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