| Temperature is an important factor for plant of geographical distribution 、 growth and development of the environment. In the long-term natural evolution, plants have their temperature range witch suit plant grow and develop. Once beyond it, their normal growth and development will be inhibited. Chilling caused which normal physiological functions of plants are destroyed, and even leaded to death. Cucumbers are thermophilic crops and sensitive to temperature. Less than 10~12 ℃temperature, cucumber physical activity is disordered, and grow slowly or are stopped growing. Below 5 ℃, cucumber is difficult to survive. So the 10 ℃be defined as the "minimum temperature cucumber economy". Low temperature is the main factor that limits cucumber growth, high yield, high quality. But in the early spring cucumber cultivation and often low temperature damage in the process of cultivation of autumn and winter season protected area. Chilling has become one of the main factors restricting annual production of cucumber. Therefore, this article evaluates low-temperature resistance of cucumber germplasm. This article studied the inheritance of resistance to low temperature and molecular markers about low temperature. As well as it will provide a theoretical basis and method for screening chilling tolerance cucumber germplasm and breeding new varieties. The test evaluated budding and seedling of cucumber in chilling tolerance. Day temperature 12 ℃、night temperature 9℃、light intensity(3000 Lx)、humidity 70% is identified to evaluate chilling tolerance of cucumber temperature. And 43 cucumber germplasm is divided into chilling tolerance varieties, medium chilling tolerance varieties and chilling sensitive varieties.Then four chilling tolerance and three chilling sensitive cucumber breeds were chose to be the cross parents. The D0420-4×D0631-1 constructed the six-generation conjoined genetic analytic group in order to find the inheritance of the chilling tolerance trait in the cucumber, which is the greast chilling tolerance and greast chilling sensitive. For parents, crosses F2 segregating population were identified analyze inheritance of resistance. 200 and five pairs of SSR primers were screened through the genome of both parent plants. Near the near-isogonics pool of 244 F2 segregating population constructed parental exhibit polymorphism 39 pairs of SSR primers were screened complex. Finally, we got 12 pairs of SSR primers that the cucumber tightly linked to low temperature tolerance. It resulted that there were 1 genetic linkage groups linking with the chilling tolerance trait of the cucumber tightly. Six QTLs were found in the group.The main results were as follow:(1) The test material are significant differences germination index and germination rate at 12 ℃. So 12 ℃ is temperature selection.(2)Seedling and germination period of low temperature tolerance have no significant correlation.(3)With Chilling injury index as the screening index, evaluate the low temperature resistance of 43 cucumber germplasm.Eventually 7 varieties of strong chilling tolerance and 26 varieties of middle chilling tolerance and 10 varieties of low-sensitive were identified.(4)Chilling tolerance is mainly controlled by the additive effect of early generation selection of effective conventional crossbreeding. Narrow sense heritability, broad-sense heritability was high, can be an excellent parent matching, through genetic breeding ways to improve plant resistance to low temperature, and then bred varieties.(5)In this study, 250 pairs of SSR primers were screened through the genome of both parent plants and the near-isogonics pool of F2 generation, and then were authenticated by 244 cucumber individuals of F2 generation. It resulted that there were1 genetic linkage groups correlating with the chilling tolerance trait of the cucumber. Then 6 Atlas were found in the 1 group. |
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