Effect of foliar applications of silicon and titanium dioxide nanoparticles on growth, oxidative stress, and cadmium accumulation by rice (Oryza sativa)

The cadmium (Cd) has been regarded the toxic trace element to plants and humans, while there is very little information available about the application of titanium dioxide (TiO2) and silicon (Si) nanoparticles (NPs) in the mitigation of Cd stress in crops and particularly in rice (Oryza sativa). The experiment is aimed to investigate how foliar applications of Si and TiO2 NPs affected Cd uptake, photosynthesis and antioxidant enzyme system in rice. The rice seedlings were grown in Cd-contaminated soil and various concentrations of both NPs were foliar applied at different time intervals. The data indicate that both NPs significantly increased the rice biomass while decreasing Cd concentration in tissues. The NPs application enhanced the chlorophyll concentrations and gas exchange attributes of rice leaf. The NPs decreased electrolyte leakage, and malondialdehyde content and improved the activities of superoxide dismutase, preoxidase, catalase, and asorbate peroxidase in rice shoots over the control. The effectiveness of NPs in mitigating Cd toxicity varied with the type and dose of NPs applied. The results depicted that foliar use of NPs was effective in improving biomass, photosynthesis and diminishing Cd accumulation in rice, which was mainly attributed to the reduced oxidative burst and improvement in antioxidant defense system resulting from NPs application.