[Silicon application enhances resistance to sheath blight (Rhizoctonia solani) in rice]

The enhancing resistance and decreasing incidence to sheath blight (Rhizoctonia solani) by silicon were studied from cytological and physiological aspects by using rice plants solution-cultured with silicon supplementation or with silicon-deficiency. By an environmental scanning electron coupled with X-ray microanalysis, as well as gravimetric quantification, the number of siliceous cell and Si content of the Si(+) rice leaf were much more than those of Si(-) rice leaf (Figs.1,2; Table 1). After being inoculated with R. solani MDA content in Si(+) rice plants was almost higher than that in Si(-) rice plants, SOD activity in Si(+) rice plants was always higher than that in Si(-) rice plants, SOD activity in Si(+) rice plants reached a minimum on 4 d, and POD activity was at the maximum, but POD activity in Si(-) rice plants was lower. These results suggested that silicon could enhance the harmony of SOD and POD. And silicon had no effect on CAT and PAL activity, but weaken PPO activity (Fig.3). After being inoculated with R. solani, the Si(+) rice plants had significantly lower disease index with relative control effect of 1/4 compared to the Si(-) rice plants (Table 2).