Comparative effects of nano and bulk-Fe₃O₄ on the growth of cucumber (Cucumis sativus)

Cucumber (Cucumis sativus) plants were cultivated in hydroponic media with nano and bulk- iron oxide (Fe₃O₄) (50, 500 and 2000 mg/L) over a period of 21 days. At the low concentration (50 mg/L), nano-Fe₃O₄ resulted in reduction of biomass and enzyme activities compared to the control. However, at the higher concentration of nano-Fe₃O₄ dosage (2000 mg/L), there was a significant increase in biomass, antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD). In contrary, the high concentration of bulk-Fe₃O₄ caused phytotoxicity in terms of biomass and enzymes activity. The phytotoxicity was dependent on the particles property (mainly sizes and aggregation) for nano-F3O4 and concentration dependent for bulk-Fe₃O₄. The particle size is an important factor that can influence the bioavailability of nanomaterials, which need to be included when evaluating the exposure of nanomaterials and their deleterious effects in the environment. These promising results can help to develop the possible application of Fe₃O₄ NPs which may improve nutrient management to overcome food security.