Effects Of Waterlogging Stress On Morphology And Physiological And Biochemical Characteristics Of Pak-Choi

Under different waterlogging stress, the morphology and physiological and biochemical characteristics were studied at3different growth stages in two pak-choi cultivars by using simulation experiment. The results showed that:1. The exterior characteristics of two cultivars in pak-choi (’xin xia qing’and’xin ai qing’) changed after different waterlogging stress. Effects on pak-choi were slightly in the prophase of the surface submergence; but the leaves that changed yellow appeared water spots, significantly the numbers of new leaves reduced and the heart leaf shrinkaged as the waterlogging stress intensifying; the plant growth ceased basically during the whole submergence.2. The shoot fresh weight, shoot dry weight and the leaf growth were suppressed after different waterlogging stress, the inhibitory effect of these exterior indicators were markedly decreased with the increase of depth and the prolongation of waterloggingg, and the every index of’xin xia qing’was affected more at every growth stage.3. The chlorophyll content of’xin xia qing’and’xin ai qing’ all decreased differently under the different degrees of waterlogging, and the declining degree of chlorophyll in two cultivars was higher significantly by days and depths. The declining range of chlorophyll content in’xin ai qing’was lower.4. The soluble sugar content of’xin xia qing’and’xin ai qing’changed differently at all the growth stages with depth and duration of waterlogging stress. Under the surface subemergence and semi-submergence, the soluble sugar content of pak-choi that in two-leaf and four-leaf ages increased with the waterlogging prolonging, but the content of pak-choi that in seven-leaf age which was higher compared with control increased firstly and then decreased. The soluble sugar content of pak-choi decreased differently at every stage of plant growth under whole-plant subemergence.5. The changes of proline content in pak-choi were complex after different waterlogging stress because of different cultivars and leaf ages, and the proline content of ’xin ai qing’ that had the higher ability of adapting to the waterlogging stress was more than ’xin xia qing’ relatively. The soluble protein content of pak-choi increased first and then dropped during the surface subemergence and semi-subemerged waterlogging, especially the thirth-day waterlogging was most sensitive; the protein content was fall off after the whole-plant subemergance with the prolongation.6. The MDA content of plant continued to rise with the depth increasing and stress prolonging, and ’xin xia qing’ increased more than ’xin ai qing’, so it was improved that the membrane lipid peroxidation of ’xin xia qing’ was heavier than that of’xin ai qing’. The activity of SOD in pak-choi leaves was high during mild waterlogging stress, but it dropped gradually deeper waterlogging,’xin ai qing’ which had higher SOD activity than ’xin xia qing’.7. Comprehensive analysis showed that,the effect of waterlogging depth is in order of whole-plant subemergence> semi-subemergence> surface subemergence of soil; the order of inhibitory effect on growth stages is two-leaf age> four-leaf age> seven-leavf age. Though the growth of two cultivars in pak-choi were affected differently,’xin ai qing’showed the higher ability of waterlogging resistance than ’xin xia qing’.