Figure 2.

Time courses of chlorophyll fluorescence parameters in intact attached leaves of PqR (▵) and PqS (○) biotypes of E. canadensis in the presence of 0.5 mm Pq under HL (1,400 μmol m⁻² s⁻¹). Pq was applied under dim-light (15 μmol m⁻² s⁻¹) conditions and the treated leaves were then kept in the dark for 10 min to allow the surface of the leaves to become dry before HL illumination. Fluorescence induction kinetics were recorded after 10-min dark adaptation to obtain the F_v/F_m of PS II (A), and subsequent saturating flashes (3,000 μmol m⁻² s⁻¹) were applied to determine the QY of PS II electron transport (B), qP (C), and the non-photochemical quenching levels (D) at the end of 10 min at a PPFD of 600 μmol m⁻² s⁻¹. The data are means of five replicates and se are shown when larger than the symbols.