Abstract:
Stomata respond to increasing leaf-to-air vapour pressure difference (LAVPD) ( D) by closing. The mechanism by which this occurs is debated. A role for feedback and peristomatal transpiration has been proposed. In this paper, we apply a recent mechanistic model of stomatal behaviour, and compare model and experimental data for the influence of increasing D on stomatal conductance. We manipulated cuticular conductance ( g<sub>c</sub>) by three independent methods. First, we increased g<sub>c</sub> by using a solvent mixture applied to both leaf surfaces prior to determining stomatal responses to D; second, we increased g<sub>c</sub> by increasing leaf temperature at constant D; and third, we coated a small area of leaf with a light oil to decrease g<sub>c</sub>. In all three experiments, experimental data and model outputs showed very close agreement. We conclude, from the close agreement between model and experimental data and the fact that manipulations of g<sub>c</sub>, and hence cuticular transpiration, influenced g<sub>s</sub> in ways consistent with a feedback mechanism, that feedback is central in determining stomatal responses to D
