Evaluation of Water Balance Components and Water Productivity of Rice Under Interval Irrigation and Nitrogen Fertilizer Conditions

In order to investigate thewater productivity of rice in Rasht، a study was carried out in a RCBD during 2005 and 2007 years، with 3 replications in Rice Research Institute of Iran، Rasht. Irrigation management (3 regimes) was the main factor and N application (4 levels) was the other factor. In this study، simulation modeling was used to quantify water productivity، and water balance components of alternate for water–nitrogen interactions in rice. Results showed، the significant (28–56%) share of evaporation into evapotranspiration، using the actual yield (measured) and simulated water balance (ORYZA2000)، the calculated average WPET was significantly lower than the average WPT: 37%. The average WPI، WPET، WPT and WPETQ were 1. 01، 0. 89، 1. 41 and 0. 65 kgm-3. Also Results showed that، Irrigation with 8 days interval and 60 kg N ha-1، was the optimum combination.