Figure 4.
Changes in the biophysics of photosynthesis as a result of emerged versus submerged growth and Cu stress, revealed by Chl fluorescence parameters. All samples were measured in the FKM at an actinic irradiance of 120 μmol m−2 s−1. See “Materials and Methods” for details of the measuring protocol, including timing of events. The data are averages of two independent experiments. Treatment labels are as follows: E, experiment (treatment) in emerged state; S, experiment in submerged state; Cu, treated with 10 μm Cu2+; Ct, control (0.1 μm Cu2+). A, Selected parameters. Indices of sections of the measuring protocol are as follows: “_d” stands for “dark adapted,” “_i” stands for “irradiated with actinic light,” and “_r” stands for “relaxation period after actinic irradiance.” The numbers in the index sequentially number the SIPs in the respective protocol section. A short explanation of individual fluorescence kinetic parameters is provided in Table I; for details, see reviews on Chl fluorescence kinetics or Küpper et al. (2007a). Top row, Basic parameters of fluorescence yield in nonactinic (F0) and supersaturating (Fm) light; second row, parameters measuring photochemical activity (Fv/Fm and ΦPSII); third row, parameters measuring NPQ; bottom row, light saturation as measured by Fp in relation to Fm with correction of F0 effects. B, Typical examples of complete fluorescence kinetic measurements. See “Materials and Methods” for details of the measuring protocol, including timing of events. The black bars at the bottom of the panels indicate periods of the measurement when actinic light is switched off, and the white bars symbolize the time period of actinic irradiance. The arrows indicate the positions of the SIPs.