Explore the vast range of titles available.

The circulation of seed among farmers is central to agrobiodiversity conservation and dynamics. Agrobiodiversity, the diversity of agricultural systems from genes to varieties and crop species, from farming methods to landscape composition, is part of humanity’s cultural heritage. Whereas agrobiodiversity conservation has received much attention from researchers and policy makers over the last decades, the methods available to study the role of seed exchange networks in preserving crop biodiversity have only recently begun to be considered. In this overview, we present key concepts, methods, and challenges to better understand seed exchange networks so as to improve the chances that traditional crop varieties (landraces) will be preserved and used sustainably around the world. The available literature suggests that there is insufficient knowledge about the social, cultural, and methodological dimensions of environmental change, including how seed exchange networks will cope with changes in climates, socio-economic factors, and family structures that have supported seed exchange systems to date. Methods available to study the role of seed exchange networks in the preservation and adaptation of crop specific and genetic diversity range from meta-analysis to modelling, from participatory approaches to the development of bio-indicators, from genetic to biogeographical studies, from anthropological and ethnographic research to the use of network theory. We advocate a diversity of approaches, so as to foster the creation of robust and policy-relevant knowledge. Open challenges in the study of the role of seed exchange networks in biodiversity conservation include the development of methods to (i) enhance farmers’ participation to decision-making in agro-ecosystems, (ii) integrate ex situ and in situ approaches, (iii) achieve interdisciplinary research collaboration between social and natural scientists, and (iv) use network analysis as a conceptual framework to bridge boundaries among researchers, farmers and policy makers, as well as other stakeholders.

Over the recent past, there has been a growing concern on the need for mapping cropping practices in order to improve decision-making in the agricultural sector. We developed an original method for mapping cropping practices: crop type and harvest mode, in a sugarcane landscape of western Kenya using remote sensing data. At local scale, a temporal series of 15-m resolution Landsat 8 images was obtained for Kibos sugar management zone over 20 dates (April 2013 to March 2014) to characterize cropping practices. To map the crop type and harvest mode we used ground survey and factory data over 1280 fields, digitized field boundaries, and spectral indices (the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI)) were computed for all Landsat images. The results showed NDVI classified crop type at 83.3% accuracy, while NDWI classified harvest mode at 90% accuracy. The crop map will inform better planning decisions for the sugar industry operations, while the harvest mode map will be used to plan for sensitizations forums on best management and environmental practices.

Les insectes ravageurs représentent une contrainte majeure à l’augmentation du rendement en culture cotonnière en Afrique de l’Ouest. Les filières cotonnières se sont engagées, à des degrés divers, dans des démarches de gestion intégrée des ravageurs pour réduire l’utilisation des insecticides et limiter en amont les risques sanitaires et environnementaux. Toutefois, un changement fondamental des pratiques, au bénéfice de la stimulation des services de régulation naturelle des ravageurs, s’impose pour mettre au point des systèmes de production encore plus économes en pesticides et plus résilients. Les leviers permettant de stimuler les processus écologiques de régulation naturelle des ravageurs sont multiples et redevables d’actions à différentes échelles, du champ cultivé au territoire, mais nécessitent d’approfondir notre connaissance du système de vie des ravageurs et de leurs ennemis naturels. Ils nécessitent aussi une plus grande prise en compte de la perception et des pratiques des acteurs dans une approche participative de la gestion collective des ressources et des processus d’innovation. À terme, il s’agit de construire une organisation territorialisée d’actions individuelles et collectives de gestion des ravageurs et des services écosystémiques, incluant des dimensions écologiques, économiques et sociales. Insect pests represent a major constraint to the increase of cotton yield in West Africa. The cotton value chain has been involved to varying degrees in integrated pest management approaches (IPM) to reduce the use of insecticides and to limit health and environmental risks. However, a fundamental change in farming practices, oriented toward the stimulation of natural pest control services, is needed to invent more pesticide-efficient and resilient production systems. The levers for promoting natural pest regulation are multiple and actionable at different scales from field to territory, but still require deepening our knowledge of the life system of pests and their natural enemies. They also necessitate to better take into account the perception and practices of stakeholders, in a participatory approach of the collective management of resources and processes of innovation. Ultimately, the aim is to build a territorialized organization of individual and collective actions for the management of pests and ecosystem services, including ecological, economic and social dimensions.

