Diurnal changes in the delayed fluorescence response of an ambient light-excited green alga

W. Eckert, F. Leunert, Y. Z. Yacobi, J. Köhler, E. Kurzbaum

Research output: Contribution to journalArticlepeer-review


Delayed fluorescence (DF) is a characteristic feature of light-excited plant cells caused by the back-reaction of electrons through the electron transport chain. Targeting the response of light-adapted green algae to diurnal light changes, the present study presents novel results of DF measurements in the absence of an artificial excitation light source. Based on a linear relationship between the DF counts and light intensities from 0.15 to 0.65 W m–2 during daybreak, we estimated an initial algal response to light intensities of 0.01 W m–2. Dissolved oxygen concentrations began to increase at 1.0 W m–2. A noon depression similar to that reported for prompt fluorescence occurred above 100 W m–2. Our results from multiple day–night cycles emphasize that the DF response is a function of the chlorophyll concentration and of a rapid light adaptation. The DF counts alone cannot provide a reliable unambiguous measure of photosynthetic activity.

Original languageAmerican English
Pages (from-to)40-46
Number of pages7
Issue number1
StatePublished - 2019


  • Additional Chlorella vulgaris
  • Chlorophyll fluorescence
  • Diurnal light cycle
  • Phytoplankton

All Science Journal Classification (ASJC) codes

  • Physiology
  • Plant Science


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