Removal of faecal bacteria and nutrients from domestic wastewater in a horizontal surface flow wetland vegetated with Echinochloa pyramidalis

The aim of this study was to evaluate the removal of faecal bacteria and nutrients from domestic wastewater, in surface flow wetlands vegetated with Echinochloa pyramidalis. Horizontal surface flow (HSF) wetlands were fed with primarily treated domestic wastewater at organic loading rates varying from 20.74 to 27.15 g BOD/m2/day for two consecutive years. Water samples were collected at two weeks interval from the inflow and the outflow of the treatment wetlands for physicochemical and faecal bacteria analyses. Physicochemical parameters with highest removal rates were total suspended solids (TSS, 62-80%), Nitrates (57-73 %) and PO4-3 (57-84 %). Faecal indicators reductions of 1.4 and 0.3 log units (1st year) and 1.15 and 0.65 log units (2nd year) were respectively recorded in the vegetated and the control wetlands. Reductions of total coliforms, faecal coliforms and faecal streptococci were significantly higher in the vegetated wetland than in the non-vegetated control in both seasons of the first year. In the contrary, there was no significant difference in the removal rates of faecal indicators between vegetated wetland and the non-vegetated control during the dry season of the second year. Wetlands vegetated with E. pyramidalis was proven to be continuously efficient in the removal of faecal indicators for the two years of study, with no significant differences between the seasons of the year and between the years.Key words: Wastewater, wetlands, Echinochloa pyramidalis, faecal bacteria removal, nutrients removal

EFFECTS OF THE REUSE OF UNTREATED WATER FROM THE AVO’O RIVER (CAMEROON) CONTAMINATED BY FECAL SLUDGE FOR THE GROWTH OF SOLANUM NIGRUM L.

Objective: The main objective of this research was to evaluate the growth parameters and sanitary quality of Solanum nigrum L. irrigated with polluted water from Avo’o river in Nomayos. Methods: Faecal sludge, water from Avo’o River and Solanum nigrum L., were analysed with respect to microbiological and parasitological parameters. Four points (S0: Control site, located in Mbankomo at 3 km away from faecal sludge discharge area; S1: located at 810 m before the faecal sludge discharge area; S2: located at 100 m away from the faecal sludge discharge area; and S3: located at 350 m after the faecal sludge discharge area) were considered for sampling events. For faecal indicator (FC: Faecal coliforms and FS: Faecal Streptococci), the membrane filtration method was used. Helminthes eggs were determined using the method of Bailenger, modified by Rodier. The growth parameters of S. nigrum L., measured in different site mentioned above, were plant height, number, length and width of fresh leaves. Results: High concentration of FC (6857 ± 5180) and FS (2500 ± 1876 CFU/100 ml), as well as helminths eggs (273 ± 186 eggs/L) were obtained in Avo’o water samples. The strong correlations (r=0.9) clearly show that the waters of the Avo’o stream influence the growth of S. nigrum L. Conclusion: Despite the best growth of Solanum Nigrum L. irrigated with water from Avo’o River, high concentration of parasites was obtained on their leaves (43 eggs/100 g) highlight the necessity of a better management of faecal sludge in this city

Phytosanitary situation of maize streak virus in the main maize production zones of Cameroon

Open Access Article; Published online: 09 Apr 2021Maize streak caused by the Maize streak virus (MSV, genus Mastrevirus) is transmitted by Cicadulina spp., and is responsible for considerable maize yield losses in all maize production zones in Africa, including Cameroon. A survey was conducted in 3 agro-ecological zones (AEZ) of Cameroon (Sudano-Sahelian: zone I, Western Highlands: zone III and Bimodal Rainforest: zone V) between November 2017 and November 2019 to determine the status of streak disease in maize farms. The incidence and severity were determined in 90 maize fields, 30 fields per AEZ; the effect of lightning on the disease was also assessed using 15 fields under shade and 15 opened fields per AEZ. The highest streak disease incidence (60%) was found in AEZ I, whereas the lowest incidence was 10% in AEZV. The highest disease incidence and severity (80% and 4.5 respectively) were observed in maize fields under shade as compared to open fields (70% and 4.5 respectively). The phylogenetic analysis of MSV sequences from symptomatic plants indicated it as MSV-A strain identical to be previously reported to determine the virus diversity in relation to the other characterization isolates. This information is important for the development of control strategies to limit yield losses due to MSV

