Assessment of Genetic Diversitiy among Some Iranian Summer Squash Accessions Using Morphological Traits

In this research, 26 accesions of Cucurbita pepo sub pepo, were collected from differen Provinces of Iran in 2010 and their morphological diversity was assessed by UPOV cucurbita discriptor. Experimental plots were seeded on 3 June 2010, using a randomized complete-block design with three replications. Thirty nine traits (20 quantitative and 19 qualitative) were measured on all plants. Correlation analysis was performed to determine relationships between traits. Cluster and principle component analysis (PCA) were performed among populations using quantitative, qualitative and combination of quantitative-qualitative traits, separately and were compared with each other. Results indicated importance of qualitative traits is more than quantitative traits in both analyses. The first four principal component axes accounted for 66.75% of the total variation among the populations. The greater part of variance was accounted by flesh thickness, fruit shape, fruit diameter, fruit profile at blossom end, fruit profile at stem end, position of broadest part on fruit. Cluster analysis by UPGMA method using Gower genetic distance grouped 26 accessions into three groups.