Relationships between Salt Tolerance of Green Soybeans and Calcium Sulfate Applications in Sand Culture

Abstract

Green soybeans (Glycine max Merr.) were grown to maturity in sand to determine relationships between salt tolerance of the plants and CaSO₄ applications, using diluted sea water. Dry weight of the whole plant, fresh weight of pods and seeds, and number of pods and root nodules were greatest at 0 ppm Cl and decreased with increasing sea water concentrations. Growth at 0 and 250ppm Cl tended to be greater at 1mM CaSO₄ than at 12mM CaSO₄. There was no effect of CaSO₄ treatments on the growth at 500, 1, 000 and 2, 000ppm Cl. Na and Cl in leaves and sand solution, and EC values of sand solution increased with increasing sea water concentrations. CaSO₄ applications scarcely affected Na and Cl in leaves and sand solution, and EC values of sand solution at each sea water concentration. Ca in leaves, and Ca and SO4₄ in sand solution tended to be higher at 4, 8 and 12mM CaSO₄ than 1mM CaSO₄. In the current experiment, salt tolerance of green soybeans in sand culture was not enhanced by the application of CaSO₄, indicating that the role of Ca to salt tolerance may differ with crops.