Table 3.
Quantum Efficiency, Nonphotochemical Quenching, and Photoinhibition in Wild-Type and lto1 Lines
| Wild Type | lto1 | |
| Actinic Light Intensity | Average ± sd, n = 6 | Average ± sd, n = 8 |
| 170 μE m−2 s−1 | ||
| FV/FM | 0.81 ± 0.01 | 0.49 ± 0.11 |
| NPQ | 1.17 ± 0.08 | 0.90 ± 0.79 |
| 1400 μE m−2 s−1 | ||
| FV/FM | 0.80 ± 0.01 | 0.48 ± 0.11 |
| NPQ | 1.370 ± 0.06 | 1.82 ± 1.15 |
| Photoinhibition (%) | 6.0 ± 1.3 | 9.9 ± 1.9 |
Fluorescence parameters FV/FM (maximum quantum yield of PSII), nonphotochemical quenching (NPQ), and photoinhibitions were calculated based on fluorescence measurements like those shown in Figure 4 using formulae described by Rohacek and Bartak (1999). FV/FM = (FM − F0)/FM, where F0 is the initial fluorescence emission after dark adaptation and immediately before a saturating pulse, FM is the maximal fluorescence emission immediately after the saturating pulse, and the variable fluorescence parameter, FV = FM − F0. NPQ = (FM − FM)/FM, where FM is the maximal fluorescence emission after adaptation to the actinic light (after 2 min). Photoinhibition = 1 – (FV/FM)/(FV/FM), where FV and FM are the variable and maximal fluorescence, respectively, after 2 min of exposure to 1400 μE m−2 s−1 actinic light followed by 8 min of dark recovery (i.e., irreversible loss of quantum efficiency).