| Non-heading Chinese cabbage[Brassica campestris ssp. chinensis Makino]is the main vegetable in the middle-lower the Yangtze River and its south area, the problem of humidity from rainfall and protection in the spring and summer affect the production of non-heading Chinese cabbage seriously. Screening and identification of waterlogging tolerant genotypes to development WT cultivars has an important significance in the non-heading Chinese cabbage industry. From crop research, the more are in Gramineae, Solanaceae, Leguminosae and Asteraceae, has made some progress. But the research of waterlogging stress in non-heading Chinese cabbage is the initial stage still. Especially the identification is not yet involved in the non-heading Chinese cabbage and the continuous physiological reaction differences of different waterlogging tolerant genotype non-heading chinese cabbage has not been reported. Therefore, research on waterlogging tolerance identification and the mechanism in non-heading Chinese cabbage is the basis to carry out breeding of non-heading Chinese cabbage.We used8different non-heading Chinese cabbages genotypes as materials, studied the forms of reaction and common performance of non-heading Chinese cabbage under waterlogging respectively, and identified the best environmental conditions as waterlogging stress. The results in field identification are showed that the temperature have some relevance with the humidity, In the case of increased air humidity by spraying in small shed, non-heading Chinese cabbages growth normal if daytime temperature is below30℃, their leaves will chlorotic yellowing, resulting in soaked ulcers, prone to genetic diseases or bacterial rot disease in higher temperature. Soil moisture saturation similar to high air humidity, however, high temperature(above30℃) is easily hurt the roots of non-heading Chinese cabbage.Used8different non-heading Chinese cabbages genotypes as materials, when leaves of the seedlings were6, continuously treated with25℃/15℃(d/n),28℃/18℃(d/n),30℃/20℃(d/n),32℃/22℃(d/n) and35℃/25℃(d/n)5different temperature,and the saturated soil moisture, air humidity=95%for high humidity treatment at artificial climate chamber. finally determine30℃/20℃(day12h/night12h) treatment seedlings6d,as the non-heading Chinese cabbage identification of differences in moisture conditions, with size and degree of the chlorotic leaf as the grade of indicators on wet injury, and thus to investigate the wet injury index.4non-heading Chinese cabbages materials were continuously treated with saturated soil moisture, air humidity=95%,30℃/20℃(day12h/night12h) treatment for8days in the artificial climate box in order to be measured content of chlorophyll, soluble protein, soluble sugar, proline, relative electrical conductance, malondiadehyde, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT). The results after wet injury treatment indicated that the content of chlorophyll of all varieties decreased at a slow rate, but could not distinguish the WT among varieties. Soluble protein content of treatments kept a declining trend at0～4d, increased at4-8d, and less decreased in WT varieties. Soluble sugar was the maximum content of WT varieties before treated, and its content increased after wet injury treatment. The Pro content has also emerged as an increasing tendency, the waterlogging nontolerance varieties’increase was much higher than the WT. The relative electrical increased at first and then decreased overall performance, all varieties peaked at the first4d except the waterlogging nontolerance. Ai-Jiao-Huang have the most obvious changes in MDA content, other varieties were relatively slow growth. POD activity of the waterlogging nontolerance varieties showed a rising trend continued, but the WT varieties showed an upward trend in volatility. The CAT activity showed downward trend generally, but the relative changes in varieties was not significant. SOD activities were reduced in0～6d, but WT varieties significantly incressed than others. |
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