| In the north, cucumbers(Cucumis sativus L.) based mostly in protected cultivation, lack of light in winter and early spring days seriously affect the growth of cucumber. This test select different ecological types of cucumber, first by different light intensity, variation of cucumber plant growth indexes under different illumination time to deal with, to determine the optimum process conditions are suitable for low-light low light tolerance cucumber germplasm screening, followed by the seedling, light stress at its adult stage, through the analysis of its growth, physiological changes in photosynthetic indexes to explore the different growth stages of cucumber low light tolerance correlation Looking for screening low light tolerance cucumber species identification of quality indicators and methods of resources and use of this conclusion low light tolerance cucumber germplasm screening. Considering germplasm screening results and practical value, select the low light tolerance inbred inbred lines W25 and W31 to build low-light intolerance population were QTL analysis.The results of this study showed that:(1) Cucumber seedling resistance to low light ability is very strong, to endure the whole dark physiological limit of 8-10 days, higher than 20 mol·m-2s-1 light intensity for a short period limited impact on theof cucumber leaves, 20 mol·m-2s-1selective pressure for the best low light. 20 d when the differences were much, the best treatment time..(2) Cucumber for the various stages of Poor Light Stress different seedling.sub started low light treatment, mainly for hypocotyl elongation, leggy plants, significantly lower than the shoot. Leaf as one that after light stress at mainly as hypocotyls thinning, plant dry weight decreased significantly. Two-leaf seedlings start process does not show leggy, and began to deal with the late "flower topping" and early fruiting phenomenon. After three periods change after the Leaves Light Stress is very obvious, after the beginning of the cotyledons 3d chlorotic yellowing. 6d after leaf yellowing begins around to the middle, with the increase in low-light time, water loss wilting leaf yellowing, plant death.(3) The use of low-light treatment resulted in cucumber leaf yellowing chlorotic leaves this important feature, after the weak light stress, cucumber grading the degree of chlorotic leaves, chlorotic index calculation, the establishment of chlorosis index-based low light tolerance cucumber grading standards, and established by stepwise regression analysis chlorosis index and dry weight of the optimal regression equation Y = 0.663-0.679X6(r2=0.957, p=0.001). Seedling leaves chlorotic index can be used as indicators to identify low light tolerance evaluation of Cucumber, plant dry weight can be identified as a secondary indicator.(4) Low light tolerance cucumber seedling and adult plant resistance to low light there is a correlation, that is, the fruit yield of cucumber seedling and adult stage of chlorosis index reached a significant negative correlation. Consistent varieties in seedling and adult stage exhibited low light tolerance.(5) In chlorosis index as an indicator of the tested 36 varieties of cucumber low light tolerance identification. A total of 4 parts screened varieties resistant to low light, low light varieties resistant to 27 parts medium, 5 parts of low-light-sensitive varieties.(6) Two parents and F2 allele pool built nearly 220 pairs of SSR primers were screened to obtain 16 pairs of low light tolerance associated primers. After 197 plant verification F2 population to obtain two low light tolerance cucumber related SSR linkage group and found eight with low light tolerance cucumber linked QTL loci. CI1, CI2, CI3, CI4 CI5, CI-6, CI-7, CI-8 from the nearest marker map distance respectively 9cm, 20.09 cm, 10.02 cm, 8.98 cm, 17.35 cm, 7.02 cm, 8cm, 13.42 cm. |
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