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La production de banane constitue un défi majeur pour la filière horticole Sénégalaise dans sa stratégie de lutte pour la sécurité alimentaire de sa population. L’objectif de cette étude est de contribuer à la valorisation de la filière banane dans le Balantacounda. L’étude a été menée dans les 05 périmètres bananier du département de Goudomp avec deux outils de collecte de données que sont le questionnaire et le guide d’entretien pour engranger le maximum d’information aux fins d’une analyse sans complaisance de la culture de banane dans le Balantacounda. Il ressort que les acteurs de la filière banane sont majoritairement des adultes soit 87,5% contre 7 % de jeunes. La filière occupe plus de 720 personnes réparties au niveau des cinq GIE dans le Goudomp. Les superficies exploitées varient de 19 à 29,9 ha avec un rendement moyen de 12,22 t /ha. La variété la plus utilisée est la Poyo avec 94,4% suivi de la Robista avec 50%. Il a été constaté un fort taux d’utilisation de fumier organique 95,6 % contre 54,4% d’Urée et 20,6 % NPK. L’autofinancement est la forme de financement la plus dominante avec 96,3% et le crédit 2,6%. La filière banane permet aux producteurs de gagner un chiffre d’affaire qui varie de 33,181 millions FCFA à 52,345 millions FCFA par an. Le taux de rentabilité (> 0) montre un dynamisme positif des GIE. Cette filière contribue fortement au développement de l’économie rurale., Journal d’Economie, de Management, d’Environnement et de Droit, Vol. 4, No 1 (2021)

L’octroi de dérogations à l’interdiction d’importation de matériels végétal susceptibles de présenter un risque d’introduction d’organismes nuisibles nécessite, selon les termes de l’article 15 de l’arrêté du 3 septembre 1990, « qu'il soit établi par un ou plusieurs des facteurs suivants qu'une propagation d'organismes nuisibles n'est pas à craindre : origine des végétaux ou produits végétaux ; traitement approprié ; mesures de précautions particulières à prendre lors de l'introduction des végétaux ou produits végétaux ». L’arrêté du 17 octobre 1995 définit ainsi les conditions d’entrée par dérogation de matériel végétal de bananiers dans les départements et régions d’outre-mer : « En application de l'article 16 de l'arrêté du 3 septembre 1990 susvisé, l'autorisation d'entrée est délivrée exclusivement pour du matériel végétal de bananiers sous forme stricte de vitroplants non réacclimatés et de " semences artificielles " à l'exclusion de toute autre plante cultivée in vivo, sous réserve que l'opération satisfasse aux exigences [de deux cahiers des charges] » :- un cahier des charges relatif aux obligations incombant aux établissements producteurs de VP de bananiers à destination de la Guadeloupe, la Guyane, la Martinique, de Mayotte et de la Réunion ;- un cahier des charges relatif aux conditions d’acclimatation de vitroplants (VP) de bananiers en Guadeloupe, en Guyane, en Martinique, à Mayotte et à la Réunion.Depuis 1995, ces cahiers des charges ont été révisés à plusieurs reprises, la dernière révision en date remontant à 2016.Bien que les problématiques des filières bananières divergent selon l’espace phytosanitaire considéré (des Antilles, de la Réunion, de la Guyane ou de Mayotte), le recours aux VP comme matériel végétal destiné à la plantation s’est généralisé en particulier pour la filière banane destinée à l’exportation. Ces cahiers des charges, qui sont en application depuis 25 ans, ont donné lieu à des applications et des pratiques parfois différentes conduisant à une gestion différenciée des risques selon les territoires.Parallèlement, les professionnels de la filière banane, qui sont confrontés aux charges croissantes des analyses, expriment des demandes d’importation de matériel végétal destiné à diversifier les sources d’approvisionnement en VP de manière à pouvoir disposer de variétés et cultivars performants et adaptés aux conditions agroenvironnementales des territoires. Par exemple, les professionnels sont demandeurs de variétés apportant des résistances à certaines maladies fortement impactantes comme la cercosporiose noire (Pseudocercospora fijiensis) qui affecte de plus en plus la qualité des fruits les rendant impropres à la commercialisation une fois arrivés dans le pays de destination ou encore la fusariose (Fusarium oxysporum fsp TR4) qui est une maladie émergente en progression préoccupante et induisant le dépérissement des bananiers.Ce contexte, allié à l’actualisation en 2020 du règlement de la santé des végétaux dans les DROM, pousse à une refonte des cahiers des charges dont le respect par les opérateurs permet d’obtenir une autorisation d’importation de VP de bananiers dans les DROM. Ceci motivait donc la sollicitation d’un avis de l’Anses dont les conclusions et recommandations pourront servir de base pour actualiser et standardiser les procédures de contrôles pratiquées aux différentes étapes du cycle de production et de commercialisation des VP, avec pour objectif premier le maintien d’un niveau satisfaisant de maîtrise des risques et avec pour objectif secondaire l’identification de solutions flexibles permettant de réduire les coûts à la charge des professionnels. Le résultat attendu doit, en aval, permettre d’apporter aux services en charge de l’application des cahiers des charges les moyens adaptés aux situations leur permettant d’assurant la maitrise des risques.L’Anses est saisie afin d’apporter son avis sur les points suivants :« Comment faire évoluer les deux cahiers des charges tout en prenant en compte les évolutions réglementaires, en harmonisant les pratiques entre les différents espaces phytosanitaires d’Outre-mer (EPOM) et en maintenant un niveau de sécurité sanitaire satisfaisant ?Plus précisément, cette saisine devra apporter les précisions suivantes :- la liste des organismes nuisibles (ON) à contrôler aux différentes étapes des dispositifs mis en œuvre dans les établissements producteurs et acclimateurs de VP et aboutissant à la production des plants destinés à la plantation issus de VP ;- les stratégies de contrôle et de suivi à adopter en fonction des risques, en prenant en compte le contrôle de la qualité sanitaire de l’eau d’irrigation ;- la liste des matériels végétaux pouvant être autorisés en fournissant les outils utiles à la prise de décision en fonction de la carte d’identité des plantes mères (origine géographique, nature génétique, et tout autre élément susceptible d’aider à la prise de décision, en particulier les conditions de culture des pieds-mères et la connaissance de leur environnement). »

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The burrowing nematode Radopholus similis and the lesion nematodes Pratylenchus spp. are considered as major constraints to banana cultivation worldwide. As an alternative to the use of chemical pesticides in commercial banana plantations, the possible role of the earthworm Pontoscolex corethrurus was studied regarding the reducing harmfulness of the main plant-feeding nematodes of banana. The interactions among banana plants, plant-feeding nematodes and earthworms have been tested in a controlled experiment combining treatments including or not earthworms and nematodes, over a complete vegetative banana development cycle. The aim of the work was to evaluate how earthworm activity can affect the pathogenicity of the three main plant-feeding nematodes associated with dessert banana (Musa spp. AAA group, cv. Cavendish) in Guadeloupe (French West Indies), R. similis, Pratylenchus coffeae and Helicotylenchus multicinctus. Results showed that damages caused by plant-feeding nematodes were lowered in the presence of the earthworm P. corethrurus; the population of plant-feeding nematodes did not decrease whereas root damage induced by nematodes was significantly reduced (50% reduction of root necrosis in the presence of earthworms). Moreover, in the presence of P. corethrurus, we observed a change of soil porosity. On the one hand, the burrowing activity of earthworms destroyed most of the initial structural porosity (mesobiotic pores, 3–300 _m) and on the other hand, they increased the volume of the finest structural pores diameter class (microbiotic pores, 0.3–3 _m). P. corethrurus also stimulated phosphorus mineralization. Soil bioturbation carried out by P. corethrurus could have enhanced the efficiency of microbial community that is involved in phosphorus bioavailability. This observation was corroborated by a higher phosphorus availability in earthworm casts (1386 ± 38 mg P kg−1 of dry matter in cast versus 778 ± 61 mg P kg−1 of dry matter in the soil compartment not influenced by earthworm activity), and a better plant phosphorus nutrition in the presence of earthworms. Phosphorus uptake resulted in a better plant nutrition and a better tolerance to plant-feeding nematodes. Besides, the reduction of the mesobiotic porosity by bioturbation could also have disturbed the nematodes activities during their soil phase and contributed to the reduction of their damage.

