OSMOTIC ADJUSTMENT IN LEAVES OF LYCOPERSICON-ESCULENTUM AND L-PENNELLII IN RESPONSE TO SALINE WATER IRRIGATION

Two tomato species (Lycopersicon esculentum and L. pennellii) were grown under unheated plastic greenhouse and irrigated with 0 or 140 mM NaCl. Salinity induces a more important reduction in predawn leaf water potential (PSI(pd)) in L. esculentum than in L. pennellii. In both species the osmotic adjustment was achieved by active solute accumulation. The leaf water potential at turgor loss point (PSI(tlp)) seemed to be controlled by leaf osmotic potential (PSI(os)). The results revealed the existence of limits to the accumulation of osmotic solutes in leaf tissues and the existence of an ontogenetic effect on the solute accumulation. In both species, but essentially in L. pennellii the inorganic solutes contribution especially Na+ and Cl- accumulation to PSI(os) was higher than the organic solutes. Therefore, wild species save energy more markedly.