SOLUTE ADJUSTMENT TO SALINITY AND CALCIUM SUPPLY IN CULTIVATED AND WILD BARLEY

Ion relations, water content, leaf water potential, and osmotic adjust ment were determined for cultivated barley (cv Harrington) and wild ba rley grown under mixed sulphate (SO4) salts with varied calcium (Ca) s upply using a hydroponic system. Salinity induced significant increase s of leaf, stem and root sodium (Na) concentrations in both species. S alt-stressed wild barley roots accumulated more Na than shoots, and tr ansport of Na from roots to shoots was low compared to Harrington. Cul tivated barley had lower Ca concentrations than wild barley, especiall y in the low Ca salt treatment. Although potassium (K/Na) and Ca/Na ra tios were higher in control wild barley plants than in Harrington, the y declined under salt stress, irrespective of Ca supply. Major osmotic a in wild barley leaves were K, sugars, organic acids, and quaternary ammonium compounds, while in Harrington they were cations, including N a, K and Mg, and anions such as phosphate (PO4) and SO4. Wild barley m aintained better water status than Harrington under low Ca salt treatm ent. Supplemental Ca improved water status more in Harrington than in wild barley. Lack of osmotic adjustment to salinity in wild barley app arently resulted from its ion exclusion. Low Ca salt treatment caused Ca deficiency, Na toxicity, and loss of turgor in Harrington. In the h igh Ca salt treatment, Harrington had improved water and ion relations , as well as positive turgor.