Plant-ZnO nanoparticles interaction: An approach to improve guinea grass (Panicum maximum) productivity and evaluation of the impacts of its ingestion by freshwater teleost fish.

We aimed to evaluate the possible effects of the application of zinc oxide nanoparticles [ZnO NPs; 68.96 ± 33.71 nm; at 100 and 500 mg/kg in a soil mixture of the Typic Dystrophic Red Latosol type and sand (2:1 ratio)] in the cultivation of Panicum maximum (until 125 days), using different biomarkers in addition to evaluating the uptake of Zn by the plants. Furthermore, we assessed the possible transfer of ZnO NPs from P. maximum leaves to zebrafish and their potential. Plants cultivated in substrates with ZnO NPs at 500 mg/kg showed reduced germination rate and growth. However, at 100 mg/kg, plants showed higher biomass and productivity, associated with higher Zn uptake, without inducing oxidative and nitrosative stress. Zinc content in zebrafish was not associated with ingesting leaves of P. maximum cultivated in substrate containing ZnCl or ZnO NPs or with genotoxic, mutagenic, and biochemical effects. In conclusion, ZnO NPs (at 100 mg/kg) are promising in the cultivation of P. maximum, and their ingestion by zebrafish did not cause changes in the evaluated biomarkers. However, we recommend that studies with other animal models be conducted to comprehensively assess the ecotoxicological hazard associated with applying ZnO NPs in soil.