Water-condition effects on rhizobia competition for cowpea nodule occupancy

Two indigenous bradyrhizobia strains displaying different natural behaviours towards water regime (strain ORS 3257, nodulating more frequently in favourable-water conditions and strain ORS 3260, in limited-water conditions) were studied for their competitivity for nodulation of cowpea (Mouridecultivar) under favourable and limited water conditions in non-sterile soil. The nodule occupancy was studied by PCR-RFLP analysis. Both strains showed good competition with other indigenous rhizobia populations under favourable- and limited-water conditions. Competition between the inoculatedstrains in the mixture varied between water regimes. In non-limited-water conditions, strain ORS 3257 was the best competitor, whereas in limited-water conditions, strain ORS 3260 was the best competitor. Results indicated that screening of strains according to their environmental origin could ensuresuccessful rhizobia inoculatio

Senna occidentalis L., une plante prometteuse dans la lutte contre Caryedon serratus Ol. (Coleoptera, Bruchidae), insecte ravageur des stocks d’arachide au Sénégal

Dans la perspective de concevoir une stratégie de protection intégrée des nuisibles associés aux produits post-récolte au Sénégal, la bioactivité des extraits et huile essentielle de Senna occidentalis L. sur les oeufs et adultes de Caryedon serratus (Ol.), a été étudiée. Les extraits bruts (éthéré et méthanolique) et fractions d’extrait (hexane, acétate d’éthyle, méthanol) ont été appliqués sur l’insecteà 0,1 ; 0,01 et 0,001 g/ml. Les principaux résultats révèlent que S. occidentalis L. affectent significativement la survie des stades traités, selon sa concentration et sa polarité. L’extrait éthéré et la fraction hexanique provoquent 79,17% de mortalité embryonnaire en C1, tandis que la fraction méthanolique tue 39,58% des oeufs en C1. Les produits polaires (extrait et fraction méthanoliques) provoquent respectivement 69,92 ± 2,87% et 72,01 ± 6,86%de mortalités d’adulte. Par contre, ceux apolaires (éthéré et hexanique) tuent respectivement en moyenne 30,41 ± 1,74% et 27,9 ± 0,34% des adultes. L’activité adulticide de l’huile essentielle augmente avec la concentration (91,67% pour 3 ml/l et 30,56% pour 1 ml/l). Cette bioactivité s’exprime aussi par un déséquilibre du sex-ratio en faveur de mâles, une modification du cycle de développement, une fécondité réduite de 67,2% pour la fraction acétate et une fertilité limitée.Mots clés : Caryedon serratus, arachide, Senna occidentalis, plantes biocides

Yield stability analysis of promising pearl millet genotypes in Senegal

Genotype environment interaction in pearl millet (Pennisetum glaucum (L.) R. Br.) was studied for grain yield by growing 10 to 12 genotypes at 4 locations for 4 years in Senegal. Genotype environment interaction was present; a large portion of the interaction was accounted for by the non-linear regression on the environmental means. Although the linear component was significant, its magnitude was considerable smaller than that of the non-linear component. All the genotypes except Souna III were stable and their responses to changes in environments could be predicted. The highest yielding entry was IBV 8001 which was significantly superior to the local checks in terms of grain yield production. IBV 8001 was the most desiderable genotype as it had the highest grain yield and slope of unity, and the mean square due to deviation from regression was zer

Registration of 'ICMV 2' Pearl Millet

The Pennisetum glaucum [P. americanum] cv. ICMV2, was developed by bulking equal quantities of seed from the 3 paired crosses among the following 3 entries: a line from Nigeria resistant to downy mildew (Sclerospora graminicola), 700516; a composite from Uganda (Serere 2A); and a Cassidy dwarf population from Kansas acquired from Uganda. In 111 replicated yield trials in 19 environments (3-4 sites per year) in Senegal during 1980-84, average yield of ICMV2 was 119% that of Souna III. ICMV2 is of medium height (1.8-2.8 m) with robust stems. It flowers in 47 to 68 days and matures in 85 to 100 days. ICMV2 is resistant to Sclerospora graminicola and Moesziomyces bullatus. Ear heads are compact, making the cultivar tolerant of raghuva moth (Raghuva albipunctella). Grains are medium-sized, with a 1000-grain weight of 6.0 to 9.4 g, and have vitreous endosperm. Seed dormancy and tolerance of mold damage during ripening in humid conditions are adequat