Increased plant diversity may alter soil food web structure and soil function in agroecosystems. This thesis sets the basis for an experimental approach in order to select some plant species in regard to several functional traits and to assess their effect on soil food web and soil functioning. We focused on cover-crops able to induce regulation of the banana parasitic nematodes Radopholus similis and Pratylenchus coffeae and to promote decomposition of organic matter during the fallow period in banana plantations in the French West Indies (FWI). We used functional analysis of nematode communities as a soil food web bio-indicator. Bibliography studies show us that “plant host status” with respect to plant-parasitic nematodes, “biochemical characteristics of litters” and “primary productivity of plants” are functional traits involved in plant species effects on soil food web and on the ecosystemics service we targeted. We therefore use those traits to perform a typology of cover-plants. Furthermore, to study the effects of litter inputs with contrasted biochemical characteristics we pick out the plant species Paspalum notatum, Crotalaria zanzibarica and Acacia auriculiformis which show differential hemicellulose, cellulose, lignin and nitrogen content. A microcosm assay shows that biochemical characteristics of litter determine ecological successions in nematode communities and promote, in a contrasted manner, the decomposition pathway of organic matter. We discussed the mechanisms of plant parasitic nematodes suppression involved by those litter inputs. We also confirm that the culture of those three plant species can diminish the population of R.similis in soils. We also assessed the effects of plant covers composed of P. notatum and C. zanzibarica and a mix of those two plant species on nematodes communities during a field trial. In order to do so, we cultivated those cover-plants during a nine months period and then destroyed them to restitute plant litter in soils surface. Our results showed that cover-plant alters differentially plant-parasitic nematodes and the infectious potential of soils. Cover-crop cultivation also induced bottom-up and top-down regulations in plant parasitic nematode communities. After litter restitution, we observed high abundance of nematodes involved in litter decomposition within the soil surface layer. The latter provides underlying soil layers with mineral nitrogen and improves omnivore and predator nematode abundances. It results in the formation of a structured and diversified nematode community concomitantly with R. similis and P. coffeae regulation in soils. We observed greater effects with the cover-crop composed of C. zanzibarica and the mix of C. zanzibarica and P. coffeae. This study confirms that the functional traits of “host status”, “biochemical composition of litter” and “primary production” of plant species are decisive in the selection of cover-crop for the fallow period in banana plantation.; L’introduction de biodiversité végétale dans les agroécosystèmes peut modifier la structure des réseaux trophiques du sol et les fonctions écosystémiques qu’ils assurent. Cette thèse fixe les bases d’une démarche expérimentale pour sélectionner des espèces végétales à partir de différents traits fonctionnels et pour évaluer leurs effets sur les réseaux trophiques et le fonctionnement des sols. Nous avons plus particulièrement cherché à sélectionner des plantes de services pouvant induire la régulation des nématodes parasites du bananier Radopholus similis et Pratylenchus coffeae et favoriser la décomposition des matières organiques durant l’interculture dans les bananeraies antillaises. C'est-à-dire la période entre la destruction de la bananeraie et l'implantation d'une nouvelle. Au cours de ce travail, les réseaux trophiques du sol ont été appréhendés par une analyse fonctionnelle des communautés de nématodes. Une étude bibliographique nous a permis de montrer que les traits fonctionnels « statut d’hôtes » vis-à-vis des nématodes phytoparasites, « composition biochimique des litières » et « productivité primaire des espèces végétales » contribuent aux effets des plantes sur les réseaux trophiques du sol et sur les deux services écosystémiques étudiés. Nous avons donc effectué une typologie des plantes de services à partir de ces traits. Puis pour étudier les effets d’apports de litières de composition biochimique contrastée sur les communautés de nématodes du sol, nous avons sélectionné les espèces végétales Paspalum notatum, Crotalaria zanzibarica et Acacia auriculiformis dont les litières présentaient des teneurs variables en hémicellulose, cellulose, azote, et lignine. Une étude en microcosmes a montré que la composition biochimique des litières détermine les successions écologiques au sein des communautés de nématodes et stimule de manière contrastée les voies de décomposition de la matière organique dans les sols. Nous avons discuté des mécanismes de régulation des nématodes parasites du bananier induits par ces apports de litières. Nous avons également montré que la culture de ces trois espèces induit une diminution des populations de R. similis dans les sols. Enfin, nous avons évalué les effets au champ de couverts de P. notatum, de C. zanzibarica et d’un couvert associant ces deux espèces. Pour cela, nous avons cultivé ces couverts durant neuf mois avant de les détruire et de restituer leurs litières à la surface des sols. Nos résultats montrent que ces couverts végétaux influencent différemment l’abondance en nématodes phytoparasites et le potentiel infectieux du sol. Ils induisent également des régulations bottum-up et top down dans leurs communautés. Après la restitution des litières, nous avons observé de fortes abondances de nématodes liées à la décomposition des litières dans la couche de surface du sol. Celle-ci fournit les couches sous-jacentes du sol en azote minéral et favorise le développement des nématodes omnivores et prédateurs. Il en résulte la formation de communautés de nématodes structurées et diversifiées concomitantes à la réduction des populations de R. similis et P. coffeae. Ces résultats étaient plus marqués pour les couverts monospécifiques de C. zanzibarica et les couverts mixtes. Nos travaux confirment que les traits fonctionnels « statut d’hôte », « production primaire », « composition biochimique des litières » sont déterminant pour sélectionner des plantes de services pour l’interculture en bananeraies.

International audience; The study of movements of individual organisms in heterogeneous environments is of primary importance for understanding the effect of habitat composition on population patterns. We developed a new experimental methodology to measure individual movements of walking insects, based on radiotracking. Our aims were to understand the link between habitat heterogeneity and moving patterns, and to characterize the movements with dynamic models of diffusion. We tracked individual movements of adults of Cosmopolites sordidus (Coleoptera: Curculionidae) with passive radio frequency identification (RFID) tags under different field management practices. Diffusion models based on recapture data indicated a subdiffusive movement of this species. Substantial variation was found between individual paths, but this variation was not sex dependent. Movement of released C. sordidus was affected by banana planting pattern and the presence/absence of crop residues but not by the presence of a cover crop between rows of bananas or by banana variety. These results show that the RFID technology is useful for evaluating the dispersal parameters of cryptic insects in heterogeneous environments.

International audience; Farmers are inundated with advertisements about many innovations that are supposed to increase their yields or reduce environmental impact. However, the benefit of these innovations depends on the farming context. Here we present the ad hoc adaptation of the crop model SIMBA and a method to evaluate 16 innovations in six types of farms previously selected through a typology of the banana farming systems in Guadeloupe. The innovations include regulation of pesticide use, rotations and fallows, intercropping, conditional application of pesticides, resistant cultivars, and integrated systems. Our results show that, for a given innovation, the yield and pesticide reduction vary widely with different farm types. We show that environmentally friendly innovations often cause a greater decrease in yield in more productive farm types. Nevertheless, despite an apparent trade-off between yield and pesticide use, some innovations address both production and environmental issues, e.g., rotation with fallows improved with cover crops, regular fallows, and rotations with pineapples for the most intensive farm types. Our modelling study confirms the importance of innovation-farm type interactions and the usefulness of models for assessing large numbers of technological innovations among a wide range of biophysical and technical contexts.

Correspondance: pietro.piffanelli@tecnoparco.org; International audience; Introduction. This protocol applies to the characterization of genome structure and evolution of M. acuminata and M. balbisiana genomes; construction of physical maps around markers of interest and QTLs; comparative genomic studies with other monocot species; and study of banana streak virus (BSV) integration patterns in banana nuclear genomes. The principle, key advantages, starting plant material, time required and expected results are presented. Materials and methods. This part describes the required materials, and the protocols for isolation and lysis of banana nuclei; high-molecular-weight (HMW) DNA Hind III digestion and pulsed-field gel electrophoresis (PFGE) analysis; large-scale HMW DNA Hind III digestion and ligation to the pINDIGOBAC–5 vector; and analysis of recombinant BAC clones. It mentions the main problems which can occur. Results. The described protocols will enable the efficient construction of BAC libraries from Musa species. These libraries can be used to construct physical maps and select specific genomic regions to be sequenced.; Introduction. Le protocole s'applique à la caractérisation de la structure du génome et à l'évolution des génomes de M. acuminata et de M. balbisiana ; à la construction de cartes physiques autour des marqueurs d'intérêt et des QTLs ; aux études de génomique comparative avec d'autre espèce de monocotylédones ; à l’étude des modèles d'intégration du virus BSV dans les génomes nucléaires de la banane. Le principe, les principaux avantages, le matériel végétal utilisé, le temps nécessaire et les résultats attendus sont présentés. Matériel et méthodes. Cette partie décrit le matériel de laboratoire nécessaire, et les protocoles permettant l'isolement et la lyse des noyaux de cellules de bananier ; la digestion Hind III de ADN à haut poids moléculaire (HPM) et l’analyse électrophorèse sur gels à champ pulsé ; la digestion Hind III à grande échelle de ADN à HPM et ligation au vecteur pINDIGOBAC-5 ; l’analyse des clones recombinants de BAC. Elle mentionne les principaux problèmes pouvant se poser. Résultats. Les protocoles présentés permettent de construire des bibliothèques de BAC à partir d'espèces du genre Musa. Ces bibliothèques peuvent être utilisées pour construire des cartes physiques et sélectionner des régions du génome à séquencer.

