Processus multi-échelles, enjeux environnementaux et construction étatique : le cas de l'autorité palestinienne, des politiques de gestion de l'eau et du changement climatique

This thesis analyses the power relations involved in environmental issues (water management and climate change) and the process of state building of the Palestinian Authority, an entity dependent on international aid and under israeli occupation. This thesis mobilises sociology of public action, political ecology and science and technology studies in order to examine the multi-level processes of co-construction of social order and environment through knowledges, problems definition and public policies adopted to tackle them. This research analyses the interactions between international aid, development and environment and the objective of empowerment of the Palestinian Authority. It focuses on the circulation and hybridisation of knowledge and public policy solutions. Beyond national and international decision makers, other actors such as NGOs or humanitarian organisations participate and mobilise other representations of environmental problems and solutions in relation with their representations of the territory and the conflict. This thesis is based on a series of interviews, informal discussions, grey literature dealing with the subject and observational work.Cette thèse analyse les relations de pouvoir qui se jouent autour des enjeux environnementaux (gestion de l'eau et changement climatique) dans le processus de construction étatique de l'Autorité palestinienne, entité gouvernementale sous régime d'aide et marquée par l'occupation israélienne. Elle mobilise la sociologie de l'action publique, la political ecology et les science and technology studies afin d'étudier les processus multi-échelles de co-construction de l'ordre social et de l'environnement à travers les savoirs, la définition des problèmes et les politiques adoptées pour y répondre. Cette recherche analyse les liens entre l'aide internationale, le développement, l'environnement et la volonté de consolidation du pouvoir de l'Autorité palestinienne. Elle se penche sur la circulation et l'hybridation des savoirs et des solutions d'action publique. En dehors de l'action des décideurs nationaux et internationaux, d'autres acteurs (ONG, organisations humanitaires) interviennent et mobilisent d'autres représentations des problèmes environnementaux et des solutions à apporter en interactions avec leurs représentations du territoire et du conflit. Cette thèse se fonde sur une série d'entretiens et de discussions informelles, la littérature grise sur le sujet et de nombreuses observations participantes

Effect of water availability on changes in root amino acids and associated rhizospere on root exudation of amino acids in Pisum sativum L

Root exudation is considered to regulate the abundance of the microbial community. It may vary both qualitatively and quantitatively in response to the environment in which the plant is growing. A part of exuded N derives from amino acids (AAs). This, in turn, may help plants to cope with abiotic stresses by favouring positive interactions with the rhizosphere environment, thus playing a potential role in maintaining healthy plants. In this respect, an under-investigated area is the effect of stress due to water deficit (WD). It is proposed that the AA profile in the rhizosphere may be altered by WD, reflecting a modulation of root AA exudation linked to a physiological response of the plant to water stress. To investigate this, Pisum sativum L. plants, grown in unsterilised Rhizobium leguminosarum-enriched soil, were stem-labelled with 15N-urea for 96 h, and then subjected/not subjected to 72 h of WD. The concentrations and abundance of 15N-labelling in individual AAs were determined in both roots and the associated rhizosphere at 24, 48 and 72 h after stress application. It was found that both AAs metabolism in the pea root and AAs exudation were strongly modified in WD conditions. After 24 h of WD, the concentrations of all measured AAs increased in the roots, accompanied by a dramatic stress-related increase in the 15N-labelling of some AAs. Furthermore, after 48–72 h of WD, the concentrations of Pro, Ala and Glu increased significantly within the rhizosphere, notably with a concomitant increase in 15N-enrichment in Pro, Ser, Asn, Asp, Thr and Ile. These results support the concept that, in response to WD, substantial amounts of recently assimilated N are rapidly translocated from the shoots to the roots, a portion of which is exuded as AAs. This leads to the rhizosphere being relatively augmented by specific AAs (notably HSer, Pro and Ala) in WD conditions, with a potential impact on soil water retention

Modulation de l'exsudation racinaire de composés azotés chez les Fabacées et réponse aux stress hydriques

