Uncertainty in measurements of the photorespiratory CO2 compensation point and its impact on models of leaf photosynthesis

Walker, Berkley and Orr, Douglas John and Carmo-Silva, Ana Elizabete and Parry, Martin Afan John and Bernacchi, Carl J. and Ort, Donald R. (2017) Uncertainty in measurements of the photorespiratory CO2 compensation point and its impact on models of leaf photosynthesis. Photosynthesis Research, 132 (3). pp. 245-255. ISSN 0166-8595

Abstract

Rates of carbon dioxide assimilation through photosynthesis are readily modeled using the Farquhar, von Caemmerer and Berry (FvCB) model based on the biochemistry of the initial Rubisco-catalyzed reaction of net C3 carbon assimilation. As models of CO2 assimilation are used more broadly for simulating photosynthesis among species and across scales, it is increasingly important that their temperature dependencies are accurately parameterized. A vital component of the FvCB model, the photorespiratory CO2 compensation point (*), combines the biochemistry of Rubisco with the stoichiometry of photorespiratory release of CO2. This report details a comparison of the temperature response of * measured using different techniques in three important model and crop species (Nicotiana tabacum, Triticum aestivum and Glycine max). We determined that the different * determination methods produce different temperature responses in the same species that are large enough to impact higher-scale leaf models of CO2 assimilation. These differences are largest in Nicotiana tabacum, and could be the result of temperature-dependent increases in the amount of CO2 lost from photorespiration per Rubisco oxygenation reaction.