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Tomato (Lycopersicon esculentum Mill.) genotypes evaluated for early blight [Alternaria solani (Ellis & Martin) Jones and Grout] resistance included five tolerant breeding lines, a susceptible cultivar, and seven hybrids among them. Three of the genotypes (`Castlejay', NC EBR-2, and 87B187) were crossed in a diallel mating design to estimate general combining ability and specific combining ability for the resistance trait. Parental, F1, F2, and backcross generations of the family Cl943 x `Castlejay' were evaluated for resistance and included in generation mean analysis. Hybrid means for area under the disease progress curve were not significantly different from respective midparent values, indicating additive genetic control. Diallel and generation mean analyses also detected significant additive genetic effects. Epistasis was present in the Cl943 × `Castlejay' family.
Abstract
Four open-pollinated cultivars of muskmelon (Cucumis melo L. var. reticulatus Naud.) and five hybrids among them were grown with clear plastic mulch, black plastic mulch, and on bare soil to study genotype × mulch interactions for days to hermaphroditic flowering, days to fruit maturity, fruit soluble solids, fruit weight, and yield. Interactions were not significant for any trait measured, indicating that all genotypes responded similarly to mulch treatments. Diallel analysis showed that general combining ability (GCA) was greater than specific combining ability (SCA) for all traits measured, suggesting that additive variance was more important than nonadditive variance. Plastic mulches increased fruit maturity and total yields but reduced soluble solids content.
Abstract
Six inbred tomato (Lycopersicon esculentum Mill.) genotypes and 13 hybrids among them were evaluated at two locations for resistance to early blight (Altemaria solani). The breeding lines 71B2, C1943, and NC EBR-1 were the most resistant, while ‘Castlejay’ was consistently the most susceptible. Hybrid means for area under the disease progress curve (AUDPC) generally were intermediate to their parental values, indicating quantitative genetic control. Five of the parents were included in a diallel mating design to obtain estimates of general combining ability (GCA) and specific combining ability (SGA) for the resistance trait. Both GCA and SCA were highly significant; the GCA component accounted for 88.2% of the genotypic variation.