Figure 7.

Time course of QY (○) given by 1 − F_s/F'_m (A), NPQ (□), and its qE, (⋄; B) in intact attached leaves of PqR E. canadensis in the presence of 0.1 mm Pq and at a low PPFD of 200 μmol m⁻² s⁻¹ (open symbols). Closed symbols represent the effect of a short-term HL (5-min, 1,100 μmol m⁻² s⁻¹) pre-illumination (HL + LL). Pq was applied under dim-light (15 μmol m⁻² s⁻¹) and the treated leaves were then kept in the dark for 10 min to allow the surface of the leaves to become dry before any illumination. The quenching analysis was carried out after another 10-min dark adaptation and under low actinic PPFD (200 μmol m⁻² s⁻¹) to prevent additional effects caused by photoinhibition and related processes. The qE component of NPQ was calculated from the relaxation of the maximum fluorescence yield after the AL was switched off. The data are means of 10 replicates and ses are shown when larger than the symbols.