Alternate methods of analysing water potential isotherms: some cautions and clarifications. II. Curvilinearity in water potential isotherms

1982 ◽  
Vol 60 (6) ◽  
pp. 911-916 ◽  
Author(s):  
Melvin T. Tyree ◽  
Hanno Richter
Keyword(s):  
Linear Regression ◽  
Water Potential ◽  
Turgor Pressure ◽  
Living Cells ◽  
Tissue Water ◽  
Relative Water ◽  
Cell Turgor ◽  
Pressure Bomb ◽  
Linear Regressions ◽  
Populus Spp

The Hammel pressure bomb technique has been used to obtain measurements of water potential, Ψ, and relative water content, R*, on single leaves of Populus spp., Helianthus annuus, and Fraxinus ornus. The data were plotted either as Ψ versus 1/R* or as 1/Ψ versus R* and analysed by linear regression in the region where cell turgor was thought to be zero. In some cases the Ψ versus 1/R* transformation showed curvature in the zero turgor region whereas less curvature was found in the same region of R* in the 1/Ψ versus R* transformation. In theory, curvature can appear in the Ψ versus 1/R* transformation whenever a significant fraction of tissue water is contained in the apoplast, and this theoretical prediction can be demonstrated by some of the data in this paper. The presence or absence of curvature in the two transformations can also be due to (1) apoplast compressibility, (2) the development of negative turgor pressure in living cells, and (3) the nonideality of the osmotic solutions in living cells. Linear regressions performed on curved data plots will lead to errors in the estimation of π0, the osmotic pressure at full hydration, and of other parameters derived from the analysis.

Changes in osmotic potential, cell elasticity, and turgor relationships of 2nd-year black spruce container seedlings

1987 ◽  
Vol 17 (5) ◽  
pp. 365-369 ◽  
Author(s):  
S. J. Colombo
Keyword(s):  
Water Potential ◽  
Black Spruce ◽  
Turgor Pressure ◽  
Shoot Elongation ◽  
Growth Potential ◽  
Tree Seedlings ◽  
Tissue Water ◽  
Turgor Loss Point ◽  
Container Seedlings ◽  
Relative Water

Components of tissue water potential and shoot apical activity of black spruce (Piceamariana (Mill.) B.S.P.) container seedlings were evaluated during the 2nd-year cycle of shoot elongation. Water potential components estimated using the pressure–volume technique included osmotic potentials at full turgor (ψπ100) and the turgor loss point (ψπTLP) and their difference (Δψπ), relative water content at the turgor loss point (RWCTLP), total turgor pressure (ψPTOTAL), maximum bulk modulus of elasticity (Σmax), and elasticity near full turgor (ΣFT). All parameters changed in concert with the morphology of shoot elongation; ψπ100, ψπTLP, RWCTLP, and Σ were at minimum values prior to bud swelling, increasing to a maximum during rapid shoot elongation and decreasing slowly following bud initiation and needle primordia development. Δψπ and ψPTOTAL in contrast were at minimums during shoot elongation. The relationship between Σ and ψP varied with shoot phenology. Total turgor pressure over the range of naturally occurring relative water contents is proposed as an indicator of the survival and growth potential of out planted tree seedlings.

A comparison of systematic errors between the Richards and Hammel methods of measuring tissue – water relations parameters

1978 ◽  
Vol 56 (17) ◽  
pp. 2153-2161 ◽  
Author(s):  
M. T. Tyree ◽  
M. E. MacGregor ◽  
A. Petrov ◽  
M. I. Upenieks
Keyword(s):  
Cell Wall ◽  
Osmotic Pressure ◽  
Water Relations ◽  
Turgor Pressure ◽  
Systematic Errors ◽  
Tissue Water ◽  
Cell Wall Elasticity ◽  
Pressure Bomb ◽  
Bomb Method

The pressure bomb is being used to a much greater extent to measure some tissue – water relations parameters such as osmotic pressure, turgor pressure, and cell wall elasticity. Recently, Richards has developed a faster pressure-bomb method of obtaining these and other parameters than the method used by Hammel and modified by us. In this paper, we compare the two methods and conclude that Richards’ method should not be used when accuracy is deemed important. The Richards method usually overestimates osmotic pressure by 0.2 MPa (= 2 bars) and sometimes by 0.8 MPa (= 8 bars).

Viewpoint: Consideration of apoplastic water in plant organs: a reminder

2005 ◽  
Vol 32 (6) ◽  
pp. 561 ◽  
Author(s):  
Ian F. Wardlaw
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Solute Concentration ◽  
Pressure Chamber ◽  
Dilution Method ◽  
Water Fraction ◽  
Thermocouple Psychrometer ◽  
Relative Water ◽  
Cell Turgor ◽  
The Difference

The importance of apoplastic water was confirmed for the leaves of a range of species by a comparison of tissue solute concentrations determined by the extrapolation of water potential isotherms to 100% relative water content (symplastic solute concentration at full turgor) and concentrations derived more directly from frozen / thawed tissue, where there is dilution of the symplastic water fraction by the apoplastic water fraction. A thermocouple psychrometer was used for both water potential and solute potential measurements. Parallel measurements of the apoplastic water content, estimated by the extrapolation of pressure–volume curves to zero (1 / water potential) with a pressure chamber and measurements based on the dilution method, with a thermocouple psychrometer, showed that the two methods gave similar results. This lends support to the conclusion that water is lost from the symplast and not from the apoplast of leaves when these are subjected to increasing pressure in a pressure chamber. However, where tissues or organs are air-dried the loss of water occurs from both the symplast and apoplast. The overall data support the conclusion that the apoplastic water should not be ignored in plant water relations studies, particularly when estimating cell turgor indirectly from the difference between water potential and cell solute concentration based on the analysis of frozen / thawed tissue.

