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Abstract % Objectives] This study was conducted to investigate the differences in the physiological responses of diferent grape cultivars to high temperature. [Methods]The 19 tested cultivars were selected from the grape germplasm resources pool of Turpan Research Institute of Xinjiang Academy of Agricultural Sciences. Twelve physiological indexes including gas exchange parameters, chlorophyll content, antioxidant enzyme activity and proline content were determined in grape leaves under field conditions during the middle period of local natural high temperature period (July, daily maximum air temperature >35 S ). The heat tolerance of diferent cultivas was evaluated by fuzzy membership function analysis and optimum partitioning clustering of ordered samples. [ Results] $ Under natural high temperature conditions in Turpan, the 19 tested gape cultivars responded differently to high temperature.' Red Globe' ,' Fujiminori' ,' Beta' ,' Hetianhuang' had strong heat tolerance, while' Thompson Seedless' ,' Hongqi Tezaomeigui' ,' Shuijing Wuhe' ,' Victoria' ,' YatomiRosa' and' Crimson Seedless' had weak, heat tolerance. % Among the 12 physiological indexes, malondialdehyde content and antioxidant enzyme activity were mostly different among various grape cultivars. The grape cultivas with strong heat tolerance,' Red Globe' and' Fujiminori' , had relatively lower nmlondialdehyde contents, while' Beta' and' Hetianhuang' had relatively higher malondialdehyde contents. But they had higher activity of antioxidant enzymes. & The results of fuzzy membership function analysis showed that the cumulative membership value (AR) of each physiological index was consistent with its apparent heat tolerance performance, suggesting that AR can be a potential index for the evaluation of heat tolerance of grape cultivars. Further cluster analysis classified the tested cultivas as strong, medium and weak.' RedGlobe' ,' Fujiminori' ,' Beta' and' Hetianhuang' had strong heat tolerance. [ Conclusions] This study provides a reference for grape cultivation under high temperature and stress and breeding of heat-tolerant vaieties.
Key words Grape; Physiological index; High temperature response; Heat tolerance
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High temperature will cause grape leaves to curl, lose water and dry up, and reduce photosynthetic efficiency, which in turn affects the physiological and biochemical reactions and the expression and regulation of stress-induced genes, severely impairs the ability to regulate their own stress, and causes heat damage and even malaise death[1 4]. With the continuous increase of global average temperature[5] , the...