Effects of Dehydration and High Temperature on the Stability of Leaf Membranes of Lycoperskon esculentum, L. cheesmanii, L. peruvianum and Solanum pennellii

Abstract

Summary The stability of leaf membranes under dehydration and heat stress was studied in summer-and winter-grown plants of the cultivated tomato Lycopersicon esculentum and its wild relatives L. cheesmanii, L. peruvianum , and Solanum pennellii . The stability was assessed by determining leakage of electrolytes from leaf discs exposed to heat and dehydration stress and the integrity of naked leaf protoplasts under heat stress. In all species, the membrane was found to be more injured under stresses in the winter than in the summer. The membrane of the wild species appeared to be less stable than that of the cultivated one. In all species discs taken from salt-treated plants leaked more under heat stress than those taken from control plants. The reverse was true under dehydration stress. The latter phenomenon, which was most noticeable in S. pennellii and L. peruvianum was explained by the protection exterted on the membranes by the salt accumulated internally against dehydration caused by the externally applied polyethylene glycol.