Journal Article

Whole-plant hydraulic resistance and vulnerability segmentation in <i>Acer saccharinum</i>

Makoto Tsuda and Melvin T. Tyree

in Tree Physiology

Volume 17, issue 6, pages 351-357
Published in print June 1997 | ISSN: 0829-318X
Published online June 1997 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/17.6.351
Whole-plant hydraulic resistance and vulnerability segmentation in Acer saccharinum

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Hydraulic properties were studied in Acer saccharinum L., a riparian species that also grows well on a dry soil when transplanted. Hydraulic resistances were measured by two independent techniques: a new high-pressure flowmeter (HPFM) method and a conventional evaporative flux (EF) method. Vulnerability to cavitation was also investigated on petioles, stems and roots using a hydraulic conductivity technique.

Vulnerability segmentation was found, i.e., roots, stems and petioles had different vulnerabilities to xylem dysfunction. Petioles were most vulnerable with 50% loss of hydraulic conductivity at –0.5 MPa, roots were least vulnerable (50% loss at –2.2 MPa) and stems were intermediate in vulnerability.

The HPFM and the EF methods gave comparable results, except that the EF method gave a significantly higher value for resistance across petioles plus leaves. Native embolism was high enough to explain the discrepancy in resistance across petioles plus leaves between the HPFM and the EF methods, indicating that the HPFM estimates the minimum (potential) hydraulic resistance of plants. Whole-plant hydraulic resistance of A. saccharinum was low compared to resistances of other temperate species.

The hydraulic characteristics of A. saccharinum were consistent with adaptation to its typical environment: low whole-plant resistance assures high transpiration rates in the presence of sufficient water, and vulnerability segmentation provides the ability to survive during droughts through shedding of expendable organs.

Keywords: cavitation; embolism; evaporative flux method; high-pressure flowmeter method; petioles; roots; stems

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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