Assessing the SIMDualKc model for estimating evapotranspiration of hot pepper grown in a solar greenhouse in Northwest China

Abstract

An accurate estimation of crop evapotranspiration (ETc) in greenhouses is critical for precise water resource management and effective irrigation scheduling. In this study, the SIMDualKc model was calibrated and validated with the data from a four-season experiment to estimate the ETc of hot pepper grown in a greenhouse located in Northwest China. Various indicators have shown good agreement between the simulated ETc through SIMDualKc model and observed throughout the seasons with regression coefficient (b) of 0.97, coefficient of determination (R2) of 0.58, average root mean square error (RMSE) of 0.54 mm d−1 and average mean absolute error (MAE) of 0.44 mm d−1 for four seasons. The model fitted well the observed transpiration data with b of 0.98, R2 of 0.72, RMSE of 0.39 mm d−1 and MAE of 0.33 mm d−1. The calculated crop coefficients for the initial stage, mid-season and late-season were 0.6, 0.8, and 0.6, respectively. Based on the SIMDualKc model simulation, the average soil evaporation (E) of the initial stage over the four growth seasons accounted for 20.9% of the ETc. After this stage, it decreased to 3.3–4.5% of the ETc. The average seasonal E/ETc over the four growth seasons was 6.1%, indicating that transpiration was the dominant component of ETc of hot pepper grown in a greenhouse over the crop season. Our research supports the SIMDualKc model as appropriate to estimate crop ETc in greenhouses and may be further used to improve irrigation scheduling for hot pepper grown in greenhouses.