Figure 4.
Effect of sap surface tension on the xylem pressure provoking 50% loss of xylem conductance (A) and on the slope of the vulnerability curve at P50 for four tree species (B). Lowering water surface tension with different surfactants strongly increased both P50 and slope parameters for all species. The insets in A and B show the correlations between the measured P50 and slope values and the values predicted from a reduction of water surface tension alone according to Young-Laplace capillary equation. Error bars represent 1 se.