Effect of silicon on lodging of rice induced by added iN was studied in the field with three varieties of rice. The resistance to lodging was measured with a special equipment by applying a pulling force to the rice stalk until it broke or bent to about 30 ° angle with the surface of the soil The added silicon significantly increased the rigidity of rice stalk and this increase was remarkably higher at lower doses of nitrogen. The larger quantities of nitrogen greatly reduced the efficiency of silicon in imparting rigidity to plants. Different varieties responded differently.