Correspondance: tixier@cirad.fr; International audience; Banana monocultures (Musa spp., AAA, Cavendish sub-group cv. Grande Naine) can have a detrimental impact on the environment. In these agro-systems, pesticide treatments can lead to surface and groundwater pollution, as is the case in the tropical insular conditions of the French West Indies. Using models to design alternative cropping systems is of growing interest but most of the research work has been concentrated on annual crops and most often in temperate climate. A specific model called SIMBA was built to assess environmental risks under a large range of cropping techniques and to help design more sustainable cropping systems. SIMBA simulates banana-cropping systems at field level over several cropping cycles. It includes sub-models that simulate soil structure, water balance, root nematode populations, yield, and economic outputs with a sound balance between representing the major phenomena well and keeping the model simple to reduce the parameterization costs in a large range of conditions. Agro-environmental indicators generated by the model make it possible to assess the major potential environmental impacts. The model has been developed and calibrated in Guadeloupe and Martinique and is used to draw up practical recommendations for farmers and for virtual experiments of agro-technological innovations or field management strategies. The structure of SIMBA is presented and a methodology is proposed for designing sustainable banana-based cropping systems using the model. SIMBA has been evaluated in a broad range of cropping systems in Guadeloupe by comparing model estimates to data collected in field experiments and surveys. Simulations lead to trends in rotation-based cropping systems characterized by systems that can be considered as intensive for profit evaluation, and combinations of frequent replanting, low nematicide application, no ploughing, and low fertilization level, for environmental evaluation. Simulations performed to optimize the replanting decision rule showed that relatively frequent replanting is good for profit while low frequency replantations (over four banana cycles) give a better environmental evaluation

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Radopholus similis is a worldwide endoparasitic nematode that greatly hampers banana (Musa acuminata, Cavendish subgroup) productivity. Earthworms are known to closely interact with above-ground and under-ground soil biota and particularly with plants and microfaunal communities. This study was aimed at investigating, under greenhouse conditions, the effects of the earthworm Pontoscolex corethrurus on banana growth and nutrient uptake, and assessing the influences of this earthworm on the development of an inoculated population of R. similis. Six-week-old tissue culture banana plants were submitted to four treatments: with P. corethrurus, R. similis, P. corethrurus+R. similis, and a control with no earthworms or nematodes. At the end of the experiment, the P. corethrurus treatments showed significantly higher leaf surface areas, shoot dry root weights, and root fresh weights than those without earthworms. This root growth enhancement probably contributed to the evident but non-significant decrease in the density of nematodes in the roots, even though earthworms did not reduce the total number of nematodes per whole root system. Moreover, the presence of earthworms slightly alleviated the severity of root damage. N bioavailability in the soil, along with N, Ca, and Mg content of banana plants, were also significantly increased in the presence of earthworms. Our results demonstrated that banana plant growth and nutrition were positively influenced by earthworms. Cropping practices that boost the development of earthworm communities in soil should therefore be promoted to enhance sustainability and to naturally alleviate nematode impact.

E-mail Addresses: tixier@cirad.fr, dorel@cirad.fr, malezieux@cirad.fr; International audience; The harvest dynamic model (SIMBA-POP) was used to choose the best planting date of a banana field in order to optimise the gross income. The proposed method takes into account the seasonal variation of the selling price of bananas. The gross income was calculated weekly by multiplying the simulated number of bunches harvested weekly by the mean weight of bunches, and by the current selling price. The weekly gross income over the simulated period was then determined. The Study was carried out in Martinique (French West Indies) for climatic conditions corresponding to 50, 350, and 650 m in altitude and for different field management strategies (number of cropping cycles before replanting). The result of our simulations showed that the optimal planting month enables a 10-36% increase in income over the worst month

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; One of the most serious diseases of banana is fusarium wilt, caused by Fusarium oxysporum f.sp. cubense (Foc). The objectives of this study were to isolate and identify nonpathogenic F. oxysporum strains from soils suppressive to banana wilt, and to determine the diversity of these isolates. More than 100 Fusarium strains were isolated from the rhizosphere of banana plants and identified to species level. Pathogenicity testing was carried out to confirm that these isolates were nonpathogens of banana. A PCR-based RFLP analysis of the intergenic spacer region of the ribosomal RNA operon was used to characterize the nonpathogens. The isolates were also compared with isolates of Foc from South Africa and the known biological control isolate of F. oxysporum, Fo47. The species-specific primers FOF1 and FOR1, in addition to morphological features, were used to confirm the identity of F. oxysporum isolates included in the PCR-RFLP analysis. Twelve different genotypes could be distinguished, identified by a six-letter code allocated to each isolate following digestion with the restriction enzymes HaeIII, HhaI, HinfI, MspI, RsaI and ScrfI. Eleven of these included nonpathogenic F. oxysporum isolates, and these groups could all be distinguished from the genotype that included Foc. Fo47 was included in one of the genotype groups consisting of nonpathogenic F. oxysporum isolates from South Africa.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; On the volcanic soils of the uplands of the French West Indies, banana monocropping has been practised since about 1980, mostly with large inputs of chemicals and replanting every three to five years after ploughing. However, in Guadeloupe less intensive cropping systems with only few added chemicals are still being used. The effects of the intensive practices on the physical, chemical and biological attributes of soils were evaluated on 34 farmed fields, which were selected to include the diverse soils and management practices found in the uplands of South Basse-Terre. Management was classified into four groups to differentiate effects of fertilizers, nematicides and tillage over at least 10 years. The population of the parasitic nematode Radopholus similis was, on average, greater 3 months after the application of nematicides. Thus, the use of nematicides increases the dependency of yield on nematicides. Ploughing decreased soil organic matter in the 0–10 cm layer as well as microbial respiration and earthworm biomass, but increased banana root infestation by R. similis. Ploughing was also associated with a change in soil structure, as revealed by the decrease in soil water content at −1 kPa potential and the increased infiltration rate of water into the 0–10 cm layer. The use of fertilizers has advantages for the maintenance or increase of soil reserves of K. However, due to the decreasing of negative electrical charges in the lower layers of andosols, where pH remains low, the majority of the cations supplied by fertilizers, mainly potassium, are prone to leaching.

International audience; Rainfall interception and water transfers within canopies depend on plant architecture. Banana plants generate considerable stemflow and throughfall at some dripping locations that may induce agrochemical leaching. The DROP model developed to simulate rainfall interception and distribution by plants using 3-D digitised data was adapted to complex banana leaf shapes. We evaluated the model by comparing measured and simulated leaf area and tested the model sensitivity to architectural data errors for the estimation of important interception parameters. Our results showed that the model appropriately described the plant leaf area even for torn leaves. The errors due to the digitiser accuracy did not significantly affect the estimation of leaf area and rainfall interception parameters. The number of dripping points and their watershed area were significantly affected by a reduction in the number of digitised points used for the leaf description. Inclined leaf simulation required a lower point density than for horizontal leaves, and large leaf simulation required a lower point density than for small leaves.

Tropical crops of great economic importance such as banana are known to benefit from mycorrhizal association. Development and survival of introduced mycorrhizal propagules depend not only on the crops but mainly on the edaphic conditions and soil types where the symbiosis is established. Seven soils from banana fields of Martinique were sampled and tested to determine their receptiveness to mycorrhizal inoculation. Biological tests involved cultivation of 10 leek plantlets in pots containing soil inoculated with a range of mycorrhizal propagule densities (3, 10, 30, 100, 300 propagules/100 g soil). Mycorrhizal colonisation was recorded after 2 weeks of growth and tentatively correlated with inoculum density. For each soil regression equations enable determination of the number of propagules needed to induce mycorrhizal colonisation of 50% of the leek plantlets. This measurement unit parameter value was called ‘the mycorrhizal soil receptiveness 50 (MSR50) unit’. Values recorded varied from 22.7 (for Fafane, Enterrement, Parc a veaux soils) to 96.7 propagules/100 g (for the Morne-vidou soil). Soil receptiveness tended to decrease when the number of propagules increased. Multiple regression tests between MSR50 unit values and soil parameters (pH, P, Cu, Zn, CEC, N) permitted development of mathematical equations enabling prediction of mycorrhizal soil receptiveness. © 2000 Elsevier Science B.V. All rights reserved.

