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‘Probabilistic Atlas’, a new approach to assess complexity in agroforestry systems using UAV images: example of the spatial effect of Faidherbia albida on pearl millet NDVI
No full textInternational audienceTrees in agroforestry parklands significantly contribute to improving and adapting farming systems while providing ecosystem services. However there is limited information on crop productivity and environmental performance. How do crop growth in such heterogeneous agroforestry systems vary according to distance, crown size, and azimuthal direction ? We use a novel approach based on advanced image analysis derived from medical imaging combined with multispectral imagery (known as the "probabilistic atlas") to analyze the crop, tree and soil interactions. We analyzed the influence of 72 Faidherbia albida trees on 13 millet fields in 2021 and 2022. Using "Voronoi" diagrams to separate individual trees. The Normalized Difference Vegetation Index (NDVI), was used as an indicator to assess the tree effect on pearl millet crop. We observed that, at the early growth stages of millet, the effect of Faidherbia albida on NDVI was stronger near the crown and decreased with distance, reflecting the positive growth influence on millet near canopy. We also observed an effect of azimuthal direction on NDVI. Finally, we found that the effect of Faidherbia albida on NDVI was more significant for trees with a large crown size. These results are a step further in the characterization of spatial tree influence on crops in highly heterogeneous systems, with improvements for e.g. the evaluation of ecosystem services or precision agriculture</div
Plan de Gestion de Données pour le projet BioLycTom Data Management Plan of BioLycTom project
No full textInternational audienceDMP of the BioLycTom project where two surveys were carried out among market gardeners in France.PGD du projet BioLycTom (Lutte biologique contre l'agent de l'acariose bronzée, Aculops lycopersici) où deux enquêtes ont été menées auprès de maraîchers en Franc
Effect of seed circulation systems on the spread and diversity of Xanthomonas phaseoli pv. manihotis infecting cassava crops of the Colombian Caribbean
No full textInternational audienceCassava is a lifeline for millions of people across the tropics, but its productivity is at risk from a disease called Cassava Bacterial Blight (CBB). In this study, we explore how the everyday practices of farmers exchanging cassava cuttings—a long-standing tradition—can shape how the disease spreads and evolves in the Colombian Caribbean. By combining knowledge from socio-cultural studies, plant pathology, and genetics, we reveal an often-overlooked reality: plant diseases can spread through human activities. Our findings shed new light on CBB epidemiology and emphasize the importance of incorporating farmers' practices and local economies into the development of effective, sustainable disease control strategies. Although our knowledge about the prevalence of CBB and the diversity of Xpm populations has deepened in recent years, the role played by the seed circulation system on pathogen dispersal is still unknown. In this paper, our objective is to determine the influence of the social network shaping seed circulation on the dispersion and diversity of the pathogen at the local scale. Cassava is particularly interesting as planting material is often scarce at the time of the planting season, and diseases may not be fully visible, making it hard to control the phytosanitary condition of the propagative material. We used interdisciplinary methods based on ethnoecology, epidemiology, ecology, social network analysis, and genetics that included semi-structured interviews with farmers, coupled with molecular genotyping of cassava plants and Xpm. Our findings highlight two main effects of local seed circulation on Xpm spread and diversity: (1) a high diversity of the pathogen at the scale of the evaluated village, and (2) greater genetic similarities of the pathogen between farmers that exchanged cuttings, regardless of the geographic distance between the fields. This study reveals the multifactorial nature of Xpm diversity and spread within a single village. By combining genetic, agricultural, and social data, it shows the value of interdisciplinary approaches to understand plant pathogen dynamics. The findings support the design of locally adapted disease control strategies. Unlike studies focused solely on genetic data, this work emphasizes the importance of integrating sociocultural factors, particularly for seedborne pathogens and crops where seed circulation systems are a determining factor
Etude scientifique et participative sur la qualité du sol et de l’air et sur la perception des pollutions par les habitants dans la zone Sebikotane-Diamniadio, Sénégal - Résultats du projet AirGeo (2021 – 2024)
