Secondary chlorophyll a luminescence decay kinetics from green algae and higher plants mechanisms and application

Abstract: Barley protoplasts were shown to be a suitable experimental system for studies on the relative maximum during the decay of luminescence observed in most photosynthetic systems after excitation with far red light and in the presence of O2. The far red induced relative luminescencemaximum was shown to be a result of three coinciding events:'Randomization of the S-states of the water splitting system during illumination with far red light.'Extreme oxidation of the PSII acceptor side after excitation with far red light and in the presence of O2.'Reverse coupling, causing partial re-reduction of the PSII acceptor side in the dark after far red illumination.When the CO2 concentration in the air above an intact barley leaf waslowered in the dark, the primary PSII acceptor QA was partially reduced.The effect was obtained by changes in CO2 over a wide concentrationrange including that of saturated photosynthesis. It was thus concluded that the effect was not related to the role of CO2 as the terminal electronacceptor in photosynthesis.White light induced relative maxima during the decay of luminescence frqm low CO2 adapted green algae were shown to be the result of either one or two interacting mechanisms:'Relaxation of qE quenching.'Dark reduction of QA occuring as a result of lowered internal Cj concentration in the dark.Far red induced luminescence decay kinetics and fluorescence induction kinetics, when analyzed with multivariat data analysis, were shown to contain information allowing prediction of the state of frost hardiness in artificially hardened seedlings of Scots pine.