Foliar zinc fertilization improves the zinc nutritional value of wheat (Triticum aestivum L.) grain

The objective of this research was to provide basic information for increasing the zinc (Zn) concentration and bioavailability in wheat grain. A field study was conducted on potential Zn-deficient soil (DTPA-Zn: 0.65 mgkg(-1)) during 2007 to 2008 and 2008 to 2009 cropping seasons to determine the effect of foliar Zn application on grain Zn and phytic acid concentrations in wheat (Triticum aestivum L. cv. Xiaoyan 22) grown on a potential Zn-deficient soil with different N fertilization rates. The results show that foliar Zn application increased grain Zn concentrations in both cropping seasons, but had no significant effect on grain yield. Foliar Zn application decreased the phytic acid concentration and the phytic acid to Zn molar ratio in wheat grain. Wheat grain Zn concentrations were at a maximum and phytic acid to Zn molar ratios were at a minimum when foliar Zn was applied during the early grain filling stage. The increase in grain Zn concentration due to foliar Zn application was higher in the no N fertilizer treatment as compared to the N fertilized treatments. Foliar Zn application had no significant effect on wheat grain protein concentration. In summary, these results indicate that foliar Zn application at the early grain filling stage significantly increased grain Zn concentration and bioavailability in wheat grown on potential Zn-deficient calcareous soils, thus improving the grain's nutritional value to humans.