Improved Temperature Response Functions for Modeling Photosynthetic Carbon Assimilation in the Context of Rising Carbon Dioxide
type: CreativeWork
description: Predicting environmental responses of leaf photosynthesis is central for modeling changes in the future global carbon cycle and terrestrial biosphere. The steady-state biochemical model of C3 photosynthesis of Farquhar et al. (1980; Planta 149, 78--90) provides a basis for these larger scale predictions; but a weakness as currently parameterized has been inability to predict accurately carbon assimilation over an ecologically significant range of temperatures. The previous parameters were based on in vitro measurements made over a limited temperature range and require several assumptions of in vivo conditions. Inaccuracies in the functions predicting Rubisco- or RuBP-limited kinetic properties at different temperatures cause very significant error. Both anti-rbcS, for estimating Rubisco kinetics over a larger range of Ci, and wild-type tobacco, to estimate RuBP regeneration kinetics, were used in this study. The temperature functions required for Rubisco-limited photosynthesis were estimated in vivo from the rate of CO2 assimilation over a wide range of temperatures, and CO2 and O2 concentrations, using the anti-rbcS tobacco. Functions required for modeling RuBP-limited photosynthesis were estimated with gas exchange and fluorescence measurements on wild-type tobacco. The results differed substantially from previously published functions for Rubisco- and RuBP-limited photosynthesis. Gas-exchange measurements coupled with fluorescence were also made to determine the temperature response of mesophyll conductance for estimating Rubisco kinetics based on CO2 concentrations at the chloroplast level. These new functions were used to predict photosynthesis in greenhouse grown lemon and tobacco and found to faithfully mimic the observed temperature response. Finally, measurements of diurnal photosynthesis for three poplar clones and soybean plants exposed to current and future predicted levels of CO2 were made over the growing season in the PopFACE and SoyFACE research faci…
abstract: Predicting environmental responses of leaf photosynthesis is central for modeling changes in the future global carbon cycle and terrestrial biosphere. The steady-state biochemical model of C3 photosynthesis of Farquhar et al. (1980; Planta 149, 78--90) provides a basis for these larger scale predictions; but a weakness as currently parameterized has been inability to predict accurately carbon assimilation over an ecologically significant range of temperatures. The previous parameters were based on in vitro measurements made over a limited temperature range and require several assumptions of in vivo conditions. Inaccuracies in the functions predicting Rubisco- or RuBP-limited kinetic properties at different temperatures cause very significant error. Both anti-rbcS, for estimating Rubisco kinetics over a larger range of Ci, and wild-type tobacco, to estimate RuBP regeneration kinetics, were used in this study. The temperature functions required for Rubisco-limited photosynthesis were estimated in vivo from the rate of CO2 assimilation over a wide range of temperatures, and CO2 and O2 concentrations, using the anti-rbcS tobacco. Functions required for modeling RuBP-limited photosynthesis were estimated with gas exchange and fluorescence measurements on wild-type tobacco. The results differed substantially from previously published functions for Rubisco- and RuBP-limited photosynthesis. Gas-exchange measurements coupled with fluorescence were also made to determine the temperature response of mesophyll conductance for estimating Rubisco kinetics based on CO2 concentrations at the chloroplast level. These new functions were used to predict photosynthesis in greenhouse grown lemon and tobacco and found to faithfully mimic the observed temperature response. Finally, measurements of diurnal photosynthesis for three poplar clones and soybean plants exposed to current and future predicted levels of CO2 were made over the growing season in the PopFACE and SoyFACE research faci…
author: Bernacchi, Carl J.
language: eng
keywords: Physics, Atmospheric Science
date published: 2015-09-28T15:22:38Z
date modified: 2026-07-22T22:26:28Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/87030