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A coupled photosynthesis and stomatal conductance model for mango leaves

Urban, L., Bertheuil, F., Lechaudel, M.
Acta horticulturae 2002 no.584 pp. 81-88
calcium, carbon dioxide, data collection, flowering, gas exchange, leaves, mangoes, models, photosynthesis, stomatal conductance
The first step of the modelling approach consisted in designing a model of leaf diffusive conductance (gs) adapted from Ball, Woodrow and Berry (1987), expressing gs mainly as a function of Anet. The widely accepted biochemical model of C3 leaf photosynthesis of Farquhar, von Caemmerer and Berry (1980) was parameterized for well-lit, young, mature mango leaves using response curves of net photosynthesis to intercellular CO2 concentration (A-Ci curves). To obtain an analytical solution for leaf photosynthesis, we used the following additional conductance relation : Ci = Ca - Anet / gb - Anet / gs, where Ca stands for the ambient CO2 concentration and gb for the conductance across the laminar boundary layer. The resulting model of leaf photosynthesis was tested against three sets of data from gas exchange measurements obtained with a portable infrared gas analyser on leaves of 12 year old mango trees, cv. Lirfa, at two periods of the year : August, just before flowering, and from November to December, during the fruiting stage. The need to take into account the influence of light availability, leaf age and sink activity on photosynthetic capacity to upgrade the model is discussed.