title: Use of an analytical model to study limitations on net photosynthesis in Arbutus unedo under field conditions.
abstract: From field gas-exchange measurements on Arbutus unedo growing in Portugal, parameter values necessary to apply an analytical, physiologicallybased model of C3photosynthesis were obtained. The model successfully simulated measured diurnal photosynthetic responses in Arbutus during periods without water stress, under both natural and CO2-saturating conditions. The model was used to analyze those factors limiting primary productivity during each of the experimental days. Due to a large investment in ribulose bisphosphate (RuBP) regeneration capacity, irradiance was rarely limiting, even during cloudy periods, but the limitation imposed by stomatal conductance was quite large, averaging over 30%. The fact that experimental leaves were maintained in a horizontal position is at least partially responsible for these results. Possible other reasons for this apparent excess of RuBP regeneration capacity visa-vis RuBP carboxylase-oxygenase concentration are discussed.
authors.affiliation: Systems Ecology Research Group, San Diego State University, 92182, San Diego, CA, USA.
authors.forename: P C
authors.initials: PC
authors.lastname: Harley
authors.affiliation: Systems Ecology Research Group, San Diego State University, 92182, San Diego, CA, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Tenhunen
authors.affiliation: Lehrstuhl für Botanik II, Universität Würzburg, Mittlerer Dallenbergweg 64, D-8700, Würzburg, Federal Republic of Germany.
authors.forename: O L
authors.initials: OL
authors.lastname: Lange
keywords: Arbutus; Photosynthesis model; RuBP regeneration; Stomatal limitation