Uptake, translocation and impact of green synthesized nanoceria on growth and antioxidant enzymes activity of Solanum lycopersicum L.

Cerium oxide nanoparticles (nanoceria) were synthesized by a novel, simple green chemistry procedure using Elaeagnus angustifolia leaf extract as a reducing and capping agent. The crystalline nature of nanoceria was confirmed by XRD analysis. FTIR analysis revealed that phytochemicals are present on the surface of nanoceria. SEM and TEM images revealed that the nanoceria are well dispersed, spherical in shape with a particle size range in between 30 and 75 nm. Thereafter, the effects of various concentrations of cerium oxide (CeO₂) and green synthesized nanoceria on growth and metabolism of Solanum lycopersicum (tomato) were investigated. The bio-accumulation of Ce in tomato seedlings was found to be dose dependent and the results showed that with the increase in exposure concentrations, the accumulation of Ce contents in both root and shoots augmented. However, unlike nanoceria treated seedlings, Ce contents in the roots with CeO₂ treatments were negligible than that in the shoots at lower concentrations and this suggested the immobilization of Ce in CeO₂ treatment at lower concentrations. Nanoceria at 500 and 1000 mg/L resulted in inhibitory effect on growth of test plant as compared to CeO₂ component. The exposure of plants to nanoceria and CeO₂ has resulted in significant reduction in pigment content, increased LP, EL and H₂O₂ content. The activities of antioxidant enzymes viz. SOD, CAT, APX and GPX were significantly up regulated on exposure of nanoceria and CeO₂. It is concluded that plant exposure with nanoceria at concentrations of 20 and 100 mg/L were more beneficial for growth and metabolism of tomato plants than that of CeO₂ at equivalent concentrations.