50 research outputs found
FARM MANAGEMENT PRACTICES OF RICE BLAST IN BURKINA FASO
Get PDFRice blast is a fungal disease that causes enormous production losses. This study aimed to determine the socio-agronomic characteristics and management practices of rice blast on rice farms in Burkina Faso. An individual survey was carried out in 2021 on a sample of 180 rice farmers spread over four major production sites, namely the Sourou valley, the Kou valley, the Bagré plain and the Karfiguéla plain. The sites were selected according to the presence of rice blast and the importance of paddy rice production, while the farmers were selected according to their experience of at least three years in production. The results indicated a very high level of illiteracy among farmers (> 50%), with low participation of women with a mean rate of 9,25% in rice production, depending on the site. Cultivation practices were characterized by high use of organic manure (> 1500 Kg/ha) and mineral manure (> 400 Kg). The majority of farmers used resistant varieties (65,67% to 70,67%), chemical pesticides (60% - 86%) and organic manure (51,11% - 81,11%) to control rice blast. Very few farmers (0,87% - 2,87%) used biopesticides as a means of control. In view of these results, it is essential to raise farmers' awareness of the need to use biopesticides, with the support of research structures
Phenolics from Lippia multiflora Moldenke as potential bioactive agents against peanut pathogens
No full textInternational audienceThe phenolic composition of aqueous extract from dried leaves of Lippia multiflora Moldenke was analyzed by liquid chromatography- mass spectrometry (LC-MS) before inverse solid phase fractionation. The crude extract and the different fractions (from FL1 to FL5) obtained after fractionation were then tested in vitro for their effect on two fungi responsible of peanut foliar diseases, Phaeoisariopsispersonata and Pucciniaarachidis. The chemical analysis of the aqueous L. multiflora crude extract indicated the presence of seven phenolic compounds (nuomiosideA, isonuomiside A, samioside, verbascoside, isoverbascoside, alyssonoside and leucoseptoside A) and one monoterpene (geniposide). The antifungal activity, estimated by the efficient rate of the fungal appressorium formation, varied from 33.33% to 58.33% and 5.56% to 38.89% for P. personataand P. arachidis spores, respectively. By spraying the different fractions on artificially contaminated leaves, the best antifungal activity was noticed using FL3 and FL4 fractions, the only one in which the presence of samioside was described. The results of this study suggest that the protecting effect of Lippiaextracts against peanut pathogens may be related to the presence of four phenylethanoid glucosides: verbascoside, nuomoside A, leucoseptoside A and samiosid
Quantification of diversity sampling bias resulting from rice root bacterial isolation on popular and nitrogen-free culture media using 16S amplicon barcoding
No full textCulturing bacteria from plant material is well known to be conducive to strong bias compared to the actual diversity in the original samples. This bias is related to the bacterial cultivability, chemical composition of the media and culture conditions. Recovery bias is often observed but has never been quantified on different media using an amplicon barcoding approach whereby plant microbiota DNA extractions are compared to DNA extracted from serial dilutions of the same plant tissues grown on bacterial culture media. In this study, we: i) quantified the bacterial culturing diversity bias using 16S amplicon barcode sequencing by comparing a culture-dependent approach (CDA) focused on rice roots on four commonly used bacterial media (10% and 50% TSA, plant-based medium with rice flour, nitrogen free medium NGN and NFb) versus a culture-independent approach (CIA) assessed with DNA extracted directly from root and rhizosphere samples; ii) assessed enriched and missing taxa detected on the different media; iii) used biostatistics functional predictions to highlight metabolic profiles that could potentially be enriched in the CDA and CIA. A comparative analysis of the two approaches revealed that among the 22 phyla present in microbiota of the studied rice root samples, only five were present in the CDA (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Verrucomicrobia). The Proteobacteria phylum was the most abundant in all CDA samples, showing high gamma-Proteobacteria enrichment. The diversity of the combined culture media represented about a third of the total microbiota diversity, and its genus diversity and frequency was documented. The functional prediction tool (PICRUSt2) detected nitrogenase enzyme enrichment in bacterial taxa sampled from nitrogen-free media, thus validating its predictive capacity. Further functional predictions also showed that the CDA mostly missed anaerobic, methylotrophic, methanotrophic and photosynthetic bacteria compared to the CIA, thereby generating valuable insight that could enable the design of ad-hoc culture media and conditions to increase the rice-associated microbiota cultivability
Rice Variety Screening for Blast Control in Burkina Faso
No full textRice blast, caused by Maganporthe oryzae, is a fungal disease that causes enormous damage in rice fields in Burkina Faso. This study aimed to test the resistance of four rice varieties to this disease in a semi-controlled environment. The study was carried out over two consecutive years, 2022 and 2023, on the experimental site of the Institute for Research in Applied Sciences and Technologies in Ouagadougou, Burkina Faso. The plant material was composed of KBR2, KBR4, KBR6 and KBR8 rice varieties. The fungal material used for the varietal resistance test was M. oryzae strain BF0201. It is a strain from Burkina Faso isolated from rice leaves collected at the Farakô-Bâ site. The choice of this strain was justified by its level of virulence. The experimental design used was a randomised block with three replications. The parameters assessed were leaf and panicle severity, leaf and panicle incidence, grain yield and percentage yield loss. The results showed that the KBR8 variety was moderately susceptible to blast with a mean of 48.77% of the leaf area affected over the two experimentation years. While the KBR2, KBR4 and KBR6 varieties were susceptible to leaf blast with a mean of the leaf area affected over the two experimentation years of 54.33%, 51.66% and 53.89% respectively. The KBR8 variety was moderately resistant to panicle blast with a mean severity of 24,07%. This variety recorded the highest grain yield (59.99 g/pot) and the lowest loss rate (9.14%) with a mean of leaf and panicle incidences of 64.33% and 39.86% respectively.This variety can be improved and used as a means of varietal control against rice blast in rice fields in Burkina Faso
