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International audience; An ex post analysis of the impact of research projects related to Participatory Breeding (PB) of sorghum in Burkina Faso was carried out in 2015 and 2016 using the "Impress" method developed by CIRAD. The sorghum PB approach emerged in Burkina Faso in the late 1990s as a response to the very low adoption of improved varieties released by the conventional breeding program. This approach represents a paradigm shift from a research approach focused solely on the development of "high-yielding varieties", irrespective of the social context in which these varieties are to be used, towards the development of varieties, seed and their dissemination within a multi-stakeholder framework. The present study aims to assess the impact of the sorghum PB program and the activities related to seed production and dissemination carried out in Burkina Faso over a period of 20 years. Detailed mappings of the timeline and the actors that have been involved in the innovation process, as well as the impact pathway, have been established. The causal relationships between outputs, outcomes and impacts have been developed on the basis of 67 impact descriptors provided by research partners and beneficiaries during participatory workshops. Around thirty measurable impact indicators were assessed by means of individual or focusgroup interviews and by means of secondary data sources. The three major outputs of the study were: the new improved varieties (IV) resulting from the PB actions; the mini-pack seed strategy; and the new skills acquired by the farmer organizations regarding sorghum improvement and certified seed production. The appropriation of these outputs by the farmer organizations not only brought structure to the experimentation networks, but also ensured the promotion and dissemination of the new varieties, and the establishment of a decentralised certified seed production scheme. One major positive impact was the significant increase in the use of sorghum IVs not only in the villages covered by the program but also in neighbouring areas. The expansion and performance of these new IVs has helped reduce the hunger gap while increasing the revenues of farmers involved in seed production. Furthermore, the research projects helped bring structure to the national seed sector as well as to the certified seed market, where the farmer seed production Unions consolidated by the PB projects now play an important role in the orientation of national legislation. The experimental method of impact assessment used in this analysis explores and makes visible the complex multidimensional and multi-stakeholder processes that have helped shape technological innovation and its impact on development. Such impact assessments can also elucidate the role of research in reinforcing the individual and collective capacities needed for innovating and testing out new technologies, that is, new varieties and seed production practices according to local constraints and/or opportunities.

With its high biomass yield potential and its adaptability to a large spectrum of crop management schemes (dedicated, double cropping), sorghum is a relevant candidate crop for anaerobic digestion. Moreover, the large genotypic variability of its biochemical composition offers opportunities to cultivate specific varieties that fit the expectations of different end-users. Within this context, the need to evaluate the variability of biomethane potential (BMP) among different genotypes cultivated at various geographical sites has become crucial. In this study, four sorghum genotypes were grown at three different sites and harvested at the same maturity stage (dough grain stage). Consistent BMP obtained from different assays enabled genotype comparisons. The methane potentials observed between genotypes and production sites ranged between 200 ± 5 NmLCH4/gTS and 259 ± 12 NmLCH4/gTS. Evaluation of the genotypic and cultivation site effects produced highly significant results, thus accounting for 36 and 34%, respectively, of the phenotypic variability.

Confrontés aux évolutions des enjeux et modèles de développement touchant les secteurs de l’agriculture et de l’alimentation, les organismes de recherche interrogent les méthodes d’évaluation des impacts liées aux activités de recherche. En effet les cadres méthodologiques conventionnels utilisés depuis les années 1950 ne répondent plus aux attentes sociétales et aux réalités de l’activité de recherche dans ce domaine. Le numéro thématique des Cahiers Agricultures « Évaluer les impacts des recherches en agriculture sur la société : outils, méthodes, études de cas » présente les nouvelles approches méthodologiques proposées ces dernières années par l’INRA, le CIRAD et le CGIAR. Ces méthodes utilisent une démarche commune qui met l’accent sur les dimensions systémiques des processus d’innovation, la dimension multi-niveaux des impacts, la temporalité longue. Elles diffèrent sur certains points, comme par exemple la participation des parties prenantes dans l’évaluation des impacts. Le test empirique de ces démarches dans différentes études de cas structure une partie du numéro thématique dans les pays en développement. Il est enrichi par des analyses transversales aux études de cas ou sur des situations portées par d’autres orientations méthodologiques et dans d’autres contextes géographiques. Certaines contributions identifient les limites des différentes méthodes pour de futurs fronts de recherche. Cet article de synthèse expose des connaissances sur la compréhension des impacts de l’activité de recherche. Il invite à reconsidérer le rôle de la recherche dans les processus d’innovation., In light of the evolution of issues and development models in the agriculture and food sector, research organizations are questioning the methods to assess the impact of research activities. Indeed, conventional methodological frameworks used since the 1950s are increasingly less adapted to societal expectations and realities of agricultural research. This thematic issue of Cahiers Agricultures.[br/] "Evaluation of the impacts of agricultural research on society: tools, methods, case studies" presents new methodological approaches developed in recent years by INRA, CIRAD and CGIAR. These methods build on common theoretical underpinnings that emphasize the systemic dimensions of the innovation process, multiple perspectives and longer temporality of impact generation. They also differ in certain dimensions, such as the level of participation of stakeholders in the assessment of impacts. One part of this thematic issue is dedicated to the empirical test of these approaches in developing countries. The issue is enriched by papers providing cross-cutting analyses of the case studies, or presentation of different methods and geographical contexts. Finally, some articles identify the limitations of these methods for future research. This synthesis article presents knowledge on the understanding of the impacts of research activities, and invites readers to reconsider the role of research in the innovation process.

