Roles of Soil and Foliar Spray of Zinc Nutrition in Cadmium Reduction of Wheat Grain

This study investigates the role of soil and foliar application of zinc (Zn) in reducing the accumulation of cadmium (Cd) in wheat grains grown on Zn-depleted and Cd-contaminated soils. In particular, the effects of increasing Cd doses (0.0, 0.2, 1.0, and 5.0 mg Cd kg–1 soil) on wheat grain quality were investigated. The results showed that the combined application of soil and foliar Zn significantly increased the grain yield of wheat and reduced Cd accumulation. Specifically, foliar Zn application increased grain yield by 49.75% in Cd-free soils and by 32.79% in soils with elevated Cd5 content (the highest dose of 5 mg Cd kg–1) compared to inadequate Zn fertilization. In addition, foliar Zn application reduced the Cd concentration in grains by 70.49% in Cd-free soils and by 9.31% in Cd5 soils. In terms of nutrient uptake, foliar Zn applications led to an increase in grain Zn concentration by 77.67% in Cd0 and 173.06% in Cd5. However, the concentration of phosphorus and manganese decreased with high Zn applications and increased Cd doses. These results underline the importance of Zn management in Cd-polluted soils and provide information on how to improve wheat quality and minimize Cd pollution of crops.