Germination and seedling growth of cotton: salinity‐calcium interactions

Abstract

Abstract. The effects of NaCl salinity on germination and early seedling growth of cotton were studied. Germination was both delayed and reduced by 200 mol m−3 NaCl in the presence of a complete nutrient medium. Seedlings, 7–9 d old, were greatly reduced in fresh weight by salinity. The addition of supplemental Ca2+ (10 mol m−3 as SO42− or Cl−) to the medium did not improve germination but, to a large degree, offset the reduction in root growth caused by NaCl. Roots growing in the high salt medium without supplemental Ca2+ appeared infected by microbes. The cation specificity of the beneficial Ca2+ effect on growth was ascertained by testing additions of MgSO4 or KCl to the NaCl treatments. The contents of K4 and Ca2+ were reduced in both roots and shoots by the NaCl treatments. Supplemental Ca2+ partially offset this effect for K4 in the roots and for Ca2+ in both roots and shoots. Sodium contents were not affected by the supplemental Ca2+. It is concluded that the beneficial effect of high Ca2+ concentrations on root growth of cotton seedlings in a saline environment may be due to maintenance of K/Na‐selectivity and adequate Ca status in the root.