Sweet sorghum is highly coveted to contribute and take up food and energy challenges. A collection of 84 West Africa landraces mostly from Senegal and four control cultivars were screened to identify relevant accessions and trait combination for multi-purpose (sugar/grain/biomass). The implication of photoperiod sensitivity was particularly addressed. A total of 20 traits related to phenology, morphology, grain and sugar production were assessed in two sowing dates (July and August) at CNRA Bambey in Senegal. Late sowing resulted in shortened vegetative phase and a significant decrease in traits related to plant size, stem sugar, biomass and grain productions. Broad-sense heritability was moderate to high for most of the phenology, morphology, grain and sugar-related traits, suggesting their interest for breeding. All the traits related to plant size were positively correlated with plant sugar production except plant height. A cluster analysis identified three groups contrasting in their ability to combine sugar, grain or fodder production based on 18 traits measured for the early sowing. Clusters I and III were suitable for one purpose: grain and sugar, respectively. Cluster II was the most suitable for multi-purpose, showing the best trade-off among grain, sugar and vegetative biomass production. The best accessions for stem sugar yield belonged to durra, caudatum and their intermediate types. The relationship between internode size and sweetness should be further studied, in particular exploring their relationship with internode tissue anatomy. Further studies are also needed to evaluate the role that stay-green can play in sugar yield maintenance under post-flowering drought. (Resume d'auteur)

Agricultural production and supply chains are facing major challenges in the form of increasing demand for food products, a diversified use of agricultural products including for non-food purposes, ecologically intensive agriculture, and the necessity of taking climate change into account. The creation and adoption of new varieties that are productive, diversified, better adapted, and more environmentally friendly can help cropping systems that seek to address these issues become more efficient. Plant breeding efforts must anticipate the needs of the end users and adapt to very different agri-chains, illustrated in this chapter by two examples: first, an agri-chain that is highly structured around targeted export products, for example, the dessert banana, which requires ideotypes that meet the requirements of production and marketing systems; and second, an emerging agri-chain for multi-use sorghum, characterized by new production objectives of increased energy potential and production of biomaterials, sometimes without compromising with the requirement of high grain yields. To meet the objectives and the sustainability of agri-chains, research into genetic improvement must propose new approaches, new tools, and innovative breeding methods. The objectives, and sometimes the entire breeding process, are shared with all the actors, especially the end users, as part of an enhanced partnership within agri-chains. The breeding strategy also depends on ease of access, better use of available and useful genetic resources, in-depth knowledge of the structure and diversity of these resources, genetic determinism of desirable traits, and pre-breeding approaches. All these scientific and partnership innovations ensure the necessary responsiveness to support the execution of current breeding processes and the identification of new varieties that meet current and future uses and services.

