Evaluation of Water Balance and Water Productivity in Rice under WaterManagement and Different Plant Density Using Ceres-Rice and ORYZA2000Models

The objective of this study was the evaluation of the Ceres-Rice and ORYZA2000 models under different water-managements and planting densities of Rice, in order to determine difference between potential and actual yield and invest its reasons. An experiment was conducted in a randomized complete block design (RCBD) with three replications in Kooshal-Lahijan located in north of Iran during cropping seasons of 2014 and 2015. There were irrigation treatments in this research including: I1 = Full irrigation, I2 = Saturation, I3 = Irrigation with 8 days alternative before anthesis, I4 = Irrigation with 8 days alternative after anthesis, I5= Irrigation with 8 days alternative whole growth season) and there were density including, D1=15×15, D2=20×20, D3=25×25cm. Evaluation simulated and measured yield and biomass by adjusted coefficient of correlation and by absolute and normalized root mean square errors (RMSE). ORYZA2000 model was more accurate in simulation of grain yield (RMSE= 533 and RMSEn= 14%). Observed and predicted of I3D2 showed good agreement in both calibration and evaluation steps. The average amount of water-based components of irrigation, evapotranspiration, transpiration and total evapotranspiration and deep penetration (WPI, WPI + R, WPET, WPT and WPETQ) simulated by the ORYZA2000 and Ceres-Rice models, were 1.09, 0.90, 1.00, 1.59 and 0.79 kg/m3 respectively.