Abstract
The varietal difference in salinity tolerance of soybeans was examined by making a comparison with the relative growth as against control of three organs such as leaves, stem, and root grown in culture solution supplied with 80 mM NaCl. Moreover, the mechanisms of growth suppression of soybeans by a high concentration of NaCl. Moreover, the mechanisms of growth suppression of soybeans by a high concentration of NaCl examined by means of the detachment of leaves and roots, and the equation of osmotic pressure in culture solution. The results obtained are summarized as follows : 1) The varietal difference in salinity tolerance (salinized NaCl) for soybean were mainly due to Na and/or Cl injury rather than to the increase of osmotic pressure in the culture solution. 2) Tolerant varieties showed higher concentrations of Na or Cl ion in leaf blades or stem than did susceptible varieties. 3) To determine the susceptibility or tolerance to salinity, it was better to use the Na or Cl concentration in the stem than in leaf blades, since leaf blades showed a difference in susceptibility to Na concentration among varieties. 4) Sodium or Cl concentration in the stem decreased with the increase of the excluding power of both ions. 5) Varieties with high Na-excluding power had generally higher Na concentration in the root than did low Na-excluding ones when they were grown in culture solution added with NaCl (80 mM) for a short term (2 days).
