Iron sources determine cadmium uptake in spinach and lettuce: Fe‐ EDDHA enhances iron nutrition but increases cadmium accumulation

Cadmium (Cd) contamination of agricultural soils threatens crop productivity and food safety. The chemical form of iron (Fe) fertilizer can influence Cd mobility and plant uptake. This study evaluated the effects of different Fe sources on Cd accumulation, Fe nutrition, and growth of spinach and lettuce grown in Cd‐contaminated soil. Spinach was cultivated in soil amended with 30 mg Cd kg −1 and treated with FeSO 4 , FeCl 3 , or Fe‐EDDHA, while lettuce received Fe‐EDDHA at 5, 10, 20, and 40 mg Fe kg −1 . Cadmium stress reduced plant biomass in both crops. Fe‐EDDHA enhanced both Fe and Cd uptake, resulting in the highest Cd concentrations in plant tissues, reaching 315 mg kg −1 in spinach. FeCl 3 similarly increased Cd concentration in spinach during the first harvest, whereas FeSO 4 and FeCl 3 had no significant effect during the second harvest. Spectroscopic analyses suggested that inorganic Fe sources may have promoted the formation of secondary Fe‐bearing phases potentially associated with reduced Cd mobility, whereas Fe‐EDDHA may have contributed to maintaining Cd in relatively more mobile and potentially bioavailable forms through metal–organic interactions. These observations indicate that Fe source can influence Cd behavior in soil–plant systems. Although Fe‐EDDHA effectively improved Fe nutrition, its application in Cd‐contaminated soils may increase Cd uptake and therefore should be considered with caution.