Improved agronomic biofortification of sweetcorn achieved using foliar rather than soil Zn applications

Abstract

Background and Objectives This field and glasshouse study evaluates the relative effectiveness of agronomic zinc biofortification strategies to increase the Zn concentration in sweetcorn (Zea mays) kernels for human health, using applications of Zn fertilizer to the root‐zone or to foliage. Findings Plants accumulated additional Zn as the rate of Zn applied to the root‐zone increased, but most was retained in the stems and foliage and little was translocated into the kernels (≤7%). A large proportion of the additional Zn stored in the foliage was in the form of Zn‐phytate. In contrast, in field‐grown plants where soil Zn was adequate for maximizing commercial yields, Zn applications to foliage increased kernel Zn concentrations by up to 100%. ZnSO4·7H2O was more effective to use in foliar applications compared with Zn‐EDTA. Conclusion The elevated kernel concentrations recorded for two varieties (59.1 and 71.1 mg Zn kg−1) were greater than all previously reported biofortification responses from maize. These concentrations also matched or exceeded the HarvestPlus target of 60 mg Zn kg−1 for maize. Significance and Novelty With a total kernel Zn content of 3.6 mg Zn per cob, approximately 25%–45% of the recommended dietary Zn intake could be met with one cob of Zn‐biofortified sweetcorn.