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The effect of available soil water and root density on actual and potential transpiration relationships
Authors: Stewart, D.W., Dwyer, L.M. And R.L. Desjardins
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Download file: https://library.csbe-scgab.ca/docs/journal/27/27_1_7_ocr.pdf
Published in: CBE Journal » CBE Journal Volume 27 (1985)
Download RAW file: https://library.csbe-scgab.ca/docs/journal/27/27_1_7_raw.pdf
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Description: Plant transpiration is controlled by leaf stomatal resistance which responds to leaf water potential (Turner 1974). The leaf water potential is in turn determined by the plant available soil water (Aw) and the evaporative conditions of the atmosphere. Available water is defined here as the pro portion of water held in the soil between -0.03 MPa and - 1.5 MPa. Evaporative conditions of the atmosphere can be described by potential transpiration (PT), which is transpiration from a closed canopy at high levels of Aw such that stomates do not close due to moisture stress. How actual transpiration (AT) is related to Aw and PT is of considerable importance to understanding the effects of water stress on plant growth. These relationships are summarized by ratios of AT to PT (ATIPT) expressed as functions of Aw. A widely quoted study by Denmead and Shaw (1962) showed this ratio remained at unity over a wide range of Aw for low rates of PT, but decreased from unity at high values of Aw for high rates of Pj, On the other hand, results by Van Bavel (1967), Ritchie et al. (1972) and Ritchie (1973) indicate that the ratio remains at unity until 75-80% of the avail able soil water is depleted and then declines linearly to zero. Ritchie (1973) attributed this difference to root volumes. Measurements by Denmead anad Shaw came from plants growing in relatively small containers (87.6 L) inserted in the field. The other studies used large weighing lysimeters with much less restriction in the root zone. This issue has never been fully resolved. For example, two recent papers by Selirio and Brown (1979) and Stuff and Dale (1978) used the results of Denmead and Shaw without referring to questions raised by Ritchie (1973).
Keywords: the effect of available soil water and root density on actual and potential transpiration relationships
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Citation: Stewart, D.W., Dwyer, L.M. and R.L. Desjardins 1985. THE EFFECT OF AVAILABLE SOIL WATER AND ROOT DENSITY ON ACTUAL AND POTENTIAL TRANSPIRATION RELATIONSHIPS. Canadian Agricultural Engineering 27(1):7-12.
Volume: 27
Issue: 1
Pages 7 - 12
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Date: 1985
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Coverage: Canada
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DOI:
Description: Plant transpiration is controlled by leaf stomatal resistance which responds to leaf water potential (Turner 1974). The leaf water potential is in turn determined by the plant available soil water (Aw) and the evaporative conditions of the atmosphere. Available water is defined here as the pro portion of water held in the soil between -0.03 MPa and - 1.5 MPa. Evaporative conditions of the atmosphere can be described by potential transpiration (PT), which is transpiration from a closed canopy at high levels of Aw such that stomates do not close due to moisture stress. How actual transpiration (AT) is related to Aw and PT is of considerable importance to understanding the effects of water stress on plant growth. These relationships are summarized by ratios of AT to PT (ATIPT) expressed as functions of Aw. A widely quoted study by Denmead and Shaw (1962) showed this ratio remained at unity over a wide range of Aw for low rates of PT, but decreased from unity at high values of Aw for high rates of Pj, On the other hand, results by Van Bavel (1967), Ritchie et al. (1972) and Ritchie (1973) indicate that the ratio remains at unity until 75-80% of the avail able soil water is depleted and then declines linearly to zero. Ritchie (1973) attributed this difference to root volumes. Measurements by Denmead anad Shaw came from plants growing in relatively small containers (87.6 L) inserted in the field. The other studies used large weighing lysimeters with much less restriction in the root zone. This issue has never been fully resolved. For example, two recent papers by Selirio and Brown (1979) and Stuff and Dale (1978) used the results of Denmead and Shaw without referring to questions raised by Ritchie (1973).
Keywords: the effect of available soil water and root density on actual and potential transpiration relationships
Résumé:
Mots-clés:
Citation: Stewart, D.W., Dwyer, L.M. and R.L. Desjardins 1985. THE EFFECT OF AVAILABLE SOIL WATER AND ROOT DENSITY ON ACTUAL AND POTENTIAL TRANSPIRATION RELATIONSHIPS. Canadian Agricultural Engineering 27(1):7-12.
Volume: 27
Issue: 1
Pages 7 - 12
Contributor:
Date: 1985
Technical field:
Conference name:
Session name:
Other information:
Type:
Format:
Publication type:
Source:
Relation:
Coverage: Canada
Language 1:
Language 2:
Rights:
Notes:
Other files:
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