Improved iron use efficiency in tomato using organically coated iron oxide nanoparticles as efficient bioavailable Fe sources

Abstract Background Iron [Fe] deficiency is one of the nutritional issues of plants, especially in calcareous soils in which iron-fertilizers are used to solve this obstacle. Due to the pivotal role of iron, the introduction of efficient, cost-effective, and eco-friendly strategies is necessary to prevent its deficiency in plants. The nanoparticle-based formulations may provide efficient bioavailability, subsequently, reduce the amount of the required dosage of nutrients for extended periods, and decrease the environmental risks. Results In this study, the effects of different iron nanoparticles (NPs) including Fe 3 O 4 nanoparticles (Fe 3 O 4 ), citric acid coated Fe 3 O 4 nanoparticles (Fe 3 O 4 @CA), humic acid coated Fe 3 O 4 nanoparticles (Fe 3 O 4 @HA), and EDTA coated nanoparticles (Fe 3 O 4 @EDTA) were investigated as iron [Fe] sources on the vegetative growth and physiological parameters of tomato as a model plant in a soil system. The experimental results showed that the organically coated Fe 3 O 4 NPs significantly increased the amount of [Fe] in the shoot and enhanced its growth. The highest and lowest amount of [Fe] was observed in the Fe 3 O 4 @HA NPs and control treatments, respectively. In addition, using organically coated Fe 3 O 4 NPs, especially Fe 3 O 4 @HA increased plant growth and yield. Conclusions This study showed that using organically coated Fe 3 O 4 NPs is promising for plant nutritional supplementation. In particular, the humic acid-coated Fe 3 O 4 nanoparticles (Fe 3 O 4 @HA) were determined to be the most promising, due to more benefits for plant growth and yield compared to Fe 3 O 4 NPs. Therefore, Fe 3 O 4 @HA nanofertilizer can be introduced as an inexpensive, effective, bioavailable, and biocompatible option to address [Fe] deficiency in the soil. Graphical Abstract