Restauration de plages nues d’une brousse tachetée au Niger

Un essai de restauration de plages nues dfune brousse tachetee degradee du Parc National du W au sudouest du Niger a ete installe en 2007. Cet article etablit le bilan de cette restauration realisee par la plantation dfespeces locales dans des ouvrages antierosifs du type tranchees sylvopastorales. Dans la zonetemoin et dans la zone mise en defens par une cloture, le taux de survie des plants mis en place, leur croissance en hauteur et en diametre, la composition et la diversite floristique des herbacees ont ete suivis pendant trois ans (2007-2009). Lfeffet des ouvrages antierosifs sur lfhumidite du sol a ete evalue pendant lapremiere annee. Les analyses demontrent une amelioration nette des conditions ecologiques du site dfexperimentation, qui evolue progressivement vers lfetat dfune brousse tachetee, qui est lfecosysteme de reference. Lfamelioration de lfhumidite du sol induit des conditions beaucoup plus favorables pour la couverture vegetale. La richesse floristique dans la zone-temoin est passee en trois annees de 16 a 49, la diversite ƒ¿ de 2,1 a 4,42 et lfequitabilite de Pielou de 0,59 a 0,78. Dans la zone cloturee (mise en defens), la richesse floristique, la diversite ƒ¿ et lfequitabilite de Pielou sont respectivement passees en trois ans de 14 a 43, de 2,26 a 4,22 et de 0,53 a 0,79, ce qui traduit une amelioration progressive de la flore. Acacia senegal et Bauhinia rufescens ont enregistre les plus forts taux de survie et les plus importantes croissances en hauteur et en diametre. Les mortalites elevees des A. seyal et Ziziphus mauritiana sont vraisemblablement liees a la forte concentration de rongeurs que la presence dfune cloture ne gene guere. La pose couteuse dfune cloture nfest efficace que contre les grands mammiferes, ce qui se traduit toujourspar une croissance en diametre et en hauteur superieure pour la zone cloturee.Mots-cles : restauration ecologique, brousse tachetee, Acacia senegal, Acacia seyal, Bauhinia rufescens, Ziziphus mauritiana, ouvrage antierosif

Potentials in vegetable oils and various nutrients of eighteen varieties of Niger Cucurbitaceae

Citrullus Colocynthis and Lagenaria siceraria are two species of Cucurbitaceae whose seeds are used for the production of dough, cakes and edible oils in Niger. Yield in seeds of 18 varieties belonging to these two species were assessed on the Faculty experimental field. The average berries production was 17 berries per plant the first year in contrast 6 the second year. The best productivity was achieved with Citrullus colocynthis which gave 82 berries per plant the 1st year. The average yield in seeds was 180.15 kg/ha the first year and 704.30 kg/ha the second year. The determination of the physicochemical characteristics showed water, ashes, fat, and protein contents which vary respectively from 7 to 9.50%, 4.13 to 4.84%, 18 to 47% and 11 to 35%. The yield in seeds oil varied from 13.7 to 134 L per ha in the first year and 0.26 liters to 800 L per ha the 2nd year. These are the first studies on Cucurbitaceae which link agronomic and physicochemical characteristics of seeds. They showed very important nutrient contents and oil yield, and even higher than some conventionaloilseeds. Extraction of oils from these seeds could meet the need of the populations.Keywords: Cucurbitaceae, Niger, yield, seeds, oils, food security

