Effects of salt stress on growth, inorganic ions and proline accumulation in relation to osmotic adjustment in five sugar beet cultivars

The effect of salinity on some agro-physiological parameters in plants of five multigerm varieties of sugar beet has been investigated. Plants were submitted to four salt treatments, 0, 50, 100 and 200 mM NaCl, for 30 days in a sand culture and the physiological responses were measured. Salinity affected all of the considered parameters. Thus, high NaCl concentrations caused a great reduction in growth parameters such as leaf area, and fresh and dry weight of leaves and roots, but the leaf number was less affected. These changes were associated with a decrease in the relative water content and the K+ concentrations, but Na+ and Cl- contents were highly increased in the leaves. The solute leakage and proline content were also increased, but nitrate reductase activity was found to decrease in leaves of all of the tested varieties. Varietal differences were evident at the highest NaCl concentration for almost all of the considered parameters. The significance of inorganic ions and proline accumulation in relation to osmotic adjustment was discussed. In contrast to proline, inorganic ions seem to be involved in osmotic adjustment. (C) 2002 Elsevier Science B.V. All rights reserved.