Evaluation of combining ability in Cucurbita pepo L. and Cucurbita moschata Duchesne accessions for fruit and seed quantitative traits

A complete diallel cross study of seven Iranian accessions of Cucurbita, including five C. pepo (four naked seed and one true seed type) and two C. moschata accessions, was carried out during two planting seasons at University of Tehran, Karaj, Iran. Investigated traits were fruit number, fruit yield, seed yield, fruit weight, seed weight, ratio of fruit weight/seed weight, 100 seeds weight and seed number. ANOVA for all of the characteristics except fruit number indicated significant differences among the genotypes. Analysis of variance of the diallel data set also revealed high and significant effects of general (GCA) and specific combining ability (SCA) between genotypes in respect of fruit yield, seed yield, seed weight, ratio of fruit weight/seed weight and seed number. The GCA of fruit weight and seed weight and the SCA of 100 seeds weight were significant. The reciprocal effects were significant for all the measured traits. Heritability in broad (h2 b) and narrow (h2 n) estimates were generally high for fruit yield, seed yield, seed weight, fruit weight/seed weight and seed number, while they were low for fruit weight and 100 seeds weight. Favourable heterosis over the best parent was found for fruit yield, fruit weight and 100 seeds weight