Non-photochemical quenching of F_o in leaves is emission wavelength dependent: consequences for quenching analysis and its interpretation

Abstract

The effects of light-induced non-photochemical quenching on the minimal F_o, and variable F_v, fluorescence emissions at 690 and 730 nm in leaves were determined. Non-photochemical quenching of F_o, but not F_v, was found to be dependent upon the wavelength of emission, and was greater at 690 nm than at 730 nm. For emission at 730, compared to at 690 nm, approx. 30% of F_o was not affected by non-photochemical quenching processes in leaves of C3 plants; in maize leaves this was found to be approx. 50%. The data indicate that a substantial proportion of the pigments contributing to F_o emission at 730 nm are not quenched by light-induced, non-photochemical quenching processes and that there are large differences in the pigment matrices contributing to F_o and F_v emissions at 730 nm, compared to those at 690 nm. These findings have important implications for the accurate estimation and interpretation of non-photochemical quenching of fluorescence parameters and their use in the calculation of photochemical efficiencies in leaves. Measurements of fluorescence emissions at wavelengths above 700 nm are likely to give rise to significant errors when used for determinations of photochemical and non-photochemical quenching parameters.