Genetic diversity analysis of agronomic traits and elite accession selection in 263 cucumber germplasm resources

【Objective】To analyze the genetic diversity of 236 cucumber germplasm resources and select elite accessions and to provide suitable parent materials for new varieties and reference for exploiting elite genes and utilizing, protecting the germplasm resource.【Method】A total of 236 cucumber germplasm resources from Yunnan, other provinces of China and other countries were used in this experiment, 12 traits including 2 qualitative traits and 10 quantitative traits were analyzed.The genetic diversity and comprehensive evaluation were carried out by using genetic variation analysis, correlation analysis, principal component analysis and cluster analysis, and elite germplasm resources were selected.【Result】The variation coefficient of female flower node rate was the maximum(145.46%) and leaf shape index variation coefficient was the minimum(4.68%), the variation coefficient of quantitative traits was higher than that of qualitative traits.The average genetic diversity index was 1.633, the genetic diversity index of cotyledon width was the highest(2.092) and leaf color genetic diversity index was the lowest(0.389).Correlation analysis showed the female flower node rate was significantly positively correlated to leaf color(P< 0.05, the same below), while it was extremely significantly positively correlated with cotyledon length, cotyledon width, fruiting habits, leaf length and leaf shape index(P< 0.01, the same below), it was extremely significantly negatively correlated with the first female flower node, male flower node rate, internode length and main stem length.The first female flower node was extremely significantly positively correlated with male flower node rate and fruiting habits, but it was significantly negatively correlated with leaf color index, and extremely significantly negatively correlated with female flower node rate and cotyledon width.Principal component analysis of agronomic traits showed that cumulative contribution rate of the first five principal components was 80.823%, including the first principal component female flower node rate, the second principal component leaf length, the third principal component the first female flower node, the fourth principal component cotyledon length and the fifth principal component leaf color.The 236 cucumber accessions were classified into eight groups.Group Ⅵand Ⅶcould be used as male parent in hybrid breeding since they had strong growth vigor and high male flower rate.Group Ⅷcould be used as female parent since they had high female flower rate and high seed setting rate.【Conclusion】The 236 cucumber germplasm resources have high genetic diversity, genetic variation of major agronomic traits is abundant.In cucumber breeding, cucumber yield can be increased through selection of leaf size, leaf color, the first female flower node, fruiting habit, female flower node rate.Early maturity and high yield of cucumber depend not only on the appearance of the first female flower node, but also the male flower rate and the fruiting habits.