Three Pseudomonas fluorescens strains and the type strain Pseudomonas putida CFBP2066 inhibited invasion of the plant-parasitic nematodes Radopholus similis and Meloidogyne spp. in banana, maize and tomato roots. Results were, however, not always significantly different from controls. One Ps. fluorescens strain kept R. similis numbers significantly lower in banana roots after the initial invasion stage. All strains also showed an in vitro repellent effect towards the nematodes, with Meloidogyne spp. being more affected than R. similis. As Ps. putida CFBP2066 was negative for the enzymatic activities tested as well as HCN productivity, it was concluded that either other chemical bacterial compounds affected nematode infectivity or strains elicited induced systemic resistance in plants.

We compare the effects of minimum and conventional tillage on banana growth, under irrigated and rain-fed conditions. Measurements of leaf growth, root length density and soil water depletion were made. We used a crop simulation model to understand and explain the differential behavior of banana plants in the experiments. Our approach consisted of (i) an adaptation of the STICS model, initially developed for temperate crops, to the banana crop grown under tropical conditions and (ii) use of the integrative ability of the model to identify the respective roles of irrigation and tillage. The adaptation of the model concerned the phasic development, and leaf and root growth. Some specific characteristics of the tropical environment were also introduced. The model points out that under irrigated conditions crop water requirements were always satisfied whatever the tillage depth. In that case, the difference in terms of leaf growth and yield between shallow and deep tillage treatments can be explained by the nitrogen deficit due to a poor root system. Rain-fed crops suffered from water shortage, but the increase in soil exploration, allowed by conventional tillage, compensated for the absence of irrigation. This work improves knowledge of the agro-physiology of the banana crop. It demonstrates the fundamental part played by the root system, which appears as an important limiting factor for a correct water and nutrient supply. It provides an opportunity to elaborate a global model for the banana crop. (Resume d'auteur)

The black leaf streak disease (MNR) , caused by the ascomycete fungus Mycosphaerella fijiensis , is one of the most devastating diseases banana ( Musa spp.) . It is a major constraint to production , particularly in countries of the humid tropics where banana is a staple food crop . The objective of this thesis was to characterize the M. fijiensis populations and to study the epidemiology of the MNR in region of Kisangani (DRC) to evaluate protection strategies integrated to develop in crops of bananas and plantains . The particularity of our approach lies in the combination of studies laboratory , according to classical and molecular approaches , and field experiments to better understand the characteristics epidemiology of the disease according to the seasons and cropping systems . Phenotypic characteristics of strains isolated from Kisangani on PDA medium were typical of the species M. fijiensis . This identification was confirmed by an approach based on the molecular sequence of a part of the ribosomal DNA ITS regions including ( internal transcribed spacers ) and 5.8 gene S. The existence of two types of cross -1 and Mat1 Ma1 -2 in the population has been disclosed but an imbalance between the two euhedral was noticed . The evaluation of the pathogenicity of strains showed that all strains tested pathogenicity vis-à -vis the Cavendish cultivar ' Grand Nain '. Our study also to highlight the differences in virulence between strains . Tests sensitivity to fungicides showed that strains of the DRC sensitive to triazoles and carbendazim , but some strains are resistant to azoxystrobin . Epidemiologically , our study showed that the two forms fungal (anamorph and teleomorph ) are present not only in rainy season but also subsèche season . They therefore play a important role in the epidemiology of the disease. The incidence of the disease was slightly lower seasonal subsèche in wet season. a comparison of disease progression in both seasons by culture system revealed that the development of the MNR was more slow secondary forest in fallow and garden box and the incidence and severity was greater on plantains on bananas. the better tolerance cultivar Yangambi Km5 was confirmed. These findings shed new light on the epidemiology of disease in the region of Kisangani and the characteristics of the population involved. They have been exploited to develop a list of recommendations to better manage the damage of M. fijiensis , a significant pathogen evolutionary potential . Google Traduction pour les entreprises :Google Kit du traducteurGadget, La maladie des raies noires (MRN), causée par le champignon ascomycète Mycosphaerella fijiensis, est l'une des maladies les plus dévastatrices du bananier (Musa spp.). Elle constitue une contrainte majeure à sa production, particulièrement dans les pays des tropiques humides où le bananier est une culture alimentaire de base. L'objectif de cette thèse a été de caractériser les populations de M. fijiensis et d'étudier l'épidémiologie de la MRN dans la région de Kisangani (RDC) en vue d'évaluer les stratégies de protection intégrée à développer dans les cultures de bananiers et bananiers plantains. La particularité de notre approche réside en la combinaison d'études en laboratoire, selon des approches classique et moléculaire, et des expérimentations sur le terrain pour mieux connaître les caractéristiques épidémiologiques de la maladie selon les saisons et les systèmes de cultures. Les caractéristiques phénotypiques des souches isolées de Kisangani sur milieu PDA étaient typiques de l'espèce M. fijiensis. Cette identification a été confirmée selon une approche moléculaire sur base du séquençage d'une partie de l'ADN ribosomal incluant les régions ITS (internal transcribed spacers) et le gène 5,8S. L'existence des deux types de croisement Mat1-1 et Ma1-2 au sein de la population a été révélée mais un déséquilibre entre les deux idiomorphes a été remarqué. L'évaluation de la pathogénicité des souches a montré que toutes les souches testées ont un pouvoir pathogène vis-à-vis du cultivar Cavendish " Grande Naine ". Notre étude a aussi permis de ressortir des différences de virulence selon les souches. Les tests de sensibilité aux fongicides ont montré que les souches de la RDC sont sensibles aux triazoles et au carbendazime, mais certaines souches seraient résistantes à l'azoxystrobine. Sur le plan épidémiologique, notre étude a révélé que les deux formes fongiques (anamorphe et téléomorphe) sont présentes non seulement en saison des pluies mais également en saison subsèche. Elles jouent donc un rôle important dans l'épidémiologie de la maladie. L'incidence de la maladie 6 Résumé a été légèrement moindre en saison subsèche qu'en saison humide. Une comparaison de la progression de la maladie pendant les deux saisons selon le système de culture a révélé que le développement de la MRN a été plus lent en forêt secondaire qu'en jachère et en jardin de case et l'incidence et la sévérité ont été plus grandes sur les plantains que sur les bananes. La meilleure tolérance du cultivar Yangambi Km5 a été confirmée. Ces résultats ont apporté des éléments nouveaux sur l'épidémiologie de la maladie dans la région de Kisangani et sur les caractéristiques de la population en présence. Ils ont été exploités pour établir une liste de recommandations visant à mieux gérer les dégâts de M. fijiensis, un pathogène au potentiel évolutif important.

La maladie des raies noires (MRN), causée par le champignon ascomycète Mycosphaerella fijiensis, est l’une des maladies les plus dévastatrices du bananier (Musa spp.). Elle constitue une contrainte majeure à sa production, particulièrement dans les pays des tropiques humides où le bananier est une culture alimentaire de base. L’objectif de cette thèse a été de caractériser les populations de M. fijiensis et d’étudier l’épidémiologie de la MRN dans la région de Kisangani (RDC) en vue d’évaluer les stratégies de protection intégrée à développer dans les cultures de bananiers et bananiers plantains. La particularité de notre approche réside en la combinaison d’études en laboratoire, selon des approches classique et moléculaire, et des expérimentations sur le terrain pour mieux connaître les caractéristiques épidémiologiques de la maladie selon les saisons et les systèmes de cultures. Les caractéristiques phénotypiques des souches isolées de Kisangani sur milieu PDA étaient typiques de l’espèce M. fijiensis. Cette identification a été confirmée selon une approche moléculaire sur base du séquençage d’une partie de l’ADN ribosomal incluant les régions ITS (internal transcribed spacers) et le gène 5,8S. L’existence des deux types de croisement Mat1-1 et Ma1-2 au sein de la population a été révélée mais un déséquilibre entre les deux idiomorphes a été remarqué. L’évaluation de la pathogénicité des souches a montré que toutes les souches testées ont un pouvoir pathogène vis-à-vis du cultivar Cavendish « Grande Naine ». Notre étude a aussi permis de ressortir des différences de virulence selon les souches. Les tests de sensibilité aux fongicides ont montré que les souches de la RDC sont sensibles aux triazoles et au carbendazime, mais certaines souches seraient résistantes à l’azoxystrobine. Sur le plan épidémiologique, notre étude a révélé que les deux formes fongiques (anamorphe et téléomorphe) sont présentes non seulement en saison des pluies mais également en saison subsèche. Elles jouent donc un rôle important dans l’épidémiologie de la maladie. L’incidence de la maladie a été légèrement moindre en saison subsèche qu’en saison humide. Une comparaison de la progression de la maladie pendant les deux saisons selon le système de culture a révélé que le développement de la MRN a été plus lent en forêt secondaire qu’en jachère et en jardin de case et l’incidence et la sévérité ont été plus grandes sur les plantains que sur les bananes. La meilleure tolérance du cultivar Yangambi Km5 a été confirmée. Ces résultats ont apporté des éléments nouveaux sur l’épidémiologie de la maladie dans la région de Kisangani et sur les caractéristiques de la population en présence. Ils ont été exploités pour établir une liste de recommandations visant à mieux gérer les dégâts de M. fijiensis, un pathogène au potentiel évolutif important. (AGRO 3) -- UCL, 2013

