Validation of dual-crop coefficient method for calculation of rice evapotranspiration under drying–wetting cycle condition

Winter Wheat Evapotranspiration Estimation under Drought Stress during Several Growth Stages in Huaibei Plain, China

“…The root mean square error (RMSE) [19,21], mean absolute error (MAE) [19,21] and mean relative error (MRE) [17,19] were used to assess the applicability and accuracy of the aforementioned method for estimating winter wheat evapotranspiration. In addition, the smaller the values of RMSE, MAE or MRE, the less the error was between the observed and simulated ET c , and the stronger the applicability of the estimation method.…”

“…The dual crop coefficient method [6,15], which is an empirical model recommended by the Food and Agricultural Organization of the United Nations (FAO) for estimating crop evapotranspiration [16], has been widely applied due to its easy operation, reliable precision and strong practicability, and it can separate evapotranspiration into crop transpiration and soil evaporation [17]. Currently, this estimation method is mainly used for estimating crop evapotranspiration without a water deficit [18,19]; however, because of the complexity of crop growth mechanism under water deficit situations, more studies should be further carried out regarding the estimation of crop evapotranspiration under drought stress in areas that frequently suffer from severe drought events, especially for drought stress during several crop growth stages [6,20,21]. Meanwhile, the basal crop coefficient (K cb ) in the dual crop coefficient method recommended by the FAO has been determined based on the environmental conditions in a typical growing region, which may not be applicable for all climatic characteristics and crop species in the world [16,22].…”

Automatic image processing in the cloud as a help for irrigation management and crop monitoring. Application in horticultural crops

“…El método de la FAO-56 propone valores de Kc para un gran número de especies, en condiciones estándares de cultivo. Se necesita un ajuste de este coeficiente cuando las condiciones difieren de las condiciones estándares en la que se obtuvo (Fernández-Pacheco et al, 2014) En la literatura se puede encontrar un gran número de métodos para calcular Kc, muchos de ellos son extremadamente laboriosos, destructivos y costosos en tiempo y dinero (Xu et al, 2017). Por esta razón, se han propuesto muchas técnicas alternativas para estimarlo a partir de su relación con otras magnitudes biológicas por medio de la Alometría, tales como el índice de superficie de hoja o Leaf Area Index (LAI) (Kirk et al, 2009), la diferencia normalizada del índice de vegetación (Normalized Difference Vegetation Index) (NDVI) (Rahimi et al, 2015) y la fracción de la cobertura vegetal (fraction of vegetation cover) (López-Urrea et al, 2009) entre otros, habiéndose obtenido grandes avances en estos campos.…”