Resistance of Cucumis spp. to the Root-knot Nematode, Meloidogyne incognita acrita.

The nature of resistance in Cucumis ficifolius and C. metuliferus to the root-knot nematode, Meloidogyne incognita acrita, was studied under greenhouse conditions. Although as many larvae penetrated the roots of these species as those of the susceptible C. melo, few developed to the adult female stage. Resistance in C. ficifolius and C. metuliferus was associated with hindrance of larval development beyond the second stage, delayed development of larvae to adults and stimulation toward maleness. Tissue necrosis or hypersensitivity was not associated with larval penetration. Comparisons of the histopathology of 26-day-old infections of C. melo and C. metuliferus roots showed no observable differences in the type of giant cell development in regions of roots associated with adult females. However, in C. rnetuliferus immature nematodes were associated with small giant cells which were limited to a few cells near the head of the nematode.