A Model for Estimation of Water Flow Resistance in Soil-Leaf Pathway under Dynamic Conditions

Mishio, Masako; Yokoi, Yõta

doi:10.1093/jxb/42.4.541

Cited by 16 publications

(10 citation statements)

References 17 publications

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“…This Y L expression was first proposed by Mishio and Yokoi [15] and has proved to be a more reliable indicator of the amount of water stress suffered by plants [42] with respect to other common variables used to the same purpose like minimum Y L or the difference between pre-dawn and minimum diurnal Y L . An estimate of the seasonal changes in the hydraulic resistance (R) of plants (R plant ) as well as of that of the root system (R root ) and shoot (R shoot ) was obtained using the "evaporative flux" method (EF) which is based upon the Ohm's law hydraulic analogue i.e.…”

Section: Measurements Of Plant Water Status and Hydraulicsmentioning

confidence: 99%

Water relations and hydraulic characteristics of three woody species co-occurring in the same habitat

et al. 2003

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-Three woody species typically encroaching the Karstic region of Trieste (Northeastern Italy) i.e. Cotinus coggygria L., Prunus mahaleb L. and Fraxinus ornus L., have been measured for diurnal and seasonal time courses of leaf conductance to water vapour, transpiration and water potential (Y L ), as well as whole-plant, shoot and root hydraulic resistance (R plant , R shoot and R root , respectively) in view of investigating the impact of plant hydraulics on water stress resistance. F. ornus suffered the highest Y L drop in July and September due to the high R plant measured in this species. Positive significant relations were found of R plant and Y L to R root in all three species studied, thus suggesting that root hydraulics is a major determinant of plant hydraulics and water stress resistance. The increasing R root (and R plant ) from C. coggygria to P. mahaleb to F. ornus provided a possible explanation for the typical temporal sequence of expansion of the three species into degraded areas.

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Section: Measurements Of Plant Water Status and Hydraulicsmentioning

confidence: 99%

Water relations and hydraulic characteristics of three woody species co-occurring in the same habitat

et al. 2003

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“…In this form, diurnal changes of leaf water potential can be used to estimate the amount of the "environmental pressure" exerted on plants by water stress [23]. The present study reports measurements of water relations parameters in woody species dominant in different sites of the Mediterranean coastal area of Turkey.…”

Section: Introductionmentioning

confidence: 99%

“…More detailed information of the impact of water stress on plants might be provided by the entire diurnal time course of Ψ L , expressed in the integrated form as suggested by Mishio and Yokoi [23] or:…”

Section: Introductionmentioning

confidence: 99%

Diagnosing plant water status as a tool for quantifying water stress on a regional basis in Mediterranean drylands

et al. 2001

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-This study reports measurements of stomatal conductance, relative water content and water potential (Ψ L ) from three dominant evergreens (Ceratonia siliqua L., Quercus coccifera L. and Olea oleaster Hoffmgg. et Link) growing in four coastal sites of Turkey. In particular, a fully vegetated site (H) was selected and compared for the above parameters to three degraded sites (D1, D2 and D3) with decreasing vegetation covers. From the integral of the diurnal time course of Ψ L , the water stress impact on each species (WSIS) was calculated. C. siliqua and Q. coccifera showed similar WSIS's, increasing significantly from H to D3. O. oleaster was sensitive both to summer drought and to increasing site degradation. The impact of water stress was scaled up from the species to the vegetation level (WSIV) as WSIV = Σ WSIS S (1-f s ) where f s was the relative frequency of the species studied. WSIV was rather sensitive to the impoverishment of vegetation and was correlated to vegetation density as estimated both by field observations and remotely sensed Normalized Difference Vegetation Index. desertification / leaf water potential / Mediterranean evergreens / Normalized Difference Vegetation Index / water stress impact Résumé -Diagnostiquer l'état de l'eau dans la plante : un outil pour quantifier le stress hydrique au niveau régional dans les régions sèches méditerranéennes. Cette étude rapporte les mesures de conductance stomatique, de la teneur relative en eau et du potentiel hydrique (Ψ L ) d'arbres à feuilles persistantes (Ceratonia siliqua L., Quercus coccifera L. et Olea oleaster Hoffmgg. Et Link) croissant sur 4 sites côtiers de Turquie. En particulier, un site totalement recouvert de végétation (H) a été sélectionné et comparé, pour les paramètres ci-dessus, à 3 sites dégradés (D1, D2 et D3) ayant une couverture végétale de plus en plus faible. A partir de l'intégrale de Ψ L , pour le cycle diurne, l'impact du stress hydrique de chaque espèce (WSIS) a été calculé. C. siliqua et Q. coccifera montrent des WSIS similaires, augmentant significativement de H à D3. O. oleoaster a été sensible à la fois à la sécheresse estivale et à l'accroissement de la dégradation du site. Un changement d'échelle, du niveau de l'espèce à celui de la végétation, a été réalisé pour l'impact du stress hydrique (WSIV) par la transformation WSIV = Σ WSISs (1-f s ) ou f s est la fréquence relative de l'espèce étudiée. WSIV est particulièrement sensible à l'appauvrissement de la végétation et est corrélé à la densité de la végétation estimée à la fois par des observations aux champs et par l'indice normalisé de différentiation de la végétation par observation satellitaire. désertification / potentiel hydrique des feuilles / arbre à feuilles persistantes méditerranéen / index normalisé de différentia-tion des espèces / impact du stress hydrique Ann. For. Sci. 58 (2001) 113-125 113

