Špunda V, Navrátil M, Čajánek M, Kalina J (2001) Light induced regulation of excitation energy transfer during the development of barley photosynthetic apparatus under different irradiances. Acta Facultatis Rerum Naturalium Universitas Ostraviensis, Physica-Chemia 199: 69-87

Effect of short-term exposure to high irradiance (1500 mmol.m-2.s-1) on the transfer of excitation energy was studied during greening of barley leaves at low (50 mmol.m-2.s-1, LI) or high (1000 mmol.m-2.s-1, HI) irradiances using 77K excitation 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 the strong 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 was assessed 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. The non-uniform decrease of this excitation band supported the idea that the zeaxanthin rather mediated structural-functional changes of the LHC than acted as a direct quencher of the excited chlorophylls. During the greening under HI the nonphotochemical quenching of maximal level of room temperature Chl a fluorescence FM was strongly suppressed as compared to LI plants. Moreover, no detectable quenching of F0 fluorescence was observed for HI plants during the whole experiment. These limitations of light induced nonphotochemical fluorescence quenching may be related to the more pronounced reduction of LHC II for HI barley during greening period, even though the convertibility of violaxanthin was extremely high under HI.