Effect of FC and ABA treatments – stomatal conductance of
dehydrating leaves
For both species, treatments significantly affected gs(P <0.0001, Table 2 Supporting Information). The
gs of P. dulcis and P. communis was higher
for FC than for ABA and control leaves (Table 1, Figure 1). Very small
negative values of gs recorded for P. dulcis ABA
and control leaves were likely associated with transpiration rates below
the detection limit of the photosynthesis system and not significantly
different from 0, suggesting that stomata were mainly shut. The
gs for the different treatments is consistent with
values reported for plants growing in field conditions (Marsal and
Girona 1997; Spinelli et al. 2016). For both species, values of
gs indicate that treatments were effective in modifying
stomatal aperture across the Ψ range where FWU was analyzed (Figure 1).
The observed variation of gs with Ψ suggests that,
despite the treatments, stomatal responses were still affected by Ψ.
However, FC forced stomata to remain open even under significant stress.
ABA treatment was also successful in both species reducing
gs to near zero. The control treatment seemed to almost
fully close stomata in P. dulcis but not in P. communis ,
providing the opportunity to test the contribution of partially shut
stomata to FWU.