No full textRoot tip excision‐induced exodermis lignification impacts lateral root emergence in Brachypodium distachyon
No full textInternational audienceThe mechanisms controlling lateral root emergence in monocots, particularly the role of the exodermis, are poorly understood. We investigated how natural variation in the Brachypodium distachyon stress response shapes root system architecture by modulating cell wall dynamics. We used root tip excision to synchronize lateral root development across natural accessions. The resulting phenotypes were analysed using comparative transcriptomics, biochemical lignin quantification, confocal Raman spectroscopy, and chemical inhibition of lignin biosynthesis. Two distinct root system architectures, ‘pine tree’ and ‘fishbone’, were identified. The ‘fishbone’ phenotype results from an altered lateral emergence caused by a differential lignification intensity of the exodermis. This phenotype was accompanied by the transcriptional upregulation of lignin biosynthesis genes and was partially rescued by treatment with a lignin inhibitor. Stress‐induced exodermal lignification acts as a mechanical ‘brake’ on lateral root emergence. This positions the exodermis as a key regulatory hub that integrates environmental cues with lateral root development to control Root System Architecture plasticity in grasses
Agroécologie dans le Sud de la France. Une mise en œuvre freinée par la rémunération du travail
No full textDans ce chapitre, Sébastien Bainville, Claire Aubron et Olivier Philippon analysent les évolutions du travail agricole dans le sud de la France et les effets différenciés des transitions agroécologiques sur la rémunération du travail. Depuis les années 1950, une forte mécanisation a permis une extensification en travail, réduisant la main-d’œuvre par hectare. En réponse aux difficultés d’accès au foncier et au capital, de nouvelles formes de travail émergent depuis les années 1990 : agriculture biologique, diversification, transformation et vente directe. Ces systèmes agroécologiques mobilisent davantage de travail, souvent manuel, et sont mis en œuvre par des agriculteurs moins dotés. Si la valeur ajoutée à l’hectare peut être élevée, la rémunération journalière du travail reste généralement faible, sauf dans certains cas comme la viticulture bio en circuits courts. Le manque de soutien public et l’orientation des aides par hectare freinent la généralisation de ces modèles. Une meilleure reconnaissance économique du travail en agroécologie apparaît comme une condition clé pour une transition à plus grande échelle
Produire du lait d’équidés en France : état des lieux et perspectives
No full textArticle paru dans La lettre mensuelle « Focus projet R&D » de l'IFCE.International audienceLa production de lait d’ânesse et de jument se développe en France depuis la fin des années 1990, ce produit pouvant être destiné tant au marché alimentaire que cosmétique du fait de nombreux atouts et « vertus » : composition proche du lait de femme et effets positifs sur différentes maladies digestives et cutanées. Néanmoins, le secteur est confronté à divers défis (manque de connaissances disponibles, d’encadrement et d’organisation) et il a rarement été l’objet d’études en sciences sociales. C’est pourquoi une enquête exploratoire qualitative (entretiens et observations) a été menée auprès de 47 producteurs
L'Indonésie, l'archipel des inconnues agricoles
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616830/) * Autres projets (id;sigle;titre): ;TALENT;(IDN) TrAining on LandscapE MaNagement// * Collectivites auteurs : CIRAD-PERSYST-UMR ABSys - FRA//International audienc
Impacts of epistasis, recombination, and genome architecture on population recovery following radical habitat change
No full textInternational audienceAbstract Under radical environmental change, populations may need to adapt quickly to avoid substantial declines in abundance and threats to their persistence. The outcome of this race between evolution and demography depends on the genetic architecture of adaptation, which determines how fast evolution can proceed. In particular, adaptation may require coordinated evolution at multiple loci (e.g., cooperating ion transporters for ion uptake), with single-locus changes being deleterious. Such selection on coadapted genes leads to a fitness landscape with a valley, which can in turn favor the evolution of structural variants that link beneficial alleles at different loci. Here, we investigate how epistasis and recombination jointly affect population dynamics under such a fitness valley. We assume that adaptation occurs from standing genetic variation and model the eco-evolutionary dynamics deterministically. We show that recombination has strong impacts on population decline and recovery in this context. Higher recombination rates cause evolutionary trajectories to be pulled toward unfit states, leading to prolonged evolutionary plateaus, during which the population can decline precipitously. In highly detrimental cases where coadapted mutations are located on different chromosomes, chromosomal fusions that are preexisting at low frequency can lead to faster population recovery by allowing the genetic system to escape the attraction to unfit intermediate states. Our results provide insights into eco-evolutionary dynamics in systems where chromosome number varies drastically among sibling species, such as the copepod Eurytemora affinis species complex, and offer new perspectives on the impacts of genome architecture on population dynamics in stressful environments
