The optimum Ca2+ concentration for growth of cotton (Gossypium hirsutum cv. Acala SJ-2) was in the range 1 to 15 mol m–3 for plants growing in hydroponic culture with 100–150 mol m–3 NaCl. Most saline (but not sodic) soils contain higher Ca2+ concentrations. CaCl2 was inhibitory to the growth of cotton above 20–50 mol m–3. Increasing concentrations of Ca2+ in the range 0–2 mol m–2 drastically reduced Na+ accumulation in the leaves. As CaCl2 concentrations were increased above the optimum for growth there was a further reduction in leaf Na+ accumulation, but this was more than offset by increased leaf Ca2+ and Cl– concentrations. Leaf K+ concentrations were not much affected by changes in external CaCl2 concentrations. The response of Mg2+ varied from an increase to a decrease with increasing external CaCl2 and was influenced by nutritional status. There was no evidence that high Ca2+ caused a deficiency of Mg2+ in cotton. Except for Cl–, whose concentrations tended to decrease initially and then increase as the CaCl2 concentration increased, the anions were largely unaffected by changes in external CaCl2.
Gorham, J.; Bridges, J. Effects of calcium on growth and leaf ion concentrations of Gossypium hirsutum grown in saline hydroponic culture. Plant and Soil (1995) 176 (2) 219-227. [DOI: 10.1007/BF00011785]