Growth response ofSuaeda salsa(L.) Pall to graded NaCl concentrations and the role of chlorine in growth stimulation

Growth response of a halophyte species, Suaeda salsa (L.) Pall, to graded NaCl concentrations was examined under water culture conditions. Growth increased with increasing NaCl concentration from 2 to 200 mol m−3, but decreased at NaCl concentrations above 200 mol m−3. Maximum growth was attained at 50 to 200 mol m−3. The role of Na and Cl in the growth stimulation by NaCl was examined by growing S. salsa in nutrient solutions with or without Na and Cl separately at 5 and 50 mol m−3. The growth stimulation induced by Cl was greater than that induced by Na, and Na did not significantly induce growth stimulation. The effect of Na or Cl on O2 evolution from leaves was examined under 5 and 50 mol m−3 concentrations using an oxygen electrode. Oxygen evolution from leaves in –Cl treatments was smaller than that in +Cl treatments both at 5 and 50 mol m−3. The O2 evolution in Na treatments with Cl was similar to that at NaCl. These results indicated that the mechanism of growth stimulation induced by Cl was mainly an increased photosystem II of photosynthesis in leaves. The contribution of Na on the growth stimulation of S. salsa by NaCl was smaller than Cl.