Effect of TiO2 Nanoparticles with High Light Absorption on Improving Growth Parameters and Enzymatic Properties of Sorghum (Sorghum bicolor L. Moench)

AbstractTitanium dioxide nanoparticles are great boosters for better sunlight absorption by plants. However, their band gap is so wide that they can only absorb UV light, which is a small portion of the sunlight. To improve the absorption of visible light, in this work, titanium nanoparticles were sensitized by saffron dye and the effect of foliar application of the dyed nanoparticles on growth parameters and enzymatic properties of sorghum was investigated and the results were compared with those of conventional titanium dioxide nanoparticles. The experiment was conducted in Zabol region, Iran. Saffron, a natural organic dye, was used as a sensitizer because of its availability and high extinction coefficient in the visible regions. To perform sensitization, titanium dioxide nanoparticles were immersed in saffron dye solution to absorb the dye on their surface. Then different concentrations of the sensitized nanoparticles were applied on plants by foliar spraying. The most improved growth parameters including root and shoot lengths, shoot fresh and dry weights, root fresh and dry weights were obtained after application of dye-sensitized TiO2 nanoparticles. Zinc and iron are the elements highly affected by the application of new nanoparticles. Enzyme activities of catalase, ascorbate peroxidase and guaiacol peroxidase were also increased significantly. Chlorophyll a and Chlorophyll a/b ratio showed the highest values in 500 ppm dye-sensitized TiO2 nanoparticles. The obtained results confirm the improvement in growth parameters and enzymatic properties of Sorghum after application of the new TiO2 nanoparticles.