**Germination and Early Development of Three Spontaneous Plant Species Exposed to Nanoceria (***n***CeO 2) with Di** ff**erent Concentrations and Particle Sizes**

### **Daniel Lizzi 1,2, Alessandro Mattiello 1, Barbara Piani 1, Guido Fellet 1, Alessio Adamiano 3 and Luca Marchiol 1,\***


Received: 19 November 2020; Accepted: 15 December 2020; Published: 17 December 2020

**Abstract:** This study aimed to provide insight regarding the influence of Ce oxide nanoparticles (*n*CeO2) with di fferent concentrations and two di fferent 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 *n*CeO2 25 nm and 50 nm in the range 0–2000 mg Ce L−1. The results show that *n*CeO2 enters within the plant tissues. Even at high concentration, *n*CeO2 have positive e ffects 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 *n*CeO2 25 nm with respect to 50 nm. In summary, the results indicated that *n*CeO2 was taken up by germinating seeds, but even at the highest concentrations, they did not have negative e ffects on plant seedlings. The influence of the di fferent sizes of *n*CeO2 on germination and root development was not very strong. It is likely that particle agglomeration and ion dissolution influenced the observed e ffects.

**Keywords:** nanomaterials; cerium oxide nanoparticles; wild herbs; seed germination; root length