The water relations of hemlock (Tsuga canadensis). IV. The dependence of the balance pressure on temperature as measured by the pressure-bomb technique

1974 ◽  
Vol 52 (5) ◽  
pp. 973-978 ◽  
Author(s):  
M. T. Tyree ◽  
J. Dainty ◽  
D. M. Hunter
Keyword(s):  
Temperature Dependence ◽  
Water Potential ◽  
Osmotic Pressure ◽  
Water Relations ◽  
Turgor Pressure ◽  
Tsuga Canadensis ◽  
Constant Volume ◽  
Pressure Bomb

The temperature dependence of the balance pressure is reported for shoots of Tsuga canadensis at constant volume, i.e., when water is neither added to nor removed from the shoot. Since the balance pressure closely equals minus the water potential, the temperature dependence of the balance pressure should reflect the combined temperature dependence of the osmotic and turgor pressures. Both the osmotic and the turgor pressures decline with decreasing temperature; frequently the turgor pressure declines 2 to 3 times more rapidly than the osmotic pressure, causing the balance pressure to rise with decreasing temperature. Only when the turgor pressure is zero (only beyond incipient plasmolysis) does the temperature dependence of the balance pressure closely follow the temperature dependence of the osmotic pressure; this occurs when the balance pressure equals or exceeds 24 bars.

Tissue water relations for Brigalow and Mulga

1968 ◽  
Vol 16 (3) ◽  
pp. 487 ◽  
Author(s):  
DJ Connor ◽  
BR Tunstall
Keyword(s):  
Drought Tolerance ◽  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Relative Water Content ◽  
Arid Zone ◽  
Tissue Water ◽  
Relative Water ◽  
The Relationship ◽  
Arid Zone Plants

The relationship between the relative water content and the water potential of the phyllodes in brigalow and mulga is compared. It is shown that brigalow phyllode tissue is more resistant to desiccation than that of mulga. This is of interest because mulga has previously been considered to represent an extreme in drought tolerance of Australian arid zone plants.

Leaf and root osmotic adjustment in drought-stressed Quercusalba, Q. macrocarpa, and Q. stellata seedlings

1988 ◽  
Vol 18 (1) ◽  
pp. 1-5 ◽  
Author(s):  
William C. Parker ◽  
Stephen G. Pallardy
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Root Tissue ◽  
Tissue Elasticity ◽  
Tissue Water ◽  
Before And After ◽  
Relative Water

The leaf and root tissue water relations of Quercusalba L., Quercusmacrocarpa Michx., and Quercusstellata Wang. seedlings before and after drought were examined to evaluate the occurrence and comparative extent of osmotic adjustment in seedlings of these species. Drought resulted in active osmotic adjustment in leaves of all three species, with decreases in osmotic potential at full tissue hydration and at the turgor loss point from 0.25 to 0.60 MPa. Active osmotic adjustment in Q. stellata, and increased root tissue elasticity in Q. macrocarpa and Q. alba, resulted in turgor loss of roots occurring at a water potential 0.36 to 0.66 MPa lower in drought-stressed than in well-watered seedlings. Species differed in tissue water relations only before drought, with Q. stellata exhibiting lower osmotic potentials than Q. alba and Q. macrocarpa. Estimates of the osmotic potential at full saturation were generally lower in leaves than in roots, but the osmotic potential at turgor loss was similar. Roots exhibited turgor loss at lower values of relative water content and experienced a more gradual decrease in water potential per unit water content during dehydration than did leaves. This response indicates greater relative tissue capacitance in roots than in leaves in these species.

scholarly journals The Relationship between Turgor Pressure Change and Cell Hydraulics of Midrib Parenchyma Cells in the Leaves of Zea mays

Cells ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 180 ◽  
Author(s):  
Yangmin X. Kim ◽  
Burkhard Stumpf ◽  
Jwakyung Sung ◽  
Sang Joon Lee
Keyword(s):  
Zea Mays ◽  
Water Potential ◽  
Turgor Pressure ◽  
Root Systems ◽  
Large Degree ◽  
Pressure Change ◽  
Pressure Chamber ◽  
Pressure Probe ◽  
Parenchyma Cells ◽  
Cell Turgor

Leaf dehydration decreases water potential and cell turgor pressure. Therefore, changes in cell turgor pressure may regulate water transport across plant cell membranes. Using a cell pressure probe, the hydraulic properties of parenchyma cells in the midrib of maize (Zea mays L.) leaves were measured (half time of water exchange in cells as a measure of hydraulic conductivity Lp). Using intact plants with root systems encased in a pressure chamber, the root systems were pressurized and the turgor pressure in leaf cells increased by increments up to 0.3 MPa. However, the increase in the cell turgor did not increase but stabilized values. Increased water potential in leaf cells seemed to have stabilizing effects on the probably due to enhanced water availability. When the cell turgor decreased by 0.1 MPa to 0.3 MPa with releasing the pressure in the pressure chamber, was temporarily increased to a large degree,a factor of up to 13 within 30 min.

Relationship between cell turgor pressure, electrical membrane potential, and chloride efflux inAcetabularia mediterranea

1983 ◽  
Vol 72 (1-2) ◽  
pp. 75-84 ◽  
Author(s):  
Stephan Wendler ◽  
Ulrich Zimmermann ◽  
Friedrich-Wilhelm Bentrup
Keyword(s):  
Membrane Potential ◽  
Turgor Pressure ◽  
Cell Turgor
Sign in / Sign up

Export Citation Format

Share Document