Evaluation of Common Methods of Reference Evapotranspiration Prediction in Greenhouse by Lysimeteric Data

A study was conducted in a greenhouse to evaluate five methods of estimating evapotranspiration over a reference crop (ETo). This experiment was carried out at the agriculture research center, Tehran, Iran (latitude 35 41 N, altitude 51 19 E; 1190.8 meter above sea level). To record evapotranspiration and climatic variables (Solar radiation, air temperature, air humidity and wind speed) on a daily basis, a meteorological station was installed. Microlysimeter and a reduced pan were installed inside greenhouse to measure reference evapotranspiration and evaporation. Results indicated that the ETo values estimated by Artificial Neural Network (ANN) has an appropriate correlation with values measured by Microlysimeter and have a 1.14 mm.d-1 Root Mean Square Error and a coefficient of determination of 0.86. Controversy to relationship between ETo values measured by Microlysimeter and estimated by FAO-Belany-Cridle equation a Root Mean Square Error and coefficient of determination of 1.54 mm.d-1and 0.60, respectively wasn’t rational. In addition with use of reduced pan in study period, pan coefficient was 0.46 and coefficient of determination was 0.82.

Grass reference evapotranspiration Reduced Pan Microlysimeter Artificial Neural Networks