2022

Thèse

LOAYZA LOZA Hildo Mac Lean

Suivi expérimental du rendement de fluorescence des couverts végétaux par des techniques actives et passives. Application à la détection du stress hydrique.

Directeurs.rices de thèses : Goulas Y. & Moya I.

Date 2022-12-12
Diplôme Sorbonne Université

Fiche

Composition du jury

M. Jaume FLEXAS – Universitat de les Iles Balears, Espagne (Rapporteur)
M. Jean Philippe GASTELLU-ETCHEGORRY – Université Toulouse III – Paul Sabatier (Rapporteur)
Mme. Fabienne MAIGNAN – Laboratoire des Sciences du Climat et de l’Environnement (Examinatrice)
M. Hervé LE TREUT – Institut Pierre-Simon Laplace (Examinateur)
M. Fermín MORALES -Instituto de Agrobiotecnologia-CSIC, Espagne (Examinateur)
Mme Valérie LE DANTEC – Centre d’Etudes Spatiales de la Biosphère (Examinatrice)
M. Yves GOULAS – Laboratoire de Météorologie Dynamique (Directeur de thèse)
M. Ismaël MOYA – Laboratoire de Météorologie Dynamique (Co-directeur de thèse)

Abstract

Chlorophyll fluorescence is directly related to photosynthesis. However, at canopy level this physiological link may be blurred by structural vegetation changes and the interactions between sunlight and the 3D canopy structure. Furthermore, our knowledge about the relationship between chlorophyll fluorescence and the physiological status of plants comels from leaf level studies carried out under laboratory conditions. The physiological significance of chlorophyll fluorescence at canopy level and in outdoors conditions is still a major subject of research and a source of uncertainties in the interpretation of remote sensing data.
We built a new instrument for active measurement of chlorophyll fluorescence yield at the canopy level and studied its variations during the diurnal cycle. We showed that it was an indicator of water stress on different plant canopies. On the other hand, a comparison between active and passive measurements of fluorescence allowed us to define a new approach to derive a proxy of the fluorescence yield from solar-induced fluorescence. Finally, we investigated the airborne detection of water stress by passive measurement of fluorescence.

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