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Reuse out-of-year data to enhance land cover mapping via feature disentanglement and contrastive learning
Get PDFGiven the systematic acquisition of satellite data, it is possible to generate up-to-date land cover (LC) maps, essential for effective agricultural territory management, environmental monitoring, and informed decision-making. Typically, creating a LC map requires collecting high-quality labeled data, a process that is both costly and time-consuming. To mitigate the need to collect large volume of labeled data, we propose a deep learning framework called REFeD (data Reuse with Effective Feature Disentanglement for land cover mapping), which leverages already available out-of-year reference data to enhance the production of up-to-date LC maps. To this end, REFeD integrates remote sensing and reference data from different domains (e.g., historical and recent data) utilizing a disentanglement strategy based on contrastive learning. By separating domain-invariant and domain-specific features, REFeD isolates useful information associated to the downstream LC mapping task and mitigates distribution shifts between domains. Moreover, REFeD incorporates an effective supervision scheme to reinforce feature disentanglement through multiple levels of supervision at different granularities. Experimental evaluation on study areas characterized by diverse landscapes, including Koumbia (West Africa, Burkina Faso) and Centre-Val de Loire (central Europe, France), demonstrates the effectiveness of the proposed approach
Mapping QTLs for early leaf spot resistance and yield component traits using an interspecific AB-QTL population in peanut
Get PDFEarly leaf spot (ELS), caused by Passalora personata (syn. Cercospora arachidicola), is a highly damaging peanut disease worldwide. While there are limited sources of resistance in cultivated peanut cultivars, wild relatives carry alleles for strong resistance, making them a valuable strategic resource for peanut improvement. So far, only a few wild diploid species have been utilized to transfer resistant alleles to cultivars. To mitigate the risk of resistance breakdown by pathogens, it is important to diversify the sources of resistance when breeding for disease resistance. In this study, we created an AB-QTL population by crossing an induced allotetraploid (IpaCor1), which combines the genomes of the diploid species Arachis ipaënsis and A. correntina, with the susceptible cultivar Fleur11. A. correntina has been reported to possess strong resistance to leaf spot diseases. The AB-QTL population was genotyped with the Axiom-Arachis 48K SNPs and evaluated for ELS resistance under natural infestation over three years in Senegal. Marker/trait associations enabled the mapping of five QTLs for ELS resistance on chromosomes A02, A03, A08, B04, and B09. Except for the QTL on chromosome B09, the wild species contributed favorable alleles at all other QTLs. One genomic region on chromosome A02 contained several relevant QTLs, contributing to ELS resistance, earliness, and increased biomass yield, potentially allowing marker-assisted selection to introduce this region into elite cultivars. This study's findings have aided in diversifying the sources of resistance to ELS disease and other important agronomic traits, providing another compelling example of the value of peanut wild species in improving cultivated peanut
Micrococcus ORF15-23 biostimulant product for plant nutrition and salt stress tolerance in rice
No full textA virus-induced gene silencing (VIGS) approach to study plant-geminivirus-insect vector interactions and virus transmission
Get PDFGeminiviruses (family Geminiviridae) are plant viruses with circular ssDNA genomes encapsidated in geminate virions and transmitted by insect vectors in a persistent circulative manner, causing severe crop diseases globally. Gemiviruses of the genus Begomovirus (begomoviruses) are often associated with circular ssDNA betasatellites encoding a protein that suppresses plant RNA interference (RNAi)-based defenses and innate immunity. Geminiviruses replicate in plant cells through rolling circle replication (RCR) and recombination-dependent replication (RDR), generating circular ssDNA for encapsidation and linear concatemeric dsDNA, respectively. RDR products may serve for resurrection of cirlular ssDNA via RCR and/or for evasion of the antiviral RNAi generating virus-derived small RNAs. Recent studies showed that Tomato yellow leaf curl virus (TYLCV) can replicate in the salivary glands of its insect vector Bemisia tabaci (whitefly), which ensures persistent infection and efficient transmission to new plants. This discovery raises questions about the underlying replication mechanisms and how the whitefly antiviral RNAi and innate immunity respond. To validate the function of host plant and insect vector genes implicated in begomovirus replication and transmission, we applied a virus-induced gene silencing (VIGS) approach. We designed a disarmed betasatellite vector lacking an RNAi suppressor, for carrying inserts of candidate plant and insect genes. Initial tests confirmed efficient replication of empty VIGS constructs in host plants and successful transmission by whiteflies. Using VIGS to knock down expression of the plant PCNA gene essential for DNA replication led to severe developmental abnormalities, unlike controls. Current experiments involve silencing of the whitefly PCNA gene implicated in begomoviral DNA replication and two other whitefly genes implicated in begomovirus circulation and transmission. The results of these experiments will be presented and discussed. As an ultimate goal, we aim to develop new strategies for the control of viral disease spread at the transmission step without affecting insect viability
