Effects of Low Nitrogen and Low Phosphorus Stress on Iron, Zinc and Phytic Acid Content in Two Spring Bread Wheat Cultivars

Iron (Fe) and zinc (Zn) deficiency in cereal grains has deleterious effects on the health of millions of people, especially in developing countries. As wheat, as a staple crop, is consumed in large quantities, its micronutrient content is important. Crops in Africa are often grown under low nitrogen (N) and low phosphorous (P) conditions. The aim of this study was to determine the effect of low N and low P stress on Fe and Zn and phytic acid concentration, in two commercial spring wheat cultivars with excellent baking quality. The two cultivars did not differ significantly for the measured characteristics. Across all treatments the average values for Fe varied between 19.60-28.61 mg kg^-1, Zn between 17.68-33.79 mg kg^-1 and phytic acid between 5.03-6.92 mg g^-1. Low P stress lead to the highest values of Fe and Zn, and the lowest value for phytic acid. Phytic acid:Fe and phytic acid:Zn ratios were also highly significantly reduced under low P stress conditions. Low N conditions caused significantly increased Zn levels. Despite this, the phytic acid:Fe and phytic acid:Zn ratios were relatively high under all conditions, indicating a low bioavailability of both Fe and Zn in these wheat cultivars.