Effects of Ceria Nanoparticles and CeCl3 on Plant Growth, Biological and Physiological Parameters, and Nutritional Value of Soil Grown Common Bean (Phaseolus vulgaris).

The release of metal ions may play an important role in toxicity of metal-based nanoparticles. In this report, a life cycle study is carried out in a greenhouse, to compare the effects of ceria nanoparticles (NPs) and Ce(3+) ions at 0, 50, 100, and 200 mg Ce kg(-1) on plant growth, biological and physiological parameters, and nutritional value of soil-grown common bean plants. Ceria NPs have a tendency to negatively affect photosynthesis, but the effect is not statistically significant. Ce(3+) ionic treatments at 50, 100, and 200 mg Ce kg(-1) result in increases of 1.25-, 0.66-, and 1.20-fold in stomatal conductance, respectively, relative to control plants. Both ceria NPs and Ce(3+) ions disturb the homeostasis of antioxidant defense system in the plants, but only 200 mg Ce kg(-1) ceria NPs significantly induce lipid peroxidation in the roots. Ceria NP treatments tend to reduced fresh weight and to increase mineral contents of the green pods, but have no effect on the organic nutrient contents. On the contrary, Ce(3+) ion treatments modify the organic compositions and thus alter the nutritional quality and flavor of the green pods. These results suggest that the two Ce forms may have different mechanisms on common bean plants.