TiO2 photocatalytic antifungal technique for crops diseases control.

TiO_2 and l%Ce^{3+}-TiO_2 prepared by hydrothermal method were characterized by means of XRD and UV-visible diffusive reflectance spectra (DRS). The results of DRS analysis indicated that the 1%Ce^{3+}-TiO_2 catalyst had significant optical absorption in the visible region between 400–450 nm because electrons could be excited from the valence band of TiO_2 or cerium oxides to Ce 4f level. To investigate the photocatalytic activity of different catalysts for crop fungal disease control, a series of Quine tests were carried out for cucumber powdery mildew and litchi downy blight control in home-made photocatalytic reactor. The results showed that TiO_2 photocatalysis technique should be effective to inhibit the growth of fungal diseases to some extent and P-25 had a higher activity for antifungal control than home-made TiO_2 catalysts. TiO_2-A prepared with Ti(SO_4)_2 is more active to contro 1 antifungal disease than TiO_2-B prepared with TiOSO_4 as precursor because the crystalline of TiO_2-A was higher than that of TiO_2-B. The antifungal index litchi downy blight control was greatly enhanced by doping 1% cerium ion. The antifungal index of 1.0%Ce^{3+}-TiO_2 was (47.0±4.7)%, (82.2±3.5)%, (100±0.0)% under indoor weaker light, solar light and black light, respectively. The results of field experiments showed that the antifungal index of 1.0%Ce^{3+}-TiO_2 was more than that of P-25. The antifungal index of 1.0%Ce^{3+}-TiO_2 was (81.7 ±6.5)%, (67.5 ±4.7)%, (38.6 ±1.9)% for litchi downy blight, maize southern leaf spot, and rice blast, respectively. It was concluded that TiO_2 photocatalysis technique should be an effective way for litchi fungal disease control in practice. [ABSTRACT FROM AUTHOR]