Figure 5.

Dependence of Pe (A) and conduit diameter (B) at which bubble formation becomes likely on xylem water tension. The larger the xylem water tension the smaller Pe is required (A). Pe depends on freezing velocity, conduit diameter, and diffusivity of solutes (Eq. 12) and therefore at the same xylem water tension a different threshold conduit diameters are obtained at different freezing velocities (B).