Correction to: Linear relation between leaf xylem water potential and transpiration in pearl millet during soil drying

Pearl millet [Penniseturn americanum (L.) Leeke] consistently develops lower predawn leaf water potentials than cowpea [Vigna unguiculata (L.) Walp.] when plants are subjected to progressive soil drying, even when they are grown as intercrops in the same pot. Lack of equilibrium in water potential during the predawn, within the plants and between plants and soil, was studied as a possible explanation for this difference. Experiments were conducted in a glasshouse in pots containing an artificial rooting medium which had a high water-holding capacity and was easy to separate from roots. Leaf and root predawn xylem water potentials were measured with a pressure chamber. In cowpea, leaf water potential (ΨL) values during the dry treatment were similar to values of root water potential (ΨR), indicating an approximate equilibrium within the plants. In millet, measurements were made on plants grown in both large and small pots. With large pots, ΨL and ΨR values in millet were similar, but with small pots, predawn ΨL was lower than ΨR. When the surfaces of these small pots were covered with evaporation barriers, however, no significant differences developed between ΨL and ΨR at predawn during soil drying, indicating an approximate equilibrium within millet. During the early stages of the dry treatment, leaf surface conductances measured at predawn indicated that significant water flux occurred at night from the leaves of both cowpea and millet. Leaf surface conductances declined to negligible levels as the dry treatment progressed, however, and night-time fluxes of water from leaves cannot explain the significant difference in predawn ΨL that developed between cowpea and millet. In order to determine whether the lower predawn ΨL in millet was due to a resistance to water uptake at the root surface, an osmoticum (- 0.5 MPa mannitol solution) was applied to pots of cowpea and millet intercrops after substantial differences in predawn ΨL had developed, and ΨL was measured. Measurements taken 9 h later indicated that predawn ΨL had recovered in millet, and the values of ΨL in millet and cowpea after mannitol treatment were similar to the osmotic potential of the mannitol solution. These results suggest that the lower predawn ΨL in millet than in cowpea under drought is due to the development of a substantial soil resistance to water movement to the root surfaces of millet.

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Declining soil-root hydraulic conductance drives stomatal closure of tomato under drought

10.5194/egusphere-egu21-4192 ◽

2021 ◽

Author(s):

Mohanned Abdalla ◽

Andrea Carminati ◽

Gaochao Cai ◽

Mathieu Javaux ◽

Mutez Ahmed

Keyword(s):

Water Potential ◽

Stomatal Closure ◽

Soil Water Potential ◽

Hydraulic Conductance ◽

Soil Drying ◽

Xylem Water Potential ◽

Hydraulic Limitation ◽

Shoot Hydraulic Conductance ◽

Root Conductance ◽

Response To Water

The fundamental question as to what triggers stomatal closure during soil drying remains contentious. Thus, we urgently need to improve our understanding of stomatal response to water deficits in soil and atmosphere. Here, we investigated the role of soil-plant hydraulic conductance (Ksp) on transpiration (E) and stomata regulation. We used a root pressure chamber to measure the relation between E, leaf xylem water potential (&#968;leaf-x) and soil water potential (&#968;soil) in tomato. Additional measurements of &#968;leaf-x were performed with unpressurized plants. A soil-plant hydraulic model was used to simulate E(&#968;leaf-x) for decreasing &#968;soil. In wet soils, E(&#968;leaf-x) had a constant slope while in dry soils the slope decreased, with &#968;leaf-x rapidly and nonlinearly decreasing for moderate increases in E. The &#968;leaf-x measured in pressurized and unpressurized plants matched well, which indicates that the shoot hydraulic conductance did not decrease during soil drying and that the decrease in Ksp is caused by a decrease in soil-root conductance. The decrease of E matched well the onset of hydraulic nonlinearity. Our findings demonstrate that stomatal closure prevents the drop in &#968;leaf-x caused by a decrease in Ksp and elucidate a strong correlation between stomatal regulation and belowground hydraulic limitation.

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Measurement of leaf xylem water potential and transpiration during soil drying using a root pressure chamber system

Acta Horticulturae ◽

10.17660/actahortic.2020.1300.17 ◽

2020 ◽

pp. 131-138 ◽

Cited By ~ 1

Author(s):

G. Cai ◽

M.A. Ahmed ◽

S. Reth ◽

M. Reiche ◽

A. Kolb ◽

...

