Agronomic biofortification of wheat with zinc through co‐addition of organic carbon with zinc fertilizers

Abstract Zinc malnutrition ranks fifth in terms of the leading cause of disease in developing countries. Agronomic biofortification is an effective way to increase micronutrient concentrations in grain crops. A greenhouse experiment was conducted to investigate the effectiveness of various Zn sources (organic and inorganic) with and without organic C‐based co‐additives (AVAIL and humic acid) on the biofortification of wheat ( Triticum aestivum L.) with Zn in a mildly calcareous soil. Specifically, the objective is to determine the distribution (stems/leaves, whole grain, bran, and flour) and bioavailability of Zn in different plant parts. The results of this study indicated that application of inorganic Zn in various forms significantly increased grain yield from 26% to 41% compared with the fertilized control. Similarly, grain Zn concentration in wheat increased by 58% when applied as ZnO and by 30% when Zn is applied as ZnSO 4 . Flour phytate (PA) to Zn ratio with the addition of Zn as ZnSO 4 and ZnO with and without co‐additives to the soil was relatively lower (<8) than with the addition of granular Zn (>10) treatments (MAP‐ZnSO 4 and MAP‐ZnO), with and without co‐additives, and low PA:Zn ratio ensures increased Zn bioavailability. Between the two, less soluble ZnO showed more promising results (greater Zn concentration in whole grain, bran, and aboveground biomass) compared to soluble ZnSO 4 . Co‐additives did not improve soil Zn extractability or Zn uptake by wheat. We concluded that Zn application resulted in successful biofortification of wheat grain with Zn while simultaneously increasing yield. This is a greenhouse study under controlled environmental conditions, and therefore, we recommend further field research in multiple years and locations to confirm or challenge these results.