Zinc and cadmium availability as affected by zinc fertilization and saline water irrigation in wheat (Triticum aestivum L.) grown on cadmium polluted soil

Abstract

Two-year’s study was carried out to evaluate the effect of zinc fertilization and salinity created by NaCl and NaNO3 on the fate of zinc (Zn) and cadmium (Cd) in soil and their contents in wheat grain grown in a cadmium polluted soil. Increasing NaCl rates increased total cadmium (Cd), Cd2+, CdCl+, CdHCO3+, and CdCl2O concentrations in soil solution, whereas no such effects were found for the NaNO3 treatments. Higher salt content of saline irrigation water decreased total zinc (Zn) and free Zn2+ concentrations in soil solution and also reduced Zn concentration in the wheat grain. Zinc fertilization enhanced grain Zn contents but reduced that of Cd. Increasing salt concentration in irrigation water decreased plant dry matter and grain number per ear head especially, when no zinc was applied. Application of zinc had positive effects on the salt tolerance of plant and increased dry matter yield and grain number per ear head. Chloride mobilizes soil Cd and increased its bio-availability; therefore, higher Cd in wheat grain is mainly attributed to increased soil Cl concentration with the use of NaCl irrigation water. The results indicated that Zn application reduces Cd concentration in grain produced on Cd polluted soils. Key words: Salinity, zinc fertilization, wheat, cadmium (Cd) polluted soils.