Shifts to C675-670 and to C696-684 in etiolated leaves illuminated with series of brief flashes

Absorbance changes seen when etiolated primary bean leaves are given series of short, low-intensity flashes of light were recorded. Whatever its order in a series, each flash induced an initial, fast increase of the absorbance, producing an absorption band between 660 and 700 nm with a peak at 680 nm. This occurred in less than 30 msec and was followed within seconds by either a slow dark increase or a slow dark decrease of the leaf absorbance, depending on the order of the flash and the analytical wavelength. The dark absorbance changes were due to shifts of the initial absorption band produced by the flash, either towards 685 or 670 nm. The shift was always towards 670 nm after the first flash. It appeared to move progressively towards 685 nm from one flash to the next, this direction becoming predominant after a certain number (ninv) of flashes. The (ninv) depended on the light dose, but not on the flash frequency. Three proposals are made to account for the results. © 1977 Oxford University Press.