Description du sujet. Face aux effets attendus des aléas climatiques sur l’économie des pays d’Afrique de l’Ouest, anticiper la production agricole est devenu une priorité pour les acteurs du développement. L’article porte sur l’estimation précoce de la production cotonnière avant la récolte au Sénégal, par voie d’expertise de la SODEFITEX. Objectifs. L’étude a pour objectifs d’expliciter les connaissances mobilisées par les experts pour prédire le rendement, eu égard à l’incertitude sur les conditions climatiques à venir, et d’évaluer la performance des prévisions, selon le niveau territorial considéré. Méthode. Pour atteindre ces deux objectifs, l’article s’appuie sur l’analyse statistique de la production cotonnière au Sénégal de 2004 à 2015, combinée à une enquête réalisée auprès de 32 experts de la SODEFITEX. Résultats. L’analyse des résultats d’enquête met en évidence une prévision principalement établie sur la base de l’état des cultures, des pratiques culturales au premier rang desquelles la date de semis et, pour certains experts, de l’historique de la production et son environnement organisationnel et social. La comparaison des prévisions avec la production effective montre que les experts surestiment systématiquement les niveaux de production inférieurs à 1 000 kg·ha-1, en conditions climatiques défavorables. Conclusions. Dans un contexte de faible documentation scientifique sur l’estimation précoce de la production par voie d’expertise, les résultats de l’étude éclairent sur les connaissances mobilisées et la performance des prévisions délivrées, ouvrant ainsi la voie à une critique rationnelle de l’expertise. La diversité de points de vue mise en évidence par l’analyse multicritère, entre niveaux hiérarchiques et entre agents de même niveau, souligne le besoin de confrontation des connaissances pour faire émerger les variables explicatives nécessaires à la prévision et tendre vers une objectivité accrue de l’expertise face aux aléas climatiques récurrents. Expertise for forecasting cotton production in Western Africa: a solution to emerging climate uncertainty? Description of the subject. Climate uncertainty is expected to have a severe impact on the economy of West African countries. The use of forecasting in agricultural production has become a priority for those working in the field of development. This article focuses on the early prediction of cotton production levels before harvesting in Senegal, using expertise from the cotton development company, SODEFITEX. Objectives. This paper aims to analyze the knowledge employed to predict yield, given the uncertainty about future climate conditions, and to evaluate the quality of such predictions, depending on the territorial scale of the expertise considered. Method. The methodology used in this study was a statistical analysis of cotton production in Senegal between 2004 and 2015, combined with a survey of 32 SODEFITEX experts. Results. Analysis of the survey of experts revealed that their evaluation of the cotton production was based mainly on the state of the crops and on crop management, with the planting date being the priority. For some experts, the history of production and its organizational and social environments were also important factors. A comparison of forecasts with actual production showed that the experts had systematically overestimated the levels of production when actual yields were below 1,000 kg·ha-1, under adverse climatic conditions. Conclusions. Within a context of poor scientific documentation of the early estimation of production by experts, the results of the study shed light on the knowledge drawn upon and the performance of the forecasts delivered, thus paving the way for a rational criticism of the expertise employed. The diversity of points of view highlighted by the multi-criteria analysis, between hierarchical levels and between agents at the same level, underlines the need for a closer look at the knowledge being utilized, in order to bring out \"what matters\" in these forecasts and to move towards greater objectivity of expertise in the face of recurrent climate hazards.