In Africa, it is mostly the informal seed system that ensures farmers’ seed supply. This is partly because the formal seed systems are not always effective in meeting demand for new seed varieties. Sometimes informal seed recycling and exchange of improved sorghum varieties will take place alongside formal initiatives, as is the case in southern Mali. Focusing on one particular village in the Dioila district, we analyze the efficacy of farmers’ strategies for preserving varietal seed purity and genetic integrity of an improved inbred-line (Soumba variety). Six seed lots of Soumba, recycled for two to six years by farmers using different practices, were collected and assessed in on-station trials in order to compare their agronomic performance and phenotypic purity (off-type plant frequencies) with control versions of the variety. Additionally, 30 panicle samples were randomly collected from five farmer fields sown with recycled Soumba and assessed for phenotypic purity in a progeny nursery and investigated for molecular diversity using 12 SSR markers. A total of 150 panicles from five other non-Soumba varieties were collected in the village in order to investigate eventual gene flow and its potential genetic consequences for the Soumba variety. In fields sown with recycled Soumba seed, between 2% and 14% of plants showed phenotypic deviations from the typical Soumba variety. The progeny nursery and SSR marker analysis verified the presence of the off-type plants observed in the field. The STRUCTURE program revealed admixtures with other varieties in 23% of Soumba plants, confirming the presence of gene flow. Gene diversity values in Soumba samples ranged from 0.006 for the commercial sample to 0.257 for recycled samples. Introgression and contamination were best minimized when (1) farmers had received specific training in seed production, (2) they could take advantage of isolated fields and (3) they could practise true-to-type panicle selection. Farmers were generally able to maintain the phenotype, as well as sustain or even improve yield performance of their Soumba variety while at the same time genetically enriching their seed stock.

SUMMARYSorghum (Sorghum bicolor(L.) Moench) is a major staple crop of Burkina Faso where farmers continue to cultivate photoperiod-sensitive guinea landraces as part of the strategy to minimize risk and ensure yield stability. In the Boucle du Mouhoun region, however, sorghum farmers appear to have insufficient varietal choice due to cropping systems having shifted towards more intensive cultivation of cotton and maize, and rainfall patterns having decreased over the past decade. In search for new varietal options that can respond to this changing context, researchers decided to give farmers access to ex-situ national collections along with the opportunity to evaluate recent improved varieties. From 2002 to 2007, researchers and farmers worked closely together to implement on-farm testing, including varietal selection trials, crop management and multi-locational trials. Farmers’ choices tend to differ among groups, villages and years, with the exception of four particular landraces: two originating from a collection carried out in the Mouhoun region more than 30 years previous to this research, and two other landraces that came from the dissimilar agro-ecological zones of Burkina Faso. These four were the most commonly selected landraces out of 36 cultivars that covered both improved and landrace varieties. Farmers’ selection criteria were focused on adaptation to agro-climatic conditions as well as specific grain qualities for processing and consumption. The potential usefulness of each variety was verified via multi-locational trials. The paper also shows that wide dissemination of experimental seed, not just across the Mouhoun region but also at a national scale, was largely achieved through collaboration with a strong farmer organisation in conjunction with farmer training programs focused on the on-farm seed production and the commercialisation of this seed.

Le sorgho (Sorghum bicolor (L) Moench) est la principale cereale cultivee au Burkina Faso et la deuxieme au Mali. Une diversite varietale importante est geree par les agriculteurs pour divers objectifs de production. Malgre le fort accroissement des besoins alimentaires prevus pour ces deux pays pour les vingt prochaines annees, les rendements en sorgho sont restes faibles et l'augmentation de la production est essentiellement due a l'extension des surfaces emblavees; de plus, le sorgho subit une erosion genetique. L'objectif du projet est donc de concilier le maintien de la biodiversite du sorgho et l'accroissement de la productivite. Le projet est constitue de sept etapes de travail qui impliquent des equipes pluridisciplinaires de recherche, des services de developpement et des organisations paysannes d'une facon participative. Ces dernieres sont majoritaires dans les instances de decisions et d'execution. Le but du projet est de developper une large gamme de nouvelles varietes performantes et adaptees aux conditions climatiques locales et aux besoins et preferences des agriculteurs. Leur diffusion permettrait de preserver la biodiversite du sorgho. (Resume d'auteur)

