2.8 Conductance of the electron transport chain
(gETC)
To estimate the conductance of the electron transport chain(gETC) , we used a similar
experiment setting to the previous section monitoring the redox state of
PSI with slight modifications. The saturating pulse was given under
darkess simultaneously with the termination of AL. Notably, a 100-ms
width SP at a PPFD of 8000 μmol m-2s-1 was applied and the decay in absorbance followed
upon transition from the 100 ms SP to darkness (Klughammer & Schreiber,
1994; Klughammer & Schreiber, 2008). This intensity was found to be
saturating across all conditions used. Under these conditions,
application of a flash induced a rapid rise in the absorbance signal,
with no decrease during the duration of the flash (not shown). The
absorbance decay curve under such conditions (ctrl or salt) approximated
closely to a first-order reaction and was fitted well with a
mono-exponential curve, yielding a rate constant. This was taken as a
measure of the conductance of the electron transport chain (Golding &
Johnson, 2003; Stepien & Johnson, 2009).