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

Seed germination is a major factor limiting the establishment of plants under saline conditions. Six barley (Hordeum vulgare L.) cultivars were screened for salt tolerance (using NaCl) during seed germination. The uptake of water, and levels of Naf and K+ of salt sensitive and salt tolerant cultivars, before and after imbibition, were measured to determine the contributions of ionic and osmotic factors to seed different response to salt stress. Imbibition of seeds incubated with NaCl solutions was reduced by approximately 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 Na+ were not associated with the differences in salinity tolerance. No differences between the two tested cultivars were noted for initial K+ concentration, but the salt tolerant cultivar lost less K+ relative to Na+ uptake than did the salt sensitive cultivar. The adverse effects of salt stress on seed germination might result from internal osmotic or restricted imbibition rather than from ion toxicity effects.