Biofortification of Durum Wheat with Zinc Through Soil and Foliar Applications of Nitrogen

Increasing zinc (Zn) concentration of cereal grains is a global challenge to alleviate Zn deficiency-related health problems in humans caused by low dietary Zn intake. This study investigated the effects of soil- and foliar-applied nitrogen (N) and Zn fertilizers on grain Zn accumulation of durum wheat (Triticum durum) grown on a Zn-deficient soil. In addition, localization of Zn and protein within durum wheat grain was Studied by using Bradford reagent for protein and dithizone (diphenyl thiocarbazone) for Zn. Grain Zn concentration was greatly enhanced by soil or foliar applications of Zn. When Zn supply was adequately high, both soil and foliar N applications improved grain Zn concentration. Consequently, there was a significant positive correlation between grain concentrations of Zn and N, when Zn supply wag not limiting. Protein and Zn staining studies showed co-localization of Zn and protein within grain, particularly in the embryo and aleurone. Results indicate that N and Zn fertilization have a synergistic effect on grain Zn concentration. Possibly, increasing N supply contributes to grain Zn concentration by affecting the levels of Zn-chelating nitrogenous compounds or the abundance of Zn transporters. Our results suggest that nitrogen management can be an effective agronomic tool to improve grain Zn concentration.