Les cercosporioses du bananier dues à Mycosphaerella fijiensis (agent de la maladie des raies noires (MRN) ou cercosporiose noire) et M. musicola (agent de la maladie de Sigatoka (MS) ou cercosporiose jaune) sont considérées comme les maladies foliaires les plus graves pour les productions bananières. Ces pathogènes sont présents dans la majorité des zones de cultures bananières intertropicales. Le contrôle de ces maladies indispensable pour l'exportation des fruits, consiste actuellement en des applications fréquentes de fongicides par voie aérienne, méthode néfaste pour l'environnement. Un modèle de simulation des cercosporioses a été conçu pour approfondir les connaissances du pathosystème et tester de nouvelles méthodes de lutte, en particulier l'utilisation de variétés résistantes. Un modèle mécaniste de simulation des cercosporioses en temps discret est en cours de développement. Il décrit, sans spatialisation et en conditions climatiques optimales, le développement de la maladie sur un bananier représentatif d'une parcelle pendant un cycle de culture. Ce modèle permettra d'évaluer l'efficacité de différentes composantes de résistance partielle dans le contrôle des cercosporioses et d'étudier la compétition entre les 2 espèces fongiques en cas d'invasion de la MRN (contexte parasitaire actuel en Martinique). Il se décompose en deux sous-modèles, le premier simulant la croissance du bananier, le second simulant la propagation de l'épidémie. Le sous modèle " croissance de la plante " est appréhendé de manière déterministe alors que le sous modèle " propagation de la maladie " est lui stochastique. Ce dernier décrit le fonctionnement du pathogène sur son hôte: contamination, reproduction asexuée (production de conidies), rencontre de lésions, reproduction sexuée (production d'ascospores), dispersion des spores. Les données disponibles pour calibrer le modèle ont été recueillies au Cameroun (MRN) et aux Antilles (MRN et MS) en conditions naturelles d'infestation et en conditions contrôlées (croissance des lésions, nombre de spores émises par lésion). L'estimation des paramètres de ce second sous-modèle a été réalisée dans un cadre Bayésien par le biais de techniques MCMC (Markov Chain of Monte Carlo). On obtient alors une distribution à posteriori de l'ensemble des paramètres du modèle ainsi qu'une distribution a postériori de la variance résiduelle. L'inférence des paramètres et les résultats des premières simulations seront présentés et discutés.

Banana (Musa sp.) residues contain two thirds of the plant nitrogen (N) content at harvest which may represent a large N source for the daughter plant and contribute to reducing fertilizer rates. Our aim was to assess the decomposition kinetics of above- and below-ground banana residues, and to determine the uptake of the released N by the daughter plant. Residue decomposition was analyzed under laboratory and field conditions, and plant N uptake was evaluated in the field using 15N-labelled above-ground residues. The decomposition kinetics was interpreted with a simulation model. In the laboratory, residue decomposition showed an immobilization phase followed by remineralization. The immobilization phase was longer and remineralization was smaller for roots due to their higher C:N ratio and lignin content. The model satisfactorily described both phases and the effect of the residue C:N ratio. Experimental and model results indicated that root residues would be a minor N source for the daughter plant. In the field, above-ground residues decomposed according to first order kinetics. Residue half-life was 2 d in the laboratory and 32 d in the field, which was due to poorer soil–residue contact in the field. At the time of harvest of the daughter plant, 39% of residue N was recovered in the plant, 54% in the topsoil, and 3% in the remaining residues. About 4% of residue N was probably lost by leaching. Nitrogen derived from residues represented 19% (14 kg N ha−1) of N in bunches of the daughter plant and 18% (39 kg ha−1) of the whole plant N. Our study showed that above-ground residue N was an effective N source for the daughter plant, with a good overlap between the period of N release and that of greatest plant demand which reduced the risk of N leaching.

Contact: fabrice.vinatier@grignon.inra.fr Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The development of alternative pest-control strategies based on the spatial design of cropping systems requires a thorough understanding of the spatial links between the pest and its environment. Mechanistic models, especially individual-based models (IBMs), are powerful tools for integrating key behaviours, such as habitat selection and dispersal, with spatial heterogeneity. In this paper, we used an IBM calibrated and evaluated from real data to represent the spatial dynamics of the banana weevil in relation to the cropping system. We considered crop fragmentation and mass trapping as tools for suppressing pest numbers. Our simulation results showed that manipulating crop residues in the area surrounding each pheromone trap greatly improved trap efficiency. For an intensive banana plantation in fallow, traps were most effective when situated at the transition zone between banana area and fallow so as to maximize the trapping of weevils escaping the fallow. The model also showed that weevil numbers decreased when fragmentation of banana plantations was reduced.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Free and glycoconjugated volatile composition of three bananas from cultivars of Musa sp. grown in the French West Indies (FWI): Cavendish, Frayssinette and Plantain were investigated. They were extracted from the pulp of bananas thanks to an accelerated solvent extraction method for the free volatile compounds. Glycosides were isolated from aqueous extracts then aglycons were obtained after enzymatic hydrolysis of glycosidic extracts. Free volatile compounds and aglycons were analysed by GC–MS. The main volatile compounds found in Cavendish banana were (E)-2-hexenal and acetoin, in Plantain: (E)-2-hexenal and hexanal, and in Frayssinette: 2,3-butanediol and two diastereomer solerols. The most abundant of aglycons were 3-methyl-butanol, 3-methyl-butanoic acid, solerol (two disatereoisomers) and acetovanillone. This compound, rarely identified in fruits, is detected for the first time in glycocon-jugated volatile compounds of fruits. The abundance of these two isomers in the extracts of Frayssinette seemed to be characteristic of this variety of banana.

En Guadeloupe et en Martinique, la production bananière doit relever le défi de mieux conjuguer performances économiques et environnementales. Alors que différentes innovations agro-écologiques sont en cours de développement, nous avons évalué un panel d’innovations et leurs conditions d’adoption dans différents types d’exploitation. Les enquêtes de terrain et les simulations réalisées montrent que les petites exploitations familiales de plaine devraient s’orienter vers l’introduction d’une culture d’ananas ou de la plante de service Brachiaria decumbens. Néanmoins certains freins liés aux faibles surfaces couplées à des contraintes de trésorerie peuvent limiter les adoptions. Pour lever ces contraintes, nous proposons la mise en place de dispositifs de soutien économique à la conversion. D’une manière générale les systèmes innovants étudiés amènent à une substitution des pesticides par du travail. Dans le cas des cultures associées cette substitution se fait généralement au détriment du revenu des planteurs. En zone de montagne, les pratiques de jachère spontanée et d’implantation de cultures intercalaires comme Canavalia ensiformis ou Impatiens sp semblent les plus indiquées. Pour les grandes exploitations, dont les performances économiques et environnementales sont déjà relativement élevées, le système de culture à base de Brachiaria decumbens semble le plus prometteur., In Guadeloupe and Martinique, banana production is challenged to better combine economic and environmental performance. While different agro-ecological innovations are being developed, we evaluated a range of innovations and their conditions of adoption in different types of farm. Field surveys and simulations show that small family farms should rotate bananas fields with a culture of pineapple or a service crop like Brachiaria decumbens. Nevertheless, some obstacles related to small areas coupled with liquidity constraints may limit adoptions. To overcome these constraints, we propose the introduction of economic measures to support conversion. Generally, innovative systems studied lead to a substitution of pesticide use by more work. In the case of intercropping techniques, this substitution generally reduces income of farmers. In mountain areas, spontaneous fallow practices and implementation of intercropping with legume Canavalia ensiformis or Impatiens sp seem most appropriate. For large farms, whose economic and environmental performance are already relatively high, the cropping system based on the use of Brachiaria decumbens in fallow and then in intercropping seems the most promising option.

