Salt Stress and Comparative Physiology in the Gramineae. IV. Comparison of Salt Stress in Spartina × townsendii and Three Barley Cultivars

Abstract

The possible significance of the compartmentation of major solutes between cytoplasm and vacuole is described. The barley cultivars appear to have a restricted ability, by comparison with S. × townsendii, to exploit Na⁺ and Cl^- as major vacuolar ions and contributors to osmotic adjustment. They also appear less able to maintain a basal K- supply in the presence of Na⁺. The basal K⁺ supply to the shoot is interpreted as a requirement for a minimal cytoplasmic K⁺ concentration. The role of glycinebetaine and proline as cytoplasmic osmotic effectors is discussed. It is concluded that, in these hydroponic experiments, the synthesis of glycinebetaine and proline is not a limitation on the salt tolerance of these species.