Zinc (Zn) is an important micronutrient for the growth and development of plant and humans, and dietary Zn shortage is a global wide nutritional problem. A field experiment was conducted to investigate the effects of foliar Zn application at different growth stages on grain yield, grain mineral nutrients and its relation to phytic acid content in spring wheat grown on Zn-deficient soil during the 2013–2014 growing season at Maragheh University research field, Iran. Results showed that foliar spray of zinc sulfate at different growth stages, in general, had non-sig- nificant effect on thousand grain weight and harvest index, while considerably increased grain yield, number of grains per spike, fertile spikelet per spike and plant height. Zinc and ascorbic acid contents in the grain consistently increased with the timing of the foliar Zn application and were highest at early grain filling stage. However, the timing of the Zn application had no effect on copper and phytic acid contents, but changed grain iron and manganese concentrations, and decreased phytate to Zn molar ratio of wheat grains. Results indicated that foliar Zn application at the booting ? milking stages significantly increased agronomic traits, grain Zn content and bioavailability in wheat grown on Zn deficient alkaline soils, thereby improving the wheat grain’s nutritional quality for humans.
