Foliar spray of combined metal-oxide nanoparticles alters the accumulation, translocation and health risk of Cd in wheat (Triticum aestivum L.)

Nanotechnology is promising for improving sustainable crop production and ensuring food safety due to its unique properties and minimum environmental impacts. Here, we investigated the effectiveness of foliar com-bined metal-oxide nanoparticles (NPs, 100 mg/L) on cadmium (Cd) accumulation, translocation and exposure risk in wheat under field condition. Results showed that ZnO NPs combined with MgO or Fe3O4 NPs significantly increased the grain yield (13.8% and 14.8%) and straw biomass (16.9% and 18.4%) as compared to the control. Co-applied ZnO NPs with MgO, TiO2 or CeO2 NPs enhanced Cd uptake in aboveground wheat (12.4%-16.9%), while ZnO NPs combined with MnO2, CuO, Fe3O4 or Fe2O3 NPs remarkably reduced Cd concentration in wheat grains (23.8%-33.6%). According to the Cd bioaccessibility and daily intake, the health risk of Cd in wheat grains was significantly decreased by 36.1%-48.1% under ZnO NPs in combination with Fe3O4, Fe2O3, CuO or MnO2 NPs treatment. In addition, foliar spray of combined NPs also improved the nutritional quality of wheat grains by increasing micronutrients (Ca, S, Zn, Fe, B), protein content and reducing phytic acid content, especially in the combination of ZnO and MnO2 NPs. Taken together, this work demonstrates a feasible approach to achieve higher Cd removal efficiency and lower Cd levels and health risks in wheat grains with a tailored combination of metal-oxide NPs.