Physiological Response Of Red-osier Dogwood To Salt And Waterlogging Stress

The problem of alkaline soil is more and more graveness presently and there is about a billion mu in the world. A large number of alkaline soils can not be used in China. It is a feasible method that selecting proper halophytic vegetation especially salt-enduring species to ameliorate and utilize alkaline soil. There are large acreage of bottomland which has high salt content (NaCl is the main component) and high humidity in Shanghai, so it needs proper greening specie. Red-osier dogwood (Comus stolonifera Michx.) in Cornaceae which has a better adaptability is a plant which is able to endure middle degree salt, alkali and water, so it has a great utility foreground. It has been studied that NaCI stress in different concentration to the red-osier dogwood seedlings during a short time and middle NaCl stress of waterlogging condition and watedogging stress to the red-osier dogwood seedlings during a long time. The changes of several main seedlings physiological indices have been measured, such as the membrane permeability, the water potential of leaf, the chlorophyll contents, the net photosynthetic rate, the soluble sugar contents and the proline contents and so on. The enduring consistency and enduring time can been found through studying physiological response of redosier dogwood seedlings to NaCl and waterlogging stress.The NaCl stress in different concentration to the red-osier dogwood seedlings were studied, some results were gained as following: the physiological indices of the red-osier dogwood seedlings in low NaCl stress was close to the control test, although the soluble sugar contents and the proline contents were heightened in the beginning of the stress, they approached to the control test later; the water potential of leaf, the chlorophyll contents and the net photosynthetic rate of the red-osier dogwood seedlings in middle NaCl stress were obviously different from the control test, and the soluble sugar contents and the proline contents were increased in 36 hours but reduced gradually in the follow time; the physiological indices of the red-osier dogwood seedlings in high NaCl stress was marked difference from the control test, and the differences were more and more obvious as time goes by; when the redosier dogwood seedlings in the middle NaCl stress of wateflogging condition, the membrane permeability, the soluble sugar contents and the proline contents were increased as time goes by, but the water potential of leaf, the chlorophyll contents and the net photosynthetic rate were educed as time goes by.The critical concentration to endure of NaCl stress of the red-osier dogwood was about 300mmol/L and the critical time to endure of middle NaCl stress in waterlogging condition was about 6 days. The red-osier dogwood had a rapid response to NaCI stress and it resisted to external environment during the beginning of the stress. And several main physiological indices were made notable influence after 48 hours of stress when overstepping the enduring range of stress.The waterlogging stress to the red-osier dogwood seedlings were studied, some results were gained as following: compared to the NaCl stress in waterlogging condition, the membrane permeability, the water potential of leaf, the chlorophyll contents, and the proline contents were closed to the control test; the net photosynthetic rate was reduced a little when stress sustaining 6 days and 9 days, but then increased to the control test nearly; the soluble sugar contents was increased a littler when stress sustaining 6 days, but then reduced to the control test nearly.Waterlogging stress was not greatly damage to the red-osier dogwood. And the resistance of the seedlings to the external environment was most intensive when stress sustaining about 6 days. And then the seedlings adapted the external environment and each physiological index was driven to the normal. So it can be inferred that the damage to seedlings of NaCl stress in waterlogging condition mostly resulted from salt stress but not waterlogging stress.Through observing the expression of red-osier dogwood in Shanghai and combining the achievement of the study, the red-osier dogwood can be planted experimentally on the bottomland in Shanghai, which was high salt and high soil humidity. It will bring fine ecological efficiency and economy efficiency when introducing plant successfully. So the study has the reference values for increasing the plant species variety and enriching the greening species on the bottomland of Shanghai. And it also provides the basic theory and science evidence for introducing plant scientifically.