Comprehensive Evaluation of High Temperature Physiological Response and Heat Tolerance of Different Cut Chrysanthemum Cultivars

In order to select the heat-resistant cultivars of spray-cut chrysanthemum and establish a comprehensive evaluation method for heat tolerance, the tolerance toward high temperature stress of 12 cut chrysanthemum cultivars were studied. The results revealed that as the stress temperature rose, the physiological and biochemical indexes showed corresponding changes, while the trend of changes varied significantly, indicating differences in heat tolerance among different varieties. Furthermore, four principal components were extracted by principal component analysis. Membership function analysis and cluster analysis categorized the 12 cultivars into four groups: a heat-sensitive group that included 'Kaisahong', a group with moderate heat resistance consisting of 'Jimucheng''Nuoxicheng''Duolunduo', a more heat-resistant group with 'Kundi''Ruibai''Zijingling''Yinyang''Lvjing-ling', and a heat-resistant group comprising 'Weinisi' and 'Kaisahuang', which were potential candidates for cultivation in high-temperature zones. And building on this classification, the stepwise regression method was used to set up a multiple regression equation that incorporates the content of malondialdehyde(MDA), the quantum yield for electron transfer(φ_Eo), and the mass fraction of solubel suqar(SS) as reliable indicators for assessing heat resistance.