Application of modified Penman-Monteith in greenhouse with limited weather data
[Objective] Penman-Monteith equation is the main method to calculate the evapotranspiration (ETc) of field crops,which can be used to predict short-term water status in future.However,due to the differences in water and heat movement patterns between greenhouses and fields and limited weather data,it is necessary to improve the accuracy for predicting the water status of greenhouse crops.[Method] Using meteorological and soil moisture data in the main growth period of tomato in greenhouse,the modified Penman-Monteith equation and the principle of water balance were compared for ETc calculation,andthe accuracy of the modified Penman-Monteith equation to calculate evapotranspiration of reference crop (ET0) in greenhouse with limited weather data was analyzed.[Result] The modified Penman-Monteith equation had high accuracy to calculate ET0 with mean relative error (MRE) of less than 10％.Based on FAO recommended methods,the modified Penman-Monteith equation calculated ET0 had different errors with limited weather data.The method using sunshine duration (n) to calculate net solar radiation (Rn) had MRE of 17.35％.The method using temperature (T) to calculate Rn had MRE of 41.69％.The method using lowest temperature (Tmin) to calculate actual water vapor pressure (ea) had the MRE of 19.09％.The method using n and Tmin to calculate Rn and ea had the MRE of 36.31％.The method using T to calculate both Rn and ea had the MRE of 61.23％.[Conclusion] The modified Penman-Monteith equation can be used to predict future short-term water status of crops in greenhouse.Rn can be calculated with n and ea can be calculated with Tmin when RH is missing.
the modified Penman-Monteith equation in greenhouselimited weather dataFAO
NETL
NSTL
万方数据
维普
