Evaporative Flux Method of Leaf Hydraulic Conductance Estimation: Sources of Uncertainty and Reporting Format Recommendation

Abstract The accurate estimation of leaf hydraulic conductance ( K leaf ) is important for revealing leaf physiology characteristics and function. However, there are some uncertain influencing factors in K leaf measurement by using evaporation flux method (EFM), a widely used method. In this study, we investigated the potential impacts of plant sampling method, measurement setup, environmental factors, recording instrument, and transpiration steady status identification on K leaf estimation. Our results indicated that the sampling and rehydration time, the small gravity pressure on leaf, and degassing treatment had limited effects on K leaf values. Transpiration rate ( E ) was significantly affected by multiple environmental factors including airflow around leaf, light intensity, and leaf temperature. K leaf values decreased by 40% from 1000 to 500 µmol m -2 s -1 light intensities and by 15.1% from 27 to 37 o C. In addition, the accurate flow rate ( F ) steady state identification and the leaf water potential measurement were important for K leaf estimation. Based on the analysis of influencing factors, we provided a format for reporting the details of the EFM-based K leaf measurement methods and metadata that future studies could interpret the results in method issue.