Effects of Rutile Type Nano-TiO2 on Photosynthetic Characteristics and Cd and Ti Enrichment in Rice under Cd Stress

The planting box test was used to study the effect of rutile nano-titanium dioxide (TiO 2 -NPs) on the photosynthetic properties and its enrichment in rice under Cd stress. The experimental results showed that the single treatment of rutile TiO 2 -NPs had little influence on rice chlorophyll content with the concentration of rutile TiO 2 -NPs. Single Cd treatment resulted in an increase in chlorophyll content and the toxicity of high concentration and small size Cd and rutile TiO 2 -NPs had great influence on chlorophyll content in rice. Under rutile TiO 2 -NPs single treatment, single Cd treatment and both, rice transpiration rate and stomatal conductivity gradually increased, but net photosynthetic rate and intercellular CO 2 concentration significantly decreased. The transpiration rate, intercellular CO 2 concentration and stomatal conductivity were not significantly different from the control, but the net photosynthetic rate changed differently under the combined stress of rutile TiO 2 -NPs and Cd. The content of Cd and Ti in roots of rice were much greater than those in the leaves. The rutile TiO 2 -NPs could reduce the mobility of Cd, but increase the mobility of Ti. These experimental results can provide some help and reference for exploring the single and joint effect of TiO 2 -NPs and Cd on rice.