Response of Lycopersicon species to salinity by principal component analysis

In thirty-six tomato genotypes from the species Lycopersicon pimpinellifolium, L. hirsutum, L. peruvianum and L. esculentum, the dependent relationship of fifteen agronomical and nutritional characteristics were determined at four salinity levels by principal component analysis. Genotype distribution on the plane defined by the first two principal components was also studied. The characteristics that constituted the three principal components were different in the control plants and in the plants grown at different salinity levels. In the control plants, the first component was mainly defined by Cl⁻, Na⁺, K⁺, Ca⁺²and Mg⁺² leaf concentrations, the second component was defined by leaf and stem weights, plant height and number of leaves and the third component was defined by number of clusters and number of flowers. In the plants grown on saline medium, the three principal components were fundamentally defined by the same characteristics for each salinity level. The first component was defined by Cl⁻ and Na⁺ leaf concentrations, stem diameter and leaf and stem weights. The second component was considered a growth factor since it mainly consisted of plant height and number of leaves. As in the control plants, the third component was considered a fructification factor consisting of the number of clusters and the number of flowers. Salinity varied genotype location on the plane defined by the first two components, but it did not modify the distance between genotypes. L. esculentum and L. peruvianum were the most homogenous species.