Monitoring the Environmental Effects of CeO2 and ZnO Nanoparticles Through the Life Cycle of Corn (Zea mays) Plants and in Situ μ-XRF Mapping of Nutrients in Kernels
2015
Zhao, Lijuan | Sun, Youping | Hernandez-Viezcas, Jose A. | Hong, Jie | Majumdar, Sanghamitra | Niu, Genhua | Duarte-Gardea, Maria | Peralta-Videa, Jose R. | Gardea-Torresdey, Jorge L.
Information about changes in physiological and agronomic parameters through the life cycle of plants exposed to engineered nanoparticles (NPs) is scarce. In this study, corn (Zea mays) plants were cultivated to full maturity in soil amended with either nCeO₂ or nZnO at 0, 400, and 800 mg/kg. Gas exchange was monitored every 10 days, and at harvest, bioaccumulation of Ce and Zn in tissues was determined by ICP-OES/MS. The effects of NPs exposure on nutrient concentration and distribution in ears were also evaluated by ICP-OES and μ-XRF. Results showed that nCeO₂ at both concentrations did not impact gas exchange in leaves at any growth stage, while nZnO at 800 mg/kg reduced net photosynthesis by 12%, stomatal conductance by 15%, and relative chlorophyll content by 10% at day 20. Yield was reduced by 38% with nCeO₂ and by 49% with nZnO. Importantly, μ-XRF mapping showed that nCeO₂ changed the allocation of calcium in kernels, compared to controls. In nCeO₂ treated plants, Cu, K, Mn, and Zn were mainly localized at the insertion of kernels into cobs, but Ca and Fe were distributed in other parts of the kernels. Results showed that nCeO₂ and nZnO reduced corn yield and altered quality of corn.
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