The Effect Of Cold Resistance For Different Fall Dormancy Alfalfa By Late Autumn Cutting

There are 3 types of different fall dormancy as well as 9 grades of different fall dormancy as experimental material. The research is about the effect of cold resistance by different cutting time taking free proline,soluble sugar,soluble protein,POD,SOD,MDA as valued indices. The results showed:1,The free proline of over-ground part of low fall dormancy is more sensitive than that of midial and high fall dormancy. The change of free proline in low fall dormancy alfalfa is smooth and small with the remarkable relationship between cold resistance.2,There is a drop to the soluble protein on Sep20^th which is a trasition time of reservation-supply for over-ground part of 3 different fall dormancy. The soluble protein is necessary material, as well as, with the high relationship between cold resistance.3,The change of soluble sugar is similar with that of the soluble protein,but with no remarkable relationship between cold resistance.4,POD and SOD activity are alwaws keeping high level of over-ground part for low fall dormancy alfalfa; The change of over-ground part is more sensitive than that of root. The change of POD and SOD activity in medial and high fall dormancy alfalfa is more sensitive than that of root. low fall dormancy alfalfa, at the same time, with the high relationship between cold resistance of alfalfa. The change of MDA is relatively smooth in the over-ground of low fall dormancy alfalfa, with certain relationship between cold resistant.5,The cutting time about alfalfa in the later autumn, 20days before the coming of frost is a trasition time of reservation-supply in the root of alfalfa; It is a key period to the cold resistance of alfalfa for the first ten days of November.6,There were great influences on the rate of overwinter and regrowth in the next spring by different cutting time on alfalfa.