Plasticité phénotypique et compétitivité chez les hydrophytes : étude expérimentale et de modélisation de Ranunculus peltatus Schrank

Abstract : Phenotypic plasticity is an important aspect of how plants develop, function and evolve in their environments. This thesis aimed at investigating the ecological significance of plasticity in hydrophytes and analysing its influence on plant competitiveness. We selected, as a study model, Ranunculus peltatus Schrank, well-known for its high plasticity. Its adaptations to nutrient or light stress and to disturbances were analysed through in situ, laboratory and semi-controlled experiments and a modelling approach. The following results were highlighted: R. peltatus adapted its biological traits according to stress and disturbance via different resource allocation patterns. R. peltatus rapidly adjusted its morphology in response to variations in shade and water depth following classical adaptive patterns. Adaptations developed in response to nutrient stress were essentially physiological and consisted mainly in the increase of nutrient uptake and nutrient-use efficiency in stressful conditions. With respect to disturbance, R. peltatus regeneration types were plastic. Mechanistic modelisation was used to simulate and improve the understanding of adaptative patterns highlighted experimentally. This approach constituted a first step in the evaluation of costs and benefits of a physiological adaptation in response to environmental stress. Hence, adaptive plasticity favours R. peltatus competitiveness and its ability to colonise and adapt to new sites. A large number of hydrophytes possesses this capacity. Its competitive interests is therefore essentially dependent on the plant combination of traits and on the amplitude and dynamic of their plastic adjustments.
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Cendrine Garbey. Plasticité phénotypique et compétitivité chez les hydrophytes : étude expérimentale et de modélisation de Ranunculus peltatus Schrank. Sciences agricoles. Université Paul Verlaine - Metz, 2003. Français. ⟨NNT : 2003METZ030S⟩. ⟨tel-01749792⟩

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