Global fluorescence lifetime distribution analyses of PSII energy dissipation mechanisms at low physiological temperatures: xanthophyll photoprotection, photochemistry and photoinhibition

摘要

One of the main problems associated with measuring photosynthetic activity at low physiological temperatures using chlorophyll (chl a) fluorescence is that photosynthetic, photoprotective and photoinhibitory damage associated processes all tend to reduce the PSII fluorescence yield concomitantly. It is therefore difficult to distinguish the relative influence of each process especially with relative or ratiometric intensity yields of the chl a fluorescence, as obtained with conventional pulse-amplitude modulation (PAM) chl fluorometers (Schreiber et al 1986). Conventional PAM instruments do not provide the necessary direct information concerning the excited state lifetimes or energy levels of the chl fluorescence emission. This paper illustrates how measuring both wavelength- and timedependent changes in the chl fluorescence and subsequent global analysis of the data facilitate resolution and quantification of the main processes competing for excitation in PSII under low physiological temperatureconditions in vivo.