Les légumineuses ont des rhizodépôts riches en azote (N). Leur emploi dans les rotations de cultures permet de réduire l\u27usage de fertilisants de synthèse. Parmi les composés azotés exsudés par les racines, les acides aminés (AA) sont reconnus pour leur rôle dans la régulation des communautés microbiennes de la rhizosphère, avec un impact sur la nutrition des plantes et leur résistance aux stress abiotiques. Cette exsudation est difficile à mesurer en raison des interactions avec les microorganismes et les particules minérales du sol. Nous avons fait l\u27hypothèse que l\u27exsudation racinaire d\u27AA varie en fonction du substrat, de la croissance et de l\u27humidité sol. Une méthode d\u27extraction des AA du sol a été mise au point pour estimer l\u27empreinte rhizosphérique en acides aminés (ERAA) dans le sol non stérilisé, comme résultat net des interactions entre l\u27exsudation d\u27AA et le milieu rhizosphérique. L\u27évolution de l\u27ERAA a ainsi été étudiée chez Medicago truncatula cultivée sur sable stérilisé ou sol non stérilisé, à 3 stades de croissance végétative, et chez Pisum sativum soumis ou non à un déficit hydrique ou un excès d\u27eau. Le marquage au 15N a été utilisé pour appréhender le mouvement des 15N-AA libérés par les racines vers la rhizosphère. L\u27ERAA augmente au cours de la croissance végétative et est dépendante en quantité et en qualité, du stade de la plante. Le déficit hydrique modifie l\u27ERAA avec la présence de plus de N récemment assimilé par la plante, plus de proline, d\u27alanine et de valine. En tenant compte des limites expérimentales, ces travaux ont permis de mieux comprendre les facteurs qui influencent l\u27ERAA et d\u27appréhender la rhizodéposition azotée des légumineuses

Etude expérimentale de la dégradation des lignines de Peuplier dans un sol alluvial et dans l'eau d'un fleuve (Garonne).

Le taux de dégradation de lignocelluloses de peuplier marquées sur la lignine à partir de phénylalanine 14C(U) est sensiblement le même, en conditions contrôlées, dans l'eau de la Garonne et dans un sol alluvial en bordure du fleuve. L'évolution du dégagement de 14CO2 est cependant différente dans les deux types de milieux, de même que le taux de récupération de produits de dégradation hydrosolubles. La quantité de produits marqués incorporés à la fraction humique directement extractible du sol est relativement faible mais varie selon les fractions granulométriques considérée

Lignin Degradation and Humus Formation in Alluvial Soils and Sediments

The contribution of lignin to the formation of humic compounds was examined in different environments of the terrestrial-aquatic interface in the Garonne River valley in southwestern France. Alluvial soils and submerged or nonsubmerged river and pond sediments containing alder, poplar, or willow C-ligninligno-celluloses were incubated. After a 49-day incubation period, 10 to 15\% of labeled lignins in alluvial soils was recovered as evolved CO(2). In nonsubmerged sediments, 10\% of the applied activity was released as CO(2), and in submerged sediments, only 5\% was released after 60 days of incubation. In the different alluvial soils and sediments, the bulk of residual activity (70 to 85\%) remained in the two coarsest-grain fractions (2,000 to 100 and 100 to 50 mum). Only 2 to 6\% of the residual activity of these two coarse fractions was recovered as humic and fulvic acids, except in the case of alder C-ligninlignocellulose, which had decomposed in a soil collected beneath alders. In this one 55\% of the residual activity was extracted as humic substances from the 2,000- to 100-mum fraction. Humic and fulvic acids represented from 6 to 50\% of the residual activity in the finest-grain fractions (50 to 20 and 20 to 0 mum). The highest percentages were obtained in soil collected beneath alders and in submerged pond sediment. The contribution of different groups of microorganisms, as well as nutrients and clay content, may influence humic-substance formation in such environments. Physical stability also may be an important factor for complex microbial activity involved in this process

Amino acid fingerprint in the rhizosphere of Pisum sativum in response to water stress

