Comprehensive Evaluationand Physiological Reaction Of Ground-cover Chrysanthemum(Chrysanthemum×morifolium) Under Heat And Humidity Stress

Ground-cover chrysanthemum plays an important part in landscaping for its multiple stress resistance, such as drought-tolerant, cold resistance. However, its ability of heat and humidity resistance is weak. This article studies on comprehensive evaluation of heat and humidity tolerance in Crossostephium chinense, Chrysanthemum nanjingense, Chrysanthemum lavandulifolium var.seticuspe and Chrysanthemum×morifolium ’Jingqi’, C.’Pudifendai’, C.’Chongbanzaohuang’, C.’Mibaizao’, C.’Xiangfei’, C.’Meiaifen’, C.’Jinguangwanzhang’, C.’Fanbailu’, C.’Wanfen’ at seedling stage and its physiology of the heat and humidity resistance, in order to filter out the planting resources with strong resistance to heat and humidity. The results can lay the foundation for ground-cover chrysanthemum breeding in heat and humidity resistance.The main findings are as follows:(1) According to the study,’Jingqi’, Crossostephium chinense,’Pudifendai’, Chrysanthemum nanjingense have strong tolerance to heat and humidity;’Chongbanzaohuang’,’Mibaizao’,’Xiangfei’;’Meiaifen’ Chrysanthemum lavandulifolium var.seticuspe have middle tolerance to heat and humidity;’Jinguangwanzhang’,’Fanbailu’,’Wanfen’have weak tolerance to heat and humidity.(2) Determination of9physiological and biochemical indicators of the ’Jingqi’,’Wangfen’, Chrysanthemum lavandulifolium var. seticuspe showed us that:The wilting index, SOD activity, proline, soluble sugar, soluble protein, content of Chlorophyll and POD activity are positively correlated with heat and humidity resistance. Relative permeability of cell membrane and MDA are negatively correlated with heat and humidity resistance. Correlation analysis showed that:The wilting index, relative permeability of cell membrane, proline, MDA and soluble sugar were highly significant correlation; Chlorophyll content, soluble protein, SOD activity and POD activity were significantly correlated.(3) Through the principal component analysis and the membership function analysis, all the indicators showed that:Between the9indicators, the wilting index and relative permeability of cell membrane had larger impact on comprehensive evaluation value. Through regression analysis, heat and humidity resistance evaluation system was established based on wilting index (X6) and relative permeability of cell membrane (Xs). The evaluation model formula is VP=11.821-0.010X6-0.094X8.