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Does the direct effect of atmospheric CO 2 concentration on leaf respiration vary with temperature? Responses in two species of Plantago that differ in relative growth rate
Author(s) -
Bruhn Dan,
Mikkelsen Teis N.,
Atkin Owen K.
Publication year - 2002
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2002.1140109.x
Subject(s) - plantago , respiration , respiration rate , chemistry , carbon dioxide , zoology , photosynthesis , degree (music) , botany , biology , biochemistry , physics , organic chemistry , acoustics
The objective of this study was to investigate the direct effect of elevated atmospheric CO 2 concentrations on leaf respiration in darkness (R) over a broad range of measurement temperatures. Our aim was to further elucidate the underlying mechanism(s) of the often‐reported inhibition of leaf R by a doubling of the atmospheric CO 2 concentration. Experiments were conducted using two species of Plantago that differed in maximum relative growth rate (fast‐growing Plantago lanceolata L. and the slow‐growing P. euryphylla Briggs, Carolin & Pulley). Rates of leaf respiration (R) were measured at atmospheric CO 2 concentrations ranging from 75 to 2000 µmol mol −1 at temperatures from 12 to 42°C. R was measured as CO 2 release with a portable gas exchange system with infrared gas analysers. Our hypothesis was that the changes in temperature alter the flux coefficient (i.e. the extent to which changes in potential enzyme activity has an effect on the rate of a reaction) of enzymes potentially affected by CO 2 . Initial analysis of our results suggested that R was inhibited by elevated CO 2 in both species, with the apparent degree of inhibition being greatest at low temperature. Moreover, the apparent degree of inhibition following a doubling of atmospheric CO 2 concentration from 350 to 700 µmol mol −1 was similar to that reported by several previous studies (approximately 14% and 26% for P. lanceolata and P. euryphylla , respectively) at a temperature equal to the mean of the previous studies. However, subsequent correction for diffusion leaks of CO 2 across the gas exchange's cuvette gaskets revealed that no significant inhibition had occurred in either species, at any temperature. The inhibitory effect of elevated CO 2 on leaf respiratory CO 2 release reported by previous studies may therefore have been overestimated.