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Improving postharvest and cold storage related indices is one of the main purposes of melon breeding programs. With regards to the growing global market, it is important to introduce new melon types with prolonged storability. In this experiment, six melon inbred lines were used to establish a full diallel F₁ population. Harvested fruit was stored and the main postharvest indices were monitored during the storage period. The results showed that some indices were controlled by additive gene effects such as mesocarp firmness and Soluble Solids (SS). Mesocarp firmness analysis proposed that this index was controlled by additive and non-additive gene effects. General Combining Ability (GCA) analysis showed that “Khatouni” inbred line could be considered as a promising parent in breeding programs to produce melon hybrids with more appealing firmness, fewer cold storage losses, and a longer postharvest life.

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In this study, genetic diversity among watermelon accessions was studied by analyzing morphological and physiological traits using Random Amplified Polymorphic DNA (RAPD). Thirty-seven morphological and physiological traits showed significant variation among the accessions. Some watermelon accessions showed typical attributes of seed characters and fruit flesh and skin color. Principle component analysis allocated the high variance percentage for fruit and seed characters. Cluster analysis of morphological and physiological characters separated Citrullus colocynthis in one independent cluster clearly. The 18 RAPD markers represented 126 polymorphic bands of 154 total bands. Cluster analysis using RAPD markers at similarity 0.54 also clarified colocynth genotypes in one separated group. Three main clusters distinguished for other accessions that were classified mainly by fruit shape and flesh color, then, by fruit skin color. The most similarity (1) was observed among three accessions in the same cluster, contrary to the different collecting areas, which may indicate that accessions were distributed in different areas from the same genetic sources. The Genetic Similarity coefficients (GS) among evaluated accessions ranged from 0.45 to 1.00, indicating that they had relatively high genetic diversity. Altogether, the high variation, especially for phenotypic traits, of watermelon accessions in Iran could be considered as a good resource for selection and breeding program.

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Introducing new melon types able to endure cold storage and cold transportation is among the major goals of breeders. Therefore, providing a better understanding of the fruit physiological traits and postharvest associated genes expression can help to select the superior type for cold storage condition. This experiment was carried out to investigate the postharvest behavior of various melon lines and their F1 breeds based on fruit characteristics and their relation to the expression of CMe-ACS1, CM-ETR1 and CM-ETR2 genes during cold storage. For this purpose, six melon inbred lines were cross-pollinated to form a full diallel F1 population. Thus, the studied population constituted 6 parental lines, 15 direct hybrids, and 15 reciprocal F1 hybrids. After fruits harvest and during one month of storage, fruits firmness loss, color changes, and weight loss were evaluated. A significant positive correlation coefficient was found between CMe-ACS1 gene expression and ACC content with two distinct clusters based on this relation. Gene expression profiles referred to the presence of gradual and continuous senescence behaviors in the studied types, which was reflected in their physiological postharvest performance. G1 cluster types expressed the studied receptor genes at lower rates compared to the other groups. The G1 corresponded with P3 and P4 groups that were characterized by low physiological changes and thus better postharvest performance during cold storage. This result highlights the importance of Persian inodorus melons, generally, and the line ‘Khatouni’, specifically, in melon breeding programs for postharvest purposes.