Essai de germination et de croissance de Artemisia annua L. au Niger

L’essai a été conduit à la pépinière de l’INRAN de Niamey et à la cuvette de l’INRAN de Kollo, et a porté sur la germination, croissance, développement de Artemisia annua (l’hybride F2 et M), plante qui a des vertus  anti-paludique. Cette étude a pour objectif d’évaluer les meilleures  conditions de culture de artemisia annua et le meilleur substrat pour son adaptation. Le Niger, pays d’endémie du paludisme, maladie qui constitue la première cause de morbidité et de mortalité. Face à cette menace, les autorités ont opté pour l’utilisation des dérivés d’artémisinine comme molécule de choix dans la prise en charge du paludisme comme l’a recommandé l’OMS. Les tests de la levée en pépinière ont été effectués dans un bac à semis et un germoir en planche. Les plants ont été repiqués après levée dans des pots avec trois types de substrats (substrat dunaire,substrat de bas fond et substrat de sable du fleuve) afin de déterminer le meilleur substrat pour la culture de la plante en pépinière. Il ressort des résultats obtenus que le substrat de bas fond offre les meilleurs valeurs pour la hauteur, le diamètre au collet et le nombre de feuilles que les substrats dunaire et du fleuve. Les plants ont été transférés sur le site de Kollo et transplantés sur terre ferme. Pour la biomasse c’est la variété F2 qui a enregistrée les meilleurs rendements même si au niveau de la hauteur, elle enregistre les valeurs les plus basses comparativement à la variété M. Cette étude a montrée que Artemisia annua peut s’adapter au Niger et son introduction offre à la population un moyen supplémentaire de lutte contre le paludisme.Mots clés : Artemisia annua, artemisinine, paludisme, Niger

Effet de la combinaison des fumures organo-minérales et de la rotation niébé-mil sur la nutrition azotée et les rendements du mil au sahel

Peu de données existent sur la contribution en azote des légumineuses, et leurs impacts en présence des fumures sur la nutrition azotée des  céréales. Ainsi, pour évaluer les effets du niébé et des fumures organo-minérales sur la nutrition azotée et les rendements du mil subséquent, une expérimentation a été conduite de 2008 à 2009 à Sadoré au Niger. Dans un dispositif en split-plot, trois doses de résidus, de fumier et d’engrais minéraux ont été appliquées dans une rotation niébé-mil. La méthode isotopique de 15N a été utilisée pour déterminer le coefficient réel d’utilisation d’engrais azoté (CRU). En présence de résidus, le CRU a varié de 16 à 23%. Les doses du fumier ont entraîné sa variation de 16 à 22%. Le CRU du mil subséquent était de 30% contre 22% pour le mil en monoculture. Le mil subséquent a prélevé du sol 54 kg N ha-1 contre 38 kg N ha-1 pour le mil en continu. Les doses des fumures et leur  combinaison dans les systèmes de culture, ont augmenté les rendements du mil de 17 à 272%. La nutrition azotée et la productivité des systèmes peuvent donc être améliorées en combinant les fumures organo-minérales et les rotations avec légumineuses.Mots clés : Céréale, légumineuse, rotation, azote, dilution isotopique, Niger

Natural Categorization: Electrophysiological Responses to Viewing Natural Versus Built Environments

Environments are unique in terms of structural composition and evoked human experience. Previous studies suggest that natural compared to built environments may increase positive emotions. Humans in natural environments also demonstrate greater performance on attention-based tasks. Few studies have investigated cortical mechanisms underlying these phenomena or probed these differences from a neural perspective. Using a temporally sensitive electrophysiological approach, we employ an event-related, implicit passive viewing task to demonstrate that in humans, a greater late positive potential (LPP) occurs with exposure to built than natural environments, resulting in a faster return of activation to pre-stimulus baseline levels when viewing natural environments. Our research thus provides new evidence suggesting natural environments are perceived differently from built environments, converging with previous behavioral findings and theoretical assumptions from environmental psychology

Interet D’une Supplementation En Spiruline Chez Les Enfants Drepanocytaires Homozygotes A L’hopital National De Niamey. (Essai Clinique Randomise En Double Aveugle A Propos De 53 Cas)

