Modelling water use efficiency in a dynamic environment: An example using Arabidopsis thaliana.
Intrinsic water use efficiency (Wi), the ratio of net CO2 assimilation (A) over stomatal conductance to water vapour (gs), is a complex trait used to assess plant performance. Improving Wi could lead in theory to higher productivity or reduced water usage by the plant, but the physiological traits for improvement and their combined effects on Wi have not been clearly identified. Under fluctuating light intensity, the temporal response of gs is an order of magnitude slower than A, which results in rapid variations in Wi. Compared to traditional approaches, our new model scales stoma behaviour at the leaf level to predict gs and A during a diurnal period, reproducing natural fluctuations of light intensity, in order to dissect Wi into traits of interest. The results confirmed the importance of stomatal density and photosynthetic capacity on Wi but also revealed the importance of incomplete stomatal closure under dark conditions as well as stomatal sensitivity to light intensity. The observed continuous decrease of A and gs over the diurnal period was successfully described by negative feedback of the accumulation of photosynthetic products. Investigation into the impact of leaf anatomy on temporal responses of A, gs and Wi revealed that a high density of stomata produces the most rapid response of gs but may result in lower Wi.
School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
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Vialet-Chabrand
School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
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JSA
Matthews
EEF, INRA, Université de Lorraine, F-54280 Champenoux, France.
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Brendel
Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK.
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MR
Blatt
Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK.
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Wang
Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK.
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A
Hills
Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
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Griffiths
Computing Science, University of Glasgow, Alwyn Williams Building, Glasgow G12 8QQ, UK.
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Rogers
School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK. Electronic address: tlawson@essex.ac.uk.
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Lawson
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001499:Bayes Theorem; D002245:Carbon Dioxide / Q000378:metabolism; D002940:Circadian Rhythm; D003247:Conservation of Natural Resources; D008962:Models, Theoretical; D054046:Plant Stomata / Q000502:physiology*; D018526:Plant Transpiration; D014867:Water / Q000378:metabolism*
D014867:Water; D002245:Carbon Dioxide
Diurnal; Dynamics; Intrinsic water use efficiency; Photosynthesis; Stomatal conductance