investigation of genetic diversity and broad sense heritability in watermelon accessions of sistan

to conserve the genetic resources and identify the strong and weak points in sistan watermelon accessions and compare these with improved cultivars of: sugarbaby and fairfax, an experiment was carried out, based on rectangular lattic design of two replications in 2007. the morphological traits studied, included plant length, plant weight, seed weight, fruit number, fruit length, fruit width, sugar percentage and yield. phenotypic, genetic and environmental variations, broad sense heritability, ratios of genetic variation and environmental variation, coefficient of phenotypic correlation, stepwise regression, cluster analysis and principle component analysis, using excell and sas version 9.1 were carried out. results showed that fruit length, fruit width, suger percentage and yield of cultivars and of accessions had exhibited different significances at 5% level. in all traits, coefficient of phenotypic variation was greater than coefficient of environmental variation, indicating the effect of environment on investigated traits. ratio of genetic variation to environmental variation was low in all the traits, except for seed weight. phenotypic correlation of traits, indicated positive and significant correlations between yield and fruit weight, fruit length and fruit width. cluster analysis separated the accessions into two clusters. results of principle component analysis for traits, indicated that the first two pcs explained 36 and 19 percent of total variations, and the first five pcs explained 78% of total variations. in pc1 fruit width (54%), yield (53%), fruit weight and fruit length, and in pc2 fruit number (52%), seed weight and suger percentage contributed the widest in explaining the genetic variations.