Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 19 avril 2012
Amphi 206 (Coeur d’Ecole) à 14h
Monitoring spatial/temporal heterogeneity of rhizospheric parameters with non-invasive sensors: planar optodes
Éco&Sols – UMR Écologie fonctionnelle et biogéochimie des sols et agrosystèmes, postdoc Rhizopolis, « optodes »
Planar optodes are the state-of-the-art optical sensors for noninvasive bioprocess analysis inrhizosphere research. They allow determination of pH, CO2, O2 and other parameters in high spatial and temporal resolution. The optical detection of changes in fluorescence properties of analyte-specific fluorophores makes it possible to de-couple sensor and detector: The sensor is initially inserted into the system (for example: a rhizobox), but detection is possible from outside, leaving the system undisturbed. Detection approaches are based on fluorescence lifetime measurement or ratiometric fluorescence measurement. The principles of optode measurement and their implementation in rhizobox environments are presented along with examples of their use in rhizosphere research: O2– and pH-Optodes are used to determine the status of flooding-stressed plant roots – dead or alive, the latter being quite important for plant use in erosion protection. The possibility of long-time sensor use (weeks to months) allows monitoring of circadian rhythms of roots, which are indicators of rhizospheric activity. But strategies of plants to access nutrients or react to stresses differ widely: Some tend to acidify their rhizosphere (Chickpea, Maize, Eucalypt…), some alkalize (Wheat, Sedge…) or release O2, which is beneficial depending on prevailing soil characteristics – or not! Optodes help decipher and quantify these dynamics, which are highly specific and hitherto scarcely explored. Also presented are options to combine the optode technique with other approaches, e.g. low invasive soil solution analysis, determination of soil nutrients or biogeography. The development of new sensors for different analytes is planned to cover a wider range of parameters and possible applications. An outlook to future optode use and development is given: from one to many parameters (pH, NH4, Ions… on a single sensor foil) and from a single application to cross-linking with other imaging methods (transparent optodes).
Contact : Sabine Zimmermann