Evaluation of photosynthetic electron flow using simultaneous measurements of gas exchange and chlorophyll fluorescence under photorespiratory conditions

Publication Type:
Journal Article
Citation:
Photosynthetica, 2012, 50 (3), pp. 472 - 476
Issue Date:
2012-09-01
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Simultaneous measurements of leaf gas exchange and chlorophyll fluorescence for Koelreuteria paniculata Laxm. at 380 ± 5. 6 and 600 ± 8. 5 μmol mol-1were conducted, and the photosynthetic electron flow via photosystem II (PSII) to photosynthesis, photorespiration, and other electron-consuming processes were calculated. The results showed that the photosynthetic electron flow associated with carboxylation (Jc), oxygenation (Jo), and other electron-consuming processes (Jr) were 72. 7, 45. 7, and 29. 4 μmol(e-) m-2s-1at 380 μmol mol-1, respectively; and 86. 1, 35. 3, and 48. 2 μmol(e-) m-2s-1at 600 μmol mol-1, respectively. Our results revealed that other aspects associated with electronconsuming processes, except for photosynthesis and respiration, were neither negligible nor constant under photorespiratory conditions. Using maximum net photosynthetic rate (Pmax), day respiration (R), photorespiration rate (Rl), and maximum electron flow via PSII (Jmax), the use efficiency of electrons via PSII at saturation irradiance to fix CO2was calculated. The calculated results showed that the use efficiency of electrons via PSII to fix CO2at 600 μmolmol-1was almost as effective as that at 380 μmol mol-1, even though more electrons passed through PSII at 600 μmol mol-1than at 380 μmol mol-1. © 2012 Springer Science+Business Media B.V.
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