Photosynthesis Research

, Volume 9, Issue 1, pp 261–272

Detection of rapid induction kinetics with a new type of high-frequency modulated chlorophyll fluorometer

  • U. Schreiber
Methods

DOI: 10.1007/BF00029749

Cite this article as:
Schreiber, U. Photosynth Res (1986) 9: 261. doi:10.1007/BF00029749

Abstract

A newly developed modulation fluorometer is described which operates with 1 μsec light pulses from a light-emitting diode (LED) at 100 KHz. Special amplification circuits assure a highly selective recording of pulse fluorescence signals against a vast background of non-modulated light. The system tolerates ratios of up to 1:107 between measuring light and actinic light. Thus it is possible to measure the “dark fluorescence yield” and record the kinetics of light-induced changes. A high time resolution allows the recording of the rapid relaxation kinetic following a saturating single turnover flash. Examples of system performance are given. It is shown that following a flash the reoxidation kinetics of photosystem II acceptors are slowed down not only by the inhibitor DCMU, but by a number of other treatments as well. From a light intensity dependency of the induction kinetics the existence of two saturated intermediate levels (I1 and I2) is apparent, which indicates the removal of three distinct types of fluorescence quenching in the overall fluorescence rise from F0 to Fmax.

Key words

chlorophyll fluorescencefluorometerfluorescence quenchingKautsky effectphotosynthesisphotosystem II

Abbreviations

QA and QB

consecutive electron acceptors of photosystem II

PS II

photosystem II

P 680

reaction center chlorophyll of photosystem II

F0

minimum fluorescence yield following dark adaptation

Fmax

maximum fluorescence yield

DCMU

3-(3, 4-dichlorophenyl)-1, 1-dimethyl-urea

DCCD

N,N′-dicyclohexylcarbodiimide

PQ

plastoquinone

DAD

diaminodurene

Copyright information

© Martinus Nijhoff/Dr. W. Junk Publishers 1986

Authors and Affiliations

  • U. Schreiber
    • 1
  1. 1.Lehrstuhl Botanik IUniversität WürzburgWurzburgFRG