Effect of FC and ABA on leaf rehydration via the adaxial
surface
To evaluate the potential effects of FC and ABA treatments on water
uptake and leaf rehydration not associated with changes in stomatal
aperture, a preliminary experiment aiming to analyze FWU via only the
adaxial, stomata-free surface was conducted with P. dulcisleaves. The abaxial surfaces and margins of fully rehydrated leaves
supplied either with FC, ABA or water (six leaves per treatment) were
covered with paraffin wax, and their cut-end petioles sealed. Leaf mass
was recorded before and after wax application, as well as before
treatment application. Leaves were allowed to dehydrate until reaching
the mass associated with the target Ψ and placed in a ‘fog chamber’ (see
below). After 100-120 min of fog exposure, leaves were taken out of the
chamber and weighed after their surface was dried with pulses of dry
air. A second set of leaves of each treatment (three leaves per
treatment) was fully covered with wax, i.e. both their adaxial and
abaxial surface, and placed in the chamber. After 100-120 min, the mass
of the leaves from this second set remained the same which confirms that
wax application was effective in sealing the surface. After the
rehydration experiment, leaves were scanned and their area was
calculated with ImageJ (v.1.45s National Institutes of Health, Bethesda,
MD, USA). The amount of water absorbed via the adaxial leaf surface was
calculated as the increment in mass following fog application per
projected leaf surface area; the treatment effect was assessed by ANOVA
in R.