decreased, with a peak between （177.39±4.86）U·g^-1 and （183.94±1.71）U·g^-1. The content of MDA of M. glauca and M. chapensis tended to increase, whereas that of M. chapensis remained steady, with a peak between（0.018±0.001）μmol·g^-1 and （0.037±0.002）μmol·g^-1. The comprehensive evaluation showed that the order of submerging resistance of the three seedlings was C. equisetifolia>M. glauca>M. chapensis.