Growth and development of date palm (Phoenix dactylifera L.) seedlings under drought and salinity stresses

The present investigation has been performed to evaluate date palm (Phoenix dactylifera L.) tolerance to osmotic stress induced by polyethylene glycol (PEG) or NaCl during the early stages of plant development. Two varieties Nakhla hamra (NHH) and Tijib widely cultivated in Mauritania were tested.NHH showed increasing of epicotyl length, primary root length, secondary root number and proline content when water deficit was induced by PEG. In contrast, on the basis of the same developmental and biochemical characters, the Tijib cultivar was more tolerant in salinity stress. This difference of cultivars’ behavior according the growth conditions is discussed

Relationships between soil seed banks and above-ground vegetation along a disturbance gradient in the W Park trans-boundary biosphere reserve, West Africa

Aims: Vegetation succession depends on the availability of suitable propagules in the soils, thus knowledge of soil seed banks is essential for formulating effective strategies for restoring the vegetation of degraded sites. The W National Park, the only trans-boundary biosphere reserve in West Africa, is being extensively fragmented and degraded in recent decades. The aims of this study were to assess the reserve’s soil seed banks, their relationships with standing vegetation and bundle of disturbances, and their potential significance for vegetation restoration. Methods: The size and composition of the above-ground species vegetation were assessed in nine plots of 1 ha each representing a range of habitats with differing disturbance severity (low, intermediate and high). A total of 702 soil samples were taken from three layers (0-3, 3-6 and 6-9 cm) and soil seed bank was analyzed using the seedling emergence technique. Important Findings: Generally, seeds of non-woody taxa dominated in samples from all soil depths and habitats of all disturbance severities. The mean soil seed density was 17.8, 24.4 and 26.3 seeds dm-3 in samples from the least, intermediate and most disturbed sites, respectively, and highest in the upper soil layers in all cases. The results indicate that there is limited potential for restoring woody vegetation solely from soil seed banks, and that woody species in the region rely more on recently shed seeds trapped in the standing dead biomass and litter on the ground than soil seed banks for regeneration. Thus, human intervention is needed to accelerate forest recovery, mainly through alleviating anthropogenic impacts on the ecosystem (for instance, avoiding destruction of new seeds by intense fire), and site manipulation to improve environmental conditions for seedling establishment and growth

Sensory diversity of fonio landraces from West Africa

This study aims to establish if there is some sensory variability among fonio landraces. Fonio, the oldest indigenous and very tasty cereal growing in West Africa, is usually consumed as a couscous. Group interviews of consumers were conducted in Bamako, Mali to identify the main quality criteria of a cooked grain. Fonio grain must be swollen, not sticky with a soft consistency, pale and containing low impurities. Sensory properties of 20 fonio landraces from Mali, Guinea and Burkina Faso were established using a descriptive sensory analysis. Five sensory descriptors were chosen among the quality criteria. Each landrace was tasted and scored in triplicate by a group of 18 trained panellists. Principal component analysis and hierarchical cluster analysis were used. The 20 landraces clustered into four sensory classes. Sensory criteria of variability were first visual characteristics (colour and impurities) and then the consistency of cooked grains. Landraces from Guinea and Mali were variable for both visual and textural characteristics; those from Burkina Faso appeared to be more homo-genous. The sensory variability of fonio offers to processors, who intend to promote this tiny cereal both in the sub-region and beyond, the possibility to choose adapted landraces to develop new products

La Pathologie Anorectale Au Chu Campus De Lome (Togo)

Objective: To describe the clinical and endoscopic presentation of anorectal pathologies in the gastroenterology department of the CHU campus of Lomé. Patients and methods: Retrospective study based on reports of low digestive endoscopy carried out at the university teaching hospital Campus of Lome. We collected the age of the patients, their sex, the indications of the examination and the different anorectal lesions encountered. Results: The mean age was 41.8 ± 14.3 years. There was a predominance of 30-40 years (38.8%). There was also a male predominance with a sex ratio of 1.6. The most frequent indication was rectal bleeding (64.1%). Anal pain was found in 40.8% of cases. The most frequent lesions were hemorrhoids (69.9%) and anal fistula in 8.7% of cases. Cancer of the anus was rarely observed (1.9%) as was the rectal polyp (0.1%). Conclusion: Anorectal pathologies are relatively frequent in our department, especially in young patients and are dominated by hemorrhoidal disease

Windborne long-distance migration of malaria mosquitoes in the Sahel

Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa1,2. Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3–8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration3. Here we confirm this hypothesis through aerial sampling of mosquitoes at 40–290 m above ground level and provide—to our knowledge—the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii, were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000 Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus. These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled

