Effect of Water Restriction on Nitrogen Use in Paddy Field and Its Effect on Yield and Yield Components of Rice (Oryza Sativa L.) Hashemi variety

Water constraints and nitrogen deficiency are important factors that can affect rice plant growth. In order to study the optimum nitrogen application under water constraints, a factorial experiment was conducted in Rice Research Institute of Iran in a randomized complete block design with a factorial arrangement. Treatments included four levels of nitrogen fertilizer from source of urea [zero (N0), 60 (N60), 90 (N90) and 120 (N120) kg N ha-1] and three levels of continuous flooding (I0), eight Day (I8) and twelve days (I12) alternate. The results showed that irrigation treatments were not effective on plant height, panicle length and straw yield, while the number of tillers, 100 seed weight and empty seed weight were affected by irrigation practices. Interaction of irrigation and nitrogen treatments showed that increasing nitrogen fertilization in conditions of water deficit could lead to increase of yield, 100 seed weight and number of tillers.