regulation; excitation energy

Effect of short-term exposure to high irradiance (1500 umol.m-2.s-1) on the transfer of excitation energy was studied during greening of barley plants at low (50 umol.m-2.s-1, LI) or high (1000 umol.m-2.s-1, HI) irradiances using 77Kexcitation spectra and room temperature modulated chlorophyll a fluorescence. The ability to down-regulate the efficiency of excitation energy transfer was inhibited for the HI plants grown under the intermittent light regime, due to thestrong suppression of the accumulation of light harvesting complexes (LHC's) of both photosystems II and I. During greening under continuous light the ability to promptly regulate the excitation energy transfer within both photosystems wasassessed from the light induced decrease of the excitation band attributed to the chlorophyll b and carotenoids (460-500 nm) in the 77K excitation spectra of Chl a fluorescence detected at 685 nm and 743 nm, respectively.

Effect of short-term exposure to high irradiance (1500 umol.m-2.s-1) on the transfer of excitation energy was studied during greening of barley plants at low (50 umol.m-2.s-1, LI) or high (1000 umol.m-2.s-1, HI) irradiances using 77Kexcitation spectra and room temperature modulated chlorophyll a fluorescence. The ability to down-regulate the efficiency of excitation energy transfer was inhibited for the HI plants grown under the intermittent light regime, due to thestrong suppression of the accumulation of light harvesting complexes (LHC's) of both photosystems II and I. During greening under continuous light the ability to promptly regulate the excitation energy transfer within both photosystems wasassessed from the light induced decrease of the excitation band attributed to the chlorophyll b and carotenoids (460-500 nm) in the 77K excitation spectra of Chl a fluorescence detected at 685 nm and 743 nm, respectively.