The study on the cold resistance and physiology change of root in meadow fescue━alfalfa mixture and monoculture in winter

In order to improve cold resistance of alfalfa (Medicago sativa), three alfalfa cultivars (Gongnong1st(GN1st), the Wega7F and the WL319HQ ) and one meadow fescue (Festuca ovina) cultivar were used in this study. Soluble sugar, soluble protein, free proline and POD activity, and winter survival rate were measured at six different time. The results showed that the winter survival rate were different among different varieties, the average winter survival rate in mixture was more than 90%,better than monoculture,and the winter survival rate in the each field had significant difference between mixture and monoculture. Variations in soluble sugar, soluble protein, free proline contents increased along with temperature decrease in late fall, then decreased along with temperature increase in spring of the following year, soluble sugar content reached peaked in mid-November, and there were significant different between monoculture and mixture (P<0.05); soluble protein content reached peaked at the end of October, there were significant difference between monoculture and mixture (P<0.05), except WL319HQ; free proline content of WL319HQ reached peak at the end of October, other treatments reached peaked in mid-November, there were significant difference between monoculture and mixture in the same measure stage (P<0.05); the POD activity change showed up-down-up trend in the whole wintering stage, showed the highest activity in mid-November. Membership function analysis and winter survival rate showed the order of cold-resistance of alfalfa cultivars was GN1st+meadow fescue>GN1st>Wega7F+meadow fescue>Wega7>WL319HQ+meadow fescue>WL319HQ.