Silver birch ability to refill fully embolised xylem conduits under tension

Whether trees have the ability to refill embolised xylem conduits and possibly to do it under tension, i.e., in a physiologically active state, has been a topic of research and debate for many years.
However, direct experimental evidence for embolism refilling remains scarce.
Combining traditional tree hydraulic methods (e.g., hydraulic conductance measurements on excised stems), new approaches (cut end of a branch placed in contact with water held in an agar matrix), and newer technology (X-ray microtomography), we tested the potential of silver birch branches to refill embolised xylem conduits even under negative water potential.
The hydraulic method suggests that refilling of embolised xylem can occur even under negative pressure.
The successful ability of birch to refill xylem was confirmed by X-ray microtomography.
Furthermore, our results suggest that refilling is unlikely to be driven osmotically given the small difference measured between sap and the osmolality of the source water (tap water, agar). Finally, our results have direct influence on the method of choice when studying the vulnerability of silver birch to cavitation.

X International Workshop on Sap Flow

Y. Salmon, A. Lintunen, L. Lindfors, H. Suhonen, S. Sevanto, T. Vesala, T. Hölttä

sapwood, refilling, embolism, methodology, X-ray microtomography, hydraulic, Betula pendula

https://doi.org/10.17660/ActaHortic.2018.1222.10