THE EFFECTS OF ISOOSMOTIC SALT AND WATER STRESSES ON THE GROWTH OF HALOPHYTES AND NON-HALOPHYTES

Seedlings of the halophytes Atriplex lentiformis and Suaeda salsa, and the drought resistant Prosopis chilensis were grown in liquid cultures with their roots exposed to salt (NaCl) or water stress (PEG). A. lentiformis and S. salsa were exposed to 0, 0.496 and 0.992 MPa osmotic potentials imposed by each treatment, and P. chilensis to 0, 0.248 and 0.496MPa. Dry weight and moisture contents of A. lentiformis and S. salsa were reduced by PEG but were unaffected, enhanced, or only slightly reduced by NaCl. In contrast P. chilensis was affected to a greater extent by NaCl than by PEG. A. lentiformis and S. salsa accumulated large amounts of Na+ with a higher concentration being found in the shoots than in the roots. P. chilensis accumulated less Na+ and this was largely confined to the roots. The results are discussed in terms of the distinctive nature of osmotic and ionic stresses and the mechanisms of salt resistance.