Keyword(s):

Water Potential ◽

Pressure Chamber ◽

Soil Drying ◽

Chamber System ◽

Xylem Water Potential ◽

Root Pressure

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Mist Irrigation Reduces Post-transplant Desiccation of Bare-root Trees

Journal of Environmental Horticulture ◽

10.24266/0738-2898-12.1.1 ◽

1994 ◽

Vol 12 (1) ◽

pp. 1-3 ◽

Cited By ~ 1

Author(s):

Rick M. Bates ◽

Alex X. Niemiera

Keyword(s):

Water Stress ◽

Water Potential ◽

Acer Platanoides ◽

Sensitive Species ◽

Xylem Water Potential ◽

Post Transplant ◽

Norway Maple ◽

Relative Water ◽

Bare Root ◽

Cherry Trees

Abstract Desiccation during storage and reestablishment is a major factor contributing to poor regrowth of transplanted bare-root trees. The effect of overhead mist irrigation on reducing post transplant water stress in Norway maple (Acer platanoides L. ‘Emerald Lustre’) and Yoshino cherry (Prunus x yedoensis) was examined. Bare-root Norway maple (desiccation tolerant) and Yoshino cherry (desiccation sensitive) trees were transplanted into pine bark-filled containers and subjected to mist or non-mist treatments. Stem xylem water potential, relative water content, and survivability were determined. Xylem water potential increased (became less negative) for misted maple and cherry trees. Water potential increased for non-misted maple and decreased for non-misted cherry trees. Twenty-seven percent of non-misted cherries were evaluated as nonmarketable due to stem dieback compared to 0% for misted trees. Results of this study indicate that mist irrigation effectively reduces desiccation damage for desiccation sensitive species such as cherries and hawthorns.

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Needle water potential and soil-to-foliage flow resistance during soil drying: a comparison of Douglas-fir, western hemlock, and mountain hemlock

Canadian Journal of Forest Research ◽

10.1139/x85-033 ◽

1985 ◽

Vol 15 (1) ◽

pp. 185-188 ◽

Cited By ~ 3

Author(s):

T. M. Ballard ◽

M. G. Dosskey

Keyword(s):

Water Potential ◽

Soil Water ◽

Water Flow ◽

Flow Resistance ◽

Soil Water Potential ◽

Douglas Fir ◽

Western Hemlock ◽

Soil Drying ◽

Experimental Conditions ◽

Needle Water Potential

Needle water potential in western and mountain hemlock falls as the soil dries, but under our experimental conditions, it remained stable in Douglas-fir. Resistance to water flow from soil to foliage is higher for the hemlocks and increases more steeply as the soil dries. These findings physically account for the observation that water uptake is reduced relatively more for the hemlocks than for Douglas-fir, as soil water potential declines.

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Growth and Xylem Water Potential of White Oak and Loblolly Pine Seedlings as Affected by Simulated Acidic Rain

The American Midland Naturalist ◽

10.2307/2426432 ◽

1993 ◽

Vol 129 (1) ◽

pp. 26 ◽

Cited By ~ 5

Author(s):

R. F. Walker ◽

S. B. McLaughlin

Keyword(s):

Water Potential ◽

Loblolly Pine ◽

White Oak ◽

Xylem Water Potential ◽

Pine Seedlings ◽

Acidic Rain

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Soil water matric potential rather than water content determines drought responses in field-grown lupin (Lupinus angustifolius)

Functional Plant Biology ◽

10.1071/pp97072 ◽

1998 ◽

Vol 25 (3) ◽

pp. 353 ◽

Cited By ~ 29

Author(s):

C.R. Jensen ◽

V.O. Mogensen ◽

H.-H. Poulsen ◽

I.E. Henson ◽

S. Aagot ◽

...

Keyword(s):

