Salinity effects on water relations in Lycopersicon esculentum and its wild salt‐tolerant relative species L. pennellii

Cultivated tomato Lycopersicon esculentum (L.) Mill. cv. P‐73 and its wild salt tolerant relative L. pennellii (Correll) D'Arcy accession PE‐47, were grown during spring‐summer 1989 under unheated plastic greenhouse conditions. Plants were submitted to two different salt treatments using 0 and 140 mM NaCI irrigation water. In both tomato species, salinity caused a proportionally larger reduction in leaf area than in leaf weight and, in L. esculentum , a proportionally larger decrease in stem weight than in leaf weight. Daily variations in leaf water potential (Ψ 1 ) were fundamentally due to changes in the evaporative demand of the atmosphere. Reductions in Ψ 1 due to salinity were consistent only in L. esculentum . In all the conditions studied, leaf turgor was maintained. Leaf conductance (g 1 )was higher in L. esculentum than in L. pennellii .Salinity induced a clear reduction in g 1 levels in L. esculentum whereas, in L. pennellii , this reduction was noted only in May. In both species the Ψ o s (leaf osmotic potential at full turgor) levels were reduced by salinity. The bulk modulus of elasticity (E) and relative water content at turgor loss point (RWC tlp ) were not affected by salinity. The RWC tlp values in L. pennellii seem to be controlled by E values.