Abstract:
In order to explore the heat resistance ability and establish evaluation system of heat resistance among different Chinese cabbage cultivars, 20 varieties were used as experimental materials in this study, by setting two processes, normal(control) and 37 ℃ high temperature, and the 15 indicators of different genotypes at seedling stage were measured, and taking the heat resistance coefficient(γ) of each individual indicator as the basis for measuring heat resistance, different Chinese cabbage varieties of heat tolerance were evaluated by multivariate analysis. The results showed that the effects of high temperature stress on each index were different, and there were information overlap and crossover among evaluation indexes. Principal component analysis revealed that 15 individual indicators were converted into 5 independent comprehensive components. Based on the membership function method comprehensive obtained the comprehensive heat resistance D value of each variety. 20 Chinese cabbage cultivars were classified into 3 types by cluster analysis. On this basis, the heat resistance evaluation equation of fast growing Chinese cabbage was established by stepwise regression method. B16, B18, B10, B13, B3 and B20 were the fast growing Chinese cabbage varieties with high heat resistance at seedling stage, which could be used as materials for research on cultivar breeding, mechanism, and regulation and alleviation mechanism of heat resistance in Chinese cabbage. The malondialdehyde content, superoxide dismutase activity, soluble sugar content, dry weight, proline content, root activity, hydrogen peroxide content and catalase activity could be used as the simple and intuitive identification indices of heat resistance in Chinese cabbage resources at seedling stage.