Evaporative flux method of leaf hydraulic conductance estimation: sources of uncertainty and reporting format recommendation

Background The accurate estimation of leaf hydraulic conductance (K-leaf) is important for revealing leaf physiological characteristics and function. However, the K-leaf values are largely incomparable in previous studies for a given species indicating some uncertain influencing factors in K-leaf measurement. Result We investigated the potential impacts of plant sampling method, measurement setup, environmental factors, and transpiration steady state identification on K-leaf estimation in Oryza sativa and Cinnamomum camphora using evaporation flux method (EFM). The effects of sampling and rehydration time, the small gravity pressure gradients between water sources and leaves, and water degassing on K-leaf estimation were negligible. As expected, the estimated steady flow rate (E) was significantly affected by multiple environmental factors including airflow around leaf, photosynthetically active radiation (PARa) on leaf surfaces and air temperature. K-leaf decreased by 40% when PARa declined from 1000 to 500 mu mol m(-2) s(-1) and decreased by 15.1% when air temperature increased from 27 to 37 degrees C. In addition, accurate steady-state flow rate identification and leaf water potential measurement were important for K-leaf estimation. Conclusions Based on the analysis of influencing factors, we provided a format for reporting the metadata of EFM-based K-leaf to achieve greater comparability among studies and interpretation of differences.

Automated summary

Accurate estimation of leaf hydraulic conductance (K-leaf) is crucial for understanding leaf physiological characteristics and function. However, previous studies have shown difficulty in comparing K-leaf values for the same species, indicating the presence of uncertain influencing factors. In this study, we investigated the potential impacts of various factors on K-leaf estimation and provided a format for reporting metadata to improve comparability among studies.