Determined The Cold Resistance On Pear Varieties Resource And Studied On Its Resistance Physiology In Yanbian Area

The cold resistance of different pear tree with generally managed and different tree potential pear tress was determined by the method of electric conductance, which based on the biologic membrane theory. Studies were made on the different pear tree in Yanbian by testing the changes in water status, cell membrane permeability, the contents of soluble sugar, free praline, soluble protein during the dormancy period.The results indicated that the relationship between relative electric conductance, injury ratio and temperature represented linearity negative correlation, and the coefficient of correlation reached to obvious significance in the pear tree with generally managed and the different tree potential. The sequence of cold resistance of the pear tree with generally managed was Daxiangshui>Shanli>Nanguoli>Zaosuli >Xiaoxiangshui>Xiehuatian>Pingguoli by the b value. The sequence of different tree potential pear tree was Pingguoli(strong) > Pingguoli(middle) > Pingguoli(weak).The relationship between soluble sugar and bound water: free water ratio, soluble protein represented obviously positive correlation, and approved that the soluble sugar was the dominant factor in the cold-resistance of pear tree by the multiple correlation and path analysis. The direct path coefficient of soluble sugar was -7.4107.The indirect path coefficient of soluble protein and bound water/free water based on the soluble sugar was respective -7.3826 and -6.9192.The changes trend of the soluble sugar contents with air temperature was increase→reduce. The contents of soluble sugar in some hardier varieties were more, whereas that in the less hardy varieties was less. The coefficient of correlation with relative electric conductance was -0.8963**.The contents of free praline and soluble protein increased gradually as air temperature reduced, and the coefficient of correlation was respective -0.8806 and -0.8590*.The bound water: free water ratio was at 0.9806~1.5296.The relationship between bound water: free water, soluble sugar, free praline, soluble protein and relative electric conductance represented obviously negative correlation, and the coefficient of correlation was respective -0.9276*,-0.9246*,-0.9063* and -0.9398*.