Study and Evaluation of the Calculation Methods of Reference Crop Evapotranspiration in Solar-heated Greenhouse

In this paper,we analyzed the application conditions of Penman-Monteith(P-M) equation recommended by FAO in solar-heated greenhouse microclimate factors.We divided the P-M equation to two parts such as radiation item(ET(rad)) and aerodynamics(ET(aero)),and acquired the modified P-M equation for calculation of reference crop evapotranspiration in solar-heated greenhouse,and resolved some question when supposed wind speed equals to zero.The modified P-M equation is verified by the measured data of weather and water evaporate in 2004 and 2005.The correlation analysis results show that the modified P-M equation has less error and higher precision than P-M equation.The modified P-M equation is suggested to calculate the reference crop evapotranspiration in solar-heated greenhouse.