ASHS 2025 Conference

Iron (Fe) is an essential micronutrient involved in numerous metabolic processes and is vital for proper growth and development in plants and humans. However, in humans, dietary Fe deficiency is one of the leading micronutrient deficiencies affecting approximately 10 million people in the U.S., and over 1 billion people worldwide. Fe deficiency can lead to many health complications, including Fe deficiency anemia. Pregnant women and young children are particularly at risk for developing Fe deficiency and severe consequences can result in maternal and neonatal deaths during pregnancy. Improving dietary Fe intake is critical and utilizing agronomic approaches to enhance Fe levels in plants could be a viable, sustainable solution. Microgreens are a noteworthy nutritional source and are a convenient candidate crop for agronomic Fe biofortification as they can be grown quickly, have low anti-nutrient levels, require fewer inputs for cultivation, and can be consumed raw. Conventional Fe fertilizers like ferrous sulfate (FeSO4) have been widely used in agriculture and research for Fe biofortification, however in oxidizing and alkaline conditions, plant Fe uptake is reduced, even with sufficient levels present in the environment. Various studies have reported the use of Fe chelate and Fe nanofertilizers as an alternative, more efficient option for improving Fe availability, than conventional Fe fertilizers. However, there is limited information comparing multiple Fe fertilizer sources and their effectiveness in Fe biofortification in microgreens. Herein, we investigate, in a soilless system, the effect of different Fe sources (Ferrous sulfate, Ferric sulfate, Fe-EDTA, Fe-EDDHA, Fe-NP) applied via fertigation at different concentrations (0, 15, 30, 45 mg/L of Fe) on the Fe content in radish and pea microgreens. We found that Fe-EDTA was the most effective fertilizer source and increased Fe content by 2-3-fold in pea microgreens and 3-5-fold in radish microgreens, compared to the untreated control. Additionally, Fe-EDTA treatments increased Zn concentration by 5-20% in pea microgreens. In radish microgreens, however, we found that the same treatments showed slight phytotoxicity symptoms and reduced fresh and dry biomass. Further evaluation of Fe sources and concentrations is needed to avoid compromising yield and nutritional quality. However, these results suggest that using alternative Fe fertilizers through fertigation can improve Fe concentration in pea and radish microgreens more effectively than standard sources. Fe-enriched microgreens may be used as functional foods to combat Fe malnutrition at both individual household and larger community scales.