Salt Tolerance in the Wild Relatives of the Cultivated Tomato: Responses of Lycopersicon esculentum, L. cheesmanii, L. peruvianum, Solanum pennellii and F₁ Hybrids to High Salinity

Abstract

The performance of three wild relatives of the cultivated tomato (Lycopersicon cheesmanii, L. peruvianum and Solanum pennellii) and two tomato cultivars in control and saline media was compared. The parameters studied were elongation rate of the main stem, succulence, and accumulation of Na⁺, K⁺, and Cl^- in the roots, stem, leaf, and shoot tip. The same parameters but in the leaf only were also studied comparatively in two of the wild species L. cheesmanii and S. pennellii, the same two cultivars, and F₁ hybrids.

Under control conditions, the elongation rate of the stem of the two cultivars was higher than that of the wild plants, but under salinity it was relatively lower. Among all species, S. pennellii was the most succulent in all its major parts under both control and saline conditions. The wild species, especially S. pennellii, showed high accumulation of Na+ in the leaf and top and a greater decrease in K⁺ content under salinity as compared with the cultivated plants. In all three species, Na⁺ probably substitutes for potassium in, at least, some of its physiological functions.

Complete dominance of S. pennellii over the cultivated plants is indicated for the relative decrease of elongation rate and K⁺ level and for the increase of succulence under salinity. In contrast, L. cheesmanii seems to be completely dominant only for the relative decrease of K⁺ under salinity.