Chlorophyll fluorescence decay profiles of O₃‐exposed spruce needles as measured by time‐correlated single photon counting

Abstract

SUMMARYChlorophyll fluorescence decay profiles have been measured in the wavelength range 680-720 nm for needles from Norway spruce [Picea abies (L.) Karst] trees which have been exposed to ozone. All profiles required three exponential components of lifetime 100-150 ps, 400-600 ps and 3-5-5-0 ns to fit the experimental data. Compared to control samples, the ozone-treated needles exhibited a greater amount of the longest-lived chlorophyll fluorescence and a redistribution in intensity for both the other components from 720+ to 690 nm. These observations are interpreted in terms of disruption of energy transfer and break-up of light-harvesting complexes on exposure to ozone. The potential for use of the technique in monitoring forest decline is discussed.

The effect of fungal metabolites on leaves as detected by chlorophyll fluorescence

“…They have shown a clear increase in the ratio of emission at 690 nm compared with 730 nm. This may also reflect changes in energy transfer characteristics between light harvesting chlorophyll proteins, and is a consistent observation, seen also in the ozone-damaged spruce study (Evans et al , 1992).…”

“…Such a ns. decay component has been detected in leaves of in vitro plants where photosynthesis was compromised (Lees et al , 1991) and following 0 3 damage in spruce (Evans et al , 1992). In the latter case the observation was interpreted as damage to the thylakoid membrane causing disruption to energy flow within and between chlorophyll complexes, resulting in a chlorophyll fluorescence decay time comparable with chlorophyll in solution.…”

“…decay component has been detected in leaves of in vitro plants where photosynthesis was compromised (Lees et al. , 1991) and following 0 3 damage in spruce (Evans et al. , 1992).…”

“…In this study, following earlier experiments on ozone damage in spruce (Evans et al. , 1992), fluorescence emission spectra and fluorescence decay excited by a short pulse of light has been measured rather than fluorescence induction.…”

“…In this study, following earlier experiments on ozone damage in spruce (Evans et al , 1992), fluorescence emission spectra and fluorescence decay excited by a short pulse of light has been measured rather than fluorescence induction. The spruce study and a further investigation of mature and micropropagated Clematis (Lees et al , 1991) showed that leaf to leaf results were highly reproducible for measurements of fluorescence decay profiles.…”