Seralarda Evapotranspirasyon Tahmini için Geliştirilen Denklemler

Abstract

It is estimated that the world population will be 9.6 billion by 2050. In order to meet the food needs of the growing population, it is necessary to increase the yield obtained from existing agricultural land. As the greenhouse provides a more controlled environment, the yield taken from the unit area is higher than the field conditions. For this reason, the greenhouse cultivation has been increased in year by year. Irrigation is one of the major cultural applications for increasing yield from the unit area. It is important that crop water requirement should be determined correctly for proper irrigation scheduling in greenhouse. The use of equations based on climate to determine evapotranspiration has been increased in recent years. In this study, estimation performances of evapotranspiration equations based on the reference crop (Penman, Hargreaves, FAO-24-Radiation, Priestley-Taylor, FAO-Penman Monteith, FAO24-Pan Evaporation) and main crop (Stanghellini, Fynn, Takakura, Simplified Model) developed from the past to the present day were reviewed. It is concluded that there is no standard equation under greenhouse conditions to determine evapotranspiration of a specific crop. The reason for this is that greenhouse climate changes depending on greenhouse type, location, direction, cover material, greenhouse volume, ventilation mechanism, usage of thermal curtain and shadow powder and even cultural applications such as hanging. However, it is possible to develop new equation or calibrate existing equations for each different greenhouse in the same region. Therefore, it is suggested that evapotranspiration equations to be used should be selected depending on the type of greenhouses commonly used in the region and, if necessary, modified according to these conditions.

Estimating cucumber crop coefficients under different greenhouse microclimatic conditions

“…A Priestley-Taylor model (Eq. ( 2 )) was used to compute λE O on a 10-min time step basis in each climatic treatment using the net radiation values, the slope of the saturated vapor pressure-temperature, and assuming that soil heat flux advection is considered negligible (Liu et al 2008 ; Karaca et al 2018 ; Gong et al 2020b ; Ghiat et al 2021 ). where λ is the heat of water vaporization (J kg −1 ); λET O is the latent heat flux (W m −2 ); α is the P-T coefficient (dimensionless); Δ is the slope of the saturated vapor pressure-temperature curve (kPa °C −1 ), γ is the psychometric constant (kPa °C −1 ); Rn is the net radiation (W m −2 day −1 ); G is the soil heat flux (W m −2 day −1 ; relatively small and usually neglected).…”

“…Today, there is no universal method to determine ET C in a greenhouse even though several models have been used under Mediterranean climatic conditions after recalibration and validation (Karaca et al 2018 ; Katsoulas and Stanghellini 2019 ). However, for an efficient water-saving strategy, the response of ET C to varying environmental conditions must be known on a minute time scale (Meijer et al 1985 ).…”

“…Τhe FAO56 Penman-Monteith (P-M) equation has been generally recommended as the standard method for the definition and computation of ET O in the calculation procedures of K C parameters. On the other hand, P-M equation model requires many climatic data to be available; thus, several researches used others’ ET O models (e.g., FAO Radiation; Hargreaves; Priestley-Taylor) with reduced climatic inputs (Fernández et al 2010 ; Zi-kun et al 2010 ; Karaca et al 2018 ; Yan et al 2019 ). This is the case, for medium technology plastic greenhouses, in the Mediterranean region (Fazlil Ilahi 2009 ; Yan et al 2021 ), using simplified ET O equations after local recalibration (Pereira et al 2021 ).…”

“…In a recent study, the P-T model was recommended as the first choice to compute ET O reference evapotranspiration in a greenhouse (Gong et al 2021 , 2020b ). In addition, to content, the P-T α coefficient was considered to take a constant value of 1.26 within greenhouses (Liu et al 2008 ; Karaca et al 2018 ). However, it has been documented that this empirical coefficient necessitates recalibration according to the surrounding environment.…”

Evapotranspiration Model-based Scheduling Strategy for Baby Pakchoi Irrigation in Greenhouse

“…(Villarreal-Guerrero et al, 2012). Several models developed to estimate ET in greenhouses have been reviewed, suggesting greenhouse ET models should be selected depending on the type, location, and crop type (Karaca et al, 2018). In another review article, 10 models used in different type of greenhouses were compared, and the FAO Penman model was recommended for plastic greenhouse ET estimation (Ilahi, 2009).…”