干旱区生态环境知识资源中心

Evapotranspiration (ET) rates from irrigated rice differ across environments and cultivars. To quantify these differences, we developed a computational model for prediction of crop ET of irrigated rice from meteorological variables and crop parameters. The model was based on a generalized combination formula and a stomatal response function derived from a controlled environment. Model predictions compared favorably with ET rates from crops measured by microlysimetry. Using this model, we simulated ET rates from hypothetical rice crops under different climatic conditions. Regardless of cultivars and leaf area index (LAI), all the crops demonstrated higher ET rates relative to the potential in a humid temperate climate than in an arid tropical climate. Strong winds generally prevailing in a tropical dry climate make stomatal control of ET in this climate more significant than that in a calm temperate climate. Furthermore, a cultivar with smaller minimum crop resistance (Rmin) always evaporated at a higher rate than a cultivar with larger Rmin when the same atmospheric demand was imposed. Such a difference was more distinct in the dry tropical conditions than in the humid temperate conditions. These findings agree with observations so far reported for irrigated rice. Thus, we conclude that our numerical model is capable of accounting for the effects of cultivars and environments on ET rates from irrigated rice.