1 Academy of Agriculture and Forestry Sciences，Qinghai University，Key Laboratory of Vegetable Genetics and Physiology of Qinhai Province，Xining 810016，Qinghai，China；2 Laboratory for Research and Utilization of Qermplasm Resources in Qinghai-Tibet Plateau，Xining 810016，Qinghai，China
Abstract：To select tomato varieties and breeding material suitable for local cultivation and with high yield and superior quality，this paper conducted variation analysis，correlation analysis，principal component analysis and cluster analysis on agronomic characters of 50 tomato varieties．The results showed that the coefficients of variation of 23 agronomic traits in 50 of tomato materials ranged from 0%-103%，exhibiting relatively rich variation．Correlation with different degrees was existed between different traits．The single fruit weight was very significantly positively correlated with maturity，leaf length，leaf width，first node inflorescence，fruit transverse diameter，fruit longitudinal diameter，and yield per plant．There was significantly negative relationship between soluble solid content with maturity，first node inflorescence，single fruit quality，fruit transverse diameter，fruit longitudinal diameter，and yield per plant．The principal component analysis simplified the 23 agronomic traits into 6 principal components，respectively reflecting fruit development characteristics，fruit color before ripening，pollination and fertilization characteristics，fruit quality characters，fruit shape characters，inflorescence type characteristics and fruit color and quality characteristics．Furthermore，comprehensive evaluation was carried out using principal component score，and 10 excellent tomato varieties were screened out．Character specialties of these 10 excellent tomato varieties were analyzed through two-dimensional distribution map．Cluster analysis divided 50 materials into 6 groups．Among them，tomato varieties in group I performed well in yield and quality．Nine of the 10 varieties screened out through comprehensive evaluation were belonged to group I，indicating the comprehensive evaluation was basically consistent with the objective facts．
