| Non-heading Chinese cabbage,an original Chinese vegetable belonging to the family of crucifer brassica species,is one of the extensively cultivated vegetables in the middle and lower reaches of Yangtze River region.In recent years,high temperature weather in summer are frequent in our country.The supply of non-heading Chinese cabbage is tension and the quality become poor.The existing heat-resistant non-heading Chinese cabbage has been unable to fully meet the needs of the people.Identification of new cultivars of heat-resistant non-heading Chinese cabbage were in urgent need.Two cultivation methods by open field cultivation and insect net cultivation,completely randomized block design to detect the yield,heat injury index,disease index,agronomic traits,nutritional quality and enzyme activity of ten new varieties under high temperature.Correlational analyses has been conducted in its heat damage index,disease index,agronomic traits,enzyme activity and nutritional quality.The results provided experimental data and theoretical basis for the identification of non-heading Chinese cabbage varieties in heat-resistance in Jiangsu province.Meanwhile,this study induced heat-resistance non-heading Chinese cabbage varieties’ Ai Zhuang qiu guan ’using colchicine,screening new varieties of autotetraploid non-heading Chinese cabbage.The main results are as follows:1.In insect cultivation,the yields of 1503,1504,1505,1506,1509 are 43.02%,44.19%,38.69%,47.67%,75.00%higher than the control extremely significant.The yields of 1501,1508,1510 were different from the control significantly,while the other two species were not significantly different from the control.In the open field cultivation experiment,the yields of 1503,1504,1505,1506,1509 are 84.36%,67.64%,34.55%,31.64%,52.49%which extremely higher than the control group.The difference was significant at the yield between 1501,1508,1510 and the control group,while the other 2 species make.little sense from the control.The results showed that the effects of the two cultivation methods on the yield performance of the tested varieties were consistent.2.1n insect cultivation experiment,the species of three top plant weight were 1503,1504,1509 that were respectively 69.14%,69.59%,and 68.80%higher than the control significantly.The species of three top height were 1501,1504 and 1509 that were respectively 12.90%,17.05%,44.26%higher than the control significantly.The species of two top leaf weight/petiole weight were 1509 and 1510.3.Both in two cultivation methods,heat injury index of 1503,1504,1509 were significantly lower than the control varieties,anthrax index of 1501,1503,1504,1506,1508 were significantly lower than the control varieties,viral disease index of 1503,1504,1506 and 1509 were significantly lower than the control varieties.4.Through analyzing the correlation test of yield and disease resistance,enzyme activity,main agronomic characters of different non-heading Chinese cabbage varieties,we found that under the environment of high temperature,the yield of the tested varieties was significantly related to the POD activity(r=0.886**),CAT activity(r=0.874**)and weight per plant(0.742**)at the 0.01 level.And the yield was significantly negatively related to the ratio of leaf weight and petiole weight(r=-0.809**),anthrax disease index(r=-0.837**),virus disease index(r=-0.797**),heat damage index(r=-0.733**)at 0.01 level.5.A comprehensive evaluation of the ten varieties was conducted from the aspects of agronomic traits,commodity quality,nutritional quality,heat resistance,disease resistance and flavor quality.The results showed that the green-petiole non-heading Chinese cabbage of the top three comprehensive performance was ’Kao Qing’,’Qing Fu Ling’ and ’Lv Ling 35’,while ’Re Huo No.1’have a better performance in white-petiole non-heading.6.In this study,the shoot apical point of non-heading Chinese cabbage ’Ai Zhuang qiu guan’ was treated with 0.2%colchicine to induce the variation of plant.The results showed that four time treament with 0.2%colchicine have the best effect,the induction rate was 8.33%.Compared with diploid plants,length and width of tetraploid stomata increased by 42.9%and 27.6%,length and width of pollen grain increased by 35.4%×31.8%,tetraploid bud,petal were increased by 42.9%x22.4%,21.79%×63.2%respectively,length of tetraploid pod increased by 30%,average seeds number of single pod decreased by 54.6%,seed diameter increased by 47.28%,1000 seeds weight increased by 33.1%.The results of flow cytometry showed that the relative content of DNA in the diploid "Ai zhuang qiu guan" was peaked at 200,while tetraploid was at 400.The number of diploid root tip chromosome was 2n=2x=20,and the number of tetraploid root tip chromosome was 2n=4x=40. |
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