National audience

National audience; Agro-ecological innovations are needed to reduce the impacts of current intensive agricultural practices on biodiversity and ecosystems. Whereas many published studies focus on the biophysical impacts of such innovations at field level, few attention has been given to the analysis of the potential of adoption of these innovations at farm and regional levels. In order to reduce the gap between on station and in silico innovation and farmer’s adoption process, we developped an interdisciplinary method based on the combination of simulations models and on farm surveys to assess ex ante the potential of adoption of agro-ecological innovations by farmers.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; No consensus currently exists about how climate change should affect the status of soil organic matter (SOM) in the tropics. In this study, we analyse the impact of climate change on the underlying mechanisms controlling SOM dynamics in a ferralsol under two contrasting tropical crops: maize (C4 plant) and banana (C3 plant). We model the effect of microbial thermal adaptation on carbon (C) mineralisation at the crop system scale and introduce it in the model STICS, which was previously calibrated for the soil-crop systems tested in this study. Microbial thermal adaptation modelling is based on a reported theory for thermal acclimation of plant and soil respiration. The climate is simulated from 1950 to 2099 for the tropical humid conditions of Guadeloupe (French Antilles), using the ARPEGE model and the IPCC emission scenario A1B. The model predicts increases of 3.4 °C for air temperature and 1100 mm yr−1 for rainfall as a response to an increase of 375 ppm for atmospheric carbon dioxide concentration in the 2090–2099 decade compared with the 1950–1959 decade. The results of the STICS model indicate that the crop affects the response of SOM to climate change by controlling the change in several variables involved in C dynamics: C input, soil temperature and soil moisture. SOM content varies little until 2020, and then it decreases faster for maize than for banana. The decrease is weakened under the hypothesis of thermal adaptation, and this effect is greater for maize (−180 kg C ha−1 yr−1 without adaptation and −140 kg C ha−1 yr−1 with adaptation) than for banana (−60 kg C ha−1 yr−1 and −40 kg C ha−1 yr−1, respectively). The greater SOM loss in maize is mainly due to the negative effect of warming on maize growth decreasing C input from residues. Climate change has a small effect on banana growth, and SOM loss is linked to its effect on C mineralisation. For both crops, annual C mineralisation increases until 2040, and then it decreases continuously. Thermal adaptation reduces the initial increase in mineralisation, but its effect is lower on the final decrease, which is mainly controlled by substrate limitation. No stabilisation in SOM status is attained at the end of the analysed period because C mineralisation is always greater than C input. Model predictions indicate that microbial thermal adaptation modifies, but does not fundamentally change the temporal pattern of SOM dynamics. The vegetation type (C3 or C4) plays a major role in SOM dynamics in this tropical soil because of the different impact of climate change on crop growth and then on C inputs

There is actually a surge for reintroducing biodiversity in agricultural systems in order to reduce chemical inputs, suppress pests, and close biogeochemical cycles (Malézieux et al., 2009). The use of cover-crops is a promising way to reintroduce biodiversity into the fields. Cover-crops have the potential to decrease chemical use against weeds (by competition) and pests (by increasing in natural enemies). To decrease herbicide use, suitable plants must be able to grow in appropriate conditions, to do not compete the cultivated crop for nutrients or water, but should compete weeds for light and space. There is a trade-off between these objectives. Banana is a semi-perennial crop, each plant develops at its own rhythm leading to an unsynchronized plant population in three years; canopy and nitrogen demand of the crop follow this unsynchronized pattern (Tixier et al., 2004). Banana cropping systems remain based on bare soil management and a large amount of herbicides is used. In tropical environment, the growth of weeds and cover-crop is complex because it is not constrained by seasons; a constant growth is possible due to relatively constant climate. In these conditions, variation in radiation due to canopy closure is one of the major drivers of their growth. First, we present the evaluation of the impact of the cover-crop on the yield in the case of two graminaceous cover-crops. Secondly, we present results of the evaluation of 11 species of potential cover-crop using measures under different levels of shade. We used a simulation model to contextualize their growth and conclude on the most appropriated species to intercrop with banana.

The postharvest development of crown rot of bananas depends notably on the fruit susceptibility to this disease at harvest. It has been shown that fruit susceptibility to crown rot is variable and it was suggested that this depends on environmental preharvest factors. However, little is known about the preharvest factors influencing this susceptibility. The aim of this work was to evaluate the extent to which fruit filling characteristics during growth and the fruit development stage influence the banana susceptibility to crown rot. This involved evaluating the influence of (a) the fruit position at different levels of the banana bunch (hands) and (b) changing the source-sink ratio (So-Si ratio), on the fruit susceptibility to crown rot. The fruit susceptibility was determined by measuring the internal necrotic surface (INS) after artificial inoculation of Colletotrichum musae. A linear correlation (r = ?0.95) was found between the hand position on the bunch and the INS. The So-Si ratio was found to influence the pomological characteristics of the fruits and their susceptibility to crown rot. Fruits of bunches from which six hands were removed (two hands remaining on the bunch) proved to be significantly less susceptible to crown rot (INS = 138.3 mm2) than those from bunches with eight hands (INS = 237.9 mm2). The banana susceptibility to crown rot is thus likely to be influenced by the fruit development stage and filling characteristics. The present results highlight the importance of standardising hand sampling on a bunch when testing fruit susceptibility to crown rot. They also show that hand removal in the field has advantages in the context of integrated pest management, making it possible to reduce fruit susceptibility to crown rot while increasing fruit size. (Resume d'auteur)

International audience

Correspondance: gary@supagro.inra.fr; International audience

International audience; Musa species, comprising dessert and cooking bananas, represent the fourth most important crop in developing countries. They are monocotyledons of the Musa species, comprising dessert and cooking bananas, represent the fourth most important crop in developing countries. They are monocotyledons of the Zingiberales order and the Musaceae family. We have compared genomic sequence in two Musa species with orthologous regions in the rice genome. We produced 1.4 Mb of Musa sequence from 13 BAC clones, annotated and analyzed them along with 4 previously sequenced BACs. The 443 predicted genes revealed that Zingiberales genes share GC content and distribution characteristics with eudicot and Poaceae genomes. Comparison with rice revealed microsynteny regions that have persisted since the divergence of the Commelinid orders Poales and Zingiberales at least 117 Mya. The previously hypothesized large-scale duplication event in the common ancestor of major cereal lineages within the Poaceae was verified. The divergence time distributions for Musa-Zingiber (Zingiberaceae, Zingiberales) orthologs and paralogs provide strong evidence for a large-scale duplication event in the Musa lineage after its divergence from the Zingiberaceae approximately 61 Mya. Comparisons of genomic regions from M. acuminata and M. balbisiana revealed highly conserved genome structure, and indicated that these genomes diverged circa 4.6 Mya. Further sequencing efforts should be focused first on the A genome of M. acuminata, which has a major contribution to banana and plantain diversity. This will enable: - alignment of the Musa genome in relation to major grasses, including rice and sorghum- phylogenomic analysis of gene families and metabolic pathways among monocots- use as a template for positional cloning of genes of agricultural interest- use as a support to develop genomic tools for whole-genome expression analysis- use as a template for re-sequencing and deep diversity analysis in the Musa gene pool.

