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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

in ecosystems

Roland Pieruschka, Uwe Rascher, Denis Klimov, Zbigniew S. Kolber, Joseph A. Berry

February, 08. 2007


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


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


Fast Repetition Rate Fluormetry

(Kolber et al. 1998; Kolber et al. 2005. Ananyev et al. 2005)


(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


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




Electron Transport Rates

gas exchange vs. fluorescence

PAM

FRR

(Genty et al. 1989)


Electron Transport Rates

from FRR fluorescence and gas exchange



Corrected ETR

Estimate of underestimation

of ETR by FRR

4*(A+Rd)/PAR vs. Fv/Fm


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


Field experiments

  • Impact of cold stress on photosynthesis

  • Capsicum annuum

  • Ficus spec.

  • Lycopersicon esculentum

  • Persea americana

  • grass community dominated by Lolium spec.


Predawn measurements on Lycopersicon esculentum


Diurnal course: Lycopersicon esculentum


Predawn measurements on Persea americana

2

1

4

3


Diurnal cours: Persea americana

target 1

target 3



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


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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