Germination and Early Development of Three Spontaneous Plant Species Exposed to Nanoceria (nCeO₂) with Different Concentrations and Particle Sizes

This study aimed to provide insight regarding the influence of Ce oxide nanoparticles (nCeO2) with different concentrations and two different particle sizes on the germination and root elongation in seedlings of spontaneous terrestrial species. In a bench-scale experiment, seeds of the monocot, Holcus lanatus and dicots Lychnis-flos-cuculi and Diplotaxis tenuifolia were treated with solutions containing nCeO2 25 nm and 50 nm in the range 0–2000 mg Ce L−1. The results show that nCeO2 enters within the plant tissues. Even at high concentration, nCeO2 have positive effects on seed germination and the development of the seedling roots. This study further demonstrated that the particle size had no influence on the germination of L. flos-cuculi, while in H. lanatus and D. tenuifolia, the germination percentage was slightly higher (+10%) for seeds treated with nCeO2 25 nm with respect to 50 nm. In summary, the results indicated that nCeO2 was taken up by germinating seeds, but even at the highest concentrations, they did not have negative effects on plant seedlings. The influence of the different sizes of nCeO2 on germination and root development was not very strong. It is likely that particle agglomeration and ion dissolution influenced the observed effects.