The impact of xylem cavitation on water potential isotherms measured by the pressure chamber technique in Metasequoia glyptostroboides Hu & W.C. Cheng

Pressure–volume (PV) curve analysis is the most common and accurate way of estimating all components of the water relationships in leaves (water potential isotherms) as summarized in the Höfler diagram. PV curve analysis yields values of osmotic pressure, turgor pressure, and elastic modulus of cell...

Full description

Saved in:
Bibliographic Details
Published in:Journal of experimental botany 2016-08, Vol.67 (15), p.4571-4580
Main Authors: Yang, Dongmei, Pan, Shaoan, Tyree, Melvin T.
Format: Article
Language:English
Subjects:
Cupressaceae - physiology
Osmotic Pressure - physiology
Plant Leaves - physiology
RESEARCH PAPER
Water - metabolism
Xylem - physiology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Pressure–volume (PV) curve analysis is the most common and accurate way of estimating all components of the water relationships in leaves (water potential isotherms) as summarized in the Höfler diagram. PV curve analysis yields values of osmotic pressure, turgor pressure, and elastic modulus of cell walls as a function of relative water content. It allows the computation of symplasmic/apoplastic water content partitioning. For about 20 years, cavitation in xylem has been postulated as a possible source of error when estimating the above parameters, but, to the best of the authors’ knowledge, no one has ever previously quantified its influence. Results in this paper provide independent estimates of osmotic pressure by PV curve analysis and by thermocouple psychrometer measurement. An anatomical evaluation was also used for the first time to compare apoplastic water fraction estimates from PV analysis with anatomical values. Conclusions include: (i) PV curve values of osmotic pressure are underestimated prior to correcting osmotic pressure for water loss by cavitation in Metasequoia glyptostroboides; (ii) psychrometer estimates of osmotic pressure obtained in tissues killed by freezing or heating agreed with PV values before correction for apoplastic water dilution; (iii) after correction for dilution effects, a solute concentration enhancement (0.27 MPa or 0.11 osmolal) was revealed. The possible sources of solute enhancement were starch hydrolysis and release of ions from the Donnan free space of needle cell walls.
ISSN:0022-0957
1460-2431
DOI:10.1093/jxb/erw234