The impact of cerium oxide nanoparticles on the physiology of soybean (Glycine max (L.) Merr.) under different soil moisture conditions

The ongoing global climate change raises concerns over the decreasing moisture content in agricultural soils. Our research investigated the physiological impact of two types of cerium oxide nanoparticles (CeO2NPs) on soybean at different moisture content levels. One CeO2NP was positively charged on the surface and the other negatively charged due to the polyvinylpyrrolidone (PVP) coating. The results suggest that the effect of CeO2NPs on plant photosynthesis and water use efficiency (WUE) was dependent upon the soil moisture content. Both types of CeO2NPs exhibited consistently positive impacts on plant photosynthesis at the moisture content above 70% of field capacity (θfc). Similar positive impact of CeO2NPs was not observed at 55% θfc, suggesting that the physiological impact of CeO2NPs was dependent upon the soil moisture content. The results also revealed that VCmax (maximum carboxylation rate) was affected by CeO2NPs, indicating that CeO2NPs affected the Rubisco activity which governs carbon assimilation in photosynthesis. In conclusion, CeO2NPs demonstrated significant impacts on the photosynthesis and WUE of soybeans and such impacts were affected by the soil moisture content.