Stomatal sensitivity to vapor pressure deficit and its relationship to hydraulic conductance in Pinus palustris

Abstract

We studied the response of stomatal conductance at leaf (gS) and canopy (GS) scales to increasing vapor pressure deficit (D) in mature Pinus palustris Mill. (longleaf pine) growing in a sandhill habitat in the coastal plain of the southeastern USA. Specifically, we determined if variation in the stomatal response to D was related to variation in hydraulic conductance along the soil-to-leaf pathway (KL) over the course of a growing season. Reductions in KL were associated with a severe growing season drought that significantly reduced soil water content (theta) in the upper 90-cm soil profile. Although KL recovered partially following the drought, it never reached pre-drought values. Stomatal sensitivity to D was well correlated with maximum gS at low D at both leaf and canopy scales, and KL appeared to influence this response by controlling maximum gS. Our results are consistent with the hypothesis that stomatal response to D occurs to regulate minimum leaf water potential, and that the sensitivity of this response is related to changes in whole-plant hydraulics.

Response of Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) to soil and atmospheric water deficits under Mediterranean mountain climate

“…A high variability in hydraulic traits among closely-related Submediterranean deciduous oaks has been recently reported in two studies carried out in the Iberian Peninsula [12,19] Finally, we also found a significant correlation between k L, s−l and independent measurements of maximum leaf-level g s in both species (Fig. 9) as observed elsewhere for pine [1] and some angiosperm species [33], but still unreported for oaks. A linear relationship between g s and k L, s−L has been suggested to be characteristic of isohydric species (regulate ψ l at a constant value), while a curvilinear relationship has been attributed to anisohydric species (intermediate between constant ψ l regulation and no ψ l regulation) [20].…”

Responses of shelterbelt stand transpiration to drought and groundwater variations in an arid inland river basin of Northwest China

“…The response of plant water use to precipitation and soil water conditions is associated with stomatal control. Stomatal closure was identified as the main mechanism to regulate transpiration, avoiding irreversible damage to plant hydraulic system (Addington et al, 2004). Under drought stress conditions, stomatal conductance decreased with decreasing hydraulic conductance along the soil-to-leaf pathway due to high vapor pressure deficit (Motzer et al, 2005), xylem cavitation (Eberbach and Burrows, 2006), or soil dryness (O'Grady et al, 2008).…”

Transpiration and stomatal conductance of mistletoe (Loranthus europaeus) and its host plant, downy oak (Quercus pubescens)

“…The exact mechanism underlying stomatal reactions to D has not yet been identified (Buckley 2005). Nevertheless, a strong correlation between g s and D led to the assumption of a functional relationship (Grantz 1990;Aphalo & Jarvis 1991;Addington et al 2004). However, other hypotheses, such as direct reactions to sap flow rate (Mott & Parkhust 1991;Monteith 1995) or hydro-active local feedback (Buckley 2005), have also been proposed.…”