Figure 7.

Diurnal characterization of (A,B) light incident on the upper leaf surface (PFD_i) and percent of the xanthophyll cycle present as zeaxanthin and antheraxanthin (Z + A), (C,D) dissipation of excitation energy as thermal energy via a regulated non-photochemical route (quantified from chlorophyll fluorescence as Stern–Volmer quenching), and (E,F) percentage of absorbed photons allocated to photochemistry (quantified from chlorophyll fluorescence as photosystem II efficiency) in leaves of the herbaceous annual sunflower (A,C,E) and the woody evergreen Euonymus kiautschovicus (B,D,F) on summer days. V = violaxanthin. Data for sunflower are from Demmig-Adams and Adams [48] and Demmig-Adams et al. [49]. Data for E. kiautschovicus are from Verhoeven et al. [50].