Impact of Zinc Oxide and Iron Oxide Nanoparticles on Uptake, Translocation, and Physiological Effects in Oryza sativa L.

Sustainable use of nanoparticles (NPs) in agricultural sector requires knowledge of probable harmful impacts of NPs and the crop’s life cycle. Delivery pathways of NPs play an important role in NPs uptake in plants. The foliar pathway of NPs uptake, translocation and accumulation is even less documented than the soil to root pathway. In this study, biocompatible zinc oxide NPs (ZnO NPs) and iron oxide NPs (FeO NPs) have been phytosynthesized using Senna occidentalis L. leaf extract. Different characterization techniques such as XRD, PSA, FTIR, FE-SEM and AFM were used to show efficacious synthesis of NPs capped with phytochemicals. The key objective of this study was to equate the effect of the synthesized ZnO (37 ± 2 nm) and FeO NPs (27 ± 2 nm) over a concentration (10, 50, 100 and 500 mg L−1) range by foliar and root exposure methods on physiological and biochemical parameters, as well as on uptake, translocation and accretion of NPs in different rice plant parts. The results showed that there is a critical concentration of NPs up to which the rice crop growth is promoted with no enhancement beyond that. Foliar treatment was found to be more effective than the root treatment with respect to uptake of the NPs in plants. NPs uptake, translocation and consequential plant responses are also discussed.