This research aims to evaluate adaptation of two contrasting sorghum genotypes to flooding: a landrace from Cameroon described as a “floating sorghum” (Wulaga) and a typical dryland improved variety (Cirad437) from Burkina Faso. Anatomical and morphological features of the basal internodes were quantified in control conditions (drained pots) and long-term flooded conditions from the five-leaf stage for the entire cropping cycle. This study revealed that the Wulaga variety expressed aerenchyma in basal internodes in both control and flooded treatments (constitutive aerenchyma) whereas Cirad437 only developed aerenchyma in flooded conditions (inducible aerenchyma). The level of lignification and epidermis thickness of basal internodes was identical for the two varieties and the two treatments, suggesting that lignin does not contribute to the enhancement of a tight barrier against O2 losses. However, Cirad437 showed shorter and larger internodes in flooded conditions while Wulaga did not show any difference between the two conditions. Results indicate the existence of diversity in adaptive response to flooded conditions for the two varieties. Further studies on phenotypic traits associated with phenology, leaf traits, root traits and yield components, are needed to confirm these preliminary results and to explore a broader range of genetic diversity that could be used for future sorghum breeding programs designed for flood-prone environments. (Resume d'auteur)

Participation of farmers in the genetic improvement of staple crops in vulnerable environments is now widely accepted as a necessary approach for enhancing the acceptance of improved varieties. Our study set out to assess the genetic gains achieved by collaborative decentralized participatory breeding programmes in comparison with those obtained by conventional breeding. The gains were estimated on farmer acceptance and combination of agronomic and quality-related traits, from three breeding programmes on tortillero sorghum for low-input cropping systems in northern Nicaragua. In each programme, three selection modes were compared: selection by the farmers on-farm (FoF), by the breeder on-station (BoS), and by the breeder on-farm (BoF). Our results showed that the lines produced by FoF selection were more praised by the farming community, compared to BoS and BoF selection. Comparative advantage of FoF selection was to develop higher proportion of lines with an adequate balance between agronomic traits, and with better quality traits related to grain appearance and plant type. A composite selection index, ISFA, was computed for each line as a combination of agronomic performance in the target environment, and ex post farmer appraisal. Based on this index, FoF selection proved again to be more efficient than BoS and BoF selection. We propose that such a selection index be used in participatory breeding programmes to improve their efficiency.

International audience

Few studies have assessed the effective gains achieved by collaborative decentralized participatory breeding, in terms of yield and other agronomic traits, in comparison with centralized conventional breeding using the same breeding schemes. Our study concerned an experience of participatory improvement of tortillero sorghum for low-input cropping systems in northern Nicaragua. It set out to compare the effect of two breeding schemes simultaneously managed on-station and on-farm. Two synthetic populations were used as sources of genetic variability. The study was designed to distinguish between three “selection modes”: farmers’ selection on-farm (FoF), breeder’ selection on-station (BoS) and breeder’s selection on-farm (BoF). After two selection cycles, we found that FoF selection reduced phenotypic variability as much as BoS selection. In general, BoS selection produced higher-yielding lines under the target on-farm conditions. But FoF selection was more effective in promoting lines with higher values for an index of agronomic suitability (IAS), expressing a better balance between earliness, plant height, grain size and yield. Such genotypes might cope more easily with local environmental constraints and farmers’ preferences. BoF selection did not prove to be effective for either yield or IAS. This research shows the need for close collaboration between farmers and breeders as well as complementarities between the selection phases managed on-farm and on-station, to make breeding for difficult environments fully efficient. © 2010 Elsevier B.V. All rights reserved.

SUMMARYIn the dry areas of Nicaragua, white-grain sorghum is an important subsistence crop for resource-poor farmers. From 2002 to 2007, participatory varietal selection (PVS) was implemented in three regions with the aim of identifying new varieties matching small farmers' needs. This paper describes the general approach, the partnership and the methods used to identify farmers' selection criteria (FSC), as well as the evaluation of new germplasm using the scoring method. Data analysis involved relating farmers' evaluation data to agronomic data and farmers' selection decisions (FSD), using Spearman correlations and the chi-square test. In the three regions, higher grain yield and good grain quality for making tortillas were identified as the two main FSCs for both the ‘tortillero’ and ‘millón’ sorghum types; the ranking of the other important FSC differed between the sites and the sorghum types. Our data shows that farmers' scores for earliness were highly correlated with breeder's observations while farmers' assessments of grain yield were correlated with measured yield in half the cases, depending on their knowledge of the crop. The study shows that in evaluating grain quality the farmers used several specific traits which were not considered by breeders. Overall appreciation, grain yield and grain quality were the key farmers' criteria that contributed to FSD. The PVS work enabled breeders to obtain a better understanding of farmers' criteria as well as identifying new progenitors, which should be useful for the sorghum breeding schemes in Central America in the future. Furthermore, by exploring wide genetic diversity, it was possible to release several farmer-preferred and high-performing varieties within a fairly short period.

