Primary Studies On Physiological Characteristics Of Drought And Salt Resisting And Resistance Mechanism Of Medicago Falcata L.

Medicago falcata L. is a perennial herb in leguminosae. There are many excellent characteristics which are cold and drought resistance, salt tolerance, windy and dusty resisting, leanness tolerance and diseases and pests resisting. In this paper, drought resistance, physiological characteristics of salt tolerance and resistance mechanism were studies primarily base on the drought resistance and identification of ability to salt tolerance .The results were as follows:1. Response of physiology indices of Medicago falcata L. to drought stress is different. There are not obvious correlation among indices and ability to drought resistance. The indices include critical water saturation deficiency, free and bound water content, tissue water, peroxidase isozyme, free proline content, chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll (a/b). These indices are not fitting for assessing ability of drought resistance of Medicago falcata L.. There are some correlations among indices and ability to drought resistance. The indices include natural saturation deficit, the degree of water requirement, bound water/ free water, water retaining capacity of isolated leaves, electrical conductivity, SOD activity, soluble sugar content, malondialdehyde content, photosynthetic rate of daily average, transpiration rate. They can reflect the difference of ability to drought resistance of the materials in various degree and angles. So these indices were recommended to establish index system for comprehensive appraisal and discrimination of ability to drought resisting.The uppermost factor that effect on ability of drought resistance of Medicago falcata L. is photosynthetic rate of daily average. The role of electrical conductivity in effecting on ability of drought resistance is minimum.Medicago falcata L. belongs to drought avoidance type in the method of drought resistance.2. Response of physiology indices of Medicago falcata L. to salt stress is different. SOD activity, peroxidase isozyme and chlorophyll content cannot reflect the difference of the ability to salt tolerance of the materials. These indices are not fitting for studying the ability of salt tolerance of Medicago falcata L.. Free and bound water, tissue water ,bound/free water, water retaining capacity of isolated leaves, electrical conductivity, free proline content, soluble sugar content and malondialdehyde content can reflect the difference of ability to salt tolerance of the materials in some degree. So these indices were recommended to study the difference of ability to salt tolerance and analysis physiological characteristic of salt tolerance and resistance mechanism.The uppermost factor that effect on ability of salt tolerance of Medicago falcata L. is soluble sugar content. The role of free water content in effecting on ability of salt tolerance is minimum.Medicago falcata L. belongs to sparse salt type in the method of salt tolerance.