Effect of CeO2, TiO2 and SiO2 nanoparticles on the growth and quality of model medicinal plant Salvia miltiorrhiza by acting on soil microenvironment

In this study, a six-month pot experiment was conducted to explore the effects of nanoparticles (NPs), including CeO 2 , TiO 2 and SiO 2 NPs at 200 and 800 mg/kg, on the growth and quality of model medicinal plant Salvia miltiorrhiza . A control group was implemented without the application of NPs. Results showed that NPs had no significant effect on root biomass. Treatment with 200 mg/kg of SiO 2 NPs significantly increased the total tanshinone content by 44.07 %, while 200 mg/kg of CeO 2 NPs were conducive to a 22.34 % increase in salvianolic acid B content. Exposure to CeO 2 NPs induced a substantial rise in the MDA content in leaves (176.25 % and 329.15 % under low and high concentration exposure, respectively), resulting in pronounced oxidative stress. However, TiO 2 and SiO 2 NPs did not evoke a robust response from the antioxidant system. Besides, high doses of CeO 2 NP-amended soil led to reduced nitrogen, phosphorus and potassium contents. Furthermore, the NP amendment disturbed the carbon and nitrogen metabolism in the plant rhizosphere and reshaped the rhizosphere microbial community structure. The application of CeO 2 and TiO 2 NPs promoted the accumulation of metabolites with antioxidant functions, such as D-altrose, trehalose, arachidonic acid and ergosterol. NPs displayed a notable suppressive effect on pathogenic fungi ( Fusarium and Gibberella ) in the rhizosphere, while enriching beneficial taxa with disease resistance, heavy metal antagonism and plant growth promotion ability ( Lysobacter , Streptomycetaceae, Bacillaceae and Hannaella ). Correlation analysis indicated the involvement of rhizosphere microorganisms in plant adaptation to NP amendments. NPs regulate plant growth and quality by altering soil properties, rhizosphere microbial community structure, and influencing plant and rhizosphere microbe metabolism. These findings were beneficial to deepening the understanding of the mechanism by which NPs affect medicinal plants. • The addition of 200 mg/kg of SiO 2 NPs significantly increased the total tanshinone content. • TiO 2 NPs and 200 mg/kg of CeO 2 NPs tended to facilitate the accumulation of salvianolic acid B. • Exposure to NPs reduced the relative abundances of Fusarium and Gibberella . • The NP amendment disturbed the carbon and nitrogen metabolism in the plant rhizosphere.