Effects Of Silicon On Some Physiological Metabolisms Of Tobacco

It had been proved that silicon can protect plants from abiotic or biotic stresses and silicon fertilizer can increase the yield of silicophilic crops, such as rice, sugarcane and wheat, as well as the yield of silicon sensitive crops, such as cucumber and watermelon. However, there was few research reports about the effects of silicon on tobacco. In this paper, with the method of combining field sampling, hydroponic experiment, soil-culture and field experiment were used to establish the silicon diagnosis indexes of tobacco leaf and soil to evaluate the silicon content status of tobacco and tobacco soil in Fujian, to study the effect of silicon on some physiological metabolisms of tobacco and the effect of silicon fertilizer on tobacco bacterial wilt,and to find the methods of improving silicon biological effectiveness of chicken manure ash. The results could provide bases for tobacco applying silicon fertilizer..1. Evaluation silicon content of Fujian’s tobacco and tobacco-growing soil148 tobacco leaf samples and the corresponding 0-20 cm surface soils were collected from 13 counties in three major tobacco producing areas in Fujian province to test silicon content. The results showed that the tobacco silicon content range and the average was 0.04%-0.64%,0.22% respectively,52% tobacco samples’s silicon content was lower than 0.26%. The content of soil available silicon ranged from 34.59 to 665.18 mg/kg, averaged 153.78 mg/kg. Soil available silicon content of 70.95% soil samples was higher than the critical value of 110mg/kg,29.05% soil samples was lower than critical value of 110mg/kg. The correlation analysis showed that the soil available silicon content had a significant positive correlation with pH, but had no relationship with soil organic and CEC.2. Effects of silicon on some physiological metabolisms of tobaccoWith 5 silicon concentrations (0,0.5,1.0,2.0,3.0 mmol/L), hydroponic experiment was carried out to study the effects of silicon on some physiological metabolisms of tobacco K326. The main results were as follows:2.1 Silicon improved the dry weight of stems, leaves and biomass significantly in topping stage, but had less effect on tobacco growth in rosette stage. Comparing with the CK, silicon reduced tobacco nicotine content, increased nitrogen/nicotine ratio significantly.2.2 Comparing with CK, the photosynthetic rate, carotenoid content, light saturation point, carboxylation saturation point, apparent quantum yield and carboxylation efficiency increased significantly, but the dark respiration rate, light compensation point decreased significantly under silicon treatments. Silicon treatment increased the water use efficiency by 37.82%-43.27%, while decreased the transpiration rate by 12.15%-13.33%. Silicon had no effect on chlorophyll fluorescence kinetics parameters and the content of chlorophyll a, chlorophyll b and the ratio of chlorophyll a to chlorophyll b.2.3 The results indicated that the organs’silicon content increased dramatically with increasing silicon concentration in culture solution. The Si content of tobacco organs was in order of root> leave >stem, lower leave> leave> upper leave. Silicon treatment increased the content of K, P and Zn, but decreased the content of N, Ca, Cu, Fe and B of tobacco.3. Control of bacterial wilt and effect on active oxygen metabolism of tobacco by sodium silicateField experiments were carried out to study the effects of sodium silicate(Na2SiO3) on controlling bacterial wilt and active oxygen metabolism of tobacco Y87. The main results were as follows:3.1 Na2SiO3 reduced the disease incidence and disease index of tobacco bacterial wilt significantly. On transplanting 90d and 100d, Na2SiO3 application decreased significantly the disease incidence and the disease index by 13.14%,12.08% and 23.34%,21.26%respectively, compared with the control.3.2 With the development and aggravation of tobacco bacterial wilt, the contents of H2O2, MDA, the membrane permeability and cell K+ extravasation of tobacco increased; Na2SiO3 application decreased the contents of H2O2, MDA and the injury of membrane, Comparing with CK, Na2SiO3 application increased CAT activity, while reduced SOD and POD activity significantly.4. Research on silicon activation in chicken manure ashCombusting chicken manure and chaff mixture in the fluidized bed incinerator, the ash could be used as silicon fertilizer’s raw materials. Research on silicon activation of ash was carried out. The result showed that the optimum treaments for silicon activation of ash were ash and Na2CO3 ratio 1:1, melt temperature 800 ℃ and melt time 2h. By these treaments,the water soluable silicon of chicken manure ash increased significantly. Soil-culture experiment showed that adding 15 g chicken manure ash silicon fertilizer per kg soil could increase soil available silicon by 18.11%.