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.

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.

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.

Effects of repeated stress on turgor pressure and cell elasticity changes in black spruce seedlings

1991 ◽  
Vol 21 (9) ◽  
pp. 1329-1333 ◽  
Author(s):  
T. J. Blake ◽  
E. Bevilacqua ◽  
Janusz J. Zwiazek
Keyword(s):  
Polyethylene Glycol ◽  
Black Spruce ◽  
Turgor Pressure ◽  
Stress Relief ◽  
Tissue Elasticity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Relative Water ◽  
One Year ◽  
Osmotic Potentials

One-year-old black spruce (Piceamariana (Mill.) B.S.P.) seedlings were preconditioned by exposing them to either one or two dehydration–rehydration cycles by using the osmoticum polyethylene glycol 3350. Preconditioned and unconditioned seedlings were then subjected to a more severe osmotic (water) stress by exposing them to a higher concentration of polyethylene glycol. Effects of repeated dehydration–rehydration cycles on cell-water relations were studied after 3, 7, and 13 days of stress relief using pressure–volume curve analysis. Repeated dehydration–rehydration cycles caused a cumulative increase in turgor potentials at full saturation. In these preconditioned plants there was also a progressive lowering of osmotic potentials and relative water contents at zero turgor, which increased over time with stress relief. The decline in osmotic potentials at zero turgor in osmotically stressed black spruce was associated with increased cell wall relaxation, followed by increased turgor potentials, in preconditioned but not in unconditioned seedlings. Saturated osmotic potentials were not altered by repeated, short-term conditioning stresses, suggesting that tissue elasticity was more important for turgor regulation than osmotic adjustment.

Mechanisms for drought tolerance in two Mediterranean seasonal dimorphic shrubs

1999 ◽  
Vol 26 (6) ◽  
pp. 587 ◽  
Author(s):  
G. Grammatikopoulos
Keyword(s):  
Drought Tolerance ◽  
Water Content ◽  
Relative Water Content ◽  
Turgor Pressure ◽  
Tissue Elasticity ◽  
Dry Period ◽  
Turgor Loss Point ◽  
Relative Water ◽  
Seasonal Basis ◽  
Cistus Creticus

Pressure-volume curves were constructed on a seasonal basis in two malacophyllous, drought semi-deciduous Mediterranean species (Phlomis fruticosa L. and Cistus creticus L.). Summer reduction of water potential at the turgor loss point in both species was less pronounced than corresponding changes in relative water content (RWC) at the turgor loss point, implying the existence of turgor maintenance mechanisms. However, actual summer leaf water potentials and RWCs in the field indicate that plants may experience zero or negative turgor pressure during the dry period. In both species, gradual decreases in osmotic potential and apoplastic relative water content, as well as increases in tissue elasticity, were observed during the summer. In particular, P. fruticosa exhibited a remarkable elasticity throughout the year. Indications for osmotic adjustment processes were also recorded. Critical (sublethal) RWCs measured during the winter and summer were lower not only from the corresponding RWCs at turgor loss point but also from the actual midday RWCs usually observed in the field. Both species seem to use a combination of elastic and osmotic adjustments in order to maintain their turgidity during the dry period. However, even though turgor may be lost during part of the summer, water deficits do not usually surpass critical levels under field conditions. This is probably achieved through the occurrence of two leaf populations (summer and winter leaves) with differential physiological drought tolerance.

Pressure–volume analysis of leaves of Robiniapseudoacacia L. with the sap expression and free transpiration methods

1988 ◽  
Vol 18 (9) ◽  
pp. 1211-1213 ◽  
Author(s):  
William C. Parker ◽  
Stephen G. Pallardy
Keyword(s):  
Leaf Tissue ◽  
Tissue Water ◽  
Volume Analysis ◽  
Water Fraction ◽  
Turgor Loss Point ◽  
Relative Water ◽  
Leaf Relative Water Content ◽  
The Relationship ◽  
Bulk Tissue ◽  
Osmotic Potentials

Leaf tissue water relations parameters of well-watered and drought-stressed black locust (Robiniapseudoacacia L.) seedlings were compared using the sap expression and free transpiration pressure–volume analysis techniques. Osmotic potentials at full tissue hydration and at the turgor loss point were higher using the sap expression method for well-watered but not for drought-stressed seedlings. These differences appeared to be related to the percentage of water left uncollected during the sap expression procedure. Osmotic adjustment in response to drought was detected by both methods. Leaf relative water content at the turgor loss point and the symplastic water fraction did not differ between methods. The relationship between bulk tissue elastic modulus (E) and turgor potential estimated by both techniques was not significantly different, although E values derived from sap expression curves for well-watered seedlings were generally higher at a given turgor potential.

Gibberellin A4/7 enhances seed-cone production in field-grown black spruce

1988 ◽  
Vol 18 (1) ◽  
pp. 139-142 ◽  
Author(s):  
Rong H. Ho
Keyword(s):  
Vitamin E ◽  
Black Spruce ◽  
Seed Orchard ◽  
Shoot Elongation ◽  
Bud Burst ◽  
Lateral Shoot ◽  
Cone Production ◽  
Seed Cone ◽  
Vegetative Bud ◽  
Needle Primordia

Black spruce (Piceamariana (Mill.) B.S.P.) grafts growing in a seed orchard were sprayed with gibberellin A4/7, and grafts and trees in families growing in arboreta were sprayed with gibberellin A4/7 and (or) vitamin E from vegetative bud burst to the end of shoot elongation. Gibberellin A4/7 was very effective in promoting seed cones and 400 mg/L appeared optimal. Vitamin E at 1000 mg/L was not effective. Vegetative bud burst occurred in mid-May and shoot elongation ended in late June. Needle primordia were visible on the apices of newly formed buds at the end of June. Reproductive buds had fewer bud scales than vegetative buds. It appeared that potential reproductive buds terminated their bud scale initiation earlier. Gibberellin A4/7 application to promote seed-cone production should be carried out before bud-type differentiation. This coincides with the end of lateral shoot elongation.

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