Studies On Cold-resistance Indices Appraisal And Selecting At The Seedling Stage On Brassica Oleracea L. Varieties

Brassica oleracea L.originated from Mediterranean to the North Sea coast.It is adapt to a wide range of temperature,but grows in warm and cool climate.It is usually subjected to cold injury that is the main obstacle of cabbage production,so the varieties resistant to cold are badly need,breeding varieties of cold resistance have to provide materials with cold resistance,while screening breeding materials for cold resistance needs cold resistance indices correspondly.Change of biochemical,physiological indices and Correlation among these indices on four cabbage varieties which have differences in cold resistance were studied while cabbage seedlings treated under -1℃C and 6 hours and to make histocytological observation on cabbage seedling's leaf of four cabbage varieties after the treatment. Two simple,fast and useful indices had been screened to indicate cabbage cold resistance.The main results of experiment were as follows;1.The difference was extremely significant on Electric conductivity percentage between strong cold-resistance varieties and weak cold-resistance varieties after low temperature treatment,it could be one of the indices to appraise coldresistance of cabbage at the seedling stage.2.The difference was significant on soluble sugar content in cabbage seedling's leaves between strong cold-resistance varieties and weak cold-resistance varieties after low temperature treatment.so soluble sugar content of cabbage seedling's leaves after low temperature treatment could appraise the cold resistance of different cabbage varieties.3.The difference was extremely significant on the content of proline of cabbage seedling's leaves between strong cold-resistance varieties and weak cold-resistance varieties after low temperature treatment.Therefore,the content of proline of cabbage seedling's leaves after low temperature treatment could act as appraisal index of cold-resistance of cabbage.4.The difference was not significant on the SOD,POD activity and the MDA content of cabbage seedling's leaves between strong cold-resistance varieties and weak cold-resistance varieties after low temperature treatment,but the change of them had significant difference,so the SOD,POD activity and the MDA content act as reference indices of cold-resistance of cabbage.5.Electric conductivity percentage,the content of proline had respectively better correlation with other indices;the SOD,POD activity and the MDA content had worse correlation with others.6.Through Comparative analysis,because the methods of Electric conductivity percentage,the content of proline were simple and easy to operate,less necessary equipment,so they were suitable for a large number of germplasm resources' appraisal and selecting.Comparatively speaking,soluble sugar content,the SOD,POD activity and the MDA content also could react cold-resistance of cabbage from different ways,but they were complex and hard to operate,so they were not suitable for a large number of germplasm resources' appraisal and selecting.