To comply with the intensive industrial agriculture model of the Green Revolution, the modern plant breeding combines professionalized variety selection using germplasm conserved ex situ and commercial production of seeds. This model has been widely adopted in the North and very partially in the South because it is based on strong policies options and investments not tailored for developing countries. The Convention on Biological Diversity in 1992 offers an alternate approach to current varietal research with the raise of the concept of “agrobiodiversity” that promotes forms of agriculture able ensuring maintenance of genetic resources for the future. Using actual examples, this chapter illustrates advances in different plant breeding situations for crops predominantly cultivated by family farmers. In forest areas farmers are involved in the processes of creating and disseminating new varieties of coffee and cocoa while maintaining sustainable their agroforestry systems that give them advantages when price in international markets fluctuates. In dry areas with high population growth and weak agricultural production, emphasis is given to participatory breeding methods for traditional food crops which have high adaptation and multiple traditional uses, for example, sorghum in Africa and quinoa in Chile. Finally, this chapter discusses how research, through companion modeling, encourages local seed production systems, and promotes their development by enhancing knowledge exchanges between actors and creating new partnerships.

Objectif: L’objectif de cette etude etait d’identifier les types et caracteristiques de grains preferes par les transformatrices pour produire une bonne qualite de malt de sorgho et/ou la biere traditionnelle de sorgho communement appelee dolo. Methodologie et resultats: Des enquetes semi-structurees ont ete realisees en 2015 dans dix localites reparties dans trois provinces du Burkina Faso (Kadiogo, Kouritenga, Mouhoun) aupres d’un echantillon global de 105 malteuses et de 105 brasseuses de dolo choisies de maniere aleatoire. L’analyse des donnees d’enquetes a ete realisee avec le logiciel Sphinx. Les resultats ont montre que le sorgho rouge est le type de grain prefere pour le maltage et le brassage du dolo. Les malteuses preferent le sorgho rouge surtout pour son aptitude a bien germer. Au sein des varietes de sorgho rouge, les grains durs sont les plus apprecies des brasseuses. Cependant, il existe des differences regionales dans ces preferences. Dans le Kadiogo, les brasseuses preferent autant les grains rouges et legers que les grains rouges et lourds tandis que dans le Kouritenga, les preferences vont en premier lieu pour les grains rouges lourds et durs puis pour les grains rouges et lourds. Quant au Mouhoun, les types de grains preferes par les brasseuses sont plus diversifies, avec une legere preference pour les grains rouges, lourds et durs, et les grains blancs et lourds sont assez bien apprecies. Conclusion et application des resultats: Cette etude a permis d’identifier les types et caracteristiques de grain de sorgho desires par les transformatrices de malt et de dolo. Elle fournit ainsi des informations techniques aux selectionneurs pour la creation des varietes de sorgho destinees a la production artisanale de malt et de biere de sorgho. Mots cles: Sorgho, qualite de grain, malt, biere traditionnelle English Title: What varieties of sorghum meet the demands of producers of malt and dolo in Burkina Faso English Abstract Objective: The objective of this study was to identify the types and characteristics of grain preferred by the processors to produce a good quality of sorghum malt and/or traditional sorghum beer commonly known as dolo. Methodology and results: Semi-structured surveys were conducted in 2015 in 10 locations in three provinces of Burkina Faso (Kadiogo, Kouritenga, Mouhoun) from a sample of 105 brewers and 105 dolo producers selected randomly. The data of the survey were analysed using Sphinx software. The results showed that red sorghum is the type of grain preferred for malting and brewing of the dolo. The brewers prefer red sorghum mainly for its ability to germinate well. Within the varieties of red sorghum, hard grains are the most popular among the brewers. However, there are regional differences in those preferences. In the Kadiogo, the brewers prefer both red and light grains and red and heavy grains while in the Kouritenga, preferences are primarily for red, heavy and hard grain, and then for red and heavy grains. As for the Mouhoun, types of grain preferred by brewers are more diverse, with a slight preference for red, heavy and hard grains, and, white and heavy grains are fairly appreciated. Conclusion and implementation of the results: This study identified the types and characteristics of sorghum grains desired by the malt and dolo processors. It thus provides technical information to breeders for the creating sorghum varieties for of the artisanal production of malt and dolo. Keywords: sorghum, malt, grain quality, traditional beer

