Genetic potential of Brazilian papaya (<i>Carica papaya</i> L.) lines and hybrids for improving fruit quality via specific combining ability and heterosis

Summary The development of new papaya cultivars with high genetic potential for production, combined with quality traits that meet the demands of emerging markets, facilitates the expansion of the genetic base, reduces production costs, and broadens papaya cultivation. This study continues the largest Brazilian papaya breeding program, a partnership of over 25 years between UENF and Caliman Agrícola S.A. The objective was to evaluate the ability of inbred lines to generate hybrids with market potential in Brazil and for export. A total of 62 hybrids were obtained through topcross strategy. The lines were evaluated based on their specific combining ability (SCA), and the hybrids were analyzed through estimates of functional and varietal heterosis (VH) using three widely cultivated commercial varieties in Brazil: ‘UENF/CALIMAN 01’, ‘Tainung 01’, and ‘UC10’. Promising lines were identified for both hybrid creation and use as commercial varieties, exhibiting desirable traits for domestic and international markets, such as high fruit firmness and elevated soluble solids content (the lines UCLA08-053 and UCLA08-087 with the ‘Intermediate’ pattern and the lines UCLA08-066, UCLA08-122, and UCLA08-080 with the ‘Formosa’ pattern). Several hybrids, including H23, H26, H51, and H89 from the ‘Intermediate’ type and H4, H9, H19, and H68 from the ‘Formosa’ type, outperformed their parental lines and commercial varieties. These genotypes demonstrated superior SCA and VH compared to commercial controls, highlighting their strong genetic potential for the production market, increasing the shelf life of the fruits during storage and transportation, and allowing them to travel long distances without compromising fruit quality.