Four species but only three apomictic evolutionary significant units in the Limonium confusum aggregate (Viridiplantae, Plumbaginaceae)
No full texthttps://www.researchgate.net/publication/401321370_Four_species_but_only_three_apomictic_evolutionary_significant_units_in_the_Limonium_confusum_aggregate_Viridiplantae_PlumbaginaceaeInternational audienceIn apomictic genus, conservation planning is undermined by taxonomic complexity. The Limonium confusum aggregate is a taxonomically complex group of Mediterranean coastal plant species. Morphological criteria alone are insufficient to distinguish its members, complicating conservation efforts in a context of habitat degradation. The aggregate includes Limonium confusum, Limonium cuspidatum, Limonium densissimum, and Limonium legrandii, four taxa with overlapping distributions and unclear delimitation. To design conservation targets that respect the evolutionary legacy of this Limonium aggregate, we sampled all known populations of the four taxa with the aim of delimiting Evolutionary Significant Units (ESUs). The screening of 305 genotypes from 30 populations by 12 nuclear microsatellite markers identified 23 multilocus genotypes, grouped into three distinct clusters, challenging current taxonomy. Populations genetic diversity screening, as well as a progeny analysis, support the absence of genetic admixture within or between these clusters, even in sympatry, which is explained by apomictic reproduction. Each genetic cluster form a unique lineage with geographic and ecological patterns indicating that they deserve to be considered as ESUs. The first ESUs is endemic to the French Languedoc region. The second ESU has a scattered distribution in France and is associated with rocky habitats such as coastal cliffs and limestone plateaus. The third ESU exhibits a disjunct distribution: a first group of populations are distributed along the Iberian coasts of Valencia and Castellón and a second range in the French regions of Camargue and Provence. The results underline the importance of phylogeography studies conducted across taxonomic and geographical boundaries for conservation planning of apomictic species complexes.Dans les genres apomictiques, la planification de la conservation est compromise par la complexité taxonomique. L’agrégat Limonium confusum constitue un groupe taxonomiquement complexe d’espèces végétales côtières méditerranéennes. Les seuls critères morphologiques sont insuffisants pour distinguer ses membres, ce qui complique les efforts de conservation dans un contexte de dégradation des habitats.L’agrégat comprend Limonium confusum, Limonium cuspidatum, Limonium densissimum et Limonium legrandii, quatre taxons aux répartitions qui se chevauchent et dont la délimitation reste incertaine. Afin de définir des objectifs de conservation respectant l’héritage évolutif de cet agrégat de Limonium, nous avons échantillonné l’ensemble des populations connues des quatre taxons dans le but de délimiter des Unités Évolutivement Significatives (ESU).Le criblage de 305 génotypes issus de 30 populations à l’aide de 12 marqueurs microsatellites nucléaires a permis d’identifier 23 génotypes multilocus, regroupés en trois clusters distincts, remettant en question la taxonomie actuelle. L’analyse de la diversité génétique des populations, ainsi qu’une étude de descendance, confirment l’absence de mélange génétique au sein ou entre ces clusters, même en situation de sympatrie, ce qui s’explique par la reproduction apomictique.Chaque cluster génétique forme une lignée unique présentant des caractéristiques géographiques et écologiques indiquant qu’il mérite d’être considéré comme une ESU. La première ESU est endémique de la région française du Languedoc. La deuxième ESU présente une distribution fragmentée en France et est associée à des habitats rocheux tels que les falaises littorales et les plateaux calcaires. La troisième ESU montre une distribution disjointe : un premier groupe de populations est réparti le long des côtes ibériques de Valence et de Castellón, et un second ensemble se situe dans les régions françaises de Camargue et de Provence.Ces résultats soulignent l’importance d’études phylogéographiques menées au-delà des frontières taxonomiques et géographiques pour la planification de la conservation des complexes d’espèces apomictiques