Despite the high sensitivity of Flux Variance Similarity (FVS) partitioning to leaf‐level water use efficiency (WUE), relatively little work has been done comparing WUE algorithms. We evaluated four intercellular CO₂ concentration parameterizations (constant_ppm, constant_ratio, and linear and square root functions of vapor pressure deficit) and one optimized WUE approach using eddy covariance data for three C₃ (wheat – Triticum aestivum L., canola – Brassica napus L., and soybean – Glycine max L.) and two C₄ (maize – Zea mays L. and sorghum – Sorghum bicolor L. Moench) grain crops. The different data requirements of the WUE models resulted in discrepancies in the number of partitioned outputs among WUE algorithms. The transpiration:evapotranspiration (T:ET) ratios found with the five WUE algorithms varied by 6%–8% for soybean and maize, 12%–13% for wheat and canola, and 22% for sorghum. The crops producing larger variations in computed T:ET also tended to have higher estimated WUE magnitudes. The constant_ppm and constant_ratio parameterizations showed better potential to partition ET in all crops, except soybean. The linear and square root WUE models failed to produce reduced T:ET ratios during wet periods in all crops, except soybean. The optimized WUE approach has potential as a benchmark for comparing other WUE algorithms for C₃ crops. The applicability of the linear and optimized WUE approaches was uncertain in C₄ crops. Agreement and disagreement among the five WUE algorithms in multiple crops provide new perspectives for applying FVS partitioning to a range of biomes and climate conditions.

中文翻译：

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基于通量方差相似度的蒸散在C3和C4作物上的水分利用效率算法的评估

尽管通量方差相似度（FVS）划分对叶级水分利用效率（WUE）具有很高的敏感性，但是比较WUE算法的工作却相对较少。我们评估了4个CO ₂使用涡协方差数据浓度参数化（蒸汽压赤字constant_ppm，constant_ratio，以及线性和平方根函数）和一个优化的WUE方法用于三架C ₃（小麦-小麦L.，卡诺拉-甘蓝型油菜大号。，以及大豆– Glycine max L.）和两个C ₄（玉米– Zea mays L.和高粱–高粱双色）L. Moench）谷物作物。WUE模型的不同数据要求导致WUE算法之间的分区输出数量存在差异。在五种WUE算法中发现的蒸腾：蒸腾（T：ET）比率在大豆和玉米中变化6％–8％，在小麦和油菜中变化12％–13％，在高粱中变化22％。在计算出的T：ET中产生较大变化的农作物也往往具有较高的估计WUE幅度。constant_ppm和constant_ratio参数设置显示除大豆以外的所有农作物中ET分配的潜力更大。线性和平方根WUE模型在除大豆以外的所有作物的湿润时期均未能降低T：ET比率。优化的WUE方法有潜力作为比较C _3的其他WUE算法的基准庄稼。线性和优化的WUE方法在C ₄作物中的适用性尚不确定。五种WUE算法在多种作物中的一致与否为将FVS划分应用于一系列生物群落和气候条件提供了新的视角。