Inheritance of root knot nematode resistance in lima beans

Mcguire, D. C.; Allard, R. W.; Harding, J. A.

Inheritance of resistance to galling by root knot nematodes was studied in F2 individuals and F3 progenies of hybrids of 2 resistant strains, L76 and L136, crossed with a susceptible variety. Comparatively low heritabilities prevented correlation of genotype and phenotype. It was therefore not possible to analyze inheritance in terms of a precise factorial scheme. Nevertheless, the evidence suggested that comparatively few major genes govern resistance in both crosses. Appearance of susceptible plants in the F2 generation of the hybrid between the 2 resistant parents indicated that the main genes governing resistance are not the same in these parents. Stringent selection is necessary if complete nematode resistance is to be recovered from hybrids involving L76 and L136. Since stringent selection is also necessary to recover types with good horticultural characteristics in hybrids of these resistant strains with commercial varieties, a step-wise program is suggested as most efficient for developing nematode-resistant commercial types.