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Évaluer la multifonctionnalité des élevages au pâturage au sein des territoires : exemples du Sahel et de l'Asie du Sud-Est
Get PDFPotentiel pour la régulation de la chenille légionnaire d'automne sur maïs de l'apport au sol de biochars de balle de riz et résidus solides d'extraction d'huiles essentielles et huiles végétales
No full textComparison of termite resistance of wood modified with lignin cleavage products-phenol-formaldehyde and phenol-formaldehyde resins against subterranean and drywood termites
Get PDFWood modification with phenol-formaldehyde (PF) impregnation resins increases the resistance against fungal decay and subterranean termite attacks. However, phenol is obtained from non-renewable resources. Prior research explored partially replacing phenol with lignin cleavage products (LCP), and the good fungal decay resistance remains. However, the influence on termite resistance has not been studied. In this study, 30 % (w/w) of phenol in PF resins was replaced with LCP (LPF resin). Pinus sylvestris sapwood was treated with PF and LPF resins, and its resistance against European subterranean termites (Reticulitermes flavipes) and tropical drywood termites (Cryptotermes dudleyi) was evaluated by non-choice screening tests. Additionally, choice tests were carried out to confirm that the modifications were non-biocidal. The PF and LPF resin treatments improved termite resistance (reducing the mass loss) against both termite species. Low termite survival rates were observed after the non-choice test against subterranean termites. The choice tests confirmed that both treatments were non-biocidal. Visual evaluation (EN 117 (2023)) led to worse resistance ratings of treated specimens against tropical drywood termites, compared to European subterranean termites, due to different mode of actions of the termites' attacks. Thus, new standards (or appendixes) could be useful to evaluate treated woods resistance against different termite species
Diagnostic et analyse des pratiques culturales influant sur le flétrissement bactérien de la pomme de terre à Madagascar
Get PDFLes pratiques agricoles jouent un rôle clé dans la gestion des maladies des plantes. À Madagascar, le flétrissement bactérien est une maladie tellurique qui affecte les cultures de pomme de terre, pouvant entraîner des pertes de récolte considérables. Cette étude vise à caractériser les principaux systèmes de culture de pomme de terre existant dans la région Vakinankaratra, l'un des bassins majeurs de production, et à analyser comment les pratiques culturales contribuent à la gestion de cette maladie. Pour ce faire, 259 parcelles de pommes de terre, réparties entre la saison des pluies et la contre-saison, ont été étudiées. La typologie des pratiques culturales a mis en évidence six groupes (groupes 1 à 3 en contre-saison et groupes 4 à 6 en saison des pluies), montrant des profils de groupes similaires entre les deux saisons. Les groupes 1 et 4 sont caractérisés par des parcelles plantées en billon à faible densité de plantation. Dans ces groupes, du compost est utilisé et le sarclo-buttage et le défanage sont pratiqués. Dans les groupes 3 et 5, le fumier remplace le compost. Quant aux groupes 2 et 6, ils se distinguent par une plantation à plat, une densité de plantation élevée, un minimum d'entretien, et ils utilisent moins de fertilisation minérale que les autres groupes. Les pratiques culturales mises en oeuvre par les agriculteurs pour lutter contre le flétrissement bactérien ont été identifiées. Au-delà des méthodes communes, telles que la prophylaxie via l'élimination des plants malades, les rotations culturales, en particulier avec le riz irrigué, les pratiques culturales comme la plantation en planche, l'apport de compost et le défanage contribuent significativement à la réduction du flétrissement bactérien. La diversité des souches présentes dans les systèmes de culture devra être prise en compte pour mieux appréhender l'efficacité des pratiques culturales sur le contrôle du flétrissement bactérien. L'enquête reflète l'engagement des cultivateurs de pomme de terre à Madagascar dans la transition agroécologique
Analyse prospective de l'agriculture sénégalaise en 2050 : agro-industrie versus agroécologie ? Rapport sur la prospective "Agroeco2050-Sénégal"
Get PDFCe rapport présente les résultats d'AgroEco2050-Sénégal, le premier exercice de prospective au Sénégal à l'échelle nationale explorant deux visions contrastées de l'agriculture sénégalaise à l'horizon 2050: une agriculture agroécologique et une agriculture industrielle conventionnelle.Ces trajectoires ont été analysées à travers des dimensions clés telles que l'emploi, la production alimentaire, l'utilisation des terres, la performance économique et le bien-être des populations rurales. L'approche méthodologique combine des outils de modélisation quantitative, des récits qualitatifs et une forte participation des acteurs de la société civile, académique, gouvernementaux et privé pour coconstruire des visions de futurs agricoles cohérentes, crédibles et contrastées.Au-delà des deux scénarios initiaux — agroécologique et agro-industriel — les échanges ont permis de faire émerger une vision intermédiaire, appelée "Coexistence verte", reflet des aspirations partagées par certains acteurs lors des ateliers participatifs. Le rapport vise à alimenter la réflexion stratégique sur les futurs possibles de l'agriculture sénégalaise, en apportant des éléments concrets pour orienter les politiques publiques et les choix collectifs. En particulier, il révèle les enjeux cruciaux à chacun des scénarios pour que ceux-ci émergent. Il s'accompagne également de la compilation de plusieurs bases de données dans un outil cohérent et visuel inédit sur les systèmes agricoles et alimentaires du Sénégal, offrant un éclairage structurel historique et prospectif précieux pour comprendre les transformations en cours
