Evapotranspiration partitioning of greenhouse grown tomato using a modified Priestley–Taylor model

Abstract Greenhouse industry has been rapidly expanded worldwide. An accurate partitioning evapotranspiration (ET) into transpiration (Tr) and evaporation (Es) is critical for developing precise irrigation scheduling and enhancing water productivity in greenhouses. Here, we proposed a modified Priestley–Taylor (MPT) model considering the effects of leaf senescence and plant temperature constraint on Tr and effect of index of soil water stress (fsw) on Es to estimate Es, Tr, and ET. In the MPT model, the performance of three sub-models for estimating Es was evaluated. The MPT model was assessed based on the measurements in 2016, 2017, 2019, and 2020. The ET, Es, and Tr of greenhouse grown tomato under drip irrigation were measured by the weighting lysimeters, micro-lysimeters and sap flow monitor system, respectively. Results showed that the total seasonal ET of tomato was 315.1–350.8 mm, of which 15.4–26.5% was consumed by Es. The partitioning of ET was controlled by leaf area index (LAI), as indicated by a significant logarithmical relationship between Es/ET and LAI. LAI and air temperature (Ta) are two important factors affecting ET as shown by good correlations between PT coefficient (αm) and LAI/Ta. The daily Es can be reasonably estimated by the sub-model with the soil water-related fsw. Moreover, the MPT model can also well estimate hourly and daily Tr and ET, hence can be used as a tool to develop precise irrigation scheduling for similar greenhouse cultivation.