Characterization of Resistance to Major Tropical Root-Knot Nematodes ( spp.) in .

Root-knot nematodes ( spp.) are important contributors to yield reduction in tomato. Though resistant cultivars to common species (, , and ) are available, they are not effective against other major species of root-knot nematodes. Cultivars or lines of were examined to assess the presence and level of resistance to five major species: race 1, race 3, , , and Differences in response to the nematode infection were apparent when susceptibility or resistance was classified by the egg counts per gram fresh weight of root and the multiplication rate of the nematodes. The cultivar Diamond was highly susceptible, Quattro and White Star were susceptible, while Sis Syn II was resistant to . Quattro, White Star, and Sis Syn II exhibited a moderate to high level of resistance to but the nematode increased 2.5-fold from the initial population of the on Diamond. All cultivars were highly resistant to both and , while highly susceptible to . A microplot study under field conditions using Sis Syn II confirmed that , , and were not pathogenic on the plant. Likewise, an examination on cross-sections of galled root tissues confirmed the susceptibility and resistance of lines to spp. Using as a resistant rootstock or a new source of resistance may result in the development of nonchemical and sustainable management strategies to protect the tomato crop.