SALINITY-CALCIUM INTERACTIONS ON ROOT-GROWTH AND OSMOTIC ADJUSTMENT OF 2 CORN CULTIVARS DIFFERING IN SALT TOLERANCE

The effects of NaCl-salinity and supplemental CaCl2 on root elongation and osmotic adjustment were investigated for two corn (Zea mays L.) cultivars, Pioneer hybrid 3906 and Dekalb hybrid XL75. Increasing concentrations of NaCl (0 to 120 mM) progressively inhibited root elongation. Root elongation of Pioneer hybrid 3906 was more sensitive to salinity than that of Dekalb hybrid XL75. The osmolality of the growing zone of salt-stressed roots increased with increasing salinity. High Ca2+ increased the osmolality for both cultivars. Dekalb hybrid XL75 had a greater response to Ca2+ than that of Pioneer hybrid 3906. The concentrations of soluble sugars, amino acids, proline, Na+, K+ and Cl- were determined to assess which solutes were involved in osmotic adjustment. Sodium and Cl- were the principal solutes involved, although minor increases in K+ and soluble sugars were also observed. We found no significant effects of salinity or Ca2+ on concentrations of proline or amino acids.