An experiment was conducted to investigate soil evaporation (E), crop transpiration (T), evapotranspiration (ET) and the ratio of evaporation to evapotranspiration (E/ET) of drip-irrigated tomato, which was planted in a typical solar greenhouse in the North China, under different water conditions [irrigation amount was determined based on accumulated pan evaporation (Ep) of 20 cm pan evaporation, and two treatments were designed with full irrigation (0.9Ep) and deficit irrigation (0.5Ep)] at different growth stages in 2015 and 2016 at Xinxiang Comprehensive Experimental Station, Chinese Academy of Agricultural Sciences. Effects of deficit irrigation on crop coefficient (Kc) and variation of water stress coefficient (Ks) throughout the growing season were also discussed. E, T and ET of tomato were calculated with a dual crop coefficient approach, and compared with the measured data. Results indicated that E in the full irrigation was 21.5% and 20.4% higher than that in the deficit irrigation in 2015 and 2016, respectively, accounting for 24.0% and 25.0% of ET in the whole growing season. The maximum E/ET was measured in the initial stage of tomato, while the minimum obtained in the middle stage. The Kc the full irrigation was 0.45, 0.89, 1.06 and 0.93 in the initial, development, middle, and late stage of tomato, and 0.45, 0.89, 0.87 and 0.41 the deficit irrigation. The Ks the deficit irrigation was 0.98, 0.93, 0.78 and 0.39 in the initial, development, middle, and late stage, respectively. The dual crop coefficient method could accurately estimate ET of greenhouse tomato under different water conditions in 2015 and 2016 seasons with the mean absolute error (MAE) of 0.36-0.48 mm·d-1, root mean square error (RMSE) of 0.44-0.65 mm·d-1. The method also estimated E and T accurately with MAE of 0.15-0.19 and 0.26-0.56 mm·d-1, and with RMSE of 0.20-0.24 and 0.33-0.72 mm·d-1, respectively.
2015—2016年在中国农业科学院新乡综合试验基地,以华北地区典型日光温室滴灌番茄为研究对象,分析2种灌溉水平[参考20 cm标准蒸发皿的累积蒸发量(Ep),设置2种灌溉水平(高水: 0.9Ep;低水:0.5Ep)]下番茄不同生育期土壤蒸发(E)、作物蒸腾(T)、蒸发蒸腾(ET)和土壤蒸发占蒸发蒸腾比值(E/ET)的变化,探讨水分亏缺对作物系数(Kc)的影响以及水分胁迫系数(Ks)在全生育期的动态变化.采用双作物系数法分别估算E、T和ET,并与实测结果进行对比分析.结果表明: 2015和2016年全生育期高水处理的E分别比低水处理高21.5%和20.4%, 占总蒸发蒸腾量的24.0%和25.0%,E/ET在生育初期最大、中期最小;高水处理的Kc值在生育初期、发育期、生育中期和生育后期分别为0.45、0.89、1.06和0.93,低水处理下分别为0.45、0.89、0.87和0.41;低水处理的Ks值在0.32～1.0,生育初期、发育期、生育中期和生育后期分别为0.98、0.93、0.78和0.39.双作物系数法可较精确地估算不同水分处理的ET,其平均绝对误差(MAE)为0.36～0.48 mm·d-1,均方根误差(RMSE)为0.44～0.65 mm·d-1;该方法也可精确地估算E和T,其MAE分别为0.15～0.19和0.26～0.56 mm·d-1,RMSE分别为0.20～0.24和0.33～0.72 mm·d-1.
Keywords: crop coefficient; crop transpiration; soil evaporation; solar greenhouse; water stress coefficient.