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Comparative measurements of gas‐exchange, acid accumulation and chlorophyll a fluorescence of different species of Clusia showing C 3 photosynthesis, or crassulacean acid metabolism, at the same field site in Venezuela

Haag‐Kerwer, A. ; Grams, T. E. E. ; Olivares, E. ; Ball, E. ; Arndt, S. ; Popp, M. ; Medina, E. ; Lüttge, U.

New Phytologist, October 1996, Vol.134(2), pp.215-226 [Periódico revisado por pares]

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  • Título:
    Comparative measurements of gas‐exchange, acid accumulation and chlorophyll a fluorescence of different species of Clusia showing C 3 photosynthesis, or crassulacean acid metabolism, at the same field site in Venezuela
  • Autor: Haag‐Kerwer, A. ; Grams, T. E. E. ; Olivares, E. ; Ball, E. ; Arndt, S. ; Popp, M. ; Medina, E. ; Lüttge, U.
  • Assuntos: Clusia ; Chlorophyll Fluorescence ; Malate And Citrate Deacidification ; Photosynthesis ; Cam
  • É parte de: New Phytologist, October 1996, Vol.134(2), pp.215-226
  • Descrição: Four different species showing C photosynthesis () or crassulacean acid metabolism (CAM) (, an unidentified sp. and co‐occur in the same habitat in the northwest of Venezuela. The aim of this field study was to correlate the adaptive changes in chlorophyll a fluorescence with gas exchange patterns and deacidification of nocturnally accumulated organic acids. The results indicate that in and sp. a lowering of the potential quantum yield, measured as F/F after 10 min of dark adaptation, is restricted to the early morning hours. With the onset of deacidification there was no further decline in F/F, although the irradiance upon the leaves remained high. For the C‐plant, , changes in F/F were correlated with changes in irradiance incident on the leaves before predarkening for 10 min for F/F measurements. The fast relaxation of F/F under low light indicates that was not suffering photoinhibitory damage. Effective quantum yield as determined by ΔF/F, was low under high irradiances for and sp. and did not change significantly for during phase III of CAM. During the time of low incident irradiance and reached an effective quantum yield that was close to the optimal quantum yield of electron transport. It is noteworthy that apparent electron transport rates through photosystem II (PS II) (ΔF/F') × PPFD) were highest for sp. and during phase III of CAM. Electron transport rates in were lower under high irradiance and did not differ from those found in phases II and IV of CAM. The possible role of CO, evolution from acid decarboxylation with respect to photosynthetic efficiency is discussed.

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