Fig. 4.

Recovery of chlorophyll-fluorescence parameters in leafy shoots of Polytrichum formosum following re-wetting (arrows). (A) F_v/F_m, with fitted exponential curve; the half-recovery time is 160 s. This parameter shows much faster recovery than photosynthetic CO₂ fixation, reflecting the very rapid recovery of maximum quantum efficiency of photosystem II. (B) ΦPSII at 500 µmol m^–2 s^–1. This is a measure of effective quantum yield and thus of electron flow through PSII, and much more nearly parallels the recovery of photosynthesis.