The Study On Identification Techniques Of Resistance To Fusarium Wilt In Cabbage Seedling Stage And Identification And Screening Of Germplasm Resources

Cabbage Fusarium wilt is one of the major serious diseases for the cabbage industry in China.It has become an urgent problem to be solved that accelerate the breeding of new varieties and germplasm innovation of cabbage resistance to Fusarium wilt,and identify the disease resistance of germplasm resources conveniently,quickly and accurately.In this study,the varieties with clear resistance background to cabbage Fusarium wilt were selected to further improved the identification technology of resistance to Fusarium wilt at seedling stage of cabbage on the basis of previous studies,at the same time,the relevant physiological indexes before and after inoculation at seedling stage were studied.The purpose of this study was to establish a set of accurate and practical methods and standards for identification of resistance to Fusarium wilt at seedling stage of cabbage,to provide technical support for the breeding of cabbage resistance to Fusarium wilt.The main findings were as follows:1.5×10~6 spores/mL bacterial suspension in five inoculation concentrations of 1×10~6,3×10~6,5×10~6,1×10~7,and 3×10~7 spores/mL in the seedling resistance identification technique of cabbage wilt For optimal inoculation concentration;Comparison of three methods of inoculation,bacterial liquid method,bacterial soil method and root soaking method,the inoculation with bacteria soil method can better reflect the degree of disease and the type of disease resistance of different disease-resistant varieties;Inoculation in the cotyledon stage,one-leaf one-heart stage,two-leaf one-heart stage,three-leaf one-heart stage,and the other two stages,especially the two-leaf one-heart stage is the best inoculation period;According to the degree of leaf vein yellowing of the seedling plants,the plant leaves retreat The main symptoms of green,wilt and even death,the cabbage susceptible plants were divided into six levels,and finally a complete set of methods and standards for identification of resistance to Fusarium wilt in cabbage seedlings were established.2.In the identification and screening of resistance to Fusarium wilt in cabbage germplasm,64 materials were identified by using the methods and standards established in this study.The results showed that 41 materials showed resistance to Fusarium wilt,including 12 high resistance materials.At the same time,the relationship between resistance performance and maturity of varieties was analyzed.It was found that the resistant materials were mainly mid-late maturity varieties and late maturity varieties,and the susceptible materials were mainly early maturity varieties.3.In the analysis of two physiological indexes of the resistant varieties of cabbage in the seedling stage,the chlorophyll content decreased by 0.67~17.14 mg/g·FW compared with the control resistant varieties,and the susceptible varieties decreased by 3.81~31.89mg/g·FW;The reduction range of resistant varieties was 0.01~0.12 mg/g·h·FW,and the variation of susceptible varieties was 0.12~0.43 mg/g·h·FW.It was concluded that Fusarium oxysporum had no significant effect on chlorophyll content and root activity of resistant varieties of cabbage,but significant reduction influence on susceptible varieties.