Osmotic sensitivity in relation to salt sensitivity in germinating barley seeds

Abstract Cultivars of barley (Hordeum vulgare L.) were tested for germination sensitivity to progressively higher concentrations of salt, mannitol, and betaine. The three solutes were equally inhibitory at equal osmotic potential, but there was a consistent difference in osmotic sensitivity between two cultivars, CM-67 and Briggs (Briggs was the most sensitive). There was no difference between the two cultivars in salt or water uptake from salt solutions during imbibition. Brief presoaking in water did not improve salt resistance, indicating that a hydration-dependent decrease in membrane permeability is not involved in salt tolerance. The calcium content of Briggs was higher than CM-67. These results suggest that salt inhibits barley germination primarily by osmotic effects, and that salt influx during imbibition does not play a role in this inhibition. A hypothesis regarding salt effects on germination is discussed.