Effects of Saline lrrigation Water and Zn Application on Soil Cd Solubility and Cd Concentration in Wheat

A factorial experiment with two levels of Zn (0 and 1.5 mg Zn kg-1), five salinity levels of irrigation water (0, 60, 120 and 180 mM NaC1, and 120 mM NaNO3) in three replications was conducted. Wheat (Triticum aestivum cv. Roshan) was seeded in pots. After plant harvesting, zinc and cadmium concentrations were determined in the shoot. Activities of metal species in the soil solution were predicted using the computer program MINTEQA2. Treating the soil with NaC1-salinized water increased total concentration of cadmium (CdT) as well as Cd2+, CdC102, and CdCl+ species whereas, NaNO3 treatment had no significant effect on CdT. Shoot Cd concentrations were positively related to CdT and soil solution Cl- but negatively related to ZnT. Application of Zn-fertilizer decreased Cd and increased Zn concentrations in shoot, significantly. The results of this experiment showed that Cl- has an effective role in increasing mobility of soil Cd and its uptake by plant.