Figure 2.

Changes in effective PSII photon efficiency (Φ_PSII under irradiation and F_v′/F_m′ following darkening) to excess PPFD (1,500 ± 50 μmol m⁻² s⁻¹) treatments of varying wavelength distribution. A, Illuminated with white (400–800 nm) light; B, illuminated with blue (400–550 nm) light; C, illuminated with red (640–710 nm light) for red- (circles) and yellow- (squares) senescing red-osier dogwood leaves. The light was turned off after 30 min (as indicated by the shaded box) and Φ_PSII recovery measured as described in “Materials and Methods.” Measurements were made under the conditions described in Figure 1. Each curve for A through C is an average of five leaves per treatment and error bars denote the sd.