The phenotypic diversity and fruit characterization of winter squash (Cucurbita maxima) populations from the Black Sea Region of Turkey

Winter squash are one of the most important Cucurbit crops in Turkey. Winter squash populations show great diversity in morphological characteristics, particularly fruit length, fruit diameter, fruit shape, fruit brightness, skin thickness, flesh thickness and colour in the Black Sea region of Turkey. In this research, 115 populations of winter squash, Cucurbita maxima Duch, were collected from different provinces of the Black Sea region in 2006 and 2007 and phenotypic diversity in their fruit characters was assessed. The collection showed appreciable phenotypic variation in fruit shape, fruit colour, fruit brightness, fruit dimension and fruit weight. Cluster and principal component analysis (PCA) were performed to determine relationships among populations and to obtain information on the usefulness of those fruit characters for the definition of groups. Cluster analysis based on 14 quantitative and 7 qualitative variables identified 10 different groups. The first five principal component axes accounted for 65.0% of the total multivariate variation among the populations. The greater part of variance was accounted for by fruit weight, fruit diameter, fruit length, length of seed cavity and flesh thickness. This evaluation of fruit trait variability can assist geneticists and breeders to identify populations with desirable characteristics for inclusion in variety breeding programs.