Developing and Phenotypic Evaluation of Nematode Resistance in K326 X DDV 23 Tobacco Population

Resistance to the root - knot nematode (Meloidogyne spp) was identified in the nicotiana tabacum. The phenotypic evaluation was between F2 population obtained from a cross between DDV23 (Resistant) and K326 (Susceptible) parents respectively. The experiment was conducted in 2018/2019 growing season in the greenhouse at TORITA (Tabora region) to determine nematode resistance from different tobacco genotypes.90F2 plants with parents 90DDV23 and 90K326 were inoculated with nematode eggs at the rate of 1050 eggs/plant. Results showed that among 90 F2 tobacco plants inoculated 68 were found resistants? and 22 susceptible. Chi - square analysis (X2) showed that, the number of individual plant segregate at 3: 1 ratio of resistant to susceptible. This indicates that, the gene for resistance from DDV 23 was transferred to F2 individuals and the trait was controlled by one or closely linked genes. Also data on disease incidence showed that larger number of F2 progenies (25.5%) were resistant, followed by moderately resistant parent (21.75%) showing a scale of 2.5 and 2.4 respectively while the remaining susceptible parent showed a scale of 5 infection levels. Most of F2 genotype exhibited resistance; these results confirmed the presence of dominant gene for resistance to root knot nematodes. Phenotypic evaluation and characterization is limited regarding the knowledge of the specific genes responsible for resistance therefore molecular genetic characterization has to be performed to identify the markers linked to nematode resistance.