Overuse of Phosphorus Fertilizer Reduces the Grain and Flour Protein Contents and Zinc Bioavailability of Winter Wheat (Triticum aestivum L.)

To supplement human dietary nutrition, it is necessary to evaluate the effects of phosphorus (P) fertilizer application on grain and flour protein contents and especially on the bioavailability of zinc (Zn). A field experiment of winter wheat with six P application rates (0, 25, 50, 100, 200, 400 kg/ha) was conducted from 2013 to 2015. The grain yield increased with P application but was not further enhanced when P rates exceeded 50 kg/ha. As P application increased, the protein concentration in grain and standard flour and the viscosity of standard flour decreased. Phosphorus and phytic acid (PA) concentrations in grain and flours increased and then plateaued, whereas Zn concentration decreased and then plateaued as P application increased from 0 to 100 kg/ha. Estimated Zn bioavailability in grain and flours decreased as P application increased from 0 to 100 kg/ha and then plateaued. Estimated Zn bioavailability was greater in standard flour, bread flour, and refined flour than in grain or coarse flour. Phosphorus supply in the intensive cropping of wheat can be optimized to simultaneously obtain high grain yields, high grain and flour protein contents, and high Zn bioavailability.