International audience; Over the last decade, the merits of sorghum as a dedicated feedstock have been highlighted. The relevance of sorghum biomass as an energy or biomaterial source relies on the possibility that its composition meets the requirement of the different production processes. In order to better assess the phenotypic variation existing in sorghum for stem composition, 103 accessions representing a broad genetic panel of insensitive and moderate photoperiod-sensitive landraces were evaluated during two consecutive years at Montpellier, South of France. Our data confirmed the existence of a great range of variation for several key parameters of stem composition, in particular for crude protein, lignin content and in vitro organic matter degradation and at a less extent for fibre digestibility. Sugar content in stems estimated by Brix was positively correlated with cycle duration and dry stem yield. Lignin content and fibre digestibility, two key traits linked to the potential utilization of sorghum biomass for fodder and 2nd-generation energy source, were strongly (positive and negative, respectively) correlated with plant height but not linked with dry stem yield. These results indicated that both biomass yield and quality can be improved simultaneously. Variability of stem composition was highly structured according to the genetic origins of the accessions. Durra and kafir groups emerged as good sources of high fibre digestibility. The same two groups and the photoperiod-insensitive caudatum from Africa comprised the best accessions for high sugar content in stems. Several Chinese caudatum and bicolor-caudatum accessions included in this panel stand out for high lignin content. This information will be mobilized to broaden the genetic diversity relevant for on-going breeding programs of sweet and biomass sorghum for temperate areas.

Genetic control of flowering time in sorghum was investigated using a recombinant inbred lines population derived from a cross between IS 2807, a slightly photoperiod sensitive tropical caudatum landrace, and IS 7680,a highly photoperiod sensitive tropical guinea landrace. Progenies were sown with their parents at six different dates between 1995 and 1997 in Burkina Faso. Direct field measures and synthetic measures derived from the implementation of a model were used to characterize the photoperiod response. Emphasis was put to identify the most relevant traits to account for Basic Vegetative Phase (BVP) and photoperiod sensitivity sensus stricto. One QTL was detected on Linkage Group (LG) F for the traits related to BVP. Two QTLs were detected on LGs C and H for the traits related to the photoperiod sensitivity sensus stricto. This gives credit to at least partially independent genetic determinisms for those two components of photoperiod response. Evidences for possible orthology of the QTLs detected here with other QTLs and major genes involved in flowering time of sorghum and rice are discussed.

Quantitative trait loci (QTLS) for grain quality, yield components and other traits were investigated in two Sorghum caudatum x guinea recombinant inbred line (RIL) populations. A total of 16 traits were evaluated (plant height, panicle length, panicle compactness, number of kernels/panicle, thousand-kernel weight, kernel weight/panicle, threshing percentage, dehulling yield, kernel flouriness, kernel friability, kernel hardness, amylose content, protein content, lipid content, germination rate and molds during germination and after harvest) and related to two 113- and 100 point base genetic maps using simple (SIM) and composite (CIM) interval mapping. The number, effects and relative position of QTLs detected in both populations were generally in agreement with the distributions, heritabilities and correlations among traits. Several chromosomal segments markedly affected multiple traits and were suspected of harbouring major genes. The positions of these QTLs are discussed in relation to previously reported studies on sorghum and other grasses. Many QTLS, depending on their relative effects and position, could be used as targets for marker-assisted selection and provide an opportunity for accelerating breeding programmes.

