Effect of Silicon and Host Resistance on Sheath Blight Development in Rice

Rice cultivars high in partial resistance (Jasmine, LSBR-5), moderately susceptible (Drew and Kaybonnet), and susceptible (Lemont and Labelle) to sheath blight were grown in a silicon-deficient Histosol with and without calcium silicate slag. The treatment with silicon increased the concentration of this element in plant tissue by 80%over all experiments. Fertilization with silicon significantly reduced the severity of sheath blight, and the total area under the vertical lesion extension progress curve on moderately susceptible and susceptible cultivars compared to those cultivars high in partial resistance without silicon. The percentage of infected tillers was significantly reduced by 82, 42, 28, 41, 26, and 17%respectively for Jasmine, LSBR-5, Drew, Kaybonnet, Lemont, and Labelle, when silicon was applied, over all experiments. Dry matter accumulation was significantly greater with added silicon. In the absence of disease, silicon enhanced dry matter accumulation by 15%over the control, whereas silicon more than doubled the mean dry matter accumulation in infected plants. The application of silicon to complement host resistance to sheath blight appears to be an effective strategy for disease management in rice, especially when the soil is low or limiting in plant-available silicon.