Freshwater availability for irrigation decreases because of increasing demand from urban and industrial areas, degrading irrigation infrastructure, and water quality. The demanding for high production of rice with less water use is crucial for food supply. In this research, a field experiment was conducted during 2001 and 2002 to determine the effect of crop density on water productivity of rice crop. The study was carried out in a split-plot design with three plant spacings as subplots (20 cm × 20 cm, 15 cm × 15 cm, and 10 cm × 20 cm) and four different irrigation regimes (continuous submergence as the control and 100%, 75%, and 50% evaporation of pan) as main plots. To model the various water productivity components, the ORYZA2000 model was used. The comparison of model results with observed data was performed using different statistical methods. The results showed that the irrigation by 75% evaporation from pan evaporation and 20 cm × 20 cm crop size are the optimum irrigation method and crop density management.

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