2.5. Determination of crop water an

2.5. Determination of crop water and irrigation requirement
The FAO Penman-Monteith method (Allen et al., 1998) was used
to calculate the reference evapotranspiration ETo in the CROPWAT
8.0 Program. Crop water requirements or crop evapotranspiration
(ETc) over the two growing seasons were determined from
ETo according to the following equation using crop coefficient
Kc:
ETc =
KcETo
where ETc is the crop water requirement, Kc is the crop
coefficient and ETo is the reference evapotranspiration. Crop
evapotranspiration was calculated by multiplying the reference
evapotranspiration values with the onion crop coefficients given by
Allen et al. (1998) as 1.05 for the late season stage. Since there was
no rainfall during the experimental period, net irrigation require

Results (Chinese) 1:

2.5.测定作物水和灌溉要求采用粮农组织彭曼-蒙特斯法 （Allen et al.，1998年）计算结果在 ETo 参考作物蒸散8.0 程序。作物需水量或作物蒸散量（等） 在两个生长季节从确定根据下面的公式使用作物系数 EToKc:等 =KcETo等是作物需水量，Kc 是作物系数和环氧乙烷是参考作物蒸散。作物蒸散量计算乘以参考蒸散量值与所给出的洋葱作物系数李鹏飞等人 （1998 年） 为 1.05 季节后期阶段。因为没有在实验期间没有降雨，净灌溉要求

Results (Chinese) 2:

2.5。作物用水和灌溉要求的确定
粮农组织的Penman-Monteith公式（Allen等，1998）被用来
计算参考蒸散量E要在CROPWAT
8.0计划。作物需水量或作物蒸散量
在两个生长季节（ETC）是从确定
E要根据下列公式用作物系数
KC：
ETC =
KcETo
，其中ETC是作物需水量，Kc为作物
系数和E要为参考蒸散。作物
蒸散量是由基准乘以
蒸散值与给定的洋葱作物系数
Allen等。（1998年）为1.05的季节晚期阶段。由于当时
实验期间没有降雨，净灌溉要求