Cadmium (Cd) Minimization and Zinc (Zn) Biofortification in Wheat (Triticum aestivum L.) Grains by Spraying with the Foliar Zn Fertilizer in Cd-Contaminated Fields

Abstract

The foliar application of zinc (Zn) has been regarded as a practical and economical way to reduce grain cadmium (Cd) accumulation and enhance grain quality in crops. Herein, a two-year field experiment was carried out to examine the efficacy of different application rates of the foliar Zn fertilizer in Cd reduction and microelement biofortification in wheat (Triticum aestivum L.) grains. The results show that the T4 and T5 treatments, 500 and 250-fold dilution of the foliar Zn fertilizer, respectively, increased the grain yield to varying degrees in the two years. When compared with controls and based on the average of the two years’ results, spraying with the foliar Zn fertilizer remarkably decreased grain Cd concentrations (44.5%), Cd translocation from stem to grain (TFStem/Grain) (4.92%), the HRI values of Cd (45.5%), PA/Ca (27.8%), PA/Fe (21.4%) and PA/Mn (5.81%) under the T2 treatment (1000-fold dilution). Furthermore, the T2 treatment significantly increased the Zn (37.8%), Ca (48.9%), Fe (37.6%), Mn (14.8%) and total protein (7.92%) contents and the estimated Zn bioavailability (28.9%) in wheat grains after two years. All these findings suggest that the foliar Zn fertilizer holds considerable promise as a safe crop production technique and a means of mitigating “hidden hunger” in developing countries.