Planta

, Volume 214, Issue 1, pp 135–141 | Cite as

Photosynthetic light response curves determined with the leaf oxygen electrode: minimisation of errors and significance of the convexity term

  • Abdellah Akhkha
  • Iain Reid
  • Don D. Clarke
  • Peter Dominy
Original Article

Abstract.

From photosynthetic studies on a range of monocotyledonous (C-3 and C-4) and dicotyledonous (C-3) plants using a leaf oxygen electrode, we conclude the following. (i) A non-linear model [J.H.M.Thornley (1976) Mathematical models in plant physiology, Academic Press, London; B. Marshall and P.V. Biscoe (1980) J Exp Bot 31:29–39] significantly better describes the photosynthetic light response curve [rate of photosynthesis (P) versus incident photosynthetic photon flux density (I)] than the frequently used linear hyperbolic model [E.I. Rabinowich (1951) Photosynthesis and related processes, vol 2, Wiley, New York]. (ii) When used at the recommended CO2 partial pressures (Ca=1–5 kPa), CO2 supply saturates the photosynthesis rate in the C-3 dicot Phaseolus coccineus L. but not in the C-3 monocot Hordeum vulgare L.. (iii) Fits using a linear hyperbolic model for P versus I produce relatively large and statistically significant errors (≈60%) in the estimation of Pmax and quantum efficiency (α) if Ca is not >5 kPa. (iv) The convexity term, θ, incorporated into the non-linear models for P versus I appears to reflect the limitation placed on the carboxylation processes by the supply of CO2 to the chloroplast stroma. Therefore, the use of a non-linear model providing an estimate of θ should be encouraged, as it is likely to provide information on the physiological status of plants.

Convexity term Hordeum (photosynthesis) Light response curve Phaseolus (photosynthesis) Photosynthesis Zea (photosynthesis) 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Abdellah Akhkha
    • 2
  • Iain Reid
    • 3
  • Don D. Clarke
    • 2
  • Peter Dominy
    • 1
  1. 1.Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
  2. 2.Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
  3. 3.Undergraduate School, Institute of Biomedical and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK

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