Water Potential ◽

Water Content ◽

Soil Water ◽

Stomatal Closure ◽

Soil Water Potential ◽

Root Surface ◽

Lupinus Angustifolius ◽

Soil Drying ◽

Matric Potential ◽

Aba Content

Drought responses in leaves of lupin (Lupinus angustifolius L., cv. Polonez) were investigated in plants grown in lysimeters either in a sand or in a loam soil in the field. Abscisic acid (ABA) content, water potential (ψl) and conductance to water vapour (gH2O) were determined in leaves of both irrigated plants and in plants exposed to gradual soil drying. Amorning-peak of leaf ABA content was found in both fully watered and droughted plants. During soil drying which, on both soils types, only decreased soil water potential of the upper soil layers, mid-day leaf ABA content increased relative to that in fully irrigated plants before any appreciable decreases occurred in ψl. In the part of the soil profile from which water was taken up (0–60 cm depth), gH2O decreased when the relative available soil water content (RASW) on sand was below 12% and RASW on loam, below 30%. At this point the average soil water matric potential (ψsoil) on sand was less than –0.13 MPa and the fraction of roots in ‘wet’ soil was 0.12, while on loam, the fraction of roots in ‘wet’ soil was 0.44 while y soil was similar to that on sand. A critical leaf ABA content of 300–400 ng/g FW was associated with the onset of stomatal closure on both soil types. We suggest that the initial stomatal closure is controlled by ABA which originates from the roots where its production is closely related to ψsoiland the water potential of the root surface and that ψsoil is a more important parameter than RASW or the fraction of roots in ‘wet’ soil for affecting leaf gas exchange. Further drying on both soils led to further increases in leaf ABA and declines in ψl and gH2O. In order to gain further insight, experiments should be designed which combine signalling studies with simulation studies, which take account of soil water potential, root contact area and water flux when calculating the water status at the root surface in the soil-plant-atmosphere-continuum.

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Optimal stomatal behavior with competition for water and risk of hydraulic impairment

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1615144113 ◽

2016 ◽

Vol 113 (46) ◽

pp. E7222-E7230 ◽

Cited By ~ 100

Author(s):

Adam Wolf ◽

William R. L. Anderegg ◽

Stephen W. Pacala

Keyword(s):

Water Potential ◽

Classical Theory ◽

Plant Competition ◽

Carbon Gain ◽

Alternative Theory ◽

Xylem Water Potential ◽

Stomatal Behavior ◽

Damage Repair ◽

Functional Forms ◽

Additional Water

For over 40 y the dominant theory of stomatal behavior has been that plants should open stomates until the carbon gained by an infinitesimal additional opening balances the additional water lost times a water price that is constant at least over short periods. This theory has persisted because of its remarkable success in explaining strongly supported simple empirical models of stomatal conductance, even though we have also known for over 40 y that the theory is not consistent with competition among plants for water. We develop an alternative theory in which plants maximize carbon gain without pricing water loss and also add two features to both this and the classical theory, which are strongly supported by empirical evidence: (i) water flow through xylem that is progressively impaired as xylem water potential drops and (ii) fitness or carbon costs associated with low water potentials caused by a variety of mechanisms, including xylem damage repair. We show that our alternative carbon-maximization optimization is consistent with plant competition because it yields an evolutionary stable strategy (ESS)—species with the ESS stomatal behavior that will outcompete all others. We further show that, like the classical theory, the alternative theory also explains the functional forms of empirical stomatal models. We derive ways to test between the alternative optimization criteria by introducing a metric—the marginal xylem tension efficiency, which quantifies the amount of photosynthesis a plant will forego from opening stomatal an infinitesimal amount more to avoid a drop in water potential.

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Relationship Between Root/Soil Hydraulic Properties and Stomatal Behaviour in Sugarcane

Functional Plant Biology ◽

10.1071/pp9890241 ◽

1989 ◽

Vol 16 (3) ◽

pp. 241 ◽

Cited By ~ 21

Author(s):

NZ Saliendra ◽

FC Meinzer

Keyword(s):

Stomatal Conductance ◽

Water Potential ◽

Soil Water ◽

Leaf Water Potential ◽

Water Status ◽

Hydraulic Conductance ◽

Leaf Water ◽

Soil Drying ◽

Root Hydraulic Conductance ◽

High Soil Moisture

Stomatal conductance, leaf and soil water status, transpiration, and apparent root hydraulic conductance were measured during soil drying cycles for three sugarcane cultivars growing in containers in a greenhouse. At high soil moisture, transpiration and apparent root hydraulic conductance differed considerably among cultivars and were positively correlated, whereas leaf water potential was similar among cultivars. In drying soil, stomatal and apparent root hydraulic conductance approached zero over a narrow (0.1 MPa) range of soil water suction. Leaf water potential remained nearly constant during soil drying because the vapor phase conductance of the leaves and the apparent liquid phase conductance of the root system declined in parallel. The decline in apparent root hydraulic conductance with soil drying was manifested as a large increase in the hydrostatic pressure gradient between the soil and the root xylem. These results suggested that control of stomatal conductance in sugarcane plants exposed to drying soil was exerted primarily at the root rather than at the leaf level.

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