Description du sujet. L’impact du changement climatique remet en cause la stratégie de diffusion variétale de la Société de Développement et des Fibres Textiles au Sénégal (SODEFITEX), basée sur la distinction de deux variétés : l’une adaptée aux conditions humides et l’autre aux risques de sècheresse. À partir de données recueillies en station expérimentale et en parcelles d’agriculteurs de 2004 à 2011, l’étude évalue la pertinence de cette stratégie. Objectifs. L’objectif de l’étude est d’évaluer la méthode de sélection variétale et la performance des variétés cultivées et à l’essai, soumises à des environnements hydriques contrastés du fait de la variabilité spatiale et temporelle de la pluviosité et des pratiques culturales. Méthode. La méthodologie développée permet d’identifier l’occurrence d’un stress hydrique sévère durant les phases critiques de floraison et de développement des capsules vis-à-vis du rendement en coton-graine et la qualité de la fibre. L’indicateur de vécu hydrique produit est ensuite introduit dans l’analyse statistique en tant que co-variable descriptive de l’environnement. Résultats. L’indicateur produit permet de discriminer les rendements en coton-graine en station expérimentale et chez les producteurs. Bien qu’un effet variétal soit constaté sur le rendement égrenage et les caractéristiques technologiques des fibres, aucune variété ne se distingue des autres vis-à-vis du vécu hydrique. Conclusions. À défaut de variété adaptée aux stress hydriques, les résultats militent en faveur de l’adoption d’une seule variété sur le bassin de production. La stratégie de diffusion des variétés mériterait toutefois d’être renouvelée pour mieux rendre compte des conditions de culture en milieu réel et permettre l’évaluation des variétés par les producteurs. Climate change and cotton production in Senegal: alternate dissemination strategies of varieties Description of the subject. Climate change challenges the strategy of varietal diffusion, employed by the Senegalese cotton company (SODEFITEX), based on the distinction of two cultivars: one adapted to humid conditions and the other to drought. Based on data collected in an experimental station and farmer plots from 2004 to 2011, the study provides an assessment of that strategy. Objectives. The aim of the study was to evaluate both the methodology used for varietal selection and the performance of released and candidate cultivars, under contrasted water environments due to variability in rainfall (spatial and temporal) and crop management. Method. The methodology used allowed the identification of the occurrence of severe water stress during the critical cotton development phases (flowering and boll development) and its effect on seed cotton yield and fiber quality. The resulting indicator of plant water status was then inserted into our statistical analysis as an environmental covariate. Results. The resulting indicator allowed the discrimination of seed cotton yield in the experimental station as well as in on-farm experiments. Despite an effect of cultivar on ginning outturn and fiber quality, all cultivars showed similar resilience to water status. Conclusions. Despite a lack of cultivar adaptation to water stress, results support the adoption of a single cultivar in the whole production basin. However, the diffusion strategy would benefit from a better consideration of farmer cropping conditions, which would thus allow for the evaluation of cultivars by the producers.

Climate change challenges the strategy of varietal diffusion, employed by the Senegalese cotton company (SODEFITEX), based on the distinction of two cultivars: one adapted to humid conditions and the other to drought. Based on data collected in an experimental station and farmer plots from 2004 to 2011, the study provides an assessment of that strategy. The aim of the study was to evaluate both the methodology used for varietal selection and the performance of released and candidate cultivars, under contrasted water environments due to variability in rainfall (spatial and temporal) and crop management. The methodology used allowed the identification of the occurrence of severe water stress during the critical cotton development phases (flowering and boll development) and its effect on seed cotton yield and fiber quality. The resulting indicator of plant water status was then inserted into our statistical analysis as an environmental covariate. The resulting indicator allowed the discrimination of seed cotton yield in the experimental station as well as in on-farm experiments. Despite an effect of cultivar on ginning outturn and fiber quality, all cultivars showed similar resilience to water status. Despite a lack of cultivar adaptation to water stress, results support the adoption of a single cultivar in the whole production basin. However, the diffusion strategy would benefit from a better consideration of farmer cropping conditions, which would thus allow for the evaluation of cultivars by the producers.

