Nano-TiO2 Improve the Photosynthesis of Tomato Leaves under Mild Heat Stress

Nano-TiO2 has been reported to promote photosynthesis in some crops; however, the mechanism behind this action remains unknown. In this research, the effects of nano-TiO2 on leaf photosynthesis under mild heat stress were investigated. Results showed that the net photosynthetic rate, conductance to H2O, and transpiration rate of tomato leaves increased after application of an appropriate concentration of nano-TiO2. Nano-TiO2 also significantly decreased the minimum chlorophyll fluorescence and relative electron transport in leaves. Under mild heat stress, Nano-TiO2 increased regulated photosystem II (PS II) energy dissipation and decreased non-regulated PS II energy dissipation. These results indicate that nano-TiO2 plays a positive role in promoting photosynthesis in tomato leaves under mild heat stress.