18 research outputs found
Comparaison de lâefficacite Antifongique de lâhuile Essentielle dâOcimum Gratissimum L. et du Fongicide de Synthese Mancozebe Contre le Mycopathogene Tellurique, Fusarium oxysporum f. sp. Radicis-lycopersici en Cultures de Tomate (
Une étude a été menée à la fois in vitro et in vivo afin d’évaluer l’activité antifongique du mancozèbe et de l’huile essentielle d’Ocimum gratissimum L. sur Fusarium oxysporum f. sp. radicis-lycopersici (Forl). Une corrélation positive a été établie entre l’inhibition de la croissance radiale mycélienne du mycopathogène et la concentration de chaque produit. Les concentrations minimales inhibitrices (CMI) ont été significatives à 500 ppm et très significatives à 250 ppm pour le mancozèbe et l’huile essentielle d’Ocimum gratissimum, respectivement. Le produit (huile essentielle) a montré des taux d’inhibition nettement supérieurs au seuil de signification (25 %) pour la plus faible dose. Aucune reprise de la croissance mycélienne n’a été observée durant les 7 j d’évaluation à 500 ppm pour l’huile essentielle et 4000 ppm pour le mancozèbe. Par ailleurs, l’application du mancozèbe ou de l’huile essentielle d’Ocimum gratissimum sur les plants de tomate inoculés a entrainé une inhibition de l’expression de la fusariose 30 j après inoculation. La biomasse des plants de tomate inoculés avec l’huile essentielle a augmenté de plus de 30 % par rapport à la biomasse sèche racinaire et de plus de 40 % pour la biomasse foliaire sèche chez Tropimech, variété la plus sensible à Forl.Mots clés : Activités antifongiques, huiles essentielles, Ocimum gratissimum, mancozèbe, Côte d’IvoireA study was conducted to evaluate the efficacy of mancozeb and the essential oil of Ocimum gratissimum in both in vitro and in vivo against Fusarium oxysporum f. sp. radicis-lycopersici (Forl). A positive correlation was found between the radial growth of the fungus mycelium and the concentration of each product. The minimal inhibitory concentrations (MIC) were found to be significant at 500 ppm and highly significant at 250 ppm for mancozeb and the essential oil of Ocimum gratissimum, respectively. The rates of inhibitions of the essential oil were by far superior to the significant level (25 %) at the lowest rate of the inhibitor. No radial growth was found during the seven days at 500 ppm for the essential oil and 4000 ppm for mancozeb. Furthermore, the application of mancozeb, or the essential oil of Ocimum gratissimum on tomato plants inoculated reduced the severity of the disease caused by Fusarium 30 days after inoculation. The tomato plants inoculated and treated with the essential oil increased the dry root biomass by more than 30 % and the dry foliar biomass by more than 40 % for the Tropimech cultivar, the most sensitive tomato variety to Forl.Key words : Antifungal activity, essential oil, Ocimum gratissimum, mancozeb, Côte d’Ivoir
A Shigella boydii bacteriophage which resembles Salmonella phage ViI
<p>Abstract</p> <p>Background</p> <p>Lytic bacteriophages have been applied successfully to control the growth of various foodborne pathogens. Sequencing of their genomes is considered as an important preliminary step to ensure their safety prior to food applications.</p> <p>Results</p> <p>The lytic bacteriophage, ΊSboM-AG3, targets the important foodborne pathogen, <it>Shigella</it>. It is morphologically similar to phage ViI of <it>Salmonella enterica </it>serovar Typhi and a series of phages of <it>Acinetobacter calcoaceticus </it>and <it>Rhizobium meliloti</it>. The complete genome of ΊSboM-AG3 was determined to be 158 kb and was terminally redundant and circularly permuted. Two hundred and sixteen open reading frames (ORFs) were identified and annotated, most of which displayed homology to proteins of <it>Salmonella </it>phage ViI. The genome also included four genes specifying tRNAs.</p> <p>Conclusions</p> <p>This is the first time that a Vi-specific phage for <it>Shigella </it>has been described. There is no evidence for the presence of virulence and lysogeny-associated genes. In conclusion, the genome analysis of ΊSboM-AG3 indicates that this phage can be safely used for biocontrol purposes.</p
