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Limitation of transpiration by hydraulic conductance and xylem cavitation in Betula occidentalis

Limitation of transpiration by hydraulic conductance and xylem cavitation in Betula occidentalis ABSTRACT The extent to which stomatal conductance (gs) was capable of responding to reduced hydraulic conductance (k)and preventing cavitation‐inducing xylem pressures was evaluated in the small riparian tree, Betula occidentalis Hook. We decreased k by inducing xylem cavitation in shoots using an air‐injection technique. From 1 to 18 d after shoot injection we measured midday transpiration rate (E), gs, and xylem pressure (Ψp‐xylem) on individual leaves of the crown. We then harvested the shoot and made direct measurements of k from the trunk (2–3 cm diameter) to the distal tip of the petioles of the same leaves measured for E and gs. The k measurement was expressed per unit leaf area (kl, leaf‐specific conductance). Leaves measured within 2 d of shoot injection showed reduced gs and E relative to non‐injected controls, and both parameters were strongly correlated with kl At this time, there was no difference in leaf Ψp‐xylem between injected shoots and controls, and leaf Ψp‐xylem was not significantly different from the highest cavitation‐inducing pressure (Ψp‐cav) in the branch xylem (‐1.43 ± 0.029 MPa, n=8). Leaves measured 7–18 d after shoots were injected exhibited a partial return of gs and E values to the control range. This was associated with a decrease in leaf Ψp‐xylem below Ψp‐cav and loss of foliage. The results suggest the stomata were incapable of long‐term regulation of E below control values and that reversion to higher E caused dieback via cavitation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Cell & Environment Wiley

Limitation of transpiration by hydraulic conductance and xylem cavitation in Betula occidentalis

SPERRY, J. S.; POCKMAN, W. T.
Plant Cell & Environment , Volume 16 (3) – Apr 1, 1993
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References (25)

Publisher
Wiley
Copyright
Copyright © 1993 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0140-7791
eISSN
1365-3040
DOI
10.1111/j.1365-3040.1993.tb00870.x
Publisher site
See Article on Publisher Site

Abstract

ABSTRACT The extent to which stomatal conductance (gs) was capable of responding to reduced hydraulic conductance (k)and preventing cavitation‐inducing xylem pressures was evaluated in the small riparian tree, Betula occidentalis Hook. We decreased k by inducing xylem cavitation in shoots using an air‐injection technique. From 1 to 18 d after shoot injection we measured midday transpiration rate (E), gs, and xylem pressure (Ψp‐xylem) on individual leaves of the crown. We then harvested the shoot and made direct measurements of k from the trunk (2–3 cm diameter) to the distal tip of the petioles of the same leaves measured for E and gs. The k measurement was expressed per unit leaf area (kl, leaf‐specific conductance). Leaves measured within 2 d of shoot injection showed reduced gs and E relative to non‐injected controls, and both parameters were strongly correlated with kl At this time, there was no difference in leaf Ψp‐xylem between injected shoots and controls, and leaf Ψp‐xylem was not significantly different from the highest cavitation‐inducing pressure (Ψp‐cav) in the branch xylem (‐1.43 ± 0.029 MPa, n=8). Leaves measured 7–18 d after shoots were injected exhibited a partial return of gs and E values to the control range. This was associated with a decrease in leaf Ψp‐xylem below Ψp‐cav and loss of foliage. The results suggest the stomata were incapable of long‐term regulation of E below control values and that reversion to higher E caused dieback via cavitation.

Journal

Plant Cell & Environment – Wiley

Published: Apr 1, 1993

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