, Volume 196, Issue 2, pp 357–366

Influence of leaf water status on stomatal response to humidity, hydraulic conductance, and soil drought in Betula occidentalis

  • Nicanor Z. Saliendra
  • John S. Sperry
  • Jonathan P. Comstock

DOI: 10.1007/BF00201396

Cite this article as:
Saliendra, N.Z., Sperry, J.S. & Comstock, J.P. Planta (1995) 196: 357. doi:10.1007/BF00201396


Whole-canopy measurements of water flux were used to calculate stomatal conductance (gs) and transpiration (E) for seedlings of western water birch (Betula occidentalis Hook.) under various soil-plant hydraulic conductances (k), evaporative driving forces (ΔN; difference in leaf-to-air molar fraction of water vapor), and soil water potentials (Ψs). As expected, gs dropped in response to decreased k or ΨS, or increased ΔN(> 0.025). Field data showed a decrease in mid-day gs with decreasing k from soil-to-petiole, with sapling and adult plants having lower values of both parameters than juveniles. Stomatal closure prevented E and Ψ from inducing xylem cavitation except during extreme soil drought when cavitation occurred in the main stem and probably roots as well. Although all decreases in gs were associated with approximately constant bulk leaf water potential (ψl), this does not logically exclude a feedback response between ΨL and gs. To test the influence of leaf versus root water status on gs, we manipulated water status of the leaf independently of the root by using a pressure chamber enclosing the seedling root system; pressurizing the chamber alters cell turgor and volume only in the shoot cells outside the chamber. Stomatal closure in response to increased ΔN, decreased k, and decreased ΨS was fully or partially reversed within 5 min of pressurizing the soil. Bulk ΨL remained constant before and after soil pressurizing because of the increase in E associated with stomatal opening. When ΔN was low (i.e., < 0.025), pressurizing the soil either had no effect on gs, or caused it to decline; and bulk ΨL increased. Increased Ψl may have caused stomatal closure via increased backpressure on the stomatal apparatus from elevated epidermal turgor. The stomatal response to soil pressurizing indicated a central role of leaf cells in sensing water stress caused by high ΔN, low k, and low ΨS. Invoking a prominent role for feedforward signalling in short-term stomatal control may be premature.

Key words

Betula (water relations)Hydraulic versus chemical signallingTranspirationWater relationsWater stressXylem cavitation



abscisic acid


transpiration rate


boundary-layer conductance to water vapor


stomatal conductance to water vapor


total conductance to water vapor


leaf-specific hydraulic conductance, subscripts


soil to trunk


trunk to petiole


trunk to lamina


soil to petiole


soil to lamina


difference in molar fraction of water vapor inside the leaf and ambient air


water potential, subscripts







Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Nicanor Z. Saliendra
    • 1
  • John S. Sperry
    • 1
  • Jonathan P. Comstock
    • 1
  1. 1.Department of BiologyUniversity of Utah, Salt Lake CityUSA
  2. 2.Boyce Thompson Institute for Plant ResearchIthacaUSA