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

Greenhouse industry has been rapidly expanded worldwide. An accurate partitioning evapotranspiration (ET) into transpiration (T-r) and evaporation (E-s) 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 (f(sw)) on Es to estimate E-s, T-r, and ET. In the MPT model, the performance of three sub-models for estimating E-s was evaluated. The MPT model was assessed based on the measurements in 2016, 2017, 2019, and 2020. The ET, E-s, and T-r of greenhouse grown tomato under drip irrigation were measured by the weighting lysimeters, microlysimeters 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 E-s. The partitioning of ET was controlled by leaf area index (LAI), as indicated by a significant logarithmical relationship between E-s/ET and LAI. LAI and air temperature (T-a) are two important factors affecting ET as shown by good correlations between PT coefficient (alpha(m)) and LAI/T-a. The daily E-s can be reasonably estimated by the sub-model with the soil water-related f(sw). Moreover, the MPT model can also well estimate hourly and daily T-r and ET, hence can be used as a tool to develop precise irrigation scheduling for similar greenhouse cultivation.

Automated summary

A modified Priestley-Taylor model was proposed to accurately estimate transpiration, evaporation, and total evapotranspiration of greenhouse-grown tomatoes, adjusting model parameters based on different combinations of leaf area index and air temperature for precise water and nutrient management. Results showed that the transpiration and evaporation of greenhouse-grown tomatoes were significantly influenced by leaf area index and soil water stress.