| This study aimed to explore the differences on cold tolerance in the young trees of different peach germplasms, so as to provide a reference basis for the breeding of cold resistance varieties and the early identification of cold resistance.The annual seedlings of 21 peach germplasms were used as the materials after cold hardiness treatment with low-temperature. In order to compare and analyze the difference of cold tolerance among these materials, we calculated the lethal temperature (LT50) and recorded the survival rate of plants in the field, meanwhile, measured physiological indexes, and analyzed the relationship between the survival rate and cold resistance.Then, we used LT50 and subordinate function, respectively, to clarify the cold tolerance classification of twenty-one peach.Under cold stress, branches kept relatively high enzyme activity of phenylalanine ammonia-lyase (PAL), moreover, the high content of malondialdehyde (MDA), free proline (Pro) and soluble sugar (SS) was detected, and LT50 was relatively lower (range from -26.65 ℃ to -17.69 ℃). In the field experiment, the survival rate of the plants also decreased gradually with the decrease of temperature. Correlation analysis showed that the survival rate was significantly positively with comprehensive evaluation value (D), Pro, PAL and SS, and significantly negatively correlated with the LT50 and MDA. There were significant differences in cold resistance of peach trees during the young period. After low temperature treatment, the enzyme activity of PAL, content of MDA, Pro and SS were closely related to cold resistance, and could be used as the main indexes for cold resistance identification of peach germplasm young trees. |