Growth and Photosynthetic Inhibition of Cerium Oxide Nanoparticles on Soybean ( Glycine max )

Cerium oxide nanoparticles (CeO 2 NPs) are widely used in industries and have caused environmental problems. However, the phytotoxicity induced by CeO 2 NPs lacks detailed information on phytotoxicity. In this research, the effect of CeO 2 NPs on soybean plants ( Glycine max ) was studied. Scanning electron microscopy with the energy dispersion spectroscopy was used to characterize the NPs form in soybean. The growth of the root was increased, whereas the growth of shoot was inhibited. Besides, Chlorophyll Fluorescence Imager (CF Imager) showed that chlorophyll synthesis was inhibited: the maximum quantum yield of Photosystem II complex (PSII) (Fv/Fm) and photochemical quenching (qP) decreased. Moreover, transmission electron microscopy revealed that the chloroplast thylakoid structure was changed, and thus reduced the energy conversion in the Calvin cycle from C5 to C3. Our work suggests that CeO 2 NPs will cause growth changes as well as irreversible damage to soybean plants. Our findings will provide evidence for estimation of plant toxicity induced by CeO 2 NPs.