Tissue water relations of Pinusponderosa and Arctostaphylospatula exposed to various levels of soil moisture depletion

1994 ◽  
Vol 24 (7) ◽  
pp. 1495-1502 ◽  
Author(s):  
Paul D. Anderson ◽  
John A. Helms
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Moisture Regime ◽  
Tissue Elasticity ◽  
Tissue Water ◽  
Turgor Loss Point ◽  
Moisture Availability ◽  
Osmotic Potentials

The tissue water relations of Pinusponderosa Dougl. ex Laws, (ponderosa pine) and Arctostaphylospatula Greene (greenleaf manzanita) seedlings subjected to three levels of soil moisture availability were monitored over a 6-month period. Throughout the study, osmotic potentials at full turgor and at the turgor loss point were approximately 0.5 MPa greater for pine than for manzanita. Osmotic adjustment occurred for both species as evidenced by declines in osmotic potentials at full turgor and at the turgor loss point of 0.5–0.6 MPa over the study period. Pine maintained higher bulk tissue elasticity and lower water content at the turgor loss point relative to manzanita. Moisture regime had little effect on the measured parameters except for apoplasmic water content which increased at moderate and high stress levels for both species. Results suggest that osmotic adjustment occurred, at least partially, as a result of factors other than moisture availability. The lower tissue elasticity and higher water content at the turgor loss point for manzanita suggest that the shrub species is more dependent upon high foliar water content for the maintenance of turgor compared with the conifer.

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.

Temporal changes in tissue water relations of seedlings of Quercusacutissima, Q. alba, and Q. stellata subjected to chronic water stress

1989 ◽  
Vol 19 (5) ◽  
pp. 622-626 ◽  
Author(s):  
Ki Won Kwon ◽  
Stephen G. Pallardy
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Late Period ◽  
Tissue Elasticity ◽  
Tissue Water ◽  
Subsequent Increase ◽  
Turgor Loss Point ◽  
Period Increase ◽  
Solute Accumulation

In a greenhouse experiment, seedlings of Quercusacutissima, Quercusalba, and Quercusstellata were subjected to several lengthy drying cycles or were kept well watered. Three times during the 94-day experiment, samples were obtained for pressure–volume analysis of leaves so that tissue water relations responses to long-term water stress could be assessed. There was a general temporal decline in osmotic potential at full turgor (ψπ0) and at the turgor loss point (ψπp) for well-watered seedlings of all species. In water-stressed seedlings, ψπ0 declined from the first (pre-stress) to second sample dates, but then showed a subsequent increase from the second to third sample dates. Despite this increase in ψπ0, ψπp declined in the latter part of the experiment in water-stressed seedlings because of substantial increases in tissue elasticity. The late-period increase in ψπ0 in water-stressed plants was attributable to declines in solute levels and not to increased osmotic volume, as the latter showed a distinct decrease over the experiment. Although slight reductions in ψπp for water-stressed plants compared with values for well-watered plants were noted for Q. acutissima and Q. alba at the second sample date of the experiment, these differences were not significant. By the experiment's end, ψπp values for plants of both treatments were similar for all species. These results indicate that there is a limit to the capacity for solute accumulation under chronic water stress in Quercus, but that compensatory responses of tissue elastic properties may offset this influence.

Influence of Soil Temperature, Soil Moisture, and Seed Burial Depth on the Emergence of Round-Leaved Mallow (Malva pusilla)

Weed Science ◽  
1990 ◽  
Vol 38 (6) ◽  
pp. 518-521 ◽  
Author(s):  
Robert E. Blackshaw
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Water Content ◽  
Environmental Conditions ◽  
Control Strategies ◽  
Cultural Control ◽  
Burial Depth ◽  
Moisture Regime ◽  
Seed Burial ◽  
Rate Of Emergence

A study was conducted under controlled environmental conditions to determine the effect of soil temperature, soil moisture, and depth of seed burial on the emergence of round-leaved mallow. Emergence occurred from 5 to 30 C but was optimal at 15 to 20 C. Soil moisture had a greater effect than soil temperature on percentage emergence. Emergence progressively declined below a soil water content of −0.28 MPa, with less than 20% emergence attained at −1.03 to −1.53 MPa. In contrast, rate of emergence of round-leaved mallow was affected more by soil temperature than by moisture. A decrease in temperature from 30 to 5 C increased the time to reach 50% emergence by 10 to 12 days over the moisture regime of this study. Emergence was greatest at depths of 0.5 to 2 cm. No emergence occurred at 8 cm or below. The potential of using the findings of this study to develop cultural control strategies for round-leaved mallow is discussed.