Drivers of soil organic carbon stocks at village scale in a sub-humid region of Zimbabwe
Get PDFLand use change caused by agriculture and inappropriate agricultural management cause soil organic carbon (SOC) loss. This study was conducted in a smallholder communal area of Zimbabwe with the following objectives: i) to quantify SOC stocks under contrasting land uses and soil types, and estimate landscape-level SOC stocks, ii) to assess the impact of historical agricultural management parctices on SOC in croplands (homefields vs outfields), and iii) to estimate temporal changes in SOC stocks due to land use change using field measurements and geospatial data (Africa Soil Information Service, AfSIS). SOC stocks were measured across three soil types and eight land uses (croplands, gardens, fallows, grasslands, vleis, shrublands, forests and tree plantations) at soil depths of 0–20 and 20–40 cm. Estimates from AfSIS were also used for comparison. SOC stocks were highest on black clay soils (66.9 ± 2.30 Mg C/ha), followed by red clay soils (36.1 ± 2.04 Mg C/ha) and sandy soils (25.5 ± 0.59 Mg C/ha). Among land uses, SOC stocks were highest in vleis (67.9 ± 3.55 Mg C/ha), followed by gardens (56.4 ± 2.34 Mg C/ha) and grasslands (53.1 ± 6.18 Mg C/ha). Croplands on sandy soils had the lowest stocks (22.7 ± 0.77 Mg C/ha). Distance from homestead had no significant effect on SOC stocks. SOC stocks estimated by AfSIS were systematically underestimated in vleis, grasslands and gardens, resulting in a 20 % underestimation of landscape SOC stocks. Landscape SOC stocks declined slightly (−0.2 %) from 2002 to 2023, though the change was not statistically significant. Our findings highlight that SOC stocks hotspots are concentrated in vleis, gardens and grasslands, mostly within communal grazing lands. Their conservation should therefore be a priority, emphasizing the need for collective management. On the other hand, restoration of degraded croplands could be enhanced by strenghtening linkages between cultivated fields and communal grazing lands through improved livestock management
L'antibiorésistance d'origine animale en Afrique subsaharienne. Une approche trop exclusivement sanitaire
No full textBiofuels from cashew nut shells for diesel engines: A comparative review
No full textAmidst growing concerns regarding energy supply and environmental degradation, biofuels from cashew nut shells (CNS) are emerging as promising alternatives to petrodiesel. However, some inherent issues exist with cashew nutshell liquid (CNSL) properties for direct use in diesel engines. This review analyses the current developments in improving the fuel properties of CNSL as fuel for diesel engines. Furthermore, the fuel characteristics of the CNSL biofuels and the performance and emission characteristics of diesel engines powered by biofuels (and blends) are investigated. Current developments for improving the fuel properties of CNSL, such as vacuum catalytic and thermal cracking, involve the production of biofuels with properties that match those of diesel fuels. This review shows that up to 20% (v/v) biofuel achieves a performance similar to that of diesel. CNSL biofuels may require modification of injection pressure and injection timing of the engine and preheating of the fuel. Further, fuel blends with up to 20% CNSL, at an injection pressure of 20 MPa or preheated to 70°C (injection timing of 19° before top dead centre), successfully yielded high thermal efficiencies (up to 29.32%) in diesel engines, alongside lower emission characteristics. The current development for producing CNSL biofuels necessitates high temperatures, thereby increasing operational costs. This review suggests technical CNSL as a potential substitute for heavy fuel oil in low-speed stationary diesel engines or boilers. This could help reduce the environmental impact of cashew nutshell and the dependence of processing units on petroleum products
Mathematical modeling of multi-step kinetics of biomass pyrolysis applied to agave bagasse and char oxidation reactivity
No full textComputational Fluid Dynamics (CFD) modeling was used to investigate the pyrolysis multi-step kinetics of lignocellulosic biomass, focusing on agave bagasse (AB), including drying, devolatilization, and secondary reactions such as tar cracking and the subsequent char gasification reactivity (both heterogeneous and homogeneous reaction). The pyrolysis was carried out between 100 and 1000 °C. During this process, the release of non-condensable gases such as H2, CH4, CO, and CO2, as well as the evolution of char and its composition in terms of carbon, hydrogen, oxygen, and ash content, were simulated and validated using a thermogravimetric analyzer (TGA). The simulation results showed that the char produced at temperatures above 700 °C primarily consisted of carbon and ash, with values above 72.85 wt% and 12.39 wt%, confirmed by experimental data. Subsequently, the pyrolysis process was followed by both isothermal and non-isothermal partial oxidation reactions with air. In the non-isothermal oxidation was conducted between 700 and 1000 °C, the influence of heating rate on both gaseous and char products was examined, while in the isothermal oxidation was carried out at 850, 900, 950, and 1000 °C, the reactivity index and the peak temperature were examined to express the oxidation reactivity. The CFD results show that the reactivity rate of chars increases proportionally from 0.0080 min−1 at 850 °C to 0.0129 min−1 at 1000 °C. The models used for homogeneous and heterogeneous reactions accurately predicted the experimental results of the evolution of the gas and char products during the oxidation under isothermal and non-isothermal conditions studied
