Effects of salinity on accumulation of mineral nutrients in wheat grown with nitrate-nitrogen or mixed ammonium : nitrate-nitrogen

Two cultivars of wheat (Triticum aestivum cvs. Fresco and Hussar) were grown in hydroponic culture with nitrogen (N) supplied either as nitrate or equimolar ammonium and nitrate, and with a range of concentrations of NaCl from 0 to 100 mM. Plant growth was stimulated by low concentrations of NaCl and was depressed by high concentrations of NaCl. Growth was higher with mixed N nutrition than with nitrate supplied alone at all rates of NaCl supply. Shoot: root ratio was also depressed by salinity. Concentrations of potassium (K) decreased with salinity and were generally higher with mixed N supply, whereas concentrations of Na were higher with salinity and lower with mixed N supply. There were strong positive linear relationships between total plant dry mass and the concentrations of copper (Cu) in the roots and strong negative linear relationships between total plant dry mass and the concentrations of manganese (Mn) in both shoots and roots and zinc (Zn) in the shoots. The concentrations of Cu in the roots were higher with mixed N supply, lower with high salinity, and the concentrations of Mn in both shoots and roots were lower with mixed N supply and generally higher with high salinity. Tissue concentrations of these ions appear to be major determinants of wheat growth in saline environments.