In the Sahel of Africa, farmers often modify their cultivation practices to adapt to environmental changes. How these changes shape the agro-biodiversity is a question of primary interest for the conservation of plant genetic resources. We addressed this question in a case study on pearl millet in south western Niger where farmers used to cultivate landraces with different cycle length in order to cope with rain uncertainty. Early and late landraces were previously grown on distant fields. Nowadays, mostly because of human population pressure and soil impoverishment, it happens that the two types of landraces are grown on adjacent fields, opening the question whether gene flow between them may occur. This question was tackled through a comparative study among contrasting situations pertaining to the spatial distribution of early and late landraces. Observations of flowering periods showed that pollen flow between the two landraces is possible and has a preferential direction from early to late populations.
Despite of a growing interest in considering the role of sociological factors in seed exchanges and their consequences on the evolutionary dynamics of agro-biodiversity, very few studies assessed the link between ethno-linguistic diversity and genetic diversity patterns in small-holder farming systems. This is key for optimal improvement and conservation of crop genetic resources. Here, we investigated genetic diversity at 17 SSR markers of pearl millet landraces (varieties named by farmers) in the Lake Chad Basin. 69 pearl millet populations, representing 27 landraces collected in eight ethno-linguistic farmer groups, were analyzed. We found that the farmers’ local taxonomy was not a good proxy for population’s genetic differentiation as previously shown at smaller scales. Our results show the existence of a genetic structure of pearl millet mainly associated with ethno-linguistic diversity in the western side of the lake Chad. It suggests there is a limit to gene flow between landraces grown by different ethno-linguistic groups. This result was rather unexpected, because of the highly outcrossing mating system of pearl millet, the high density of pearl millet fields all along the green belt of this Sahelian area and the fact that seed exchanges among ethno-linguistic groups are known to occur. In the eastern side of the Lake, the pattern of genetic diversity suggests a larger efficient circulation of pearl millet genes between ethno-linguistic groups that are less numerous, spatially intermixed and, for some of them, more prone to exogamy. Finally, other historical and environmental factors which may contribute to the observed diversity patterns are discussed.
RESUMELe Niger fait partie des pays les plus vulnérables au monde en raison du contexte lié à son climat, son environnement et à son économie. Le pays se classe au bas de l'échelle sur la quasi-totalité des indicateurs de développement humain. L'agriculture est le secteur le plus important de l'économie du Niger. Elle représente plus de 40% du produit intérieur brut national et constitue la principale source de revenus pour plus de 80% de la population. La performance du secteur agricole est néanmoins très instable du fait de sa forte exposition aux changements climatiques. Au cours des 30 dernières années, le Niger a subi de nombreuses sécheresses, inondations, invasions des criquets et autres attaques parasitaires. Ces catastrophes portent un coup aux revenus des ménages, à la performance du secteur agricole, à l'équilibre budgétaire de l'État et au taux de croissance économique du Niger. Conscients de la nécessité de s'attaquer spécifiquement aux problèmes agricoles dans tous ses aspects, les chercheurs de l'Institut National de Recherche Agronomique du Niger, les cadres de l'Agriculture et ceux de l'Université Abdou Moumouni donnent un aperçu des contraintes de la production agricole et proposent quelques axes d'interventions pour y remédier. © 2016 International Formulae Group. All rights reserved.Mot clés: Agriculture, contraintes, production, changement climatique, Niger.The agricultural production system in Niger face climate change: challenges and opportunities ABSTRACTNiger is one of the most vulnerable countries in the world because of its climatic and environmental context. The country is at the bottom of the scale according to human development index. Agriculture is the most important activity in Niger. It represents more than 40% of the national gross domestic product and is the main source of income for more than 80% of the population. However, the performance of the agricultural sector is very unstable due to its high exposure to climate change. Over the past 30 years, Niger has suffered many droughts, floods, invasions of locusts and other parasitic attacks. These disasters strike a blow to the Z. ABDOUL HABOU et al. / Int. J. Biol. Chem. Sci. 10(3): 1262-1272, 2016 1263 household income, the performance of the agricultural sector, impacted on the national budgets and the rate of economic growth. The researchers from National Institute of Agronomic Research of Niger and their colleagues from University of Niamey proposed an overview to explain the constraints of agricultural production and gave a few axes of intervention for solutions.
Jatropha curcas has been introduced into Niger since 2004 by International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). This plant is cultivated for its oil, which can be used as a Biofuel. Through direct and indirect insect collection methods, an inventory of the insect associated with J. curcas has been conducted in Western Niger during two rainy seasons (from June to October) in 2010 and 2011. We have identified insects belonging to the following families: Acrididae ( Oedaleus senegalensis Krauss , Oedaleus nigeriensis Uvarov, Heteracris leani Uvarov, Catantops stramineus Walker, Parga cyanoptera Uvarov, and Acanthacris ruficornis citrina Audinet-Serville), Pyrgomorphidae ( Poekilocerus bufonius hieroglyphicus Klug), Cetoniidae ( Pachnoda interrupta Olivier, Pachnoda marginata aurantia Herbst, Pachnoda sinuata Heinrich and McClain, and Rhabdotis sobrina Gory and Percheron), Meloidae ( Decapotoma lunata Pallas), Pentatomidae ( Agonoscelis versicoloratus Dallas, Nezara viridula Linn, and Antestia sp. Kirkaldy), Coreidae ( Leptoglossus membranaceus Fabricius and Cletus trigonus Thunberg), and Scutelleridae ( Calidea panaethiopica Kirkaldy). Origin and potential impact on J. curcas of all these insect species are presented and discussed. The lower insect’s diversity indexes are observed in 2010 and 2011 for Niamey, Saga, and Gaya because of semi-arid character of the Sahelian area.
RESUME Vingt et une (21) variétés et/ou écotypes locaux d'oignon collectés dans différentes régions duNiger ont été caractérisés dans la station expérimentale de l'INRAN à Konni dans le sud-est du Niger. Les caractères agronomiques qualitatifs et quantitatifs étudiés sont ceux recommandés par l'Institut International des Ressources Phytogénétiques (IPGRI, 2001). Ainsi, la longueur, la largeur, le poids, la couleur et la densité des feuilles, le port, la vigueur des plants, le poids, le diamètre, la hauteur, la couleur et l'uniformité des bulbes et le nombre de bourgeons végétatifs ont été observés. A l'issue de l'analyse des résultats, il ressort une corrélation positive entre la longueur des feuilles et la hauteur de bulbes (0,704), le diamètre des bulbes et le rendement (r 2 = 0,653), la hauteur et le diamètre des bulbes (r 2 = 0,618), le nombre de bourgeons végétatifs et la matière sèche (r 2 = 0,570), et la longueur des feuilles et le cycle (r 2 = 0, 522). Après analyse des caractères agro-morphologiques et physiologiques quantitatifs, trois groupes ont été remarqués dont 71% de variétés et/ou écotypes locaux pour le premier, 19% pour le deuxième et 10% pour le troisième, tandis qu'aucune corrélation n'a été observée au niveau des caractères qualitatifs. La variabilité observée dans les groupes est plus grande que celle qui existe entre les groupes, ce qui explique la présence des écotypes de différentes couleurs et différentes régions dans un même groupe. Une analyse moléculaire est plus que nécessaire pour confirmer cette diversité des variétés et/ou écotypes locaux d'oignon du Niger.
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