Effects of Sodium and Potassium Salts on the Growth of a Halophyte

Abstract

Seedlings of a coastal halophyte, Alriplex gmelini C.A.Mey were grown in water culture with varying concentrations and species of salts. Plants receiving nutrients supplemented with 50 mM NaCl gave the maximum dry weight yield compared with those receiving the higher or the lower concentrations of NaCl. Addition of 50mM KCl, 25 mM Na₂SO₄ or 25 mM K₂SO₄ to the basal culture solution also stimulated the growth to the same extent. However, higher concentrations of potassium salts, such as 250 mM KCl or 125mM K₂SO₄, exerted a more deleterious effect on the plant growth than sodium salts did. At a concentration of 250 mM NaCl or KCl addition, the KCl-treated plants showed a higher sodium plus potassium concentration than the NaCl-treated plants. Time course analysis revealed that the plants exposed to a concentration of 250 mM NaCl were able to maintain their internal sodium plus potassium concentrations around certain values, while the internal sodium plus potassium concentration in the 250 mM KCI-treated plants increased linearly. This phenomenum may be ascribed to the lack of control systems for the maintenance of the internal concentration of potassium, which can operate when sodium salts are supplied.

Key Words:

• halophyte (Alriplex gmelini)
• salt tolerance
• water uptake