Présentation de l'éditeur : Le sorgho est la cinquième céréale la plus cultivée au monde. Sa domestication en Afrique et la sélection depuis des millénaires ont abouti à de nombreux types morphologiques et utilisations. Bien adapté aux zones semi-arides, le sorgho a diffusé dans tous les continents. Aujourd'hui, culture vivrière primordiale pour les populations des zones arides et subarides, en Afrique surtout, le sorgho est également cultivé en zone tempérée pour l'alimentation animale. Sa grande plasticité adaptative et sa rusticité proviennent des caractéristiques du système racinaire et du photopériodisme, qualités valorisables dans des systèmes de culture agroécologiques. Ce sont également des atouts pour la production d'agrocarburant, conciliable avec la production de grain. Sur tous ces aspects, l'ouvrage apporte des connaissances approfondies et actualisées. De plus, il détaille les systèmes tropicaux de culture, la protection contre les déprédateurs, les questions de qualité de récolte et de technologie de transformation. Il informe aussi sur la sélection variétale et la production de semences. Cet ouvrage, rédigé par des chercheurs du Cirad, est destiné à tous les professionnels des zones tropicales. Les connaissances en anatomie, en physiologie et sur les fonctions agroécologiques intéresseront les enseignants et les étudiants, ainsi que des agriculteurs des zones tempérées à la recherche de cultures économes en intrants et de plantes de service. Sommaire : Avant-propos. 1. Importance économique : Le sorgho et les grandes céréales mondiales. Les grands pays producteurs de sorgho. 2. Diversité, classification et préservation : La classification botanique raciale des sorghos cultivés. La classification américaine des sorghos en working groups. La préservation ex situ de la diversité. 3. Origine et diffusion. 4. Morphologie : Les racines. La tige principale. Les talles basales. Les feuilles. Le pédoncule. La panicule. La graine. 5. Physiologie : Croissance et développement. Besoins environnementaux. 6. Bioagresseurs du sorgho : Les maladies fongiques, bactériennes et virales. Les strigas. Les insectes du sorgho. 7. Sélection et matériel végétal : La sélection paysanne et les variétés locales. La sélection variétale par la recherche. La sélection participative. 8. Production semencière : Production de semences des variétés-lignées. La production de semences d'hybrides. 9. Systèmes de culture : Les systèmes pluviaux. Les systèmes traditionnels de culture désaisonnée des sorghos : sorghos de décrue ou repiqués. Les systèmes de culture irriguée des sorghos tropicaux. Le sorgho en culture associée. 10. Fonction écologique : Les effets agronomiques du sorgho comme plante de couverture. Le sorgho comme plante régulatrice des bioagresseurs. Le sorgho comme plante pourvoyeuse. d'autres services environnementaux. 11. Récolte et postrécolte : La récolte. Le battage. Le nettoyage. Le séchage. Le stockage. 12. Transformation et qualité des grains : La structure physique des grains. La composition biochimique des grains. La transformation primaire : décorticage, mouture. La transformation secondaire : produits roulés. 13. Utilisations du sorgho : Le sorgho dans l'alimentation humaine traditionnelle. Les nouvelles formes de consommation : boulangeries, nouveaux produits. L'alimentation animale. Le sorgho agroénergie. Glossaire. Bibliographie. Sigles et acronymes. Sites Internet. Index

Comparative mapping within maize, sorghum and sugarcane has previously revealed the existence of syntenic regions between the crops. In the present study, mapping on the sorghum genome of a set of probes previously located on the maize and sugarcane maps allow a detailed analysis of the relationship between maize chromosomes 3 and 8 and sorghum and sugarcane homoeologous regions. Of 49 loci revealed by 46 (4 sugarcane and 42 maize) polymorphic probes in sorghum, 42 were linked and were assigned to linkage groups G (28), E (10) and I (4). On the basis of common probes, a complete co-linearity is observed between sorghum linkage group G and the two sugarcane linkage groups II and III. The comparison between the consensus sorghum/sugarcane map (G/II/III) and the maps of maize chromosomes 3 and 8 reveals a series of linkage blocks within which gene orders are conserved. These blocks are interspersed with non-homoeologous regions corresponding to the central part of the two maize chromosomes and have been reshuffled, resulting in several inversions in maize compared to sorghum and sugarcane. The results emphasize the fact that duplication will considerably complicate precise comparative mapping at the whole genome scale between maize and other Poaceae.

Les travaux presentes ici rendent compte d’une strategie de preservation et de valorisation de la diversite genetique des sorghos locaux du Burkina Faso. Celle-ci est basee sur l’incorporation d’un grand nombre de caracteres interessants et importants dans des populations ameliorees par selection recurrente participative pour differentes zones agro-ecologiques. Dans ce processus, sont respectes les preferences et besoins des producteurs dans toutes les phases de la creation des populations, depuis le choix de parents pour les croisements jusqu’a la gestion des populations par les producteurs dans leurs champs. Quatre populations ont ainsi ete creees pour trois zones agroclimatiques, chacune integrant huit a quinze varietes locales et trois a quatre varietes elites. Chaque population a ete ensuite amelioree durant deux a trois generations successives dans sa region cible. Les elements cles de cette phase d’adaptation ont ete l’identification, par les producteurs, des plantes mâles steriles pendant la floraison, la recolte, l’evaluation et la classification des plantes mâles steriles par preference et maturite. Le choix final des panicules pour la constitution des nouvelles populations est le resultat d’un partage des roles entre les producteurs, les organisations paysannes et les selectionneurs.

