Hybridization is an efficient strategy to achieve selective genetic gains to control plant diseases. For papaya crop, studies have confirmed that genetic resistance to phoma leaf spot can be increased via hybridization; however, there is the need to study the manifestation of heterosis in hybrids from crosses between and within heterotic groups. This study aimed to evaluate papaya hybrids from complete diallel crosses, involving eight elite parents, four of the heterotic group 'Solo' and four of the heterotic group 'Formosa'. The experiment was conducted in a commercial field, according to a randomized block design, using four replicates, and the severity of phoma leaf spot was quantified in two seasons, March and May 2010, employing a diagrammatic scale. The average of each treatment was used to estimate heterosis and heterobeltiosis. The hybrids 'Waimanalo x Golden', 'Golden x Maradol', 'Golden x Waimanalo', 'Golden x Sunrise Solo 72/12', 'Golden x São Mateus', 'Sunrise Solo 72/12 x Waimanalo', 'Sunrise Solo 72/12 x Golden' presented the best results; they had negative estimates of heterosis and heterobeltiosis for the disease severity reduction in both evaluation periods. Selection of hybrids from crosses either within the group 'Solo' and between the heterotic groups ('Solo' x 'Formosa') can be performed to genetically control phoma leaf spot in papaya plants.
Stagonosporopsis caricae; Carica papaya; hybridization; diallel
