| Cucumber ( Cucumis Sativus L) originated from tropical area, so it is sensitive to chilling. Low temperature is one of the most important factors that stunt the growth and development of cucumber. In this experiment, by measuring the changes of indexes in physiological-- biochemical and agronomy straits under low temperatures the relationship of these changes to low--temperature tolerance in cucumber were studied. In the same time the adaptability to low temperature at stages of germination, seedling and maturity in different cucumber cultivars and the relationship between different stages were studied. The main results are as follow: ? The appropriate index of appraising the low temperature germination ability of cucumber seeds is germination index at I S0C. ? The adaptability to low temperature at seedling stage is related to the relative activity of SOD, CAT and POD. The activity of SOD, CAT and POD increase and MDA content decreases in cultivars, which can grow well under low temperature. Soluble sugar content decreases with the duration of low temperature prolong. In cultivars with good adaptability to low temperature, the soluble protein content decreases slowly, and the proline content increases. The changes of chlorophyll content show as?V æ‡etter and the electrolytic leakage increases, but neither of them has certain correlation to low-temperature tolerance ability of cucumber seedling. ? Leaf area and leaf area ratio (LAR) have significant correlation to low-temperature tolerance at seedling stage, so they are appropriate indexes on evaluating the adaptability to low temperature in cucumber. ? The adaptability to low temperature of cucumber at different developing stages is different and the alterations in different cultivars are not the same. So materials should be selected according to their concrete use. In the experiment, 602 behaved best and 9320 worst in low-- temperature germinating ability; 635 and 9320 have the best adaptability to low temperature at seedling stage; 9320 and Changchunmici are more adaptable to low temperature than any other cultivars during maturity period. Postgraduate: Wang Xinhua Major: Olericulture Supervisor: Prof. Qin Zhiwei... |
