ChlorophyllaFluorescence Induction in Higher Plants: Modelling and Numerical Simulation

Chlorophyllafluorescence induction is extensively used as a probe of photosynthesis, and thus, it has become necessary to quantitatively analyse it to extend its usefulness. We simulate the experimental data of fluorescence transients in strong light through numerical integration, both in dark- and light-adapted plants. In the mathematical model used here we have considered for the first time the redox reactions at both the acceptor and the donor sides of photosystem II, and the non-photochemical quenching by the oxidised plastoquinone molecules from the lipid matrix of the thylakoid membrane. The model is based on assumptions established in the literature and also the values of input parameters used in simulations. The simulated fluorescence induction curves show the characteristics O→J→I→P steps as in the experimental ones and, in specific conditions, the presence of a dip (D) between the I and P steps of the transient. Moreover, it has been shown here how typical patterns of fluorescence kinetics are influenced by the state of the sample by studying the basic effects of the influence of some parameters [i.e. the connectivity between different PS II units, initial QB:QB−ratio and the ratio of the starting states of the oxygen evolving complex (S1:S2), number of plastoquinone molecules in the plastoquinone pool, initial redox state of the plastoquinone pool, and the rate of plastoquinol oxidation]. In this way the information can be drawn from the experimental curves relative to these parameters.