Fungal and torrefaction pretreatment of sugarcane bagasse through fast pyrolysis: maximizing levoglucosan production
No full textThis study presents a combination of three different pretreatments of sugarcane bagasse (SCB) aimed at increasing levoglucosan (LGA) yield during fast pyrolysis. SCB samples were subjected, individually or in combination, to the following pretreatments: distilled-water leaching, torrefaction at 290 °C for varying residence times (5, 7.5, and 10 min), and fungal decay employing white rot (Trametes versicolor) or brown rot (Coniophora puteana) over durations, ranging from 2 to 12 weeks, respectively. The combined pretreatment of torrefaction (5 min) and fungal degradation by C. puteana for 12-weeks considerably reduced the hemicellulose (by 61.04%) and lignin (by 56.61%) content of the SCB, while increasing the cellulose concentration by 153.4%, leading to enhanced LGA production during fast pyrolysis. Additionally, the optimal pretreatment conditions involved water-leaching followed by torrefaction for 7.5 min at 290 °C, combined with and the action of the white rot fungus Trametes versicolor during 4 weeks which after rapid pyrolysis leads to the highest LGA yield of 11.59%. The combined pretreatments effectively improved SCB's chemical composition and enhanced the properties of its bio-oil produced during fast pyrolysis process
Molecular and genetic determinism of sorghum grain quality
Get PDFSorghum grains are rich in proteins and starch but exhibit low protein digestibility, limiting their use in food and feed. However, the genetic and molecular mechanisms underlying these traits remain poorly understood, particularly the genomic regions involved, as well as the structural genes and transcription factors (TFs) that regulate them, hindering efforts to improve sorghum grain quality. To address this, we adopted an integrated genomic and genetic approach. At the genomic level, we constructed a gene co-expression network using transcriptomic data collected during grain development (10 stages) over two years. In parallel, we quantified starch and protein content and measured protein digestibility. Two major gene co-expression modules were identified. The first was linked to the loss of protein digestibility, involving genes related to disulfide bond formation and modulation. The second contained most kafirin and starch metabolism genes, as well as orthologs of TFs known to regulate protein and starch accumulation in other cereal species. Functional assays performed in protoplasts for six TFs revealed a central role for SbPBF1a, SbPBF1b, and SbNF-YC13 in modulating the expression of genes involved in protein and starch biosynthesis. In the genetic approach, we used a diversity panel of 300 sorghum genotypes representing global genetic diversity. This panel was cultivated at two sites in France over two growing seasons. Protein, starch contents and protein digestibility were measured. Whole-genome sequencing (WGS) was performed for all genotypes. These biochemical and genotypic data were analysed through genome-wide association studies (GWAS) using both single and multilocus models. Several significant SNPs were identified near genes previously associated with grain quality traits. Together, our work provides novel insights into the genetic basis and transcriptional regulation of protein and starch accumulation, as well as protein digestibility in sorghum grains. It also identifies regulatory and structural genes that could be targeted to enhance grain quality, thereby supporting the development of improved sorghum varieties with higher nutritional value
Complete genome sequence analysis of Sarbecovirus (severe acute respiratory syndrome-related coronaviruses) from Zimbabwean insectivorous bats
Get PDFBat-borne severe acute respiratory syndrome-related coronaviruses (bat SARSr-CoVs), belonging to the Sarbecovirus subgenus of the Betacoronavirus genus pose a potential risk for zoonotic spillover. This study reports the complete genome sequences of bat sarbecoviruses from Nycteris macrotis and Rhinolophus simulator insectivorous bat species in Zimbabwe. Using genome walking and nested PCR approaches, six full viral genomes were amplified, sequenced and assembled: one from Nycteris macrotis (MAG1042) and five from Rhinolophus simulator bats species (MAG388, MAG562, MAG575, MAG850, and MAG859). Comparative genomic analysis revealed a high degree of sequence conservation (99.6–99.9%) among the Rhinolophus simulator-characterised sequences, while the Nycteris macrotis characterised sequence exhibited 96.7% identity with the Rhinolophus simulator consensus (MAG Cons) genomes, suggesting genus-specific evolution. Furthermore, the spike region exhibited notable divergence, with only 88% sequence identity between the two genera. A complete absence of ORF8, and truncation of ORF7b genes were observed, while the RNA dependent RNA polymerase genes were highly conserved across all strains. Phylogenetic analysis demonstrated distinct continental clustering, with the Zimbabwean genomic sequences forming a well-supported clade within the African lineage (Lineage 4). These newly characterized Zimbabwean sarbecoviruses sequences represent the most recent evolutionary branches within the Lineage 4-African clade, indicating ongoing viral diversification in local bat populations. These findings expand understanding of SARSr-CoV diversity in African bats and underscore the importance of geographical isolation in viral evolution
