Salinity Tolerance in Four Wild Tomato Species using Vegetative Yield-Salinity Response Curves

Abstract

The salinity tolerances of 21 accessions belonging to four wild tomato species [Lycopersicon pimpinellifolium (Jusl.) Mill., L. peruvianum (Corr.) D'Arcy, L. hirsutum (L.) Mill., and L. pennellii Humb. Bonpl.) were evaluated using their vegetative yield-salinity response curves at the adult stage, determined by a piecewise-linear response model. The slope (yield decrease per unit salinity increase), salinity response threshold, maximum electrical conductivity without yield reduction (EC o ), and salinity level for which yield would be zero (EC o ) were determined by a nonlinear least-squares inversion method from curves based on the response of leaf and stem dry weights to substrate EC. The genotype PE-2 (L. pimpinellifolium) had the highest salt tolerance, followed by PE-45 (L. pennellii), PE-34, PE-43 (L. hirsutum), and PE-16 (L. peruvianum). The model also was tested replacing substrate salinity levels with leaf Cl - or Na + concentrations. Concentrations of both ions for which vegetative yields were zero (Cl o and Na o ) were determined from the response curves. In general, the most tolerant genotypes were those with the highest Cl o and Na o values, suggesting that the dominant salt-tolerance mechanism is ion accumulation, but there were cases in which salt tolerance was not related to Cl o and Na o .