Physiological response to low temperature stress and evaluation of cold resistance of three color-leafed trees.

The annual dormant shoots of Ligustrum 伊vicaryi, Prunus persica ‘Atropurpurea', and Berberis thunbergii ‘Atropurpurea'were used to measure their physiological response to low temperatures from 0 to -36 c using eight indices, such as bud germination rate, relative electric conductivity, etc. through an artificially-simulated cooling process. Based on correlation analysis among the indices, it was shown that relative electric conductivity, soluble sugar content and superoxide dismutase (SOD) activity could be used as indices to evaluate cold resistance. Using principal component analysis and subordinate functions to assess the cold resistance of all three color-leafed trees, the values were 0.086 (L. ⅹvicaryi ), 0.106 ( P. persica ‘ Atropurpurea ') and 0.979 ( B. thunbergii ‘ Atropurpurea 爷), respectively, i. e. B. thunbergii ‘Atropurpurea'is the most cold-resistant one.