Regulation of photosynthesis by radiation quality in the lichen Evernia prunastri

Abstract

In Evernia prunastri, photosynthetic gas exchange was saturated with yellow radiation (SOX) at 400 μmol m-2 s-1, and then red (R), far-red (FR), or blue (B) radiations at irradiance of 15 (μmol m-2 s-1 were added. Because of photosynthesis saturation, any stimulation or decay in CO2 assimilation by any radiation quality could be attributed to the involvement of a non-photosynthetic photoreceptor. Thus CO2 assimilation, effective quantum yield, and photochemical quenching were enhanced when R was included, and decreased with FR. Blue radiation completely abolished CO2 fixation. Hence different spectral radiation qualities may activate non-photosynthetic photoreceptors such as phytochrome and blue photoreceptors, which are involved in regulating the photosynthetic activity in E. prunastri.