Comblement, eutrophisation et usages de lâeau de la retenue de Kogbetohoue (Sud-Ouest Benin)
Objectif : Lâobjectif de la prĂ©sente Ă©tude est dâanalyser les processus interdĂ©pendants du comblement et dâeutrophisation de la retenue dâeau de KogbĂ©tohouĂš en relation avec les menaces Ă lâaccĂšs dâeau des populations riveraines. MĂ©thodologie and RĂ©sultats : LâĂ©tude bathymĂ©trique a rĂ©vĂ©lĂ© une diminution moyenne de 0,05 m/an de la profondeur sur sept (07) ans. Cette dynamique pourrait sâexpliquer en partie par la dĂ©gradation du couvert vĂ©gĂ©tal oĂč lâanalyse diachronique de lâoccupation du sol montre que chaque annĂ©e environ 140 hectares de terres passe sous lâemprise agricole et sont de ce fait peu ou pas protĂ©gĂ©es contre lâĂ©rosion qui contribue au comblement de la retenue. Les mesures directes de la qualitĂ© physique : le pH, la tempĂ©rature et lâoxygĂšne dissous avec le multi paramĂštre PC HORIBA WATER QUALITY CHECKER U-10 ; les paramĂštres chimiques par la mĂ©thode chromatographique ICS 1000 et de dosage de la chlorophylle a avec le spectrophotomĂštre DR 5000 par la Norme AFNOR T90-117 ont permis dâĂ©valuer le risque dâeutrophisation par la grille de diagnostic dâIfremer (2000). Les eaux sont dans un Ă©tat eutrophe traduisant une eutrophisation de la retenue. Conclusion et application des rĂ©sultats : Le comblement et lâeutrophisation de la retenue constituent des menaces potentielles Ă court terme sur la pisciculture et lâirrigation tandis que la disponibilitĂ© quantitative de la ressource est menacĂ©e Ă moyen terme. Des relevĂ©s bathymĂ©triques pĂ©riodiques et des actions dâamĂ©nagement du bassin versant de la retenue sont nĂ©cessaires Ă la gestion intĂ©grĂ©e de la retenue dâeau.Mots clĂ©s : KogbĂ©tohouĂš, Retenue dâeau, Comblement, Eutrophisation, Usages de lâeau, Menaces. Objective: A study is carried out to analyze the process of filling and eutrophication of Kogbetohoue dam in relation to population water access. Methodology and results: The bathymetry study revealed 0.05 m/year reduction of dam depth during seven years. This situation would be explained in some way by the rate vegetation cover degradation. When diachronic analysis of soil occupation show 140 hectares of the basin exploited each year for agriculture, increasing the surface exposed to erosion which contributed highly for dam filling. Physical quality parameters such as pH, temperature and dissolved oxygen are measured directly with PC Horiba Water Quality Checker U-10 multi parameter; conductivity and total dissolved solids with conductivity meter WTW 340i. Water collected was analyzed with suitable and appropriate laboratory equipment such as colorimeter HACH/890 with 8025 method and chromatographic ICS 1000 method respectively for turbidity and chemical parameters. Chlorophyll content is calculated with spectrophometer DR 5000 by AFNOR T90 â 117 norms. Eutrophication risk of the dam is assessed with diagnostic gird of Ifremer (2000). Water analyses revealed that the eutrophication of the dam is great. Conclusion and application of results: The filling and the eutrophication of the dam are the basics risks in a short period for fish cropping and crop irrigation when the availability of the water is the risk in a mean period. Periodic bathymetry studies and basin management actions are useful for integrated water management. Keywords: Kogbetohoue, Dam, Filling, Eutrophication, Risk and Water uses
The relationships between cassava variety set characteristics, farmer's food security objectives, environmental and socio-economic conditions in Africa
Utilisation du ModĂšle GR4J pour la Simulation des DĂ©bits dâEtiage du Fleuve Mono (BĂ©nin, Togo) Ă lâExutoire dâAthiĂ©mĂ©
