Evaluation of the dual source model to simulate transpiration and evaporation of tomato plants cultivated in a solar greenhouse

Abstract

Modelling of crop transpiration and soil evaporation separately is important to estimate crop evapotranspiration (ETc) for achieving high yield and efficient water use. The Shuttleworth-Wallace (SW) model can estimate crop transpiration/soil evaporation partitioning in sparse farmland, but its applicability in a solar greenhouse needed exploring. Here, greenhouse tomato under drip irrigation was used to estimate daily crop transpiration, soil evaporation and crop ETc using the SW model over two years. The measured values were obtained from a sap flow system, micro-lysimeters and weighing lysimeters during the growing period. An improved SW model (ISW) was proposed in response to the estimation error at the vegetative stage. Results showed that daily variations in estimated crop transpiration, soil evaporation, and crop ETc from the SW model were similar to the measurements. However, the SW model overestimated crop ETc by 30.8% when leaf area index (LAI) was less than 0.5 and underestimated crop ETc by 12.9% when LAI was greater than 2.7. Its accuracy was the maximum when LAI was between 0.5 and 2.7. The ISW can increase the simulation accuracy by 23% by introducing the water stress coefficient at the vegetative stage. These results can be used as the theoretical basis for optimizing the irrigation scheduling for greenhouse crops.