FLUORESCENCE INDUCTION FROM PHOTOSYSTEM-II - ANALYTICAL EQUATIONS FORTHE YIELDS OF PHOTOCHEMISTRY AND FLUORESCENCE DERIVED FROM ANALYSIS OF A MODEL INCLUDING EXCITON-RADICAL PAIR EQUILIBRIUM AND RESTRICTED ENERGY-TRANSFER BETWEEN PHOTOSYNTHETIC UNITS
Hw. Trissl et J. Lavergne, FLUORESCENCE INDUCTION FROM PHOTOSYSTEM-II - ANALYTICAL EQUATIONS FORTHE YIELDS OF PHOTOCHEMISTRY AND FLUORESCENCE DERIVED FROM ANALYSIS OF A MODEL INCLUDING EXCITON-RADICAL PAIR EQUILIBRIUM AND RESTRICTED ENERGY-TRANSFER BETWEEN PHOTOSYNTHETIC UNITS, Australian journal of plant physiology, 22(2), 1995, pp. 183-193
The theoretical relationships between the fluorescence and photochemic
al yields of photosystem II (PSII) and the fraction of open reaction c
entres are examined in a model based on the following assumptions: (a)
a homogeneous, infinite PSII domain; (b) exciton-radical pair equilib
rium; and (c) different rates of exciton transfer between 'core' and '
peripheral' antenna beds. Simple analytical relations are examined for
the yields and their time-courses in induction experiments. Variation
of the inter-unit transfer rate allows continuous transition from the
case of 'separated units' to the pure 'lake' model. Widely used relat
ions for estimating the fraction of closed reaction centres from the c
omplementary area of the fluorescence, or the photochemical yield from
fluorescence levels are derived. An experimental induction curve is a
nalysed, considering its composition of 'alpha' and 'beta' centres. Th
e sigmoidicity of the induction kinetics is characterised by a single
parameter J (corresponding to Joliots' 'p'), that is shown to depend o
n both the connectivity of the photosynthetic units and on reaction ce
ntre parameters. On the other hand, the relation between J and the ext
reme fluorescence levels (or the deviation from the linear Stern-Volme
r dependence of 1/Phi(f) on the fraction of open traps) is only contro
lled by antenna connectivity. Experimental data are more consistent wi
th a model of 'connected units' for PSIIalpha than with the pure 'lake
' model.