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Plan de gestion des données du projet "Service d'Assistance Technique pour le Programme d'utilisation durable des terres de la République du Congo" [PUDT]
No full textLe Plan de gestion des données couvre les composantes numériques du projet ciblé PUDT Congo (Composantes Agriculture, Aménagement du Territoire, Bois-énergie, HVC/HSC)
Evaluation of rubber clones (IRR 500 Series) using a new phenotyping method to accelerate breeding selection in Indonesia
Get PDFThe planting material is one of the most critical technological components influencing the productivity of rubber (Hevea brasiliensis) plantations. The Indonesian Rubber Research Institute (IRRI) continuously conducts breeding program to develop new superior rubber clones possessing vigorous growth, high latex yield, disease resistance and drought tolerance. The Institute has released IRR 00, 100 and 200 series clones, and is currently evaluating the promising IRR 300, 400 and 500 series under different agro-climatic conditions Conventionally, development of rubber clones involve multiple evaluation stages, including the seedling evaluation trial (SET), small-scale clone trial (SSCT) large-scale clone trial (LSCT) and multilocation trial, taking more than 25 years before a clone can be recommended for commercial planting. In order to accelerate this process, IRRI has introduced the New Phenotyping Method (NPM), which streamlines the conventional evaluation stages by bypassing the SET stage and directly evaluating F1 progenies in the SSCT aiming to reduce the length of breeding cycle. Unlike the SET, where each genotype is represented by only one tree, the NPM employs replicated SSCT trials to improve accuracy and representativeness of each genotype. This modification is expected to shorten the selection period by 5-10 years compared to the conventional approach although it requires a larger research area. In this study, 202 F1 progenies and 8 commercial clones (as control) were planted in five replications with two plants per genotype per replication. Growth performance, yield potential under different tapping systems, resistance to main diseases especially to Pestalotiopsis leaf fall disease, clone typology, tapping panel dryness (TPD) incidence, and drought tolerance were assessed during immature (4 year) and mature period (2 -year). Based on observations of all parameters, 10 of the best genotypes were selected. These selected genotypes have a high latex yield potential and good agronomic characteristics, such as rapid growth, disease resistance, as well as tolerance to TPD and drought. The best genotypes were named IRR 500 series, and will subsequently under large-scale clone trial and multilocation trials. In addition, the NPM demonstrates a promising approach to accelerate rubber clone development while maintaining selection reliability and adaptability across environments
Multi-environment GWAS uncovers markers associated to biotic stress response and genotype-by-environment interactions in stone fruit trees
Get PDFWhile breeding for improved immunity is essential to achieve sustainable fruit production, it also requires to account for genotype-by-environment interactions (G × E), which still represent a major challenge. To tackle this issue, we conducted a comprehensive study to identify genetic markers with main and environment-specific effects on pest and disease response in peach (Prunus persica) and apricot (Prunus armeniaca). Leveraging multienvironment trials (MET), we assessed the genetic architecture of resistance and tolerance to seven major pests and diseases through visual scoring of symptoms in naturally infected core collections, repeated within and between years and sites. We applied a series of genome-wide association models (GWAS) to both maximum of symptom severity and kinetic disease progression. These analyses lead to the identification of environment-shared quantitative trait loci (QTLs), environment-specific QTLs, and interactive QTLs with antagonist or differential effects across environments. We mapped 60 high-confidence QTLs encompassing a total of 87 candidate genes involved in both basal and host-specific responses, mostly consisting of the Leucine-Rich Repeat Containing Receptors (LRR-CRs) gene family. The most promising disease resistance candidate genes were found for peach leaf curl on LG4 and for apricot and peach rust on LG2 and LG4. These findings underscore the critical role of G × E in shaping the phenotypic response to biotic pressure, especially for blossom blight. Last, models including dominance effects revealed 123 specific QTLs, emphasizing the significance of non-additive genetic effects, therefore warranting further investigation. These insights will support the development of marker-assisted selection to improve the immunity of Prunus varieties in diverse environmental conditions
The influence of meteorological variability on herbaceous biomass production in a Sahelian semiarid savanna ecosystem (Dahra, Ferlo, Senegal)
Get PDFSavanna ecosystems of the Sahel are heavily affected by climate change, leading to drier subtropical regions. These ecosystems play a fundamental role in food security of the region, so that an improved understanding of how these ecosystems are affected by these weather events is thereby critical. Several studies have assessed the herbaceous production level, dynamics during the rainy season, and biotic and abiotic factors that could impact this production. Some authors argue that rain is the main factor positively influencing the biomass production in semi-arid areas where the rainfall ranges between 200 and 750 mm. This study aims to assess the contribution of some meteorological variables to biomass production in a Sahelian semiarid savannah. From 2008 to 2018, rainfall (mm), soil moisture (%), soil temperature (°C) at 5 cm depth, number of times there was no rain (NTNR), number of rainy days, and the herbaceous biomass were monitored. The contributions of meteorological variables to biomass production were calculated using the XGBoost regression model. The most influential meteorological parameters on herbaceous biomass production are soil temperature, amount, and distribution of rainfall
