Characterization of F2:3 families of lettuce for resistance to root-knot nematode

The root-knot nematode has harmed the commercial production of lettuce in high temperature conditions. The use of resistant cultivars is an alternative to the cultivation under these conditions. This study aimed to verify the resistance to root-knot nematode Meloigogyne incognita race 1 in 17 F2: 3 families of smooth leaf lettuce. The experimental design was a randomized block design with 17 treatments and four replications. Each plant was individually assessed and received a score from one to five as the lower or the higher incidence of galls on the roots. The values obtained for each family were compared with those obtained for the cultivar Grand Rapids and Regina 71 by x(2) test. Six families were characterized as homozygous resistant nematode Meloidogyne incognita race 1 because they did not differ from cultivar Grand Rapids. The eleven other families were characterized as segregating for the character because the witnesses did not differ significantly. The classification of six families as homozygous resistant indicates the possibility of obtaining new strains of smooth leaf lettuce resistant to Meloidogyne incognita race 1. Such strains may be used in breeding programs or originate new commercial cultivars inheriting this trait.