Acclimation to temperature and irradiance modulates PSII charge recombination

Acclimation of wild type and the chlorina F2   mutant of barley to either high light or low temperature results in a 2- to 3-fold increase in non-photochemical quenching which occurred independently of either energy-dependent quenching (qE), xanthophyll cycle-mediated antenna quenching or state transitions. Results of in vivo thermoluminescence measurements used to address this conundrum indicated that excitation pressure regulates the temperature gap for S2QB- and S2QA- charge recombinations within photosystem II reaction centers. This is discussed in terms of photoprotection through non-radiative charge recombination.