The Physiological Response Of Different Chinese Cabbages In Seasonal Ecotype To Temperature Stress

This test used Chinese cabbage as materials, studied physiological and biochemical characteristics under field low temperature and the low temperature stress, characteristics of ball up in spring, and photosynthetic characteristics under high temperature and strong light. The material involved Chunda\vang,Qiangshi,XiazhenbaiNo.l,XiayouNo.3, LubaiNo.8, LiuzhenbaiNo.3, QiuzhenbaiNo. 16, JincaiNo.3. The results showed that:With field temperature decreasing, the soluble protein contents , soluble sugar contents and free proline contents in the leaves of Chinese cabbage increased obviously , but there was discrepancy among varieties, for instance, that of QiuzhenbaiNo.3 and LubaiNo.8 were lower than that of others under -10C. The activity of SOD, POD and CAT firstly increased then decreased, QiuzhenbaiNo. 16 and Chundawang have higher activities under the same condition. The MDA contents also increased firstly then decreased. The chlorophyll contents and the value of chlorophyll a/b decreased slowly, under -5癈,the value of chlorophyll a/b were wide discrepancy among varieties extremely, and QiuzhenbaiNo.3 was the lowest one. Osmotic potential in leaves firstly increased then decreased, under-10C.osmotic potential from high to low were QiuzhenbaiNo.3, lubaiNo.8,Qiangshi,QiuzhenbaiNo.!6, Chundawang. JincaiNo.3. The contents of total water decreased, but that of binding water increased, the contents of free water was nearly equal to that of binding water under -10℃.After the low temperature stress, the soluble protein contents, soluble sugar contents and free proline contents firstly increased then decreased, that of XiazhenbaiNo.l were lowest under the same condition. The MDA contents of XiazhenbaiNo.l also were lowest after the low temperature treatment, but the changes of JincaiNo.3 was the smallest one. The activities of SOD and CAT firstly increased then decreased, but the activity of POD firstly changed slowly then increased rapidly. The value of chlorophyll a/b firstly became big. then became small, lastly became big again, that of XiazhenbaiNo.l was the bigest one under the same condition.The photosynthetic characteristics of different Chinese cabbage in seasonal biotype were obviously different. The extreme value of Pn. Tr. and Gs of XiazhenbaiNo.l were higher than that of Qiangshi and LubaiNo.8 obviously, and photosynthetic midday rest was weak, the photosynthetic efficiency of PS II of LubaiNo.8 was lowest at twelve clock. Under the artificial low temperature, the photosynthetic rate of XiazhenbaiNo.l was highest, but that of LubaiNo.8 was lowest. The high conpensation point of Chinesecabbage was from 54C to 57C, and there were little difference between varieties, that of XiazhenbaiNo. 1 was a bit high than that of Qiangshi and LubaiNo.8.Under the low temperature in spring, ball up-ratio of XiazhenbaiNo. 1 and XiayouNo.3 were high and early, that of lubaiNo.8 and qiuzhenbaiNo.3 was low and late, but the central axis was long. Ball up rate of Qiangshi and Chundawang was zero, and the central axis was very short, thus have good commercial nature. After anti-freezing determine in field, anti-freezing ability of XiazhenbaiNo. 1 and XiayouNo.3 was weak, but that of JincaiNo.3 and QiuzhenbaiNo.16 was strong.