Genetics of resistance to downy mildew in muskmelon (Cucumis melo L.)

To identify parents and specific combination of parents for resistance to downy mildew, thirty F_t hybrids were developed by crossing six female parents with five male parents in a line x tester mating design. Adult muskmelon plants of parents and hybrids were evaluated in greenhouse and field conditions. Significant variances for general combining ability (GC A) and specific combining ability (SC A) indicated the importance of both additive and non-additive gene actions for the expression of resistance. Inbred lines IIHR 352 (Cucumis melo var. reticulatus), IIHR 190 (Cucumis melo var. reticulatus) and IIHR 122 demonstrated consistently high and negative GCA effects in both screening conditions. Arka Jeet x IIHR 121, Arka Jeet x IIHR 122, Punjab Sunehri x IIHR 190, Punjab Sunehri x IIHR 718, IIHR 681 x IIHR 121, IIHR 681 x IIHR 122 and IIHR 352 x IIHR 616 were the hybrids expressed high per se performance, high midparent heterosis and high SCA effects. The study highlights the importance of harnessing useful genes from diverse parental lines to improve resistance to Pseudoperonospora cubensis in adapted muskmelon varieties/cultivars.