Physiological effects of magnetite (Fe3O4) nanoparticles on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta) plants

To date, knowledge gaps and associated uncertainties remain unaddressed on the effects of nanoparticles (NPs) on plants. This study was focused on revealing some of the physiological effects of magnetite (Fe3O4) NPs on perennial ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta cv. white cushaw) plants under hydroponic conditions. This study for the first time reports that Fe3O4 NPs often induced more oxidative stress than Fe3O4 bulk particles in the ryegrass and pumpkin roots and shoots as indicated by significantly increased: (i) superoxide dismutase and catalase enzyme activities, and (ii) lipid peroxidation. However, tested Fe3O4 NPs appear unable to be translocated in the ryegrass and pumpkin plants. This was supported by the following data: (i) No magnetization was detected in the shoots of either plant treated with 30, 100 and 500 mg l(-1) Fe3O4 NPs; (ii) Fe K-edge X-ray absorption spectroscopic study confirmed that the coordination environment of Fe in these plant shoots was similar to that of Fe-citrate complexes, but not to that of Fe3O4 NPs; and (iii) total Fe content in the ryegrass and pumpkin shoots treated with Fe3O4 NPs was not significantly increased compared to that in the control shoots.