The efficiency of Fe3O4 nanoparticles coated with humic acid on tomato growth characteristics (Lycopersicon esculentum L.)

Iron is one of the essential elements for plant growth. Iron deficiency is one of the problems of calcareous soils in Iran. In order to investigate the effect of iron nanoparticle composite coated with humic acid on the agricultural characteristics of tomato plants, a factorial greenhouse experiment was conducted in the form of a completely randomized design with three replications. The test factors include the first factor, the type of iron fertilizer (iron sulfate and iron nanoparticles Fe3O4), the second factor of humic acid (use of humic acid and the absence of use of humic acid), the third factor of iron concentrations (0, 25, 50, 75, 100, 200) mg/kg. Infrared spectroscopy results showed that nanoparticles coated with humic acid behaved differently than iron nanoparticles due to the creation of new functional groups. Also, the results showed that Fe3O4 nanoparticles coated with humic acid at a concentration of 50 mg/kg caused a significant increase in plant height (31%), shoot fresh weight (68%), and iron concentration in the plant by 2.4 times) compared to the control treatment (treatment without fertilizer). The results of this research show that applying Fe3O4 nanoparticles coated with humic acid for agricultural products can improve the agronomic characteristics of tomatoes, so this fertilizer can be introduced as a suitable option for providing the iron needed by the plant.