Germination, sodium, and potassium concentrations of barley seeds as influenced by salinity

Seed germination is a major factor limiting the establishment of plants und er saline conditions. Six barley (Hordeum vulgare L.) cultivars were screen ed for salt tolerance (using NaCl) during seed germination. The uptake of w ater, and levels of Naf and K+ of salt sensitive and salt tolerant cultivar s, before and after imbibition, were measured to determine the contribution s of ionic and osmotic factors to seed different response to salt stress. I mbibition of seeds incubated with NaCl solutions was reduced by approximate ly 5% for each 100mM increase in NaCl concentration once the level of 100mM NaCl was reached. The Na+ concentration of seeds after imbibition did not differ significantly among cultivars and selective uptake or exclusion of N a+ were not associated with the differences in salinity tolerance. No diffe rences between the two tested cultivars were noted for initial K+ concentra tion, but the salt tolerant cultivar lost less K+ relative to Na+ uptake th an did the salt sensitive cultivar. The adverse effects of salt stress on s eed germination might result from internal osmotic or restricted imbibition rather than from ion toxicity effects.