Phenotypic and Molecular Screening of Thirty Tomato (Solanum Lycopersicum L.) Germplasm for Root-Knot Nematodes (Meloidogyne Incognita) Chitwood, Resistance.

Thumbnail Image
APRIL, 2010
Journal Title
Journal ISSN
Volume Title
This study was conducted to screen 30 tomato (Solanum lycopersicum) germplasm for root-knot nematodes (Meloidogyne incognita) resistance. Three experiments were conducted. Field experiment was done on a field naturally heavily infested with root–knot nematodes at Afari in the Atwima Nwabiagya district of Ashanti region of Ghana. A pot experiment was conducted in a plant house at Crops Research Institute. Molecular screening was also done at the Biotechnology Laboratory of the Crops Research Institute to detect markers for the gene that confers resistance to tomato (Mi) with specific primers (Mi23/F//Mi23/R). Six resistant cultivars - FLA 496-11-6-0, 2641A, “Adwoa Deede”, Tima, Terminator F1 and 2644A were identified in the molecular screening. The susceptible check (UC82) recorded the highest (2,508) J2/200 ml soil recovered from the rhizosphere of tomatoes which was significantly different (P=0.01) from the resistant check (VFNT) which recorded 208 J2/200ml soil in the field study. The susceptible check (UC82) also recorded a significantly high number (108) J2/g root compared to the resistant check (VFNT) which recorded none. The susceptible check, UC82, and the resistant check, VFNT, recorded mean gall indices of 4.0 and 0.0, respectively, on a scale of 0-5 in the field work. VFNT and three other resistant cultivars, - FLA 496-11-6-0, 2641A and Adwoa Deede did not gall in the pot experiment. FLA 496-11-6-0, Adwoa Deede, Tima and the resistant cultivar recorded significantly high fruit yield (3.3, 5.8, 1.3 and 2.4 t/ha) respectively. The susceptible check, UC82, however, recorded significantly low fruit yield (0.4 t/ha). Most of the susceptible cultivars identified recorded significant decreases in fresh and dry shoot weights with increasing inoculum densities (Pi = 0, 250, 500). Six resistant cultivars identified in the molecular screening correlated well with the resistant phenotypes in both the field and pot experiments.
A Dissertation Submitted to the Department of Crop and Soil Sciences of the College of Agriculture and Natural Resources in Partial Fulfilment of the Requirement for the Award of M.Sc Plant Breeding,