Le potentiel du saule pour la phytostabilisation des sols pollués par les éléments-traces métalliques

Doctoral thesis (2013)

Since the ‘80s, when the concept of phytoremediation first appeared, a lot of research has been put into studying the efficiency of woody plants in metal extraction. Willows, as fast growing plants and ... [more ▼]

Since the ‘80s, when the concept of phytoremediation first appeared, a lot of research has been put into studying the efficiency of woody plants in metal extraction. Willows, as fast growing plants and because of their tolerance to difficult edaphic conditions, have been particularly well investigated. In this investigation, the essays were done on Salix clones, which come from a Walloon collection provided by ECOLIRI and ECOLIRIMED projects. The first objective was to study the potential of these local clones by considering not only their ability to extract their pollutants, but also by adding their biomass production to this parameter. We have called the study of these criteria the phenotypic approach to the tolerance of Salix clones to metals. The second added value of this investigation lies in the second objective which aims to complete these phenotypic criteria with physiological and proteomic criteria. These last criteria are often used to study the metal tolerance of plant species, but rarely for willows. The combination of these different approaches gives a expand view of metal tolerance in Salix clones studied in this investigation. As the phenotypical parameters help to answer the extraction ability challenge, the physiological and proteomic approaches give answers linked to the “health” of the willow trees when they grow in the presence of metals. Our results indicate that the clones that produced more biomass were the ones that showed the highest metal concentrations. The clones with lower biomass production showed the same tolerance as the highest producers and our results revealed that growth reduction indicates metal tolerance. Finally, after comparing our results of the metal concentrations obtained in the twigs, to results obtained during the last two decades of research papers, we have concluded that we should reconsider the use of Salix potential in phytoextraction. The first chapter of this investigation was about Salix clones exposed to metals, but, in natural conditions, their roots are colonized by fungi. Thus, their rhizosphere constitutes a separate ecosystem, which is interesting to investigate. The rhizospheric fungi, the first interface between roots and soil pollutants, play an important role in metal tolerance in woody plants. For this reason, the second chapter of this thesis aimed to test the in vitro growth of rhizospheric fungi collected on woody plant roots in the presence of cadmium. The outcome of these essays is that fungal strains have been identified and classified as tolerant to this metal. This chapter thus constitutes a first step in a future study aiming to analyze these strains in association with woody plant roots in the presence of metals. [less ▲]

IMPACT OF HEAVY METALS ON PHYSIOLOGICAL AND PROTEOMIC RESPONSES OF WILLOWS (SALIX SP.)

Poster (2012)

In 2010, around 3,800 sites in Wallonia (Belgium) were identified as potentially contaminated by heavy metals, a result of their past industrial and agricultural activities [1]. The technique of using ... [more ▼]

In 2010, around 3,800 sites in Wallonia (Belgium) were identified as potentially contaminated by heavy metals, a result of their past industrial and agricultural activities [1]. The technique of using plants to remediate contaminated sites (phytoremediation) has been studied for over twenty years. In particular, the use of trees (alder, willow, poplar) has been considered because of their large biomass production [2] [3] [4] [5]. The aim of this study was to identify the potential of local willow ecotypes to grow in the presence of heavy metals using lysimeters filled with dredging sludge. Several willow ecotypes were compared realizing morphological and physiological measurements (chlorophyll fluorescence, electrolyte leakage, carbohydrate content). The plant responses to metal stress were also investigated using a proteomic approach. Heavy metals contents in leaves and stems were analysed. With this study, the potential of these trees to valorise contaminated, abandoned sites in Belgium was evaluated. [1] Cellule Etat de l'environnement wallon (2010). Tableau de bord de l'environnement wallon. SPW-DGARNE-DEMNA-DEE. [2] Dickinson N. M. (2000). Strategies for sustainable woodland on contaminated soils. Chemosphere 41(1-2): 259-263. [3] Meers E., Lamsal S., Vervaeke P., Hopgood M., Lust N. and Tack F. M. G. (2005). Availability of heavy metals for uptake by Salix viminalis on a moderately contaminated dredged sediment disposal site. Environ Pollut 137(2): 354-364. [4] Meers E., Vandecasteele B., Ruttens A., Vangronsveld J. and Tack F. M. G. (2007). Potential of five willow species (Salix spp.) for phytoextraction of heavy metals. Environ Exp Bot 60(1): 57-68. [5] Rosselli W., Keller C. and Boschi K. (2003). Phytoextraction capacity of trees growing on a metal contaminated soil. Plant Soil 256(2): 265-272. [less ▲]

E ffects of Cd on ectomycorrhizal fungal growth. Efficacy of in vitro screening experiment

in Agrochimica (2011), LV(2),

Relationship between tree development, mean annual increment and internal wood decay in veteran Tilia trees

in Annales de la Société Belge de Dendrologie = Jaarboek van de Belgische Dendrologische Vereniging (2010)

This study aimed at classifying nineteen veteran lime trees (Tilia cordata Mill., T. platyphyllos scop. and T. x europaea L.) in their development. Tilia spp. was chosen because it is long lived and ... [more ▼]

This study aimed at classifying nineteen veteran lime trees (Tilia cordata Mill., T. platyphyllos scop. and T. x europaea L.) in their development. Tilia spp. was chosen because it is long lived and widely present in Belgium. A classification in five steps (A to E) is proposed, based on crown and trunk status, quantity of decaying wood and mean annual girth increment (MAI) as an additionnal criterion. We tested the relationship between veteran tree development and MAI. Threshold values were determined to help distinguish steps A to E. The relationship between trunk growth dynamics, and crown and root development is also discussed. [less ▲]