Speciation-Dependent Iron Uptake Drives Biofortification Efficiency and Nutritional Quality in Radish and Pea Microgreens

In plants and humans, adequate levels of iron (Fe) are essential for proper growth and development. Dietary deficiencies in Fe are particularly prevalent and can cause numerous physical and cognitive impairments in humans. Intervention strategies like agronomic biofortification can address these issues by utilizing fertilization to enhance the Fe content in a quick and straightforward manner in plant-based foods. Microgreens are nutritional powerhouses with low antinutrient levels, making them a promising candidate crop for agronomic Fe biofortification. Although Fe fertilization can increase Fe’s abundance in the environment, Fe’s availability is limited to plants in alkaline and oxidizing conditions. Therefore, selecting an efficient Fe fertilizer source is crucial for successful Fe enrichment. In this study, we investigated the effects of five alternative Fe fertilizers, including chelated Fe sources (Fe-EDDHA, Fe-EDTA), inorganic Fe salts (ferric sulfate, ferrous sulfate), and Fe-oxide nanoparticles (Fe 3 O 4 ), provided via fertigation at different concentrations (0, 15, 30, 45 mg/L), on the Fe enrichment, yield, and quality of radish and pea microgreens. Fe-EDTA was the most effective treatment for Fe enrichment, increasing Fe content by 3-5-fold in radish and 2-3-fold in pea microgreens, compared to the untreated control, with minimal trade-offs in yield and mineral composition. Fe-EDTA also ensured greater contributions to Fe’s recommended dietary allowance (RDA) for adult males and females, compared to the other sources. These findings highlight the potential of Fe-EDTA in enriching microgreens that can serve as functional foods to combat Fe deficiencies at household and community scales.