Journal of Experimental Botany, Vol. 53, No. 379, pp. 2423-2430,
December 1, 2002
© 2002 Oxford University Press
Effect of local irradiance on CO2 transfer conductance of mesophyll in walnut
Received 4 March 2002; Accepted 12 July 2002
1 Laboratoire d’Ecophysiologie Végétale, UPRESA 8079 CNRS-Université Paris Sud, F-91405 Orsay, France
2 UMR-PIAF Integrated Tree Physiology (INRA-University Blaise Pascal), 234 avenue du Brézet, F-63039 Clermont-Ferrand Cedex 02, France
3 Present address and to whom correspondence should be sent: Laboratoire d’Ecophysiologie de la Photosynthèse, UMR 163 CNRS-CEA, DEVM, CEA Cadarache, F-13108 St Paul lez Durance, France. Fax: +33 4 42 25 62 65. E-mail: bernard.genty{at}cea.fr
4 Present address: Laboratoire d’Ecophysiologie de la Photosynthèse, UMR 163 CNRS-CEA, DEVM, CEA Cadarache, F-13108 St Paul lez Durance, France.
5 Present address: Laboratoire d’Ecologie Microbienne, UMR 5557 CNRS-Université Lyon I, bat 741, 43 bd du 11 novembre 1918, F-69622 Villeurbanne, France.
Abbreviations: An, Anmax, net assimilation rate, and maximal net assimilation rate, respectively; Ca, Ces, Cc, CO2 mole fraction in ambient air, at evaporating surfaces within the leaf and at the carboxylation sites of Rubisco, respectively; fias, volume fraction of intercellular air spaces within the leaf; gi, mesophyll conductance to CO2 transfer; gias, conductance to CO2 transfer in the mesophyll intercellular air spaces; gscmax, maximal stomatal conductance to CO2 transfer; J, Jmax, rate of electron transport, and maximal rate of electron transport, respectively; LMA, leaf mass per area; Na, leaf nitrogen content; PPFD, photosynthetic photon flux density; Rlight, Robs: leaf respiration rate in the light, and in the dark, respectively; Rubisco, ribulose-1,5-bisphosphate carboxylase-oxygenase; Vcmax, maximal rate of carboxylation; 
*, CO2 compensation point in the absence of mitochondrial respiration; 
, mean effective pathlength for CO2 transfer from the substomatal cavity to the uppermost mesophyll surface.
The acclimation responses of walnut leaf photosynthesis to the irradiance microclimate were investigated by characterizing the photosynthetic properties of the leaves sampled on young trees (Juglans nigraxregia) grown in simulated sun and shade environments, and within a mature walnut tree crown (Juglans regia) in the field. In the young trees, the CO2 compensation point in the absence of mitochondrial respiration (*), which probes the CO2 versus O2 specificity of Rubisco, was not significantly different in sun and shade leaves. The maximal net assimilation rates and stomatal and mesophyll conductances to CO2 transfer were markedly lower in shade than in sun leaves. Dark respiration rates were also lower in shade leaves. However, the percentage inhibition of respiration by light during photosynthesis was similar in both sun and shade leaves. The extent of the changes in photosynthetic capacity and mesophyll conductance between sun and shade leaves under simulated conditions was similar to that observed between sun and shade leaves collected within the mature tree crown. Moreover, mesophyll conductance was strongly correlated with maximal net assimilation and the relationships were not significantly different between the two experiments, despite marked differences in leaf anatomy. These results suggest that photosynthetic capacity is a valuable parameter for modelling within-canopies variations of mesophyll conductance due to leaf acclimation to light.
Key words: Leaf anatomy, light acclimation, mesophyll conductance, photosynthetic capacity, Rubisco specificity, walnut.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  A. Monti, G. Bezzi, and G. Venturi Internal conductance under different light conditions along the plant profile of Ethiopian mustard (Brassica carinata A. Brown.) J. Exp. Bot., May 1, 2009; 60(8): 2341 - 2350. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. Niinemets, I. J. Wright, and J. R. Evans Leaf mesophyll diffusion conductance in 35 Australian sclerophylls covering a broad range of foliage structural and physiological variation J. Exp. Bot., May 1, 2009; 60(8): 2433 - 2449. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. Niinemets, A. Diaz-Espejo, J. Flexas, J. Galmes, and C. R. Warren Role of mesophyll diffusion conductance in constraining potential photosynthetic productivity in the field J. Exp. Bot., May 1, 2009; 60(8): 2249 - 2270. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. R. Warren Stand aside stomata, another actor deserves centre stage: the forgotten role of the internal conductance to CO2 transfer J. Exp. Bot., May 1, 2008; 59(7): 1475 - 1487. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. R. Warren Soil water deficits decrease the internal conductance to CO2 transfer but atmospheric water deficits do not J. Exp. Bot., February 1, 2008; 59(2): 327 - 334. [Abstract] [Full Text] [PDF]
|
|