Physiological basis of salt tolerance in plants.

Abstract

For most plants, and under most field conditions, osmotic effects of salinity greatly predominate in restricting growth and yields. In certain cases, however, specific ion effects may be decisive. These may involve either nutrition, as in calcium deficiency in some lettuce varieties, tomato, and bell peppers, or direct toxicity (chloride or sodium toxicity, or both) in tree and vine crops. Rootstocks, or varieties that restrict the uptake of toxic ions, increase the salt tolerance of some susceptible fruit crops. Salinity-induced nutritional imbalance can, in some cases, be corrected by selecting better adapted varieties and in others by the use of foliar nutrient sprays. Recent evidence indicates simple single-gene control over uptakes of chloride and sodium, but the more general osmotic effects appear to be complex and under multigenic control.