5 annexes (24 p.) Diplôme : Diplôme d'Ingénieur des Travaux Agricoles; Banana's production in Guadeloupe was developed on intensive monoculture logic with high level of inputs. Currently, this production is cutting through an economic and an environmental crisis. Faced with this crisis, one solution is to propose sustainable innovative cropping systems. Evaluation and design of innovative systems requires the use of tools in modeling and assessment. The research unit 'AgroPedoClimatique' of the National Institute for Agricultural Research has developed a program to design banana innovative cropping systems. 18 prototypes of innovative cropping systems have been developed. The agronomic performances were simulated by the SIMBA model. The method MASC (Multi-Attribute Assessment of the Sustainability of Cropping Systems) has been adapted to the context of growing bananas in Guadeloupe to evaluate the overall sustainability of prototypes. The evaluation was conducted taking into account the type diversity of banana farms in the region. Thus, among the 18 prototypes, both get an overall sustainability from medium to high in all types and seem promising. Other prototypes are specific for a given farm type and have a medium overall sustainability. For more, these prototypes have to be tested in situ to assess their agronomic performance and functional. MASC was appropriated for its structure sufficiently flexible to be adapted to specific contexts. It can discriminate quite satisfactorily a wide range of innovative cropping systems.; La culture de la banane en Guadeloupe s'est développée selon une logique de monoculture intensive à haut niveau d'intrants. Si cette production constitue un pilier de l'économie de l'île, depuis quelques années, elle traverse une crise économique et environnementale. Face à cette situation de crise, une des solutions proposées consiste à proposer des systèmes de culture innovants plus durables. L'évaluation et la conception de systèmes innovants nécessite l'utilisation d'outils de modélisation et d'évaluation. L’unité de recherche agropédoclimatique (UR APC) de l'INRA (Institut National de la Recherche Agronomique) a développé un programme de conception de systèmes de culture de bananiers innovants et 18 prototypes de systèmes de culture ont été mis au point. Les performances agronomiques ont été simulées par le modèle SIMBA. La méthode MASC (Multi-Attribute Assessment of the Sustainability of Cropping systems) a été adaptée au contexte de la culture de la banane en Guadeloupe pour évaluer la durabilité globale des prototypes. L'évaluation a été menée en tenant compte de la typologie des exploitations bananières de la région. Ainsi, parmi les 18 prototypes, deux obtiennent une durabilité globale moyenne à élevée chez l'ensemble des types et semblent prometteuses. D'autres plus spécifiques à un des types d'exploitation ont une durabilité globale moyenne. Pour la suite, ces prototypes sont à tester in situ pour évaluer leurs performances fonctionnelles et agronomiques. L’outil MASC s’est révélé approprié par sa structure et suffisamment souple pour être adapté à des contextes particuliers. Il permet de discriminer de manière assez satisfaisante une large gamme de systèmes de culture innovants.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; A stochastic individual-based model called COSMOS was developed to simulate the epidemiology of banana weevil Cosmopolites sordidus, a major pest of banana fields. The model is based on simple rules of local movement of adults, egg laying of females, development and mortality, and infestation of larvae inside the banana plants. The biological parameters were estimated from the literature, and the model was validated at the small-plot scale. Simulated and observed distributions of attacks were similar except for five plots out of 18, using a Kolmogorov-Smirnov test. These exceptions may be explained by variation in predation of eggs and measurement error. An exhaustive sensitivity analysis using the Morris method showed that predation rate of eggs, demographic parameters of adults and mortality rate of larvae were the most influential parameters. COSMOS was therefore used to test different spatial arrangements of banana plants on the epidemiology of C. sordidus. Planting bananas in groups increased the time required to colonise plots but also the percentage of banana plants with severe attacks. Spatial heterogeneity of banana stages had no effect on time required to colonise plots but increased the mean level of attacks. Our model helps explain key factors of population dynamics and the epidemiology of this tropical pest. (C) 2009 Elsevier B.V. All rights reserved.

Chantier qualité GA Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Banana is the second most important agricultural commodity in Guadeloupe (French West Indies—FWI) and, to compensate the decline in international prices during the last 15 years, banana growers have intensified their production systems by increasing the use of technological inputs. Such intensification strategies, that require both material and investment increases, may impose economic as well as environmental risks, given the fragile island ecosystems. In order to assess the environmental performance of banana production in Guadeloupe, emergy synthesis methods were applied to six different types of banana cropping systems previously identified in the island. Additionally, aiming at improving managerial capacity and investment decision making, environmental performance results were contrasted with economic analysis for the six cropping systems. As a general outcome, these analyses showed that the better the environmental performance of the cropping system, the worse its economic performance. This result was corroborated by an increased contrast among cropping systems as related to their dependence on purchased inputs, although all cropping systems followed the same intensive and arguably wasteful agricultural model. Therefore, the analyses point out that sustainable banana production in Guadeloupe depends on a shift from the high fossil input model to a natural resources intensive one. In this sense, emergy flow analysis shows that innovation towards environmentally sound practices that would enhance nutrient cycling; integrate weeds, pests and diseases control; and improve the banana packing process might result in most positive impacts on overall sustainability. Economic analysis showed that the high labour costs contribute largely to the dependency of banana production on agricultural subsidies. However, reorienting the current European agricultural income policy to an environmental performance-based subvention might be a policy opportunity to achieve the present social goals while promoting sustainability in banana production. Furthermore, the EC regulation on quality standards for commercial bananas, by imposing strict aesthetic benchmarks, has a negative effect on the sustainability of banana production because substantial non-renewable and purchased emergy inflows into banana production systems aim to improve aesthetic standards over sound ecological management.

To minimize application of nematicides in banana fields, crop systems have been developed in the French West Indies that combine fallow or rotation crops and nematode-free in vitro plants. After two to four years, populations of the burrowing nematode Radopholus similis have developed enough to cause economic losses, leading banana growers to use nematicides. To understand how banana fields are recontaminated, we studied the dissemination of R. similis by water flow. At a 1-m scale, we analyzed the dispersion of R. similis under a rainfall simulator: we isolated a 1-m 2 study plot, placed a R. similis suspension on the upstream soil surface, and simulated a 60 mm/h rainfall for 72 min. We collected soil samples every 10 cm downstream after 12 min of rainfall, and subsequently at 20-min intervals, and extracted the nematodes using a Seinhorst elutriator and then a Baermann funnel. Our results showed that the nematode dissemination follows an inverse exponential law, and depends more on soil moisture at the beginning of rainfall than on the length of rainfall: in fresh soil, 69–80% of the R. similis recovered were found less than 10 cm downstream from the nematode inoculation line, whereas in wetted soil, 76–85% of the recovered individuals were collected in the outlet tub located downstream from the apparatus. This passive dissemination model partially explains the distance covered by individual nematodes but not the low percentage of motile nematodes recovered in the outlet tub (10% and 36% in fresh and wet soils) compared to the percentage of motile nematodes found in the soil (80% and 84% in fresh and wet soils). Indeed, water runoff is likely to disseminate R. similis over long distances only when soil moisture is close to field capacity.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; Prototyping methods are useful for designing alternative crop management systems (CMS), but they are usually considered mainly at the field level and are poorly equipped to take into account farm diversity in terms of economic, social and natural constraints. This may limit the likelihood of adoption of alternative CMS. This paper proposes a two-step methodological framework that takes into account the diversity of farms in the prototyping of new CMS. The first step of the framework is to design a farm typology that is able to characterise the diversity of current CMS in terms of their technical nature, farming context, and performance. We define a farming context as a set of characteristics at the farm level that are likely to influence the structure and the biophysical and economic performances of CMS at the field level. The typology is designed from a statistical analysis of a set of descriptive variables collected for a sample of farms. The second step of the framework uses this farm typology in a specific work agenda with a panel of experts in order to design a set of alternative CMS prototypes. Prototypes, and the objectives they are meant to reach, are designed by analysing current CMS performances and by mobilising agro-ecological knowledge to identify technical ways to improve them. The typological characterisation of farm diversity then makes it possible to define a set of constraints (SOC) for each farm type. Once the prototypes are designed, the experts use a compatibility indicator (CI) ranging from zero to one to measure the level of compatibility between each prototype and the SOC of each farm type. We define a prototype as compatible with a farm type if the prototype is not likely to increase the constraints of a farm of that type (CI = 1). Using this indicator in a process of iterative improvement of prototype design makes it possible to define a set of a priori compatible prototypes for each farm type. The aim of this paper is to present our methodological framework and its application for prototyping new banana crop management systems in Guadeloupe. The six-class typology we developed corresponded to a great diversity of CMS with contrasting performances and farming contexts. The method led to the prototyping of 16 innovative CMS, involving different modalities of intercropping, patterns of pesticide use, choices of hybrid cultivars, and rotations with cover or cash crops. Finally, we discuss the limits of our methodological framework and its utility for improving prototyping approaches.

