HETEROSIS AND COMBINING ABILITY FOR SOME FRUIT QUALITY TRAITS OF EGYPTIAN MELON INBRED LINES USING LINE × TESTER ANALYSIS

Abstract

This study was carried out during the period from 2016 to 2018 summer seasons in the open field at Kaha Vegetable Research Farm (KVRF), Kalubia, Egypt. Thirty local inbred lines of melon ( Cucumis melo var. ananas ) were evaluated in this investigation during 2016 and 2017 summer seasons in the open field to determine their mean performance. Based on the former evaluation, 12 inbred lines (RIL A2, RIL A3, RIL A7, RIL A8, RIL A14, RIL A18, RIL A19, RIL A22, RIL A23, RIL A26, RIL A29, RIL A30) and 3 testers (RIL A5, RIL A10 and RIL A20) were selected to determine their genetic performance using line × tester mating design during 2018 summer season. Thirty six crosses in one direction were conducted in the plastic house of Kaha Vegetable Research Farm, Kalubia through the 2017 late summer season. The 36 hybrids were evaluated along with their parents to determine heterosis, combining ability and heritability of leaf area index (LAI), yield components, average fruit weight, netting percentage, fruit shape index (FSI), seed cavity diameter, flesh thickness and total soluble solids (TSS). The genotype results showed highly significant mean squares for most of the studied traits. Inbred lines (female parents), Testers (male parents) and Line x Tester interaction showed highly significant differences of almost whole traits. Some crosses revealed highly significant and significant mid-parent and better-parent heterosis for many of the traits. The inbred line RIL A5 (T5) showed higher positive general combining ability (GCA) impact for all traits except early yield and FSI, which could be used as parent in breeding programs and the potential parent (good combiner) that in selection program would be effective for its efficient use in subsequent crossing programs for more LAI, total yield, marketable yield percentage, average fruit weight, netting percentage, flesh thickness, TSS and less seed cavity diameter. Nine, eight, twelve and seven hybrids revealed highly significant and significant specific combining ability (SCA) impacts of early yield, total yield, average fruit weight and TSS, respectively. The best specific combining ability (SCA) was observed in hybrids RIL A29 × RIL A5 for early yield, RIL A19 × RIL A20 for total yield and RIL A8 × RIL A10 for average fruit weight and TSS. The results confirmed the presence of genetic differences among the genotypes (female and male parents) and heterosis of crosses indicating the existence of predominance of nonadditive gene action in genetic control of the studied traits.