Reversibility of Variable Fluorescence at 77 K up to 100% Indicating the Redox States of Q_A and Q_B in Leaves

Abstract

Leaves, needles, algae and chloroplasts can be frozen to 77K. In this stage the fluorescence kinetics can be measured one or several times according to the dark time given between two excitations. The dynamic behaviour appears to be hyperbolic which confirms the hypothesis of Strasser et al.(1, 2, 3). Reversibility of variable fluorescence has been observed earlier (4, 5, 6) and interpreted in a different manner. The following experiments can be considered as a powerful tool to describe the energetics of primary reactions of photosynthesis in a new way. The technique gives acces to the description of Q(A) and Q(B) in situ of e. g. whole leaves.