Exploring morphological variation in tomato (Solanum lycopersicum): A combined study of disease resistance, genetic divergence and association of characters

Abstract

Genetic variation of quantitative traits is a prevalent characteristic among cultivated tomato varieties. Twenty tomato genotypes comprising indigenous varieties and commercial cultivars, cultured in the Western Region of Cameroon were evaluated using fourteen quantitative traits for disease resistance, phenotypic divergence and heritability estimates. The experiment was carried out using a randomized completed blocks design with three replications. Data collections were disease characteristics, plant development features and yield attributes. The analysis of variance revealed significant variation among genotypes for all the experimental quantitative traits. Hybrid varieties had significantly more fruit yield (1066.00 g/plant), single fruit weight (57.28 g), fruit diameter (4.47 cm) and pericarp thickness (0.54 cm) compared to standard and indigenous varieties. These indigenous varieties were significantly more resistant to late blight, alternaria leaf spot and viral diseases. They also had significantly higher collar diameter (16.30 mm), number of primary branches per plant (8.45), number of fruit per plant (31.58) and plant height (88.33 cm) compared to standard and hybrid plants. The genotype local 2 was the third most productive (1576.39 g / plant) after Rio Semagri (1984.80 g/plant) and Sakato F1 (1691.69 g/plant). Heritability and genetic advance estimates were high for twelve of the fourteen studied quantitative traits. Fruit yield showed significant positive correlations with single fruit weight and number of fruit per plant. However, significant negative correlation was found between fruit yield and time to 50 % flowering, 50 % fruiting, 50 % maturity and viral disease. The first three and the first four components in the principal component analysis explained, respectively, 77.85 % and 88.38 % of the total variation observed among genotypes. The first component determined 41.42 % of the total variation, dominated by the collar diameter, the number of primary branches per plant and plant height. This study clearly indicated that indigenous varieties are the most disease resistant genotypes and are having substantial fruit yield (945.30 g/plant) similar to standard varieties and at a touching distance to hybrid cultivars.

Keywords

• disease resistance
• genetic divergence
• indigenous genotypes
• quantitative traits
• germplasm
• solanum lycopersicum