Evaluation on salt tolerance to salttolerant variant materials of three alfalfa varieties

Three foreign alfalfa（Medicago sativa） varieties (Victoria, Millennium, and Cw787) with strong resistance to high temperature and humidity were selected to obtain salttolerant callus variants by using sodium chloride (NaCl) as selective reagent via positive selection (direct selection and continuous selection) methods. The physiological indexes, including MDA, proline, soluble protein and soluble sugar content, as well as superoxide dismutase (SOD) activity of regeneration plants of callus variants were measured and these physiological indexes was used to comprehensively evaluate the salt tolerance by Subordinate Function method. The results of this study showed that the MDA, proline, soluble protein and soluble sugar content, as well as superoxide dismutase (SOD) activity of regeneration plants of callus variants were significantly (P0.05) higher than that of control plants. The order of salt tolerance was Millennium CW787 Victoria.