The plastoquinone (PQ) pool of the photosynthetic electron transport chain becomes reduced under anaerobic conditions. Here, anaerobiosis was used as a tool to manipulate the PQ-pool redox state in darkness and to study the effects of the PQ-redox state on the Chl-a fluorescence (OJIP) kinetics in pea leaves (Pisum sativum L.). It is shown that the FJ (fluorescence intensity at 3 ms) is linearly related to the area above the OJ-phase (first 3 ms) representing the reduction of the acceptor side of photosystem II (PSII) and FJ is also linearly related to the area above the JI-phase (3–30 ms) that parallels the reduction of the PQ-pool. This means that FJ depends on the availability of oxidized PQ-molecules bound to the QB-site. The linear relationships between FJ and the two areas indicate that FJ is not sensitive to energy transfer between PSII-antennae (connectivity). It is further shown that a ∼94% reduced PQ-pool is in equilibrium with a ∼19% reduction of QA (primary quinone acceptor of PSII). The non-linear relationship between the initial fluorescence value (F20 μs) and the area above the OJ-phase supports the idea that F20 μs is sensitive to connectivity. This is reinforced by the observation that this non-linearity can be overcome by transforming the F20 μs-values into [QA −]-values. Based on the FJ-value of the OJIP-transient, a simple method for the quantification of the redox state of the PQ-pool is proposed.