INTEGRATED EFFECT OF IRRIGATION AND NITROGEN ON YIELD, WATER SAVING AND WATER PRODUCTIVITY OF RICE IN NORTH IRAN, USING ORY ZA2000 MODEL

摘要

For evaluating ORYZA2000 model in Iran, study was carried out in a RCBD betweenrn2005 and 2007, with 3 replications at Rice Research Institute of Iran, Rasht. Irrigationrnmanagement (continuous submergence, irrigation 5 and 8 day interval) was the main plotrnand N application (no N application, total N rate of 45, 60 and 75 kg/ha) was the supplot.rnIn this study, simulation modeling was used to quantify water productivity, and waterrnbalance components of alternate for water–nitrogen interactions in rice. Simulated andrnmeasured total aboveground biomass and yield were evaluated by adjusted coefficient ofrncorrelation, t-test of means, and absolute and normalized root mean square errors (RMSE).rnResults show, with normalized root mean square errors (RMSEn) of 5–28%, ORYZA2000rnsatisfactorily simulated crop biomass and yield that strongly varied among irrigation andrnnitrogen fertilizer conditions. Yield was simulated with an RMSE of 237–443 kg ha-1 and arnnormalized RMSE of 5–11%. Model ORYZA2000 was sufficiently accurate in the simulationrnof total biomass and yield under water and nitrogen limit conditions at our test site. Thisrnstudy demonstrates that for estimation of actual plant transpiration and soil evaporation,rnORYZA2000 model is useful at field scale. Results show, the significant (28–56%) sharernof evaporation into evapotranspiration, using the actual yield (measured) and simulatedrnwater balance (ORYZA2000). For optimizing N and water apply, one has to define thernmain constraint to rice production. If it is water shortage, then increasing WP shouldrnbe the main goal. When water resources are limited, the best irrigation scheme would.