Iron and Zinc Concentrations in Grain and Flour of Winter Wheat As Affected by Foliar Application

Abstract

Human deficiencies of iron (Fe) and zinc (Zn) are worldwide problems. Biofortification of wheat could reduce Fe and Zn deficiencies in societies that depend on wheat consumption. This study investigated the effects of foliar application of Fe with or without Zn on the concentrations of Fe and Zn in grain and especially in flour of three wheat cultivars. On average, grain Fe concentration was increased significantly from 29.5 mg kg(-1) in the control to 37.8, 35.9, or 34.9 mg kg(-1) by application of FeSO4, ferric citrate plus ZnSO4, or ferric citrate, respectively. As expected, grain Zn concentration was increased from 29.0 mg kg(-1) in the control to 45.7 or 39.6 mg kg(-1) by application of ferric citrate plus ZnSO4 or a complex of micronutrients. Although the Fe and Zn concentrations in flour were inherently lower than in bran and shorts made by experimental mill, the concentrations in flour were simultaneously increased from 10.4 to 12.4 mg kg(-1) for Fe and from 11.8 to 17.4 mg kg(-1) for Zn by application of ferric citrate plus ZnSO4. Importantly, Fe was peripherally localized within grain fractions and strictly limited to transport to endosperm, making it more difficult to increase the quantity of Fe in flour products by foliar Fe application, but the situation with Zn is promising because Zn is more readily transported to the endosperm than Fe. The current study increases the understanding of agronomic biofortification.

Biofortification of Wheat with Iron

“…It is for this reason that Fe is attributed to be less effective than Zn for enrichment of cereal grains [15,23]. For instance, the increase in grain Fe concentration through foliar spray of FeSO 4 or Fe chelates has not been recorded to exceed 36% [18] whilst the foliar application increases grain Zn concentration to a recorded concentration of 2-or 3-fold depending on the plant availability of Zn in soils [15,19]. Some independent studies have also showed that plants exhibit a lack of response to Fe fertilization in terms of grain Fe concentration.…”

“…These fertilizers play an effective role in improvement of gain concentration of Zn [16][17][18][19]. On the other hand, Fe fertilizers are not exploited to examine their role for improving Fe concentration in cereal gains.…”

Linking Agriculture with Health through Genetic and Agronomic Biofortification

“…Foliar application was found to be more effective in increasing grain Zn and Fe concentration in different crops. In wheat, soil based application of Zn was reported to be less effective in increasing grain compared to the foliar application, which remarkably increase grain Zn concentration [32] [69]. For instance, Yilmaz et al [67] reported three-fold increase of grain Zn concentration in durum wheat because of foliar application.…”

“…The various methods of Zn application may differentially influence yield and grain Zn concentration [19] [32]. So far, application methods such as soil application (during planting), seed dressing and foliar application were tested for their effectiveness in increasing Zn and Fe concentration in the grain [37] [65]- [67].…”

“…This has motivated crop experts to search out sustainable ways of improving nutritional contents of their crops. Among agronomic managements, grain biofortification is proved to improve the concentration of micronutrients in cereal grains [24] [31] [32]. Biofortification is defined as "the process of improving the concentration of essential minerals in the edible portion of staple food cops through agronomic practices as well as genetic selection" [42].…”