Diffusion du document : INRA Antilles-Guyane, Unité Agropédoclimatique de la zone Caraïbe, Domaine de Duclos, 97170, Petit-Bourg (Guadeloupe), France Diplôme : Dr. d'Université; Agricultural production is evolving towards systems able to provide multiple objectives in order to satisfy the complex concerns related to sustainability, therefore leading agricultural research to bear growing interest in the development of methodologies to allow the design and assessment of innovative cropping and farming systems able to fulfil these constraints. Although the number and the diversity of tools and concepts are increasing, only few transdisciplinary research have been done, therefore limiting the development of methodologies for integrated assessment from the design to the adoption of innovations by farmers. The objective of this thesis is to propose a trandisciplinary method for ex ante assessment of innovative cropping systems in order to palliate this shortcoming in the current research. After a survey of available assessment methodologies, we propose an original method which is made of a four-step approach: i) modelling farm diversity and prototyping innovative cropping systems, ii) use of a crop model to simulate the biophysical impacts of innovations for the different farm types, iii) development of a bio-economic farm model for assessment of the impacts of the adoption of innovations at farm level, and iv) econometric modelling of adoption by farmers. The method was then applied to the design and assessment of innovative cropping systems for banana production in the French West Indies, that are currently facing severe economic and environmental crisis. The first step led to the identification of six contrasting farm types and sixteen cropping systems prototypes, invoving rotation of banana with cover crop, intercropping, and regulation of pesticide use. The second step showed that the performances of innovation may differ greatly among fram types, and some systems appear to be promising from both agronomic and environmental critera. However simulations made in step 3 and 4 showed that promising innovations at field level maight have negative impacts at farm level while some promising innovation have low probability of adoption. Results of econometric model and bio-economic simulations made possible to define a set of proposals for local research and development stakeholders in order to improve the likelyhood of adoption of the innovations. In the last chapter we present a critical analysis of the advantages and shortcomings of our approach underling the genericity of the methodology, and the potential extension of its application to other context, for better matching the innovations with society and farmers demands.; Face à la multiplication et la complexité croissante des objectifs assignés à l’agriculture, les méthodologies de conception et d’évaluation ex ante de systèmes de culture innovants font l’objet d’un effort de recherche très soutenu. Cependant malgré le foisonnement de recherches et de productions d’outils disciplinaires, peu de recherches d’interface ont été entreprises, ce qui limite les possibilités d’évaluations ex ante globales des systèmes innovants, de la conception à l’adoption par les agriculteurs. L’objectif de cette thèse est de contribuer à l’avancée de ces travaux, en proposant une méthode transdisciplinaire d’évaluation ex ante de systèmes de culture innovants basée sur la combinaison d’outils de modélisation issus de l’agronomie et de l’économie. A partir d’une analyse de la littérature actuelle et de ses forces et faiblesses, nous construisons une méthode originale qui se décompose en 4 étapes : i) modélisation de la diversité des exploitations et prototypage de systèmes innovants plus durables, ii) utilisation d’un modèle de culture pour simuler le fonctionnement biophysique des innovations dans les types d’exploitations, iii) évaluation des impacts de l’adoption sur le fonctionnement et les performances des types d’exploitation à l’aide d’un modèle bio-économique d’exploitation, iv) modélisation ex ante de l’adoption par les planteurs à l’aide d’un modèle économétrique. La méthode est ensuite appliquée à la conception et à l’évaluation ex ante de prototypes de systèmes de cultures bananiers aux Antilles françaises, qui traversent actuellement une crise socio-économique et environnementale sévère. L’application de la première étape de la méthode a permis d’identifier 6 types d’exploitations très contrastés avec des problèmes de durabilité se déclinant différemment et de mettre au point 16 prototypes de systèmes innovants impliquant plante de couverture cultivées en association ou en rotation, nouvelles variétés de bananiers, et réduction de l’usage des intrants chimiques. La deuxième étape a montré que les performances agronomiques des prototypes peuvent varier considérablement d’un type d’exploitation à un autre, et que certains systèmes semblent très prometteurs sur le plan agronomique et environnemental. Cependant les modélisations réalisées en étape 3 et 4 montrent que d’une part, des innovations performantes à la parcelle peuvent poser des problèmes de trésorerie et de charge de travail à l’échelle de l’exploitation, et que d’autre part certaines innovations très prometteuses ont pourtant un taux d’adoption faible. Les résultats du modèle économétrique et des simulations réalisées en étapes 2 et 3 permettent alors de définir un ensemble de propositions d’action à destinations des acteurs de l’innovation et du développement en vue de maximiser les chances d’adoption de systèmes plus durables. Le dernier chapitre de cette thèse revient sur les forces et les faiblesses de la méthode et souligne sa généricité potentielle qui devrait donc permettre d’étendre son application à d’autres contextes afin d’assurer une meilleure adéquation entre les innovations produites par la recherche agronomique et les attentes des agriculteurs et de la société.

Face à la multiplication et la complexité croissante des objectifs assignés à l’agriculture, les méthodologies de conception et d’évaluation ex ante de systèmes de culture innovants font l’objet d’un effort de recherche très soutenu. Cependant malgré le foisonnement de recherches et de productions d’outils disciplinaires, peu de recherches d’interface ont été entreprises, ce qui limite les possibilités d’évaluations ex ante globales des systèmes innovants, de la conception à l’adoption par les agriculteurs. L’objectif de cette thèse est de contribuer à l’avancée de ces travaux, en proposant une méthode transdisciplinaire d’évaluation ex ante de systèmes de culture innovants basée sur la combinaison d’outils de modélisation issus de l’agronomie et de l’économie. A partir d’une analyse de la littérature actuelle et de ses forces et faiblesses, nous construisons une méthode originale qui se décompose en 4 étapes : i) modélisation de la diversité des exploitations et prototypage de systèmes innovants plus durables, ii) utilisation d’un modèle de culture pour simuler le fonctionnement biophysique des innovations dans les types d’exploitations, iii) évaluation des impacts de l’adoption sur le fonctionnement et les performances des types d’exploitation à l’aide d’un modèle bio-économique d’exploitation, iv) modélisation ex ante de l’adoption par les planteurs à l’aide d’un modèle économétrique. La méthode est ensuite appliquée à la conception et à l’évaluation ex ante de prototypes de systèmes de cultures bananiers aux Antilles françaises, qui traversent actuellement une crise socio-économique et environnementale sévère. L’application de la première étape de la méthode a permis d’identifier 6 types d’exploitations très contrastés avec des problèmes de durabilité se déclinant différemment et de mettre au point 16 prototypes de systèmes innovants impliquant plante de couverture cultivées en association ou en rotation, nouvelles variétés de bananiers, et réduction de l’usage des intrants chimiques. La deuxième étape a montré que les performances agronomiques des prototypes peuvent varier considérablement d’un type d’exploitation à un autre, et que certains systèmes semblent très prometteurs sur le plan agronomique et environnemental. Cependant les modélisations réalisées en étape 3 et 4 montrent que d’une part, des innovations performantes à la parcelle peuvent poser des problèmes de trésorerie et de charge de travail à l’échelle de l’exploitation, et que d’autre part certaines innovations très prometteuses ont pourtant un taux d’adoption faible. Les résultats du modèle économétrique et des simulations réalisées en étapes 2 et 3 permettent alors de définir un ensemble de propositions d’action à destinations des acteurs de l’innovation et du développement en vue de maximiser les chances d’adoption de systèmes plus durables. Le dernier chapitre de cette thèse revient sur les forces et les faiblesses de la méthode et souligne sa généricité potentielle qui devrait donc permettre d’étendre son application à d’autres contextes afin d’assurer une meilleure adéquation entre les innovations produites par la recherche agronomique et les attentes des agriculteurs et de la société., Agricultural production is evolving towards systems able to provide multiple objectives in order to satisfy the complex concerns related to sustainability, therefore leading agricultural research to bear growing interest in the development of methodologies to allow the design and assessment of innovative cropping and farming systems able to fulfil these constraints. Although the number and the diversity of tools and concepts are increasing, only few transdisciplinary research have been done, therefore limiting the development of methodologies for integrated assessment from the design to the adoption of innovations by farmers. The objective of this thesis is to propose a trandisciplinary method for ex ante assessment of innovative cropping systems in order to palliate this shortcoming in the current research. After a survey of available assessment methodologies, we propose an original method which is made of a four-step approach: i) modelling farm diversity and prototyping innovative cropping systems, ii) use of a crop model to simulate the biophysical impacts of innovations for the different farm types, iii) development of a bio-economic farm model for assessment of the impacts of the adoption of innovations at farm level, and iv) econometric modelling of adoption by farmers. The method was then applied to the design and assessment of innovative cropping systems for banana production in the French West Indies, that are currently facing severe economic and environmental crisis. The first step led to the identification of six contrasting farm types and sixteen cropping systems prototypes, invoving rotation of banana with cover crop, intercropping, and regulation of pesticide use. The second step showed that the performances of innovation may differ greatly among fram types, and some systems appear to be promising from both agronomic and environmental critera. However simulations made in step 3 and 4 showed that promising innovations at field level maight have negative impacts at farm level while some promising innovation have low probability of adoption. Results of econometric model and bio-economic simulations made possible to define a set of proposals for local research and development stakeholders in order to improve the likelyhood of adoption of the innovations. In the last chapter we present a critical analysis of the advantages and shortcomings of our approach underling the genericity of the methodology, and the potential extension of its application to other context, for better matching the innovations with society and farmers demands.