Effects Of Different Silicon Compounds On Wheat Powdery Mildew (Blumeria Graminis F.sp Tritici) And Their Action Mechanisms To Pathogen

Effects of different silicon compounds on the wheat powdery mildew (Blumeria graminis f. sp tritici) and their action mechanisms to pathogen were investigated. The results are as follows.1. Foliar application of silicate nano-particles (60nm and lOOnm), tetraethyl orthosilicate(TEOS), sodium silicate (lOOOug/ml SiO2) to wheat seedlings and detached wheat leaves could effectively reduce the disease severity of wheat powder}' mildew The percentages of control effect on wheat seedlings were 48.78%, 43.73%, 40.31%, and 33.29%, respectively, and on detached leaves were 61.26%, 54.28%> 51.76% and 43.22%, respectively.2. Using SEM-EDX for observing the silicon deposition on leaf epidermal surfaces demonstrated that deposition density of silicon were different on leaf surfaces with the different silicon compounds was different, and effects of these compounds on wax layer also were different. These indicated that they could change the leaf superficial properties.3. Hydrophility and hydrophobicity of surfaces of wheat leaves treated by silicate nano-particles (60nm and lOOnm), TEOS and sodium silicate was measured by using the method of trypan blue drop. The results showed that average drop diameters of leaf surfaces with different silicon compounds were 6.9mm, 6.5mm, 4.5mm and 3.9mm, respectively. These indicated these compounds had the different effects on hydrophobicity of leaf surfaces.4. Observation of the formation of primary germ tubes (PGT) and appressoria (AM) of pathogen spores on wheat leaves treated by these silicon compounds in phase contrast microscopy showed that the percentages of formation of normal AM could be greatly affected, but the germination frequencies of PGT were almost the same between the different treatments31 40 IS.5. The results of wind tunnel experiments (4.1m/s wind velocity) showed that the adhesive rates of pathogen spores on wheat leaves with the different silicon compounds at the beginning stage of infection were different at lOmin, 30min, 60min, 90min and 120min after inoculation, and also adhesive rate on leaves treated by 60nm silicate nano-particles at 60min after inoculation was highest.6. Wheat plants cultured in nutrient solutions containing the different silicon compounds (lOOug/ml SiOi) were inoculated for investing their control effects to mildew. The results indicated that disease control effects of TEOS, sodium silicate, and silicate nano-particles (60nm) were 54.08%, 51.36% and 1.02%, respectively.7. These solution-cultured wheat leaves were used for analyzing plant uptake and distribution in the leaves using SEM-EDX. We find that Wheat plants had good uptake ability to TEOS and sodium silicate, but poor to silicate nano-particles. When wheat leaves infected by Blumeria graminis f. sp tritici, there are some silicon accumulation at the site of pathogen spore infection, but we can't see any distribution of silicon on leaves beside hyphae extension.Above results not only confirmed effects of silicon on the wheat powdery mildew and clarified their effect differences between different silicon compounds or different applying methods, but also revealed some action mechanisms of silicon to wheat powdery mildew. These will lay the foundation for researches, exploitation and application of silicon fungicides.