Pulse amplitude modulation (PAM) measurements
Seedlings cultivated as described above were first dark adapted for 15
min before being placed in the FluorCam 800-C (Photon systems
instruments) for measurements. Initially F0 was recorded
for 5 sec with a measuring beam. Thereafter FM was
initiated with a saturating flash at 4000 µE. After a relaxation phase
of 17 sec actinic light at 150 µE was utilized to assess the
photosynthetic adaptation (non-photochemical quenching NPQ) for 5 pulses
every 12 sec. This was followed by another measurement in the dark for 3
pulses.