Terminology in Plant- and Soil-Water Relations

Slatyer, R. O.; Taylor, Sterling A.

doi:10.1038/187922a0

Cited by 145 publications

(37 citation statements)

References 13 publications

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“…The water deficit in P. hosiensis and E. angustifolia was characterised by wide diurnal fluctuations; it reached a peak at noon (higher than that of other two desert plants), but recovered in the evening. Water potential is an important index of water conditions in plants (Slatyer and Taylor 1960). H. ammodendron had lower water potential than the other species, which helped it to absorb water from the soil and enhanced its drought resistance (Fig.…”

Section: Discussionmentioning

confidence: 99%

Water relations, gas exchange, photochemical efficiency, and peroxidative stress of four plant species in the Heihe drainage basin of northern China

Gong¹,

Zhao²,

Huang³

et al. 2006

Photosynt.

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Haloxylon ammodendron, Calligonum mongolicum, Elaeagnus angustifolia, and Populus hosiensis had different adaptations to limited water availability, high temperature, and high irradiance. C. mongolicum used water more efficiently than did the other species. Because of low transpiration rate (E) and low water potential, H. ammodendron had low water loss suitable for desert conditions. Water use efficiency (WUE) was high in E. angustifolia, but high E and larger leaf area made this species more suitable for mesic habitats; consequently, this species is important in tree shelterbelts. P. hosiensis had low WUE, E, and photosynthesis rates, and therefore, does not prosper in arid areas without irrigation. High irradiances caused photoinhibition of the four plants. The decrease of photochemical efficiency was a possible non-stomata factor for the midday depression of C. mongolicum. However, the species exhibited different protective mechanisms against high irradiance under drought stress. H. ammodendron and C. mongolicum possessed a more effective antioxidant defence system than E. angustifolia. These three species showed different means of coping with oxidative stress. Hence an enzymatic balance is maintained in these plants under adverse stress conditions, and the concerted action of both enzymatic and non-enzymatic reactive oxygen species scavenging mechanisms is vital to survive adverse conditions.

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Section: Discussionmentioning

confidence: 99%

Water relations, gas exchange, photochemical efficiency, and peroxidative stress of four plant species in the Heihe drainage basin of northern China

Gong¹,

Zhao²,

Huang³

et al. 2006

Photosynt.

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“…Soil water retention curve (SWRC) is an intrinsic constitutive relationship between the soil water potential and water content. The water potential ( ψ ) can be formulated as (e.g., Slatyer & Taylor, ; Taylor & Slatyer, ):

ψ = \frac{normalΔ G}{\overset{true¯}{V_{w}}}

where G is the Gibbs free energy (kJ/mol), that is, the free energy at constant pressure ( p ) and temperature ( T ), and

\overset{V_{normalw}}{true}

is the molar volume of the soil water (m 3 /mol).…”

Section: Physicochemical Mechanisms For Changing Soil Water Densitymentioning

confidence: 99%

What Is the Range of Soil Water Density? Critical Reviews With a Unified Model

Zhang

2018

Reviews of Geophysics

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The soil water density is defined as the ratio of soil water mass to soil water volume. It is a cornerstone in defining thermodynamic states of either saturated or unsaturated soils for quantifying water storage and movement in the subsurface and for mechanical stability of landscape. So far, it has been widely treated as identical to the free water density, that is, a constant of 0.997 g/cm3, but can be remarkably different from this value as it is subject to a wide range of variation in energy levels. Some experimental and theoretical evidence indicate that it can be as high as 1.680 g/cm3 and as low as 0.752 g/cm3. However, to date, there is no unanimous agreement upon a reliable experimental method to measure the soil water density or a unified theory to explain why and how the soil water density can deviate remarkably from the free water density. Consequently, the understanding of the soil water density is controversial and elusive, or some theories are contradictory to each other. In this review, the authors will (1) conduct critical reviews on the experimental and theoretical methodologies to identify their limitations, flaws, and uncertainties, (2) synthesize some recent findings on intermolecular forces, interfacial interactions, and soil water retention mechanisms to clarify molecular‐scale physicochemical mechanisms governing the soil water density, and (3) propose a unified model to quantify soil water density variation. It is found that capillarity associated with surface tension tends to generate tensile stress in soil water and thereby decreases the soil water density, whereas adsorption stemmed from cation hydration, surface hydration, and interlamellar cation hydration tends to produce compressive stress thus increases the soil water density. Furthermore, the abnormally high water density greater than 1.15 g/cm3 is a result of cation and surface hydration that involves significant water structure change around exchangeable cations and mineral surface hydroxyls. The unified soil water density model, explicitly quantifying adsorptive and capillary water, could potentially reconcile the unresolved controversies. The critical reviews and the unified model also would allow us to further confine the upper and lower bounds of the soil water density. The upper bound is theoretically inferred to be around 1.872 g/cm3, whereas the lower bound is around 0.995 g/cm3; both are higher than that reported in the literature. With the unified model and measured soil water retention curves, it is demonstrated quantitatively that the soil water density significantly impacts the magnitude of various fundamental soil properties such as matric potential, specific surface area, and volumetric water content. The abnormally high soil water density has significant implications to the conventional concepts of matric potential and pore water pressure in soils and other earthen porous materials.

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“…Thermodynamic concepts are usually used to define plant water status (Slatyer and Taylor, 1960;Sinclair and Ludlow, 1985). Thermodynamic concepts are usually used to define plant water status (Slatyer and Taylor, 1960;Sinclair and Ludlow, 1985).…”

Section: Water Potentialmentioning

confidence: 99%