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| DOI：10.13522/j.cnki.ggps.2017.0507 |
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| Comparison of Different Methods for Calculating the Evapotranspiration in Venlo-type Greenhouse |
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ZHAO Baoshan, YAN Haofang, ZHANG Chuan, Samuel Joe Acquah, WU Haimei, ZHANG Hengnian
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Jiangsu University a. Research Center of Fluid Machinery Engineering and Technology; b. Institute of Agricultural Engineering, Zhenjiang 212013, China)
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| Abstract: |
| 【Objective】 Different methods are available for calculating the reference crop evapotranspiration (ET0), and the purpose of this paper is to compare their applications in irrigated greenhouses.【Method】 Experiment was carried out in a Venlo-type greenhouse with the meteorological factors in the house measured. The FAO-56 Penman-Monteith formula was modified using a fixed aerodynamic resistance r*a. We compared four commonly-used models to calculate the evapotranspiration: the FAO-56 Penman-Monteith, the FAO-24 Penman-Monteith method, the Priestley-Taylor and the Irmak-Allen, with the Penman-Monteith modified (P-MM) as the control.【Result】During the experimental period, the daily ET0 varied from 0.49 to 6.04 mm/d with an average of 2.43 mm/d. The evapotranspiration calculated using all models was linearly correlated (R2>0.9) to the values calculated from the P-MM, with the FAO-24 having RMSE=0.40 mm/d and NSE=0.93, the Irmak-Allen having RMSE=0.67 mm/d and NSE=0.81, and the Priestley-Taylor having RMSE=0.76 mm/d and NSE=0.76. The FAO-56 Penman-Monteith model was widely used in the field, but its application to the greenhouse was unsatisfactory with RMSE=1.18 mm/d and NSE=0.41. 【Conclusion】 Comparing all available models showed that the Irmak-Allen model is most suitable for calculating ET0 in the greenhouses. |
| Key words: greenhouse; meteorological data; evapotranspiration; ET0;Penman-Monteith model; crop waterrequirement |
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