The phytotoxicity of titanium dioxide nanoparticles (TiO2 NPs) is a rapidly expanding area of research with a dearth of information regarding its toxicity in plants. We assessed the TiO2 NP (<25 nm) effect on growth and photosynthesis in Oryza sativa var. Jyoti grown in a hydroponic system. Our results show that TiO2 NPs do not affect germination, however, an overall decrease in seedling growth (root, shoot length and biomass) was observed at high concentration. TiO2 NP exposure led to greater accumulation of Ti in roots than in shoots, decreasing CO2 fixation, transpiration rate and stomatal conductance at 1000 ppm with insignificant effect on photosynthetic pigments, quantum efficiency of PSII (Fv/Fm ratio) and photochemical quenching. High treatment caused oxidative and osmotic stress evidenced by increased MDA and proline content. This study thus indicates that Ti accumulation caused phytotoxicity to growth and photosynthesis leading to oxidative and osmotic stress in rice.
