Figure
1. Midday foliage abscisic acid (ABA) level as leaf water potential
(Ψl) declines during soil drought in angiosperm speciesUmbellularia californica (A) and conifer species Callitris
rhomboidea (B). Mean leaf water potential (Ψl) at
turgor loss point and standard errors are shown as grey solid and dashed
lines vertical dashed grey line in A and B. Midday canopy conductance
during soil drought in U. californica (C) and C.
rhomboidea (D). Vertical dashed lines in C and D represent the
Ψl at which peak foliage ABA level occurred. Generalized
additive model (GAM) curves and standard errors are represented in all
relationships by solid and dashed black lines, respectively.