Effects of sodium, potassium and calcium on salt-stressed barley

We grew barley ( Hordeum vulgare L. CM 72) for a 28-day period and sequentially harvested plants every 3 or 4 days. Plants were salt-stressed with either NaCl or KCl (125 m M ) with or without supplemental Ca (10 or 0.4 m M final concentration, respectively). We determined tissue concentrations of Na, Ca, Mg, K. S, P, Fe, Mn, Cu and Zn for each harvest date by inductively coupled plasma spectrometry. Uptake (specific absorption rate) was calculated from the element content and growth rates. Salinity had significant effects on the uptake and concentrations of most elements. Mg and Mn concentrations declined with time. The concentrations of all other elements determined increased over time. Element uptake on a root dry weight basis declined with time. Three variables were significantly affected by salinity and correlated with growth; 1) the Ca concentration, 2) the total sum of the cation concentration (TC), and 3) the Mn concentration of the shoot. Salinity reduced Ca uptake and concentrations. Supplemental Ca increased Ca concentrations and was positively correlated with growth during salt stress. Salinity doubled TC, which was negatively correlated with relative growth rate (RGR). Relative growth rate declined at TC values above 150 m M . Salinity reduced the uptake and concentration of Mn. Manganese concentrations in the shoot were highly correlated with RGR. Relative growth rate declined at Mn concentrations below 50 nmol (g fresh weight)⁻¹.