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Laser Induced Fluorescence Transient (LIFT): remote measurement of light use efficiency

Laser Induced Fluorescence Transient (LIFT): remote measurement of light use efficiency in ecosystems. Roland Pieruschka, Uwe Rascher, Denis Klimov, Zbigniew S. Kolber, Joseph A. Berry. February, 08. 2007. Objectives. Inaccessible outer canopies - need for remote

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Laser Induced Fluorescence Transient (LIFT): remote measurement of light use efficiency

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  1. Laser Induced Fluorescence Transient (LIFT): remote measurement of light use efficiency in ecosystems Roland Pieruschka, Uwe Rascher, Denis Klimov, Zbigniew S. Kolber, Joseph A. Berry February, 08. 2007

  2. Objectives • Inaccessible outer canopies - need for remote • measurement of light use efficiency • Evaluation of the LIFT approach by PAM • fluorometry and gas exchange • Measurement of cold/light stress of outer canopies • in the field • Implementation of the data into canopy models • to reduce their uncertainty

  3. LIFT – Fluorometer • remote measurement: from a distance up to 50 m • excitation signal: 665 nm laser diode • fluorescence emission at 690 nm: collected • by Cassegrian telescope and detected • by avelange photodiode

  4. Fast Repetition Rate Fluormetry (Kolber et al. 1998; Kolber et al. 2005. Ananyev et al. 2005)

  5. (Govindjee, 1995) What are we measuring? single vs. multiple turnover • FRR: sequence of single turnover fleshlets: • corresponds to O-J phase • (photochemical phase) • kinetics of QA- accumulation/re-oxidation • with minimal effect on PQ pool • PAM: multiple photochemical turnover: • corresponds to O-J-I-P phase (photochemical and thermal phase) • well defined final state with fully reduced PQ pool

  6. Laboratory experiments: bench top FRR vs. PAM • Combined measurements of: • gas exchange (LI-6400) • chlorophyll fluorescence • using PAM and a bench top FRR • measurements under non- • photorespiratory conditions

  7. Laboratory experiments: bench top FRR vs. PAM FRR PAM

  8. Laboratory experiments: bench top FRR vs. PAM

  9. Electron Transport Rates gas exchange vs. fluorescence PAM FRR (Genty et al. 1989)

  10. Electron Transport Rates from FRR fluorescence and gas exchange

  11. PSII quantum efficiency vs. quantum yield of CO2 assimilation

  12. Corrected ETR Estimate of underestimation of ETR by FRR 4*(A+Rd)/PAR vs. Fv/Fm

  13. Summary I • The LIFT/FRR is working with low excitation intensities • resulting in lower maximum fluorescence then • the PAM approach in particular under high light intensities • However, the LIFT approach provides an advantage of remote • measurement of Fv Fm-1’ as an index of stress correlated • to ETR within undisturbed microenvironment of leaves

  14. Field experiments • Impact of cold stress on photosynthesis • Capsicum annuum • Ficus spec. • Lycopersicon esculentum • Persea americana • grass community dominated by Lolium spec.

  15. Predawn measurements on Lycopersicon esculentum

  16. Diurnal course: Lycopersicon esculentum

  17. Predawn measurements on Persea americana 2 1 4 3

  18. Diurnal cours: Persea americana target 1 target 3

  19. Steady state fluorescence

  20. Summary II • The LIFT system can sensitively detect stress • correlated to ETR • In order to quantify photosynthetic CO2 uptake • the LIFT system has to be extended by measurements of: • - light • - stomatal conductance • - temperature

  21. Acknowledgement Joe Berry Zbigniew Kolber Uwe Rascher Denis Klimov Larry Giles Bob Haxo Marie Curie Outgoing International Fellowships (Nr: 041060 – LIFT)

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