Background and Aims: Cotton shows a marked plasticity vs. density in terms of branch development and geometry, internode elongation and leaf expansion. This paper proposes interpretations for observed plasticity in terms of light quantity and quality. Methods: 3-D virtual plants were reconstructed from field observations and 3-D digitization and were used to simulate the light regime in cotton stands of different densities. Key Results: All densities showed the same linear relationship between LAI and the sum of light intercepted by the canopy, from seedling emergence up to flowering. Simulated R : FR ratio profiles can very likely explain (1) the longer first internodes on main stem and branches and (2) the azimuthal re-orientation of branches toward the inter-row. Conclusions: Simulation tools were used to analyse plant plasticity in terms of light quantity and quality. The methodology applied here at the stand scale will now be continued at the plant scale to further strengthen the above hypotheses.

Climate change challenges the strategy of varietal diffusion, employed by the Senegalese cotton company (SODEFITEX), based on the distinction of two cultivars: one adapted to humid conditions and the other to drought. Based on data collected in an experimental station and farmer plots from 2004 to 2011, the study provides an assessment of that strategy. The aim of the study was to evaluate both the methodology used for varietal selection and the performance of released and candidate cultivars, under contrasted water environments due to variability in rainfall (spatial and temporal) and crop management. The methodology used allowed the identification of the occurrence of severe water stress during the critical cotton development phases (flowering and boll development) and its effect on seed cotton yield and fiber quality. The resulting indicator of plant water status was then inserted into our statistical analysis as an environmental covariate. The resulting indicator allowed the discrimination of seed cotton yield in the experimental station as well as in on-farm experiments. Despite an effect of cultivar on ginning outturn and fiber quality, all cultivars showed similar resilience to water status. Despite a lack of cultivar adaptation to water stress, results support the adoption of a single cultivar in the whole production basin. However, the diffusion strategy would benefit from a better consideration of farmer cropping conditions, which would thus allow for the evaluation of cultivars by the producers.

Existing experimental methods based on the measurement of crop temperature to estimate water stress have been applied for 20 years. However, the application of such techniques is limited because they are not able to totally overcome either soil interference on the measured signal or directional effects involved in temperature measurements according to sun/sensor angles configuration and crop structure. An energy balance model, based on the 3D description of plants at leaf level, is used to simulate directional cotton crop temperature variability according to crop structure and water status. The model is implemented with a bare soil compartment so that soil temperature, water balance as well heat exchanges with the crop can be computed. Once validated, this approach provides an accurate interpretation of thermal infrared information considering the directional effects involved in surface temperature measurements. This offers the opportunity of analyzing the limits of using temperature-based crop water status indices when dealing with partially covering crops. This study underlines the knowledge and tools to be further investigated in order to improve or perform such experimental techniques.

The circulation of seed among farmers is central to agrobiodiversity conservation and dynamics. Agrobiodiversity, the diversity of agricultural systems from genes to varieties and crop species, from farming methods to landscape composition, is part of humanity’s cultural heritage. Whereas agrobiodiversity conservation has received much attention from researchers and policy makers over the last decades, the methods available to study the role of seed exchange networks in preserving crop biodiversity have only recently begun to be considered. In this overview, we present key concepts, methods, and challenges to better understand seed exchange networks so as to improve the chances that traditional crop varieties (landraces) will be preserved and used sustainably around the world. The available literature suggests that there is insufficient knowledge about the social, cultural, and methodological dimensions of environmental change, including how seed exchange networks will cope with changes in climates, socio-economic factors, and family structures that have supported seed exchange systems to date. Methods available to study the role of seed exchange networks in the preservation and adaptation of crop specific and genetic diversity range from meta-analysis to modelling, from participatory approaches to the development of bio-indicators, from genetic to biogeographical studies, from anthropological and ethnographic research to the use of network theory. We advocate a diversity of approaches, so as to foster the creation of robust and policy-relevant knowledge. Open challenges in the study of the role of seed exchange networks in biodiversity conservation include the development of methods to (i) enhance farmers’ participation to decision-making in agro-ecosystems, (ii) integrate ex situ and in situ approaches, (iii) achieve interdisciplinary research collaboration between social and natural scientists, and (iv) use network analysis as a conceptual framework to bridge boundaries among researchers, farmers and policy makers, as well as other stakeholders.