Growth and Metabolic Responses of Rice (Oryza sativa L.) Cultivated in Phosphorus-Deficient Soil Amended with TiO2 Nanoparticles.

Plants have the natural ability to withstand stress conditions through metabolic adjustments. The present study aimed at investigating the effects of titanium dioxide nanoparticles (TiO2 NPs) application (0, 25, 50, 150, 250, 500, and 750 mg kg-1) in phosphorus-deficient soil in terms of growth responses, P contents, and metabolic alterations in rice. TiO2 NPs application increased shoot length up to 14.5%. Phosphorus contents in rice roots, shoots, and grains were increased by 2.6-, 2.4-, and 1.3-fold, respectively, at 750 mg kg-1 of TiO2 NPs. Gas chromatography-mass spectrometry (GC-MS)-based metabolomics revealed increased levels of amino acids, palmitic acid, and glycerol content in grains resulting from plants grown in 750 mg kg-1 TiO2 NPs-treated soil. Furthermore, no translocation of TiO2 NPs from the treated soil to rice grains was detected by inductively coupled plasma-optical emission spectrometry (ICP-OES), which suggests no risk of TiO2 NPs intake via grain consumption. The observed data indicates the strong relationship among NPs application, P contents, and metabolic alterations.