Identification And Evaluation Of Scab Resistance Of 23 Potato Cultivars

In this study,22 potato varieties in Jilin Province were used as experimental materials.Through the field natural disease test,the disease-resistant types,phenotypic traits and physiological and biochemical characteristics of potato varieties were investigated and determined,and the resistance of potato varieties was divided by routine identification method and cluster analysis.The indicators of potato resistance were screened by variance analysis,correlation analysis,principal component analysis and linear regression analysis.The main results are as follows:?1?The identification results of routine identification methods divided 22 potato materials into scab resistance into 4 categories,among which no high resistant varieties were found,the resistant varieties are two varieties,the Netherlands 806 and the Netherlands 18,the medium resistant varieties are 6 varieties including Chunshu No.4,Holland 15,Black King Kong,Holland 803,Red Beauty,and Jishu,the susceptible varieties include 8 varieties,which are Eugene,Yanshu No.4,Yanshu No.9,Holland No.7,Fujin,Xingjia No.2,Kexin No.13,and Jizhangshu No.12,The high-sensitivity include 6 varieties,which are Chunshu No.3,Yanshu No.6,Chunshu No.5,008,Red Holland and Zhonglianhong,among which no high resistant varieties were found.The results of cluster analysis showed that resistance of different varieties of sweet potatoes to scab was divided into 4 categories at 7.5 genetic distance.When the disease index?DI?was less than 40,the disease resistant varieties include 5 varieties,which are Holland No.806,Holland No.18,Spring potato no.4,Holland No.15 and Heijingang.When 40 < DI < 50,the resistant varieties were Holland No.803,red beauty and Jishu.When 50 DI < 80,the susceptible varieties were Youjin,Yanyushu 4,Yanyushu 9,Holland No.7,Fujin,Xingjia 2,Kexin 13,Jizhangshu 12 and Chunshu 3.When DI?80,the high-susceptible varieties were Yanshu 6,Chunshu 5,008,red Holland and Zhonglian red.High resistant varieties were not found,so the disease index range of high resistant varieties was unknown.?2?According to anova of different disease-resistant types in conventional identification methods,there were 31 indicators with significant differences,among which there were 27 expression trait indicators and 4 physiological and biochemical indicators.Phenotypic characters and physiological and biochemical indexes of plants,leaves,flowers and tubers were significantly different among different disease-resistant types,among which the phenotypic traits,stigma length was not significantly different among different disease-resistant types.Most of the disease-resistant types were erect plant shape,no branch number,few branches,partial colored stem,sickle shaped stipules,nearly pentagonal corolla,orange anther,bifid stigma,light green stigma and long tuber;Most of the highly sensitive types were in the form of semi-erect plant,large number of branches,narrow terminal lobule,intermediate torus,star corolla,yellow anther,green stigma,oblate and round shape of potato,round shape of potato,rough potato skin,milky white potato flesh,light yellow potato flesh.Mean POD activity,mean PPO content and mean SOD activity increased with the increase of resistance,while mean MDA content decreased with the increase of resistance.Through correlation analysis,it was found that the disease resistance was significantly positively correlated with the medium plant height,zero branch number,sickle-shaped torque-leaf,orange anther,milk white potato meat and PPO activity,and extremely significantly positively correlated with the erect plant shape.There was a significant negative correlation between the disease resistance and the number of branches,the middle shape of stipules and yellow anthers,and an extremely significant negative correlation between the disease resistance and the medium stem diameter and MDA content.Principal component analysis showed that scab was mainly manifested in the aspects of few branches,shape of developing plant,high plant,middle width of terminal lobule,sickle stigma,middle lobule,green stigma,few flowering,yellowish-green stigma,light yellow flesh of sweet potato,very heavy per plant,heavy per plant and MDA content.Equations between disease index and phenotypic traits were obtained by multiple linear stepwise regression studies,which was y disease index=-21.849 + 23.550 X_{branch number} + 21.901 X_{stigma color} + 4.014 X_{stem diameter}.