Germination and seedling growth of cotton: salinity‐calcium interactions

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 Ca 2+ (10 mol m −3 as SO 4 2− 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 Ca 2+ appeared infected by microbes. The cation specificity of the beneficial Ca 2+ effect on growth was ascertained by testing additions of MgSO 4 or KCl to the NaCl treatments. The contents of K 4 and Ca 2+ were reduced in both roots and shoots by the NaCl treatments. Supplemental Ca 2+ partially offset this effect for K 4 in the roots and for Ca 2+ in both roots and shoots. Sodium contents were not affected by the supplemental Ca 2+ . It is concluded that the beneficial effect of high Ca 2+ 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.