Chin J Plant Ecol ›› 2014, Vol. 38 ›› Issue (12): 1356-1363.DOI: 10.3724/SP.J.1258.2014.00130

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Fitting mitochondrial respiration rates under light by photosynthetic CO2 response models

KANG Hua-Jing1,2,3,4, TAO Yue-Liang5, QUAN Wei4, WANG Wei4, OUYANG Zhu2,3,4,*()   

  1. 1Wenzhou Vocational & Technical College, Wenzhou, Zhejiang 325026, China;
    2Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    3Yucheng Comprehensive Experiment Station, China Academy of Sciences, Beijing 100101, China
    4University of Chinese Academy of Sciences, Beijing 100049, China
    5College of Life & Environmental Science, Wenzhou University, Wenzhou, Zhejiang 325035, China;
  • Received:2014-03-21 Accepted:2014-05-10 Online:2014-03-21 Published:2015-04-16
  • Contact: OUYANG Zhu


Aims The objective of this study was to compare the values of respiration under light derived by fitting a photosynthetic CO2 response model and measurements, in order to provide information for model optimization.

Methods Using combined gas exchange measurements and a low O2 (2% O2) method, the responses of photosynthetic rate (Pn) to CO2 at different light intensities (2000, 1500, 1000 and 500 μmol·m-2·s-1) in the flag leaves of wheat were measured. The measured data were fitted by a biochemical model, a rectangular hyperbola model and a modified rectangular hyperbola model of the photosynthetic response to intercellular CO2 concentration (A/Ci) and air CO2 concentration (A/Ca), aiming to approach the reasonability of the fitted results obtained from the models.

Important findings The sequence of fitting effect of the three CO2 response models in descending order was as follows: modified rectangular hyperbola model > rectangular hyperbola model > biochemical model. Fitted values of A/Ca curve was more reasonable than A/Ci curve, because the photorespiration and mitochondrial respiration under light (Rd) estimated by the former better matched the measured values. However, there were significant differences in the whole between the fitted and measured values. The reason could be that the effect of CO2 concentrations on Rd and apparent photorespiration (Rpa) is neglected in all the current CO2 response models. Our results showed that CO2 concentration had a marked effect on Rpa and Rd. With increasing CO2 concentration, Rpa and Rd increased first, and then decreased sharply. Take 2000 μmol·m-2·s-1 for example, Rpa varied between 5.035 and 11.670 μmol CO2·m-2·s-1, and Rd varied between 0.491 and 2.987 μmol CO2·m-2·s-1. Regression analyses indicated that Rpa and Rd were well related to CO2 concentrations at different light intensities.

Key words: CO2 concentration, mitochondrial respiration under light, model, photorespiration, wheat