Selection of lettuce progenies for soft rot resistance, response to Meloidogyne incognita, and desirable morpho-agronomic traits

Abstract Among leafy vegetables grown in Brazil, lettuce ( Lactuca sativa L.) is the most widely consumed and one of the most important crops for smallholder farming. However, continuous cultivation favors the buildup of soilborne pathogens, such as Meloidogyne incognita and Pectobacterium carotovorum subsp. carotovorum , leading to substantial reductions in yield and market quality. In addition, premature bolting limits the adaptation of lettuce cultivars to tropical growing conditions. This study aimed to select smooth-leaf lettuce progenies combining resistance to soft rot, a favorable response to M. incognita , tolerance to premature bolting, and desirable morpho-agronomic traits. To achieve this, the cultivar 'Vitória de Santo Antão’ was crossed with the Beta line to generate F₂, F 2:3 , and F 2:4 progenies. In the F₂ generation, 608 progenies were evaluated for resistance to soft rot and subjected to an initial screening for their response to M. incognita . The selected progenies were subsequently assessed based on the nematode reproduction factor. The following generations were evaluated for soft rot resistance, tolerance to premature bolting, and morpho-agronomic characteristics. Among the F 2:3 progenies, six were resistant to soft rot, while progeny 202 exhibited the highest level of tolerance to premature bolting. In the F 2:4 generation, 27 progenies maintained a favorable reaction to soft rot, whereas progenies 172–12, 202–11, 172–08, 202–42, 023–02, 202–37, and 202–30 combined desirable agronomic traits. These findings demonstrate that the selection strategy was effective in identifying promising breeding materials for advancement to subsequent stages of the lettuce breeding program.