Physiological Response Of Different Cultivars Of Under Low Temperature Stress In Brassica Campestris L.ssp. Chinese(L.) Makino Var Rosularis Tsen Et Lee

Brassica campestris L.ssp.Chinese var.rosularis Tsen,Wutacai,Takecai,Heicai,etc.,it is crucifera canola not knot ball a variety of cabbage.The biological characteristics of cabbage is similar,it is a typical biennial herb,but tolerance more cold than cabbage,with dark green or yellow-green leaves of the main products of the biennial herbaceous plants,leaves and stems can be eaten.Wucai like low temperature environment,through previous studies we can see thatthe optimum temperature of seed germination is 20~25℃,the optimum growth temperature of 15~20℃.The current market demand more and more wucai,but the studies of the wucai’s open cultivation is less,so expanse the problem of introduce it to the lower temperature in winter areas,solow yield of thewucai in the northern region.In this study,ten different varieties of wucai were used as materials.The seedlings were stressed for 5 days under low temperature,a group of day / night temperature of 20 ℃ / 13 ℃ as the control,the other four groups moved to a temperature of 10 ℃ / 5 ℃ in the light incubator for 1、3、5 day,three of them moved to 6 ℃ / 0 ℃,2 ℃ /-5 ℃,0 ℃ /-10 ℃ artificial climate chamber for low temperature treatment,to maintain 1 day.The contents of electroconductibility,MDA,SODactivity,PODactivity,CATactivity,free proline,sugar content,chlorophyll content and carotenoid contentwere determined by mixed sampling method.During the low temperature stress,thechanges of physiological indexes of cold-resistant wucaiwhile were evaluated by correlation analysis and cluster analysis.Under the ratio ofthe measuredlow temperature and normal temperaturevalues was used as the evaluation index of cold tolerance.The single factor analysis of variance(ANOVA)was used to study the cold tolerance of each test material,and the efficiency of identification and screening of cold tolerance was improved.It was intuitionistic and simple and efficient.Breeding,introduction and cultivationof adversity provide a theoretical basis.The main results of this study are as follows: 1?Physiological and biochemical changes of ten varieties of wucai’s seedling stage at low temperaturesWith the reducing oftheprocessingtemperatureindexofthecontentof solubles ugar,freeprolinecontent,chlorophyll content and carotenoid contentwerenottheexte ntofchange.The changes of electrical conductivity and MDA content in different cul tivars were different with the increase of stress time.1407 had significant changesin MDA content,soluble sugar content,free proline content,chlorophyll content and SOD,POD and CAT activities.During low temperaturetreatment,no significantcorrelationwasfoundbetweenchlorophyll pigment content and carotenoid pigment contentwit h chillingtoleranceofsavoyvariousciiltivars.2、Correlation between physiological and biochemical indexes of ten varieties of wucai’s Seedling Stage under low temperatureConductivity and MDA showed a significant correlation,the correlation coefficient of 0.512,indicating that conductivity and MDA is the most able to reflect the extent of membrane damage.CAT enzymes were correlated with POD,and the correlation coefficients were 0.378.The results showed that under the low temperature stress,the activity of CAT was increased and the activities of POD was increased to protect the cells from frost resistance.Chlorophyll and conductivity,carotenoids were negatively correlated,the correlation coefficients were-0.58,-0.55;all cauliflower varieties of carotenoid content and conductivity were positively correlated with the correlation coefficient of 0.56.The correlation between the other indicators is not significant.3、The difference of physiological and biochemical indexes between 10 varieties of black vegetables at low temperatureLowtemperature treatment seedlings,thedetermination of physiologicaland biochemical indexes of different varieties.The analysis shows that physiological index of smaller amplitude isnumbered 1403,1427,1428,1430 are the variety of wucai;Followed by 1419,1424,1418 are the variety of wucai;The biggest change is the number 1423,1401,1407 are the variety of wucai.