HETEROSIS AND COMBINING ABILITY IN MELON (CUCUMIS MELO L.)

Abstract

The purpose of this study was to estimate heterosis, general and specific combining ability in melon hybrids to identify the best combinations during the period from 2017 to 2019 at the Vegetable Research Farm, Horticultural Research Institute, Agricultural Research Center (ARC), Kaha and Dokki, Egypt. Six parents and their respective hybrids were evaluated in a randomized complete block design (RCBD) with three replications. The following traits were assessed of: main stem length, number of leaves, average fruit weight, fruit length, fruit diameter, flesh thickness, fruit cavity, fruit shape index, TSS and total yield/fed. The heterotic expression for total yield was the most important trait in this investigation. Potence ratio that measured the average of dominance confirmed the partial dominance for plant length and total yield but over-dominance appeared in the other characters. The range of both types of F1 heterosis for studied characters indicated that the expression of heterosis varied according to different crosses and characters investigated. The results showed significant and highly significant mean squares for both GCA and SCA in all studied traits except fruit shape index, indicating the important role of both additive and non-additive gene effects in the expression of these traits. However, a greater ratio of GCA/SCA than unity as detected for number of leaves, fruit diameter, fruit weight, TSS and total yield revealing that the inheritance of these traits mainly was controlled by additive gene action. The estimates of GCA effects in individual parental genotypes of the F'1s generation were significant and highly significant for the most studied traits. However, the crosses (P1×P3) and (P2×P4) achieved highly SCA effects for the most traits in this study, which means that GCA effects of the parents were reflected in the SCA effects in the crosses for the most studied traits.