In cropping systems, legumes release substantial amounts of nitrogen (N) into the soil, via rhizodeposition, and constitute a sustainable source of N, instead of synthetic N fertilisers (Fustec et al. 2010). More frequent or/and intense droughts and floodings, due to climate change and intensification of agriculture, may affect N rhizodeposition (Preece & Peñuelas 2016). However, the effects of water stress on this process are poorly documented. A part of N derived from root exudates, mainly in amino acids (AAs) form, is suspected shape and regulate rhizosphere microbial community, thus playing a potential role in maintaining plant health in case of abiotic stress (Moe 2013). We hypothesized that root AA exudation could change significantly, according to water availability, and would help to understand N metabolism changes in plant-rhizosphere interactions. Because studying exudation from plant grown in unsterilized soil is challenging (Oburger et al. 2013), we have measured the rhizosphere AA fingerprint (RAAF), as the result of interactions between AA exudation and rhizospheric environment. In addition, plants were stem-labeled (cotton-wick) with 15N-urea for 72 h to provide direct evidence of a link between root AA and exudation in the soil. The RAAF was measured in Pisum sativum rhizosphere, under either a water deficit or a water excess for 72 h. Water deficit decreases biomass accumulation in shoots but not in roots. Then, water deficit had no significant effect on total AAs released into the rhizosphere but, it significantly modified the composition of RAAF, with a preferential increase of proline, alanine and glutamate and a rise in isotopic enrichment of AAs derived from oxaloacetate in tricarboxylic acidic cycle (asparagine, aspartate, threonine and isoleucine). These results support the idea that, under the early stages of water deficit, recently assimilated N is rapidly translo-cated to the roots, and part of it is exudated in AAs. Most of the exudated AAs are known to have a specific role in increasing the water holding capacity around the root and to favour the establishment of positive interactions with plant-growth promoting bacteria (Apostel et al. 2013, Hinsinger et al. 2003). A study aimed at establishing a better understanding of the relationship between microorganisms and AA release under water deficit is now necessary

Assessing dengue transmission risk and a vector control intervention using entomological and immunological indices in Thailand: study protocol for a cluster-randomized controlled trial.

BACKGROUND: Dengue fever is the most common and widespread mosquito-borne arboviral disease in the world. There is a compelling need for cost-effective approaches and practical tools that can reliably measure real-time dengue transmission dynamics that enable more accurate and useful predictions of incidence and outbreaks. Sensitive surveillance tools do not exist today, and only a small handful of new control strategies are available. Vector control remains at the forefront for combating dengue transmission. However, the effectiveness of many current vector control interventions is fraught with inherent weaknesses. No single vector control method is effective enough to control both vector populations and disease transmission. Evaluations of novel larval and adult control interventions are needed. METHODS/DESIGN: A cluster-randomized controlled trial will be carried out between 2017 and 2019 in urban community clusters in Khon Kaen and Roi Et cities, northeastern Thailand. The effectiveness of a pyriproxyfen/spinosad combination treatment of permanent water storage containers will be evaluated on epidemiological and entomological outcomes, including dengue incidence, number of female adult dengue vectors infected or not infected with dengue virus (DENV), human exposure to Aedes mosquito bites, and several other indices. These indices will also be used to develop predictive models for dengue transmission and impending outbreaks. Epidemiological and entomological data will be collected continuously for 2 years, with the intervention implemented after 1 year. DISCUSSION: The aims of the trial are to simultaneously evaluate the efficacy of an innovative dengue vector control intervention and developing predictive dengue models. Assessment of human exposure to mosquito bites by detecting antibodies generated against Aedes saliva proteins in human blood samples has, so far, not been applied in dengue epidemiological risk assessment and disease surveillance methodologies. Likewise, DENV detection in mosquitoes (adult and immature stages) has not been used in any practical way for routine disease surveillance strategies. The integration of multiple outcome measures will assist health authorities to better predict outbreaks for planning and applying focal and timely interventions. The trial outcomes will not only be important for Thailand, but also for the entire Southeast Asian region and further afield. TRIAL REGISTRATION: ISRCTN, ISRCTN73606171 . Registered on 23 June 2017

Underestimated role of legume roots for soil N fertility

Research ArticleNitrogen (N) is a major fertilizing element for plants. The distribution of N in legumes is influencing the efficiency of the next crop. Nitrogen storage in legumes is actually estimated by N fixation in shoots, whereas there is little knowledge on the contribution of roots and nodules to legume N and soil N. Here, we studied the contribution of roots and nodules of grain and pasture legumes to plant N and soil N in Mediterranean fields. Experiments were run under rainfed conditions for a 2-year period in three regions of Portugal. Entire plants including top plant and visible roots and nodules were sampled at the end of the growing seasons for grain legumes, sweet and yellow lupine, and over two harvests in case of pastures. N2 fixation was measured for grain legumes and pasture legumes using 15N tracing. Our results show that aboveground N concentration did not vary among legumes, but differed in the belowground tissues. Field studies show that 7–11%of total legume N was associated with roots and nodules. Data also show an allocation of 11– 14 kg N fixed t−1 belowground dry matter in indeterminate legumes, which represents half the amount of total aboveground plant. This finding demonstrates that investigation relying only on shoot Nunderestimates the role of legumes for soil N fertilityinfo:eu-repo/semantics/publishedVersio