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“…BreÂ da et al (1995) estimated the zone of oak root water uptake from the match of oak predawn Y w with soil Y w in the depth pro®le. Models that integrate plant transpiration responses to water stress and estimate hydraulic resistances also commonly assume that soil and plant Y w equilibrate by dawn (Mishio and Yokoi 1991;Rambal 1992;Brisson et al 1993). Predawn xylem Y p has also been correlated with plant physiological processes including maximum stomatal conductance or transpiration (Reich and Hinckley 1989;Romo and Haferkamp 1989;Acherar and Rambal 1992;AmeÂ glio and Archer 1996) and growth (Mitchell et al 1993).…”

Section: Introductionmentioning

confidence: 99%

Predawn disequilibrium between plant and soil water potentials in two cold-desert shrubs

et al. 1999

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Classical water relations theory predicts that predawn plant water potential should be in equilibrium with soil water potential (soil Ψ) around roots, and many interpretations of plant water status in natural populations are based on this expectation. We examined this expectation for two salt-tolerant, cold-desert shrub species in glasshouse experiments where frequent watering assured homogeneity in soil Ψ and soil-root hydraulic continuity and where NaCl controlled soil Ψ. Plant water potentials were measured with a pressure chamber (xylem Ψ) and thermocouple psychrometers (leaf Ψ). Soil Ψ was measured with in situ thermocouple psychrometers. Predawn leaf Ψ and xylem Ψ were significantly more negative than soil Ψ, for many treatments, indicating large predawn soil-plant Ψ disequilibria: up to 1.2 MPa for Chrysothamnus nauseosus (0 and 100 mM NaCl) and 1.8 MPa for Sarcobatus vermiculatus (0, 100, 300, and 600 mM NaCl). Significant nighttime canopy water loss was one mechanism contributing to predawn disequilibrium, assessed by comparison of xylem Ψ for bagged (to minimize transpiration) and unbagged canopies, and by gas exchange measurements. However, nighttime transpiration accounted for only part of the predawn disequilibrium. Other mechanisms that could act with nighttime transpiration to generate large predawn disequilibria are described and include a model of how leaf apoplastic solutes could contribute to the phenomenon. This study is among the first to conclusively document such large departures from the expectation of predawn soil-plant equilibrium for C shrubs, and provides a general framework for considering relative contributions of nighttime transpiration and other plant-related mechanisms to predawn disequilibrium.

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A Model for Estimation of Water Flow Resistance in Soil-Leaf Pathway under Dynamic Conditions

Cited by 16 publications

References 17 publications

Water relations and hydraulic characteristics of three woody species co-occurring in the same habitat

Water relations and hydraulic characteristics of three woody species co-occurring in the same habitat

Diagnosing plant water status as a tool for quantifying water stress on a regional basis in Mediterranean drylands

Predawn disequilibrium between plant and soil water potentials in two cold-desert shrubs

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