L'utilisation de droits de propriété pour la mise en oeuvre de politiques d'atténuation des changements climatiques
No full textLes quotas d'émissions de gaz à effet de serre constituent des droits de propriété, au sens du droit de réaliser certaines actions dans un cadre réglementé, dans la mesure où ils sont des permis d'émission émis en quantité limitée par un régulateur. Ils diffèrent alors des crédits carbone issus de projets et destinés au marché volontaire du carbone, qui sont principalement des outils de communication pour les entreprises soucieuses de se rapprocher d'une " neutralité carbone ", même s'ils peuvent aussi être des supports de spéculation, comme tout autre actif financier. Les crédits carbone ne deviennent des droits de propriété que lorsqu'un régulateur autorise leur usage pour compenser des émissions dans un système de plafonnement des émissions. La question de la propriété des crédits carbone, particulièrement dans le domaine des forêts, devient un thème politique dans plusieurs pays en développement, qui cherchent ainsi à obtenir une plus grande part des revenus des ventes de ces actifs générés par des projets privés
Early detection of Zymoseptoria tritici infection on wheat leaves using hyperspectral imaging data
Get PDFThis article presents a hyperspectral imaging (HSI) database of healthy leaves and leaves infected with Zymoseptoria tritici fungal pathogen responsible for leaf blotch (Lb) disease. Leaves of two durum wheat genotypes were studied under controlled conditions to track the evolution of Lb disease and capture significant spectral and spatial differences until the onset of symptoms. Hyperspectral image acquisitions were purchased with two cameras in visible-near infrared (VNIR) and short-wave infrared (SWIR) spectral ranges on eighteen dates between one day before inoculation and twenty days after inoculation. For each wavelength range studied, a total of 1175 images provided information on 3326 leaves measured throughout the experiment. These data are valuable since they can be used as a basis to monitor disease's development over time, to build leaf classification models according to their infection status per genotype per day, to develop prediction models related to symptoms' appearance, or to test imaging and spectral analysis methods
Rift Valley fever epidemiology: Shifting the paradigm and rethinking research priorities
Get PDFRift Valley fever (RVF), a zoonotic mosquito-borne viral disease with erratic occurrence and complex epidemiology, results in substantial costs to veterinary and public health and national economies. Since 1985, RVF virus (RVFV) epidemiology has focused on epidemics triggered by flood-induced emergence of transovarially infected mosquitoes, following an interepidemic period during which RVFV persists primarily in floodwater Aedes spp mosquito eggs, with potential for low-level interepidemic circulation. In this Personal View, we challenge this classic framework of RVFV epidemiology, presenting instead a spectrum of RVFV dynamics ranging from epidemic to hyperendemic. We present the case for RVFV being maintained in a variable reservoir system of livestock, wildlife, and mosquitoes, with or without transovarial transmission. We highlight that sufficient evidence supports a shift in the paradigm of RVF epidemiology to embrace a more nuanced understanding of the spectrum of RVFV dynamics and call for more research into understanding the drivers of RVFV dynamics in hyperendemic areas
Insecticidal activity of eco-extracted holopelagic Sargassum against the whitefly Bemisia tabaci infesting tomato crops
Get PDFMassive strandings of holopelagic Sargassum cause major ecological and economic problems, but its conversion into bioproducts offers a sustainable alternative. This study assessed the potential of holopelagic Sargassum (S. fluitans and S. natans) collected in the Caribbean as ecofriendly insecticides against the whitefly Bemisia tabaci, a major pest of tomato crops. Extracts were produced using green methods: ultrasound-assisted extraction (UAE) and ultrasound-assisted enzymatic hydrolysis (UAEH) with enzymes cocktails. Biochemical analyses revealed high mineral and polysaccharide contents, varying with the extraction technique. Extracts were tested at 1–6% (w/v) using clip-cage (adults) and leaf-dip (eggs) methods. All extracts reduced adult survival, with UAE and UAEH-P/C extracts achieving over 50% mortality at ≥4% concentration after 48 h (LD50: 3.9–4.5%). Egg mortality was significant only with UAE and UAEH-P extracts at 6% (LD50: 1.9–2.8%). These results suggest insecticidal activity through both ingestion and cuticle/embryo disruption. Although enzymatic extraction did not markedly enhance biochemical yields, extracts showed, for the first time, promising biocidal and ovicidal properties. This research highlights holopelagic Sargassum as a renewable source of natural insecticidal compounds, supporting sustainable management of both invasive algal biomass and agricultural pests
A multidisciplinary approach to understanding the evolution of agroforests in Timor-Leste
Get PDFTimor Leste's traditional agroforests have a significant cultural and ecological value, though assessing them is challenging and data are limited. This paper presents a multidisciplinary experiment to understand the complexity inherent in Timor Leste's agroforestry systems (AFS). Inter- connected factors, such as historical dynamics, local perceptions of the land, and economic values, are all considered. Participatory mapping and GIS tools determined the spatial distribution and properties of the various agroforests. A scoring exercise, the Pebble Distribution Method, gathered data about the uses of the AFS. Key informant interviews and household surveys were used to collect qualitative and quantitative data about the village's background and economy. A simulation model combining economic results with qualitative and quantitative data illustrated the evolution of the AFS based on the landscape configuration and demography. This multi-disciplinary study provided a holistic understanding of the evolution of the AFS and highlights the importance of local knowledge for sustainable land management in the region