Arbuscular mycorrhizal fungi associated with the rhizosphere of Piliostigma reticulatum and Guiera senegalensis shrubs in Senegal

Piliostima reticulatum and Guiera senegalensis shrubs constitute \u201cislands of soil fertility\u201d in the rhizosphere, with better availability of water and more intense biological activity in the Sudano-Sahelian agro-ecosystems. There is, however, paucity of information on diversity of arbuscular mycorrhizal fungi (AMF) fungi, which have a wide ecological range of associations with a variety of vegetation. The purpose of this study was to identify the types of AMF in the rhizospheres of P. reticulatum and G. senegalensis shrubs in Senegal. Soil samples were collected from around the shrubs in Keur Matar Arame and Keur Ndary Ndiaye in 2019 after a rainy season. Arbuscular mycorrhizae fungi spores were isolated by the wet sieving method and identified based on their morphological characteristics (shape, size, colour, attached hyphae, and spore ornamentation). Four types of AMF were identified, namely Glomus aggregatum, Sclerocystis rubiformis, Gigaspora margarita and Scutellospora gregaria. In addition, the density of spores was more abundant in the soil outside the shrub canopy compare to the soil beneath the shrub.Les arbustes Piliostima reticulatum et Guiera senegalensis constituent des \uab \ueelots de fertilit\ue9 \ubb dans la rhizosphere des sols, avec une meilleure disponibilit\ue9 en eau et une activit\ue9 biologique plus intense dans les agro-\ue9cosyst\ue8mes soudano-sah\ue9liens. Cependant, Il y a peu d\u2019informations sur la diversit\ue9 des champignons mycorhiziens arbusculaires (CMA) qui peuvent s\u2019associer avec une large vari\ue9t\ue9 de plantes. Le but de cette \ue9tude est d\u2019identifier les types de CMA dans les rhizosph\ue8res des arbustes P. reticulatum et G. senegalensis au S\ue9n\ue9gal. Des \ue9chantillons de sol ont \ue9t\ue9 collect\ue9s autour des arbustes \ue0 Keur Matar Arame et Keur Ndary Ndiaye en 2019 apr\ue8s la saison des pluies. Les spores de champignons mycorhiziens arbusculaires ont \ue9t\ue9 isol\ue9es par la m\ue9thode de tamisage humide et identifi\ue9es en fonction de leurs caract\ue9ristiques morphologiques (forme, taille, couleur, hyphes attach\ue9s et ornementation des spores). Quatre types de CMA ont \ue9t\ue9 identifi\ue9s, \ue0 savoir Glomus aggregatum, Sclerocystis rubiformis, Gigaspora margarita et Scutellospora gregaria. De plus, la densit\ue9 des spores \ue9tait plus abondante dans les sols hors couvert que dans les sols sous-couvert des arbustes

Population Growth and Forest Sustainability in Africa

Recent distressing trends in climate change, population explosion and deforestation inspired this paper, which completes existing literature by providing empirical justification to hypothetical initiatives on the impact of population growth on forest sustainability in Africa. Using three instruments of forest exploitation, the study shows how rural, agricultural and national population growths affect forest-area and agricultural-land. In this particular study the findings indicate that instruments of forest exploitation do not explain changes in forest-area and agricultural-land beyond population growth mechanisms. Hence, population growth channels are a driving force by which forest-area and agricultural-land are depleted and expanded respectively. As a policy implication in the process of deforestation, a balanced approach is needed to take account of the interests of both; a green economy promoting sustainable development and the growing population needs