The Study On Selecting Sensitive Indicator And Effects Of Ca～(2+) To Chilling Tolerance Of Cucumber

As an environmental stress, low temperature is often suffered in the protected field at winter and spring. And the chilling sensitivity of cucumber, a major vegetable cultivated in protected condition, has become the main factor disturbing its normal growth. So how to improve the chilling tolerance of cucumber has been the research focus on special breeding for protected growth of cucumber.Calcium, one of the most important elements in plant nutrition, plays its role in regulating intracellular responses to plant development and environment stress. Recent research indicated that calcium can generate appropriate cellular physiological responses to enhance chilling tolerance on plant. Meanwhile, as the second messenger intracellular, it can also induce cold tolerance genes expression. In this paper, evaluating criterias of cucumber seedlings to chilling tolerance, effects of Ca²⁺ on chilling tolerance and PAs levels in cucumber were studied in order to understand the mechanisms of chilling tolerance deeply. The follows were researched:1. Study on selecting evaluating index of chilling tolerance in cucumber seedlingsTo select evaluating sensitive index of cold tolerance of cucumber, the biochemistry and physiological changes in cucumber seedlings were studied using two cucumber cultivars 'Changchun mici' and 'Beijing jietou' possessing different chilling tolerance, under the temperature (15℃day/7-8℃ night) which was often happened in the protected field at winter and spring.The results showed that electrolyte leakage, the content of Pro and soluble sugar increased significantly, but the chlorophyll content and three antioxidative enzymes (CAT, POD and SOD) activities decreased clearly. Through correlation analysis, electrolyte leakage, the content of Pro and soluble sugar, the activity of CAT were significantly correlated with sensitive index of chilling injury, while the chlorophyll content, the activity of POD and SOD were not significantly correlated with that of cucumber seedlings.2. Effects of Ca²⁺ on the activities of antioxidative enzymes and zymogram of peroxidase in cucumber seedling during chilling stressThe effects of Ca²⁺, calcium chelator EGTA and CaM antanogist CPZ on the activities of three antioxidative enzymes (CAT, POD and SOD) and zymogram of...