RĂ©sumĂ©La gestion des ressources en eau recouvre des questions telles que lâhydrologie, les besoins des populations, la planification et la rĂ©alisation des infrastructures, la prĂ©servation de la ressource et sa gouvernance. Des mĂ©thodes dâinvestigations pour une meilleure connaissance des ressources en eau existent pour une meilleure description et une gestion des problĂšmes Ă lâĂ©chelle bassin versant par lâexploitation des donnĂ©es hyrodroclimatiques et la mise en Ćuvre de mĂ©canismes de gestion durable des ressources du bassin (Zannou, 2011 ; Fofana, 2015).Lâobjectif de la prĂ©sente Ă©tude est de simuler les dĂ©bits dâĂ©tiage du fleuve Mono Ă lâexutoire dâAthiĂ©mĂ© en prĂ©vision de lâutilisation durable des ressources en eau Ă des fins agricoles. Les donnĂ©es hydroclimatiques journaliĂšres (Pluie, Evapotranspiration, DĂ©bits), sur la pĂ©riode de 1970 Ă 2019, ont Ă©tĂ© recueillies et exploitĂ©es avec lâutilisation de la version Perrin et al., (2003) du modĂšle GĂ©nie Rural Ă 4 ParamĂštres Journaliers (GR4J) Ă lâaide du logiciel R.Les valeurs du critĂšre de Nash-Sutcliffe avant la construction du barrage en 1988, sont de lâordre de 70% (sous-estimation) en calage et validation et les valeurs de KGE (Gupta et al., 2009) de 0,8317 et 0,8421 (proches de 1). Ces valeurs traduisent une bonne performance et robutesse du modĂšle GR4J sur le bassin du Mono. Mais ces valeurs sont trĂšs dĂ©gradĂ©es sur la pĂ©riode aprĂšs barrage du fait du rĂ©gime hydrologique modifiĂ© par les lĂąchers dâeau lors du turbinage, contrariĂ©es par le caractĂšre lacunaire des observations sur cette pĂ©riode.Ces rĂ©sultats appellent Ă une meilleure attention et Ă des investissements consĂ©quents pour une meilleure connaissance des ressources en eau, base dâune planification de leur utilisation durable.Mots clĂ©s : AthiĂ©mĂ©, Bassin du Mono, DĂ©bits dâĂ©tiage, Hydrologie, GR4J.    Abstract :Simulation of low flooded of Mono river watershed (Benin and Togo) at AthiĂ©mĂ© outlet with GR4J model.Water resources management involved varied implications such hydrology, people needs, infrastructures planning and establishment, basin resources conservation and institutional management. Strategies and policy management for better knowledge of water resources by diagnostic of matter of the basin using hydroclimatic data and the implementation of integrated water resources management (Zannou, 2011; Fofana 2015).This study aims in order to simulate low flow of Mono watershed at AthiĂ©mĂ© outlet to evaluate water availability for agricultural uses. Therefore daily hydroclimatic data (rianfall, recharge and flow were collected (1971-2019) and analyzed with Perrin and al., (2003) GR4J model unsing R software.Results showed a good performance of the model to simulate low flow before the construction of Nangbeto dam in 1988, according to Nash-Sutcliffe, RMSE and KGE (Gupta et al., 2009) criteria. Criteria values of Nash-Sutcliffe before dam establishment in 1988 are around 70% both in calibration and validation where KGE values (Gupta et al.., 2009) showed 0,8317 et 0,8421 (near 1). A worst performance of the model is noticed for the period after the dam establishment due to the change in the hydrological regime due to water jets for energy production and lack of historical data for this period.This situation calls for serious attention and investment for all activities related to a better known of water resources, which is reliable tool for their sustainable use.Key words : AthiĂ©mĂ©, Mono watershed, Low flood, Hydrology, GR4J
Structure Des Composes Majoritaires Et Activite Insecticide Des Huiles Essentielles Extraites De Sept Plantes Aromatiques De Cote Divoire
The essential oils from seven aromatic plants were extracted by hydrodistillation with a Clevenger type apparatus. These oils tested by fumigation at various concentrations on adults of the flightless form of Callosobruchus maculatus Fab. present an insecticidal activity. The chemical composition was investigated by G.C. and carbon 13 NMR spectroscopy