Abstract
A part of light energy absorbed in photosystem II (PSII) antenna is used for photosynthetic electron transport and the rest is dissipated as heat and fluorescence. While there are two major methods to estimate the allocation of the absorbed light energy by chlorophyll fluorescence (Dermming-Adams et al 1996, and Hendrickson et al 2004), none of them have become generally approved.
We report (1) the establishment of a valid method to estimate the allocation of the absorbed light energy to four segments; i.e., thermal dissipation in PSII antenna, thermal dissipation dependent to xanthophylls cycle, thermal dissipation in PSII center and photosynthesis electron transport, based on the analysis of PsbS RNAi lines that lack the xanthophylls cycle-dependent thermal dissipation, and (2) diurnal changes of light stress and allocation of the absorbed light energy in rice under field conditions. Our results indicate that NPQ (=(Fm-Fm')/Fm'), a common parameter to estimate non-photochemical quenching, was disproportionate to the amount of xanthophylls cycle-dependent thermal dissipation.
