Figure 4.

Time course of changes in the E_i of the xanthophyll cycle at different light intensities in intact attached leaves of PqS (A) or PqR (B) biotypes of E. canadensis in the presence of 0.1 mm Pq. The E_i is expressed as (V + 0.5 × A)/(V + A + Z). 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 the illumination at different PPFDs of 100 (□), 200 (▵), 300 (○), and 1,400 (⋄) μmol m⁻² s⁻¹. The data are means of five replicates and se are shown when larger than the symbols.