الفهرس 
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Abstract
Genetic diversity among 19 snake melon genotypes collected from different regions of Egypt was examined in three studies. In the first (field study), results showed high significant differences among 19 accessions for most phenotypic traits, indicating the presence of considerable genetic diversity. Genotypic coefficients of variation were lower than that of phenotypic coefficients of variations. Heritability estimates was very high (>80%) for fruit diameter and fruit length, and low (<40%) for TSS. Genetic advance varied from 0.06 (seed width) to 971 (yield/plant). In the second study, ISSR markers were used to test genetic relations among 12 snake melon genotypes. The average polymorphism information content value was 0.68 over 6 primers. Jaccord,s similarity coefficient ranged from 0.88 to 0.98, indicating narrow diversity. Cluster analysis distinguished two clusters, one for accession from Cairo and the second represents the rest of accessions. It was shown that studied snake melon genotypes which were genetically close were not necessarily close in geographical distance. In the third study, genetic diversity was assessed based on the in vitro callus induction and shoot regeneration potential from cotyledon explants of 9 snake melon accessions. Results revealed significant differences among the tested genotypes, and those with high callus induction had also high regeneration capacity. These genotypes could have different genetic background, which might help in future breeding programs. In vitro regeneration technique will also aid in germplasm preservation for promising snake melon genotypes.
Keywords Cucumis melo var. flexuosus, genetic diversity, heritability, genetic advance, ISSR, polymorphism, callus, in vitro regeneration.