Combining Ability Estimates for Early Blight Resistance in Tomato

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.