Spirulina is a micro algae used for thousands of years due to its healing properties. We supplemented children suffering from sickle cell anemia in order to appreciate its impact on the anthropometrical and clinical parameters. It consisted of a randomized clinical double blind test which was carried during a period of 9 months. The study concerned 53 homozygotes children suffering from sickle cell anemia aged 6 months to 15 years. Also, they were visiting the National Hospital of Niamey for follow up. One group (28 children) received 5 g of spirulina daily, and the other group (25 children) received placebo. The aspects studied were: the number of hospitalizations and transfusions, the vaso-occlusive crisis, the body mass index, and the splenomegalia. We found that 84.90% of patients were hospitalized at least once and 45.3% of them have already been transfused. The average number of crisis has greatly decreased in the spirulina group from 2.75 before the study to 1.18 at the end of the study. This, thus, was observed when compared to 2.44 to 1.6 in the placebo group. We also noticed a decrease of the number of hospitalizations and the number of transfusions which is less important in the group supplemented with spirulina. In conclusion, this study showed that supplementation in spirulina had a significant impact on children suffering from sickle cell anemia. This is even despite the fact that the difference between the two groups is not significant in some cases

Water use, transpiration efficiency and yield in cowpea (Vigna unguiculata) and peanut (Arachis hypogaea) across water regimes

Genotypic variation in crop response to drought depends on agronomic, environmental and genetic factors, and only limited work has compared responses of crop species to water limitation. Twenty genotypes of peanut (Arachis hypogaea L.) and of cowpea (Vigna unguiculata (L.) Walp) were tested in lysimeters under well-watered (WW) and water-stress (WS) conditions during two seasons, a post-rainy season with high evapotranspiration and a rainy season with low evapotranspiration (ET), in order to assess: (i) variability in the agronomic response to stress within and between species across the seasons; (ii) the water requirement of the two crops in each season; and (iii) the stress effect on harvest index (HI), transpiration efficiency (TE), pod yield and haulm yield. Cowpea required less water than peanut during the two seasons, and water use in cowpea varied less across seasons than in peanut. Peanut yield was more sensitive to water stress than cowpea yield, although its water use under WS was higher than in cowpea. Also, under WS conditions, TE, HI and pod yield were more stable across season in cowpea than in peanut. In the post-rainy season, the decrease in pod yield and HI under WS was higher in peanut (95% and 80%, respectively) than in cowpea (70% and 35%). In addition, TE was less affected by WS in cowpea (5%) than in peanut (24%). HI explained a large part of yield variation in both crops, especially under WS. Under WW, water use explained a large portion of the residual yield variations unexplained by HI, although TE also explained a substantial part of the variation in cowpea. Under WS, the main determinant of residual yield variations in both crops was TE. Generally, genetic variation for water use, TE and HI was found in both species across water regimes and seasons. A notable exception was the absence of variation in peanut water use and TE in the rainy season. Our results showed that cowpea, with lower water requirement and efficient water use under a high-ET season, was more resilient to water-limited and high-ET conditions than peanut

An Examination of Children’s Learning Progression Shifts While Using Touch Screen Virtual Manipulative Mathematics Apps

The purpose of this study was to examine shifts in young children\u27s learning progression levels while they interacted with virtual manipulative mathematics apps on touch-screen devices. A total of 100 children participated in six mathematics learning sequences while using 18 virtual manipulative mathematics touch-screen apps during clinical interviews. Researchers developed a micro-scoring tool to analyze video data from two camera sources (i.e., GoPro camera, wall-mounted camera). Our results showed that it is possible to document evidence of shifts in children\u27s learning progressions while they are interacting with mathematics apps on touch-screen devices. Our results also indicated patterns in the children\u27s interactions that were related to the shifts in their learning progression levels. These results suggest that an open-ended number of tasks with a variety of representations and tasks at varying levels of difficulty led to children refining their understanding and shaping their concept image of mathematical ideas resulting in incremental shifts in learning. The results of this study have important implications about how mathematical tasks in touch-screen apps may prompt children\u27s incremental learning progression shifts to occur, and thereby promote opportunities for learning. We propose that design features in mathematics apps can be created to support and encourage these learning shifts