This study aimed to estimate genetic parameters and to study the inheritance of resistance to papaya black-spot, powdery-mildew and phoma-spot through diallel cross on a field plot experiment. The 56 hybrid combinations (F1's and reciprocals) and eight genotypes of papaya, four of 'Formosa' group ('Maradol', 'JS12-N', 'JS12-4' and 'Sekati') and four of the 'Solo' group ('Waimanalo', 'Golden', 'Sunrise Solo 72-12' and 'São Mateus') were evaluated. The severities of black spot on leaf and fruit and the severity of powdery mildew and phoma spot in leaf were quantified. The analyses of variance of the data were performed considering the intersections and the season (evaluation date) as sources of variation. The severity of black-spot on leaf and fruit and the severity of powdery-mildew had absence of significance concerning the three tests of sufficiency for the additive dominant model. The estimated numbers of genes or gene blocks with dominance indicated the existence of at least four genes or gene blocks to severity of powdery mildew and at least one for severities of black-spot on leaf and fruit. For severity of powdery mildew additive gene effects were more important. Additives and non-additives gene effects were important to the severities of black-spot on leaf and fruit. It was observed effect of partial dominance for severity powdery mildew and complete dominance for severities of black-spot on leaf and fruit. The parent 'Sekati' presented the highest concentration of favorable alleles for the reduction of the black-spot and powdery mildew.
Asperisporium caricae; Streptopodium caricae; Carica papaya; hybridization
