Table II.

Decay kinetics of flash-induced variable fluorescence

Analysis of the fluorescence relaxation kinetics. Measurements were performed on leaf discs, as in Figure 1, that were incubated for 2 h under 150 μmol m−2 s−1 white light in distilled water (control), or solutions containing NO donor and scavenger chemicals, each used in 1 mm concentration, then dark adapted for 15 min with or without incubation in 100 μm DCMU. The curves were analyzed in terms of two exponential components (fast and middle phases) and one hyperbolic component (slow phase). Values in parentheses are relative amplitudes as a percentage of total variable fluorescence. ses of the calculated parameters are also indicated.

TreatmentFast Phase τ1 (A1 [%])Middle Phase τ2 (A2 [%])Slow Phase τ3 (A3 [%])A0
μsmss%
Without DCMU
Control800 ± 40 (51 ± 1.4)194 ± 31 (14 ± 0.9)10.5 ± 0.8 (35 ± 0.8)0
GSNO790 ± 50 (45 ± 1.4)430 ± 62 (18 ± 1.4)11.7 ± 2.1 (35 ± 1.3)1.8 ± 1.4
GSNO + PTIO720 ± 40 (45 ± 1.5)312 ± 44 (17 ± 1.1)9.4 ± 0.8 (38 ± 1.1)0
With DCMU
Control– (0)– (0)1.6 ± 0.1 (100 ± 0.4)0
GSNO– (0)– (0)1.2 ± 0.1 (49 ± 0.6)51 ± 0.5
GSNO + PTIO– (0)– (0)2.5 ± 0.1 (73 ± 0.7)27 ± 0.6