Organic acids as complexing agents for iron and their effects on the nutrition and growth of maize and soybean

Abstract

Synthetic chelating agents have high cost and low biodegradation in the environment; thus, the use of natural complexing agents for iron increases the sustainability in crop production. The aim of this study was to verify the efficiency of natural organic acids added to the nutrient solution on the Fe acquisition. For that purpose, two experiments were carried out using soybean and maize. Citric acid (CA), malic acid (MA), tartaric acid (TA), and oxalic acid (OA) were used as complexing agents for iron. Fe-EDTA (ethylenediaminetetraacetic acid) and FeSO4 were also tested. Soluble Fe and chemical speciation in a nutrient solution were determined. Organic acids maintained less complexed Fe in the nutrient solution than EDTA, but the complexed Fe fraction was not associated with the efficiency of the Fe organic acids in supplying Fe to plants. Maize and soybean treated with Fe-MA and Fe-CA had reduced plant development. For maize, the TA treatment at both SRs increased Fe accumulation and promoted Fe translocation similar to EDTA. For soybean, Fe-OA at both SRs promoted biomass, Fe accumulation, and Fe translocation similar to EDTA. Therefore, Fe complexes were able to assure plant growth and nutrition and showed effectiveness depending on the plant species.