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| Estimation of cucumber evapotranspiration in greenhouse based on improved dual crop coefficient model and Priestley-Taylor model |
| ZHAO Shuang1, YAN Haofang1*, ZHANG Chuan2, LI Mi1, DENG Shuaishuai1,LIANG Shaowei1, JIANG Jianhui1 |
| 1. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. School of Agricultural Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract In order to estimate the transpiration(Tr)and soil evaporation(Eg)of cucumber plants in greenhouse conditions, based on the micro-meteorological data(measured in a greenhouse in spring-summer and autumn-winter planting seasons in 2018), cucumber crop leaf area index(LAI)and root soil moisture data in the area, the parameters in the dual crop coefficient model(Dual- Kc)and Priestley-Taylor(P-T)model recommended by FAO -56 were corrected, and the revised Dual- Kc and P - T models were applied( M-PT)to estimate greenhouse cucumber evapotranspiration(ETc), and the measured data of spring-summer and autumn-winter crops in 2019 were used to verify the accuracy of the model. The results show that the ETc and Tr calculated by the improved Dual-Kc and M-PT models has a good agreement with the measured values, and the performance of the Dual-Kc model is better than that of the M-PT model. The root mean square error(RMSE), mean absolute error(MAE), deviation rate(Bias)and correlation coefficient(R2)of the Dual-Kc model in predicting cucumber ETc are 0.36 mm/d, 0.28 mm/d, -0.10 and 0.98 for spring-summer planting season, and 0.28 mm/d, 0.22 mm/d, -0.11 and 0.97 for autumn-winter planting season, respectively. The RMSE, MAE, Bias and R2of M-PT model are 0.48 mm/d, 0.42 mm/d, -0.17 and 0.97 for spring-summer planting season and 0.41 mm/d, 0.31 mm/d, -0.24 and 0.95 for autumn-winter planting season, respectively. Although M-PT model has a slightly higher estimation error than Dual-Kc model, its simple structure and fewer parameter requirements make it more worthy of application in the estimation of greenhouse crop evapotranspiration(ETc).
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Received: 03 March 2022
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