Dose-dependent physiological responses of Triticum aestivum L. to soil applied TiO2 nanoparticles: Alterations in chlorophyll content, H2O2 production, and genotoxicity

Abstract

Titanium dioxide nanoparticles (TiO2 NPs) are used widely in commercial products. These high production levels have led to their increased release into natural ecosystems, where they may interact with plants and affect their physiological functions. The aim of this study was to assess the physiological responses of wheat (Triticum aestivum L.) to increasing concentrations of TiO2 NPs. TiO2 NPs with a particle size less than 20 nm were administered as soil spiked with 0, 20, 40, 60, 80, and 100 mg TiO2 NPs kg(-1), and their physiological parameters, including root and shoot lengths, biomass, phytoavailability of phosphorus (P), chlorophyll content, H2O2 production, and micronuclei (MN) formation in the plants grown from seeds in NPs-spiked soils, were subsequently recorded. All experiments were repeated twice with four replicates per treatment. After 60 days exposure to the NPs, root and shoot lengths, and P uptake by plants was significantly (p < 0.05) higher between 20 and 60 mg kg(-1) compared to the control (0 mg kg(-1) TiO2 NPs), but was then lower at 80 and 100 mg kg(-1) compared to 60 mg kg(-1) TiO2 NPs. The application of TiO2 NPs led to chlorophyll content being higher by 32.3% at 60 mg kg(-1) than in the control, but 11.1% lower content was observed at 100 mg kg(-1). The results suggested that wheat could not tolerate concentrations of TiO2 NPs higher than 60 mg kg(-1) owing to over-production of H2O2 (84.4%) and MN formation (53.6%).