Transition nécessaire de la communauté Analyse de Cycle de Vie vers la Science Ouverte pour garantir la reproductibilité des résultats scientifiques - Logiciels, jeux de données et bases de données ouvert·e·s
Get PDFLa présentation met en avant l'importance de la transition vers la Science Ouverte dans la communauté de l'Analyse de Cycle de Vie (ACV) pour garantir la reproductibilité des résultats scientifiques. Elle souligne que cette transition est nécessaire car les résultats de la recherche en ACV dépendent souvent de traitements informatiques réalisés avec des logiciels et des jeux de données, dont la disponibilité et l'ouverture sont cruciales pour la reproductibilité. La présentation met en évidence les similitudes entre la communauté ACV et d'autres communautés de recherche, telles que l'Intelligence Artificielle, les SES, la recherche biomédicale, la Psychologie, l'Imagerie-bioinformatique, et la Géomatique, qui sont également concernées par la question de la reproductibilité. Elle souligne que la reproductibilité des résultats scientifiques en ACV nécessite trois types de reproductibilité : 1. la reproductibilité des méthodes, 2. la reproductibilité des résultats 3. la reproductibilité des inférences. La présentation identifie des problèmes liés à l'ouverture et à la disponibilité des logiciels et des données en ACV, en citant des exemples tels que le portail de calcul PestLCI et les résultats différents entre SimaPro et OpenLCA. Elle met en avant l'importance du cycle de vie des données en ACV, qui repose fondamentalement sur la réutilisation de données, et souligne que les LCI ne sont pas toujours conformes aux normes FAIR. Elle présente également le succès story DataSusFood / PO2 TransformON comme une récompense de la FAIRIFICATION des données. La présentation propose des solutions à différents niveaux pour promouvoir la Science Ouverte et la reproductibilité. Elle encourage les individus et les équipes à publier en libre accès, à utiliser des standards de données et de métadonnées, et à mettre en place des plans de gestion de données et de logiciels. Elle souligne l'importance de la valorisation optimale du code et des logiciels, et de l'utilisation d'identifiants pour différents besoins. La présentation conclut en mettant en avant l'importance de la Science Ouverte et de l'intégrité scientifique, en soulignant l'utilité d'outils tels que PubPeer et le Problematic Paper Screener pour éviter de citer des articles rétractés. Elle fournit également des références bibliographiques pour soutenir ses arguments. En résumé, la présentation met en lumière la nécessité d'une transition vers la Science Ouverte dans la communauté de l'Analyse de Cycle de Vie pour garantir la reproductibilité des résultats scientifiques, en citant des exemples de problèmes et de solutions pour l'ouverture et la disponibilité des logiciels et des données
Structural characteristics of cocoa-based agroforestry systems can mitigate citrus Phytophthora foot rot disease intensity
No full textTropical agroforestry systems are recognized as an attractive way to reconcile productivity and ecosystem services. However, to optimize ecosystem services, existing agrosystems structure must be improved to enhance positive interactions within them. In this study, we evaluated the combined effect of shade rate and citrus tree's spatial structure in cocoa-based agroforestry systems (CBAS) on Phytophthora foot rot disease (PFRD). A set of 33 CBAS of 2500 m2 was selected in five citrus production basins in the humid rainforest zones of Cameroon. The citrus spatial structure was analyzed by the Ripley method, and static simulations, with shadow overlapping were run for each plot, using ShadeMotion software. This allowed to quantified shade rate received by citrus trees. Subsequently, citrus trees were divided into nine treatments based on the shade rate (dense shade, light shade or no shade) and their spatial structure (regular, aggregated or random) in the CBAS. PFRD intensity was quantified by measuring PFRD lesion extent relative to the citrus crown circumference. Citrus trees with a regular spatial structure, and located under dense or light shade showed low PFRD intensity. On the other hand, citrus trees with an aggregated spatial structure, regardless of their shade intensity situation, as well as those with a random spatial structure and no shade, showed high PFRD intensity compared to all other treatments. These results show that appropriate shade rate and spatial structure management in CBAS can significantly contribute to PFRD control and thus promote citrus production in complex agroforests. For the first time, it is demonstrated that optimizing the combined effect of shade rate and spatial structure of associated trees would allow the design of optimal models of resilient agroforestry systems, capable of self-regulating pests and reducing chemical pesticide use