Alterations in growth, photosynthetic activity and tissue-water relations of tea clones in response to different soil moisture content

Trees ◽  
2017 ◽  
Vol 31 (3) ◽  
pp. 941-952 ◽  
Author(s):  
Janhvi Mishra Rawat ◽  
Balwant Rawat ◽  
Ashish Tewari ◽  
Suresh C. Joshi ◽  
Shyamal K. Nandi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Relations ◽  
Soil Moisture Content ◽  
Photosynthetic Activity ◽  
Tissue Water

Osmotic Adjustment in Expanding and Fully Expanded Leaves of Sunflower in Response to Water Deficits

1980 ◽  
Vol 7 (2) ◽  
pp. 181 ◽  
Author(s):  
MM Jones ◽  
NC Turner
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Similar Degree ◽  
Tissue Water ◽  
Predawn Leaf Water Potential ◽  
Leaf Osmotic Potential ◽  
Osmotic Potentials

Sunflower plants were grown in large volumes of soil and slowly water-stressed by withholding water. The tissue water relationships of leaves at various stages of stress and of leaves of equivalent well watered controls were studied by the pressure chamber technique. Plants were stressed either when leaf 17 was expanding or when it was fully expanded. When expanding leaves reached a moderate level of stress (predawn leaf water potential of -0.9 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.1 MPa and 0.2 MPa, respectively. When fully expanded leaves were stressed to a similar degree (predawn leaf water potential of - 1.1 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.2 MPa and 0.3 MPa, respectively. The development of more severe stress in the fully expanded leaves was not accompanied by any further osmotic adjustment. However, when the expanding leaves reached a predawn leaf water potential of -2.3 MPa, the values of leaf osmotic potential at full turgor and zero turgor were lower than the values for the well watered plants by 0.4 MPa and 0.6 MPa, respectively. In expanding leaves prestressed to a predawn leaf water potential of -2.3 MPa, the osmotic potential at full turgor was significantly less than the control values for at least 7 days after rewatering. Stress had no effect on the bulk modulus of elasticity. It is concluded that both expanding and fully expanded sunflower leaves show osmotic adjustment.

scholarly journals Splitting the Difference: Heterogeneous Soil Moisture Availability Affects Aboveground and Belowground Reserve and Mass Allocation in Trembling Aspen

2021 ◽  
Vol 12 ◽  
Author(s):  
Ashley T. Hart ◽  
Morgane Merlin ◽  
Erin Wiley ◽  
Simon M. Landhäusser
Keyword(s):  
Soil Moisture ◽  
Root System ◽  
Resource Availability ◽  
Moisture Regime ◽  
Trembling Aspen ◽  
Moisture Availability ◽  
Resource Limited ◽  
Heterogeneous Soil ◽  
Soil Moisture Availability ◽  
The Impact

When exploring the impact of resource availability on perennial plants, artificial treatments often apply conditions homogeneously across space and time, even though this rarely reflects conditions in natural systems. To investigate the effects of spatially heterogeneous soil moisture on morphological and physiological responses, trembling aspen (Populus tremuloides) saplings were used in a split-pot experiment. Following the division of the root systems, saplings were established for a full year and then subjected to either heterogeneous (portion of the root system exposed to non-lethal drought) or homogeneous (whole root system exposed to non-lethal drought or well-watered) treatments. Above- and belowground growth and non-structural carbohydrate (NSC) reserves (soluble sugars and starch) were measured to determine how allocation of reserves and mass between and within organs changed in response to variation in soil moisture availability. In contrast to saplings in the homogeneous drought treatment, which experienced reduced shoot growth, leaf abscission and fine root loss, saplings exposed to the heterogeneous conditions maintained similar aboveground growth and increased root system allocation compared to well-watered saplings. Interestingly under heterogeneous soil moisture conditions, the portion of the root system that was resource limited had no root dieback and increased carbon reserve concentrations, while the portion of the root system that was not resource limited added new roots (30% increase). Overall, saplings subjected to the heterogeneous soil moisture regime over-compensated belowground, both in mass and NSC reserves. These results indicate that the differential allocation of mass or reserves between above- and belowground organs, but also within the root system can occur. While the mechanisms and processes involved in these patterns are not clear, these responses could be interpreted as adaptations and acclimations to preserve the integrity of the entire sapling and suggests that different portions of plant organs might respond autonomously to local conditions. This study provides further appreciation of the complexity of the mechanisms by which plants manage heterogeneous conditions and offers evidence that spatial and temporal variability of resource availability, particularly belowground, needs to be accounted for when extrapolating and modeling stress responses at larger temporal and spatial scales.

