Ion Concentration and Carbohydrate Status of the Elongating Leaf Tissue 4Hordeum vulgare Growing at High External NaCl: II. CAUSE OF THE GROWTH REDUCTION

The cause for the growth reduction of a salt-tolerant variety of barley (cv. ‘Beecher’) was investigated in plants growth for 5 d at 120 mM and 180 mM NaCl. The NaCl treatments increased the concentrations of soluble carbohydrate in the elongating tissues of the growing leaf, while starch did not change. This shows that photosynthesis was not limiting growth, and indicates that the cause for the growth reduction was located in the growing leaves, specifically in the elongating tissue. Leaf elongation increased rapidly after transfer of plants from 120 to 60 mM NaCl. The rate elongation during the first hour after transfer was already equal to that of plants grown at 60 mM NaCl, despite the persistence of high Cl− and (Na+ + K+) concentrations in elongating as well as fully elongated tissues. This indicates that the growing tissues suffered from water deficit rather than from adverse effects of ions on metabolism.