Quantification of diversity sampling bias resulting from rice root bacterial isolation on popular and nitrogen-free culture media using 16S amplicon barcoding
No full textInternational audienceCulturing bacteria from plant material is well known to be conducive to strong bias compared to the actual diversity in the original samples. This bias is related to the bacterial cultivability, chemical composition of the media and culture conditions. Recovery bias is often observed but has never been quantified on different media using an amplicon barcoding approach whereby plant microbiota DNA extractions are compared to DNA extracted from serial dilutions of the same plant tissues grown on bacterial culture media. In this study, we: i) quantified the bacterial culturing diversity bias using 16S amplicon barcode sequencing by comparing a culture-dependent approach (CDA) focused on rice roots on four commonly used bacterial media (10% and 50% TSA, plant-based medium with rice flour, nitrogen free medium NGN and NFb) versus a culture-independent approach (CIA) assessed with DNA extracted directly from root and rhizosphere samples; ii) assessed enriched and missing taxa detected on the different media; iii) used biostatistics functional predictions to highlight metabolic profiles that could potentially be enriched in the CDA and CIA. A comparative analysis of the two approaches revealed that among the 22 phyla present in microbiota of the studied rice root samples, only five were present in the CDA (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Verrucomicrobia). The Proteobacteria phylum was the most abundant in all CDA samples, showing high gamma-Proteobacteria enrichment. The diversity of the combined culture media represented about a third of the total microbiota diversity, and its genus diversity and frequency was documented. The functional prediction tool (PICRUSt2) detected nitrogenase enzyme enrichment in bacterial taxa sampled from nitrogen-free media, thus validating its predictive capacity. Further functional predictions also showed that the CDA mostly missed anaerobic, methylotrophic, methanotrophic and photosynthetic bacteria compared to the CIA, thereby generating valuable insight that could enable the design of ad-hoc culture media and conditions to increase the rice-associated microbiota cultivability
Phytochemical analysis of Ziziphus mucronata Willd. extract and screening for antifungal activity against peanut pathogens
No full textInternational audienceChemical analysis of aqueous extract of Ziziphus mucronata Willd. was determined by liquid chromatography–mass spectrometry (LC-MS) analysis. Among the 11 compounds found, catechin, rutin (quercetin 3-O-rutinoside), delphinidin-3-glucoside, isoquercetin (hyperoside) and quercitrin (quercetine3,7-O-L-dirhanmopyranoside) were identified as the major phenolics components in this aqueous plant extract. To elute the target compounds, the fractionation of crude extract was carried out on solid phase extraction (SPE) columns. The different fractions (from FZ1 to FZ5) obtained after fractionation were evaluated in vitro against economically important foliar fungal pathogens of peanut, including Cercospora arachidicola, Phaeoisariopsis personata and Puccinia arachidis. The treatments with Z. mucronata fractions were compared with negative control (water) and standard solutions of cathechin and rutin (1 mg/mL). All the fractions recorded an inhibitory effect, firstly on conidial germination and germ tube elongation, secondly on disease evolution on peanut leaves previously inoculated by fungi; the level of efficiency of inhibition varied from 40.55 (FZ1 against C. arachidicola) to 57.14% (FZ2 and FZ3 against P. arachidis). Then, spores of P. arachidis seemed to be more sensitive to the treatment
La fonction régulatrice de l'arbitre et la liberté des parties, in Le contrôle et la liberté en droit, Actes du séminaire annuel 2021 de la Conférence universitaire de Suisse occidentale
No full textInternational audienceBeyond its main mission of dispute resolution, the neutral exercises, in some cases, powers whose common characteristic is to contribute to maintaining the integrity of the legal system and which transcend the individual interests of litigants. The author provides a conceptual approach to this regulatory function and explains its peculiarities in arbitration. He then discusses the implications for the parties' freedom to consent to arbitration and to choose the applicable law, as well as for the review of public policy.Par-delà sa mission principale de règlement des différends, le tiers impartial et indépendant exerce, dans certains cas, des pouvoirs dont la caractéristique commune est de contribuer à maintenir l’intégrité du système juridique et qui transcendent les intérêts particuliers de litigants. L’auteur propose une approche conceptuelle de cette fonction de régulation et en expose les particularités en matière d’arbitrage. Il en examine ensuite les implications pour la liberté des parties quant consentement à l’arbitrage, au choix du droit applicable ainsi que face à la réserve de l’ordre public
In vitro Management of Bipolaris oryzae the Causal Pathogen of Brown Spot of Rice by Plant Extracts
No full textDistribution and mean relative abundance of the top 20 genera detected in the CDA.
No full textDistribution and mean relative abundance of the top 20 genera detected in the CDA.</p
Abundance of bacterial classes detected in rice microbiota (Wilcoxon test), and their occurrence in the culturable approach.
No full textNumbers are colored according to class frequencies in each medium and CIA amplicon data. (XLSX)</p
