Identification of papaya hybrids resistant to Stagonosporopsis caricae by heterosis: a possible reality?

Abstract

Papaya requires frequent applications of fungicides because of its high susceptibility to disease. However, no products capable of effectively managing the fungus Stagonosporopsis caricae are commercially available to date. Because of this limitation and the continuous demand for products free of chemical residues and that achieve higher yields, genetic improvement is necessary to obtain resistant and productive genotypes. The present study used lineages produced by backcrossing and hybrids obtained from the cross between these backcrossed lines and four elite genotypes (SS72-12, Sekati, JS-12, and 41/7) to identify genotypes with increased resistance to phoma spot. The analysis of the effects of heterosis evidenced the possibility of achieving high genetic gains. The evaluation of the incidence and severity of phoma spot indicated that hybrids Sekati × 1, 41/7 × 10, and JS-12 × 21 presented negative heterosis for phoma spot in all evaluated seasons. Considering standard heterosis, the hybrids Sekati × 1 and Sekati × 4 were the most resistant to disease. The Solo group genotypes SS × 04 and SS × 06 presented negative heterosis in at least one season for common and standard heterosis, evidencing that these cultivars were resistant to phoma spot. The obtained results on heterosis and papaya production allowed identifying promising cultivars.