Effects of La 2 O 3 nanoparticles and bulk-La 2 O 3 on the development of Pfaffia glomerata (Spreng.) Pedersen and respective nutrient element concentration.

Nanoparticles (NPs) have been progressively applied in the last decades, which may impact the environment. Synthesis of pigments, growing, and nutrient element uptake by plants can also be affected by NPs. The influence of lanthanum oxide nanoparticles (La 2 O 3 NPs) on growth, pigment synthesis, and nutrient element uptake by Pfaffia glomerata (Spreng.) Pedersen, a medicinal plant native in South America, was evaluated in the present study. P. glomerata plantlets were cultivated for 28 days in the absence (control) and presence of 100, 200, and 400 mg L -1 of La 2 O 3 NPs or bulk-La 2 O 3 (b-La 2 O 3 ) at the same cultivation conditions. Root development, aerial part growth, and pigment concentration in plants were affected by b-La 2 O 3 and La 2 O 3 NPs, mainly by La 2 O 3 NPs. In spite of alteration of nutrient element concentration observed for the 100 and 200 mg L -1 of La 2 O 3 NPs or b-La 2 O 3 treatments, Ca, Cu, Fe, K, La, Mg, Mn, Mo, P, S, and Zn determination in stems and leaves revealed drastically and similar decrease of these elements in plants cultivated in the presence of 400 mg L -1 of La 2 O 3 NPs or b-La 2 O 3 . Element distribution (mapping) determined by using laser ablation inductively coupled plasma mass spectrometry in leaves of plants submitted to treatment with 400 mg L -1 of b-La 2 O 3 or La 2 O 3 NPs showed differences in the distribution of elements, indicating distinct effects of b-La 2 O 3 and La 2 O 3 NPs on P. glomerata. As such, this study demonstrated that La 2 O 3 NPs may impact plant growth. However, more investigations are necessary for better understanding of the effect of La 2 O 3 on plants, including a broader range of concentration.