Fig. 4.
Slow Chlorophyll a fluorescence kinetics (in arbitrary units) using a PAM-2100 fluorometer. The dark-adapted leaf is illuminated with weak modulated measuring light to give the zero fluorescence level F 0. Application of a saturation pulse (SP) allows measurement of the maximum fluorescence level in the dark F M. Photosynthesis is then activated by an actinic light source (in this case 250 μmol photons m−2 s−1). SPs during the light phase were triggered spaced 1 min apart (indicated by arrows) to determine the maximum fluorescence intensity in the light (F M′), and for each SP, qP, Φ PSII, and NPQ parameters were calculated, and these are indicated in the figure (Penella et al. unpublished data)