Characteristics of Winter Wheat Evapotranspiration in Eastern China and Comparative Evaluation of Applicability of Different Reference Evapotranspiration Models

The humid region of eastern China is an extensive winter wheat planting area, and evapotranspiration (ET) is the dominant parameter for stabilizing agricultural production; the objectives of the study were to explore the process of evapotranspiration in winter wheat fields and obtain methods for estimating ET. We measured actual evapotranspiration (ETa) using a large weighing lysimeter in the Huanghuai Plain from 2016 to 2019. We also gathered meteorological data and compared the ETa of crops with a reference crop evapotranspiration (ETo) simulated by five models. The results showed that ET of winter wheat displayed an increasing trend at the beginning of the growth period followed by a decrease. The cumulative ET of the wheat was 614.97, 647.79, and 598.85 mm in 3 years, respectively. Temperature difference, solar radiation, and temperature were the driving factors most affecting ET in East China. In key periods (the jointing stage to the heading stage and the heading stage to the filling stage), both the H-S and FAO-56 PM models simulated higher ET values with lower errors. In the final stage of winter wheat growth (filling stage to harvesting), the R-2 of all models except FAO-56 PM did not exceed 0.500. The R-2 of the calibrated H-S model increased from 0.902 to 0.915. Relatively speaking, the FAO-56 Penman-Monteith (FAO-56 PM) and Hargreaves-Samani (H-S) models performed best. These results can improve simulations of seasonal ET and be used as a benchmark for water management of winter wheat in East China.

Automated summary

This study explored the evapotranspiration process in winter wheat fields and obtained methods for estimating evapotranspiration using actual field measurements and model simulations. The results showed that temperature difference, solar radiation, and temperature were the driving factors most affecting evapotranspiration in the humid region of eastern China. The Hargreaves-Samani (H-S) and FAO-56 Penman-Monteith (FAO-56 PM) models performed best in simulating evapotranspiration during key growth stages of winter wheat. These findings can contribute to improving water management for winter wheat in eastern China.