Food quality profile of pounded yam and implications for yam breeding

Open Access ArticleBACKGROUND Assessment of the key preferred quality traits in pounded yam, a popularly consumed yam food product in West Africa, is often done through sensory evaluation. Such assessment is time-consuming and results may be biased. Therefore, there is a need to develop objective, high-throughput methods to predict the quality of consumer-preferred traits in pounded yam. This study focused on how key quality traits in pounded yam proposed to yam breeders were determined, measured by biophysical and biochemical methods, in order to shorten the breeding selection cycle through adoption of these methods by breeders. RESULTS Consumer tests and sensory quantitative descriptive analysis (QDA) validated that preferred priority quality traits in pounded yam were related to textural quality (smooth, stretchable, moldable, slightly sticky and moderately hard) and color (white, cream or light yellow). There were significant correlations between sensory textural quality attributes cohesiveness/moldability, hardness, and adhesiveness/stickiness, with textural quality measurements from instrumental texture profile analysis (TPA). Color measurement parameters (L*, a*, and b*) with chromameter agreed with that of sensory evaluation and can replace the sensory panel approach. The smoothness (R2 = 1.00), stickiness (R2 = 1.00), stretchability (R2 = 1.00), hardness (R2 = 0.99), and moldability (R2 = 0.53) of pounded yam samples can be predicted by the starch, amylose, and protein contents of yam tubers estimated by near-infrared spectroscopy. CONCLUSION TPA and Hunter colorimeter can be used as medium-high throughput methods to evaluate the textural quality and color of pounded yam in place of the sensory panelists

Carbone des sols en Afrique

Les sols sont une ressource essentielle à préserver pour la production d’aliments, de fibres, de biomasse, pour la filtration de l’eau, la préservation de la biodiversité et le stockage du carbone. En tant que réservoirs de carbone, les sols sont par ailleurs appelés à jouer un rôle primordial dans la lutte contre l’augmentation de la concentration de gaz à effet de serre. Ils sont ainsi au centre des objectifs de développement durable (ODD) des Nations unies, notamment les ODD 2 « Faim zéro », 13 « Lutte contre le changement climatique », 15 « Vie terrestre », 12 « Consommation et production responsables » ou encore 1 « Pas de pauvreté ». Cet ouvrage présente un état des lieux des sols africains dans toute leur diversité, mais au-delà, il documente les capacités de stockage de carbone selon les types de sols et leurs usages en Afrique. Il propose également des recommandations autour de l’acquisition et de l’interprétation des données, ainsi que des options pour préserver, voire augmenter les stocks de carbone dans les sols. Tous les chercheurs et acteurs du développement impliqués dans les recherches sur le rôle du carbone des sols sont concernés par cette synthèse collective. Fruit d’une collaboration entre chercheurs africains et européens, ce livre insiste sur la nécessité de prendre en compte la grande variété des contextes agricoles et forestiers africains pour améliorer nos connaissances sur les capacités de stockage de carbone des sols et lutter contre le changement climatique

Resilience of Sudanian: savanna-woodlands in Burkina Faso

The savanna-woodlands of West Africa have been subject to disturbance by fire, grazing and tree cutting for centuries. Often the disturbance is severe, for instance when a thick patch of 4 m tall perennial grass catches fire late in the dry season or man decides to clear-cut an area. Fortunately Mother Nature is very forgiving and the woodlands show remarkable resilience. Research plots were established in the Laba and Tiogo State forests in Burkina Faso in 1992. The plots have been monitored by research institutions from Burkina Faso and Sweden ever since. The results show great inter-annual variation in grass species richness, abundance and diversity at both sites. The combined effects of fire, grazing and tree cutting were limited and varied between life forms. Grazing tended to favor diversity of perennial grasses and fire affected the richness of annual grasses. The herbaceous biomass was reduced by the presence of livestock but the effect was not statistically significant for early fire or selective tree cutting. Fire had a homogenizing effect at the species level with increased biomass of the most abundant annual grass Loudetia togoensis and decreased biomass of the most abundant perennial grass Andropogon gayanus. Fire, grazing and selective tree cutting acted independently on the population dynamics of tree saplings. Many responses are site or species specific which accentuates the importance of landscape-level approaches to understand the impacts of disturbance on structure and function of the savanna ecosystems. The lack of treatment results at some levels clearly show how resilient the woodlands are to disturbance

Resilience of Sudanian: savanna-woodlands in Burkina Faso

The savanna-woodlands of West Africa have been subject to disturbance by fire, grazing and tree cutting for centuries. Often the disturbance is severe, for instance when a thick patch of 4 m tall perennial grass catches fire late in the dry season or man decides to clear-cut an area. Fortunately Mother Nature is very forgiving and the woodlands show remarkable resilience. Research plots were established in the Laba and Tiogo State forests in Burkina Faso in 1992. The plots have been monitored by research institutions from Burkina Faso and Sweden ever since. The results show great inter-annual variation in grass species richness, abundance and diversity at both sites. The combined effects of fire, grazing and tree cutting were limited and varied between life forms. Grazing tended to favor diversity of perennial grasses and fire affected the richness of annual grasses. The herbaceous biomass was reduced by the presence of livestock but the effect was not statistically significant for early fire or selective tree cutting. Fire had a homogenizing effect at the species level with increased biomass of the most abundant annual grass Loudetia togoensis and decreased biomass of the most abundant perennial grass Andropogon gayanus. Fire, grazing and selective tree cutting acted independently on the population dynamics of tree saplings. Many responses are site or species specific which accentuates the importance of landscape-level approaches to understand the impacts of disturbance on structure and function of the savanna ecosystems. The lack of treatment results at some levels clearly show how resilient the woodlands are to disturbance