Assessment and assortment of tomato genotypes against salinity at vegetative stage

Salinity affects growth of salt-sensitive vegetable crops at an early stage. So, selection of vegetable crops at an early vegetative stage is a significant step in improving salt tolerance. In this study, twenty-four tomato genotypes were subjected to two different salinity stress viz., control, and 15 dS m-1 at 35 days after emergence under hydroponic culture. Visual scoring of salt injury and morpho-physiological traits (length, fresh and dry weights of root and shoot, leaf area, membrane stability, and content of Na+, K+, Ca2+, K+: Na+ and Ca2+: Na+) were investigated. Analysis of variance revealed that specific and interaction effects of both salinity and genotype for all measured traits were significant (P<0.05), suggesting a wide range of diversity in these genotypes. On the basis of visual scoring, genotypes G4, G7, G14, and G16 were found in lower injury scale classes 1 and 2. They also had the least reduction of root length, leaf area, and total biomass under salinity. At 15 dS m-1 salinity level, the genotypes G1, G4, G7, G14, and G16 showed the least cell membrane stability index CMSI compared to the control genotype. Moreover, these genotypes also uptake less Na+ with higher % of K+ and Ca2+, which resulted in higher K+: Na+ and Ca2+: Na+ ratios than others, that expressed their tolerance to salinity. Tomato genotypes were classified into four clusters, where, G1, G4, G5, G7, G14, and G16 genotypes were found in cluster 3 and cluster 1, with the maximum mean values and top-ranking scores in their measured morphological traits. On the other hand, G13, G20, G22, G23, and G24 were in cluster 4, with the lowest mean values and bottom-ranking scores. The results of the study consistently confirmed that G4, G7, G14, and G16 genotypes are salt-tolerant at the vegetative stage.