Water Use Efficiency, Irrigation Management and Nitrogen Utilization in Rice Production in the North of Iran

Iran with nearly 165 million hectare of land area and amount of rainfall equal to 300 mm in 67% of its territorial land, is considered as a semi-dry region in the world. Rice production in Iran needs to be increased to feed a growing population, whereas water for irrigation is getting scarce. One way to decrease water consumption in paddy field is the change of irrigation regime and replacement of continuous submergence to alternate submergence. In order to investigate the effect of different regimes of irrigation and nitrogen fertilizer on yield of hybrid rice, an experiment was conducted at the Rice Research Institute of Iran during crop season 2008. The experiment was arranged in split plot based on completely randomized block design with 3 replications in which water regimes were main factor included continuous submergence and alternately submergence (irrigation intervals of 5, 8 and 11days) and nitrogen fertilizer levels were sub factor included 0, 90, 120 and 150 kg/ha. Grain yield,water use efficiency,relative water content,total nitrogen,grain nitrogen and nitrogen harvest index were statistically the same under continuous submergence and irrigation interval of 5 and 8 days and were lowest in 11- day interval.total nitrogen,grain nitrogen and nitrogen harvest index decreased with the increment of nitrogen.we concluded that 8- day interval could reduce water consumption in paddy fields in the North of Iran.