HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (14) Citing Articles via Google Scholar Google Scholar Articles by Sperry, J. S. Articles by Hacke, U. G. Search for Related Content PubMed Articles by Sperry, J. S. Articles by Hacke, U. G. Agricola Articles by Sperry, J. S. Articles by Hacke, U. G. Related Collections Water Stress Crop Physiology & Metabolism Plant and Soil Interactions Plant and Environment Interactions

Xylem Hydraulics and the Soil–Plant–Atmosphere Continuum

Opportunities and Unresolved Issues

Biol. Dep., Univ. of Utah, 257 S, 1400E, Salt Lake City, UT 84112. Financial support from USAID and NSF (IBN-0112213)

View larger version (18K): [in a new window]   Fig. 1. Vulnerability curves of crop species, showing how the percentage loss of hydraulic conductivity in the xylem (PLC) increases as xylem pressure becomes more negative. Data from Neufeld et al. (1992), Sperry (2000), Stiller et al. (2003), and Stiller and Sperry (2002).

View larger version (19K): [in a new window]   Fig. 2. Hysteresis in vulnerability curves. During dehydration, the percentage loss of hydraulic conductivity in xylem (PLC) increases because of cavitation. During rehydration, the dashed line shows the expected pattern where embolized xylem conduits are not refilled with water until the xylem pressure rises above the -2T/r limit (see text), which is very close to atmospheric. The left-hand limit is for a conduit filled with water vapor, and the right-hand limit is for an air-filled conduit. The dotted line shows a novel rehydration pattern reported for some species in which refilling occurs despite substantial negative pressures in the transpiration stream. From Hacke and Sperry (2003).

View larger version (21K): [in a new window]   Fig. 3. The cavitation fatigue phenomenon. (A) Water birch (Betula occidentalis Hook.) stems possess the same vulnerability curve between repeated measurements on the same material (first vs. second curves). (B) Sunflower (Helianthus annuus L.) stems show cavitation fatigue, wherein the second curve is much more vulnerable than the first (asterisks denote significant differences at the p < 0.01 level). Cavitation fatigue occurs naturally in intact, droughted plants and appears to be reversible in sunflower. From Hacke et al. (2001b).

View larger version (21K): [in a new window]   Fig. 4. Hypothetical structure–function relationships in intervessel pits. From Carlquist (1989).