Communications du Colloque international sur la gestion des ressources génétiques en zone de savanes d'Afrique de l'Ouest, Bamako, 15 au 18 mai 2007. Article en libre accès : http://revues.cirad.fr/index.php/cahiers-agricultures/article/view/30702; International audience; Au Nicaragua, le Centre de coopération internationale en recherche agronomique pour le développement (Cirad) et le Centro international de agricultura tropical (CIAT) ont conduit entre 2002 et 2006 un projet de recherche sur la sélection participative du sorgho destiné aux petits producteurs des zones sèches. Ce projet a été mis en œuvre dans deux régions, en collaboration avec la recherche agricole nationale, des organisations non gouvernementales (ONG) et des organisations locales de producteurs. En ayant largement recours à du germoplasme africain, la stratégie appliquée de sélection variétale participative et décentralisée a permis d’identifier différentes lignées bien adaptées aux systèmes de culture locaux, apportant des gains significatifs en rendement et précocité par rapport aux cultivars locaux et avec une qualité de grain appropriée pour l’élaboration des tortillas et autres spécialités alimentaires locales. Par rapport à une approche conventionnelle centralisée, cette stratégie permet de diffuser plus rapidement une nouvelle variété avec de plus grandes chances d’adoption massive par les agriculteurs. En outre, elle contribue à accroître la diversité génétique et le nombre des variétés disponibles pour ces agrosystèmes vulnérables, à faibles intrants. Les schémas en cours de création variétale participative in situ annoncent à moyen terme du matériel génétique prometteur, plus performant et mieux adapté aux divers objectifs de production.

A near-saturated sorghum genetic linkage map was produced using RFLP, AFLP and morphological markers. First a composite, essentially RFLP-based genetic linkage map was obtained from analyses of two recombinant inbred populations. This map includes 343 loci for 11 linkage groups spanning 1352 cM. Since this map was constructed with many previously mapped heterologous probes, it offers a good basis for synteny studies. Separately, an AFLP map was obtained from the analysis of 168 bands revealed from 12 primer pair combinations. It includes 137 loci for 11 linkage groups spanning 849 cM. Taking into account the different data sets, we constructed a combined genetic linkage map including 443 loci spanning 1899 cM. Two main features are to be noted: (1) the distribution of AFLPs along the genome is not uniform; (2) an important stretching of the former core map is induced after adding the AFLPs.

Dinámicas campesinas y fitomejoramiento participativo: el caso de los sorgos blancos (Sorghum bicolor, L. Moench) en la región norte de Nicaragua. En las regiones secas de Nicaragua, los sorgos blancos representan un grano básico cada vez más importante para las familias campesinas pobres. Desde 2002, el CIRAD y el CIAT manejan en colaboración con ONGs y grupos de productores experimentadores un proyecto de fitomejoramiento participativo de los sorgos dirigido a los pequeños productores. En esta publicación, los autores describen el arranque de este proyecto en el departamento de Madriz, norte de Nicaragua, e indican los resultados más originales de esta fase inicial. Ésta empezó con un diagnóstico intenso sobre los sistemas de cultivos, las variedades, los problemas de producción, los usos del sorgo y una predefinición de los objetivos de selección. Se identificaron los actores y las prácticas de la producción y los intercambios de semillas. Paralelamente, las variedades locales de sorgo tortillero y millón fueron caracterizadas morfo-agronómicamente. Como resultados, se resaltan los cambios recientes en las variedades y los sistemas de cultivo, la adopción rápida de los sorgos de ciclo corto tortillero mediante procesos informales de intercambios de semillas; las características notables de las variedades locales de sorgo tortillero y millón fueron cuantificadas. Estos datos sirvieron para implementar las actividades de selección participativa e identificar los progenitores y cruzamientos para los esquemas de fitomejoramiento participativo. Como perspectivas, los autores proponen insertar más este proceso de fitomejoramiento participativo en los proyectos endógenos fortaleciendo la agricultura familiar con un enfoque agroecológico y extenderlo a otros temas, cultivos y zonas en un marco interinstitucional de investigación-acción para pequeños agricultores en zonas marginales.