Abstract:

【Objective】 Low temperature is one of the most important factors affecting the growth of chrysanthemum. To evaluate the cold tolerance of chrysanthemum, physiological and anatomical characteristics in chrysanthemum were studied under low temperature, the relationship between different indexes of cold tolerance were revealed, and mathematical evaluation model on cold tolerance was established too, which will provide a basis for cold tolerant germplasm discovery, breeding of new cold-tolerant varieties and evaluation on cold tolerant of a large number of chrysanthemum varieties. 【Method】 Physiological parameters such as SOD activity, CAT activity, content of MDA, soluble sugar and soluble protein and anatomical structure of leaves of rhizomes were studied in six chrysanthemum cultivars. Several indexes closely related to cold tolerance were screened out via correlation test. The validity of those screened indexes were further verified by main component analysis, regression analysis, hierarchical cluster analysis and path analysis. 【Result】 Analysis of related indexes with cold tolerance showed that significant negative correlations (P＜0.01) were presented and changing rate of SOD activity at -14℃ to -17℃ , soluble sugar content (SS1) at -11℃ to -14℃, thickness of palisade tissue (L2), thickness of upper epidermis cells (L4), and ratio of palisade tissue against spongy tissue (L6), compactness of palisade tissue (L7) were observed, while a significant positive correlation (P＜0.01) between LT50 and looseness of palisade tissue (L8) was found. 【Conclusion】 Four indexes closely related to the cold tolerance were screened. Mathematical evaluation model for chrysanthemum cold tolerance, i.e., Y=16.370-0.029SS1-0.075L7-0.314L8-12.250L6 (R2=1.000), was established too, and the predicting accuracy of the model is higher than 94%.

Key words: chrysanthemum, cold tolerance, physiological characteristics, anatomical structure, evaluation