Foliar Zinc, Nitrogen, and Phosphorus Application Effect on Micronutrient Concentrations in Winter Wheat

Although foliar application of Zn is highly efficient in improving Zn concentration in wheat (Triticum aestivum L.) grain, it may be beneficial to better understand its effectiveness when combined with foliar applications of N or P. A 2-yr field experiment was conducted to evaluate the efficacy of concurrent ZnSO4, and commonly used N and P applications on grain Zn, and other nutritional quality indices in wheat. On average, grain Zn concentration increased by 84,83, and 55% following foliar application of Zn, Zn+N, and Zn+P, respectively. The Zn concentration following foliar application was much greater in the leaves than in the glume or stem. The reduction in the Zn content and the distribution of Zn in the grain and leaves was similar following foliar-applied Zn and foliar-applied Zn+P. This suggests that absorption of Zn in the vegetative tissues (e.g., leaf) was reduced with the addition of P in the foliar spray, but translocation of Zn from the leaf to grain was not inhibited by P. Foliar Zn+N application significantly increased grain protein, Fe, and Ca concentrations, and foliar Zn+P application significantly increased Fe and Ca concentrations. Foliar application of Zn, Zn+N, and Zn+P significantly decreased grain phytic acid (PA)/Zn, PA/Fe, and PA/Ca molar ratios. The results of this study suggest that the inclusion of Zn in commonly used foliar applications of N or P may be effective for increasing grain Zn concentration in wheat.