Emerging 3-Hydroxy-4-pyridinone Iron Chelates for Iron Deficiency Chlorosis in Soybean: From Molecular Design to Nanofertilizer Delivery

Iron deficiency chlorosis (IDC) is a nutritional disorder that adversely affects plants, particularly in calcareous and alkaline soils. The condition arises due to low solubility of iron (Fe) in the soil, which affects effective nutrient uptake and crop yields. The need to address agricultural challenges associated with Fe deficiency, while enhancing crop nutritional value, requires the identification of chelators capable of forming Fe chelates with properties that promote more efficient plant uptake and maintenance of metal homeostasis. Commercial fertilizers suffer from poor biodegradability and potential environmental risks. Chelates derived from 3-hydroxy-4-pyridinones (3,4-HPO) have emerged as a promising alternative, demonstrating increased Fe bioavailability without evidence of persistence in leaching waters. In parallel, delivery systems have gained attention as potential enhancers of nutrient uptake, improving crop yields under alkaline stress, while offering economic and environmental benefits. This Review summarizes the studies regarding the use of 3,4-HPO Fe chelates for IDC correction in soybean crops.