Soil–plant water relations of two subalpine herbs from Mount St. Helens

1988 ◽  
Vol 66 (5) ◽  
pp. 809-818 ◽  
Author(s):  
David M. Chapin ◽  
L. C. Bliss
Keyword(s):  
Soil Moisture ◽  
Water Relations ◽  
Plant Water Relations ◽  
Plant Water ◽  
Evaporative Demand ◽  
Xylem Pressure ◽  
Turgor Loss Point ◽  
High Maximum ◽  
Tephra Deposits ◽  
Mount St Helens

The subalpine environment of Mount St. Helens and other southern Cascade volcanoes is characterized by porous, pyroclastic soils and summer droughts. To evaluate plant drought stress in this environment, we examined plant water relations of Eriogonum pyrolifolium, a wintergreen, shallow-rooted, rosette perennial, and Polygonum newberryi, a deciduous, deep-rooted semierect perennial (both in Polygonaceae), at a subalpine site (elevation 1575 m) on Mount St. Helens. In a very dry summer, soil moisture below 20 cm remained above −0.1 MPa, but surface tephra deposits developed soil water potentials below −4.0 MPa. Surface tephra deposits had a mulching effect on underlying pre-eruption soils. Predawn xylem pressure potentials for adults of each species were never below −0.8 MPa, but midday xylem pressure potentials were often measured near or below the estimated turgor-loss point when vapor pressure deficits were high (maximum 3.1 kPa). Compared with Polygonum, Eriogonum had lower xylem pressure potentials, a lower turgor-loss point (mean −1.00 and −1.42 MPa, respectively), and higher conductance. In both species there was no midday depression in leaf conductance and little photosynthetic response to high evaporative demand. Thus, these species are not particularly conservative in water use and appear to rely on abundant soil moisture throughout the short growing season.

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.

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.

Influence of soil moisture regime on the respiration response of soils subjected to osmotic stress

Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 161 ◽  
Author(s):  
GP Sparling ◽  
AW West ◽  
J Reynolds
Keyword(s):  
Soil Moisture ◽  
Microbial Biomass ◽  
Osmotic Stress ◽  
Respiration Rate ◽  
Osmotic Potential ◽  
Moisture Regime ◽  
Air Drying ◽  
Climatic Regions ◽  
Soil Moisture Regime ◽  
Osmotic Potentials

The influence of the soil moisture regime on the tolerance of the soil micro-organisms to increased osmotic stress was examined by laboratory tests with a range of New Zealand soils. Soils from various climatic regions (moist, intermediate and dry) were amended with glucose-NaCl solutions, incubated for 0.5 h, and the respiration rate over the following 2 h was used as a measure of the response of the microbial biomass to the changed osmotic potential. Osmotic potentials were varied between -4 and -80 bar by altering the concentration of NaCl. Air-drying the soils at 25�C decreased the respiration response of the microbial biomass by 3-60% but had little effect on the tolerance of the surviving populations to decreased osmotic potentials. In general, the soils showed the same patterns: an osmotic potential of -23 bar decreased the respiration response by 28-45% (18-44% after air-drying) and a -80 bar potential decreased it by 64-86% (52-84% after air-drying). For the majority of soils, a consistent relationship was obtained between the respiration rate of the moist soils and the osmotic potential applied. A reasonable prediction of the respiration response after air-drying could be obtained from the respiration response of moist soils at -25 bar osmotic potential.

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