Salt tolerance in the wild relatives of the cultivated tomato: Water balance and abscisic acid in Lycopersicon Esculentum and L. peruvianum under low and high salinity

The cultivated tomato Lycopevsicon esculentum and the more salt-tolerant wild species L. pevuvianum were used. Transpiration of whole plants and detached leaves, stomata1 density and opening, and abscisic acid level were measured for the two species grown under both control and saline conditions. Root resistance to water flow and conductivity of guttation fluid were compared only for plants growing in the control solution. Transpiration of whole plants was higher in wild plants grown in the control solution, but decreased more under salinity. Wild plants had fewer stomata per unit leaf area, but these opened wider in the control solution and closed more in the saline solution as compared with the cultivated ones. Root resistance to water flow and conductivity of guttation fluid were higher in the wild plants. The abscisic acid level was higher in the cultivated species and increased somewhat in both plant types under salinity. The significance of these findings in relation to the greater adaptability of L. pevuvianum to stress is discussed.