In order to investigate the effects of silicon of application and nitrogen rates on yield and yield components of rice in two irrigation systems. Field experiment was conducted as split-split plot laid out in a randomized complete blocks design with four replications in Sari, during 2007. Three factors; irrigation system in two levels (Continuous flooding and alternative irrigation system) as main plots and nitrogen rates in four levels (N0, N46, N92, and N138 kg ha-1) as sub plots and silicon application in two levels (Si0 and Si500 Kg ha-1) as sub-sub plots. The results showed that flooding irrigation had increase biological yield, straw nitrogen content and 1000 grain weight. With deficit irrigation number of tiller per hill and harvest index had increased. The most plant height, number of tiller per hill, number of panicle per m2, number of total spikelet per hill, number of filled spikelet per hill, as grain yield, Straw and biological yield and the maximum grain and straw nitrogen content were obtained in N138. The maximum grain yield, straw yield, and biological yield were produced with Si500. The most straw nitrogen content was obtained in Si0. Interaction of N × Si only effect on straw yield and grain nitrogen content in 5% probability level. Therefore, silicon application decreased negative effect of irrigation and higher nitrogen application on rice plant.