Salinity effect on seedling growth, water, sodium and potassium distributions in the mangrove species (Avicennia germinans L. (Avicenniaceae)) in semi controlled conditions.

The effect on plant growth of NaCl concentrations in soil, under semi-controlled conditions, water content and monovalent cations (Na+ and K+) distributions in seedlings of Avicennia germinans were studied. After 4 weeks of growth, results show that NaCl affected leaf growth more than roots and stems. For the two lower vegetal organs, 100 mmoles of NaCl brought about a significant increase in plant growth. A high retention rate of Na was noted in seedling epicotyl axes, contributing in delaying young leaves proliferation and thereby, preventing the toxic effects of this ion. Mature leaves exhibited good adaptative behavior toward salinity stress by increasing succulence due to absorption of large quantities of water and K+ in leaves. Potassium uptake in leaves was not found to be affected by NaCl concentration. As a consequence, monovalent cations adsorption resulted in an increase in the water contents of the plant organs. The high accumulation of K+ in leaves of A. germinans show that this ion was the major element responsible for osmotic adjustment in leaf cells.L\'effet de différentes concentrations du milieu en NaCl sur la croissance de la plante, l\'état hydrique et la distribution des cations monovalents (Na+ et K+) au niveau des organes de Avicennia germinans a été étudié en conditions semi-contrôlées. Après 4 semaines de culture, les résultats montrent que le NaCl améliore significativement plus la croissance des feuilles que celle des racines et des tiges. Pour ces derniers organes, une concentration de 100 mmoles de NaCl a entraîné une meilleure croissance. Une forte rétention de Na a été observée au niveau des axes épicotylés des plantules, contribuant à réduire l\'envahissement des jeunes feuilles et par conséquent, éviter les effets toxiques de cet ion. Les feuilles plus âgées s\'adaptent aux conditions de salinité, à travers l\'augmentation de la succulence, due à une absorption massive d\'eau et de K+. L\'approvisionnement en K+ des feuilles n\'a pas été affecté par la présence de NaCl dans le milieu. Par conséquent, l\'absorption des cations monovalents Na+ et K+ a entrainé une augmentation de la teneur en eau des organes étudiés. La forte accumulation de K+, au niveau des feuilles, montre que chez A. germinans, cet ion est le principal élément responsable de l\'ajustement osmotique des cellules foliaires. Keywords: Mangrove, Avicennia germinans, salinity, ionic transport, CameroonAgronomie Africaine Vol. 19 (3) 2007: pp. 263-27

Diversité floristique des écosystèmes de savane dans trois zones altitudinales des monts Bambouto, Ouest Cameroun.

International audienceThe savannahs of the Western Highlands of Cameroon are exploited for agricultural and pastoral activities. These sa-vannahs are still poorly studied and their sustainable management requires precise knowledge in terms of flora. The present work is focused on the floristic diversity of the savannah in three different altitudes of the Bambouto Mountains, West Cameroon: the lower zone (1100-1600 m), the mid-zone (1600-2000 m) and the upper zone (above 2000 m). The data on the floristic composition were collected from the inventory of all the species present in the fifty-four quadrats of 100 m² sampled in the studied area. The species richness and biological diversity index were used to express differences in diversity within the different altitude zones. A total of 209 species belonging to 139 genera and 63 families were recorded in the Bambouto Mountains. The lower zone was the richest (128 species) follow by the mid zone (107 species) and the upper zone (70 species). The species Imperata cylindrica and Aspilia africana were the most represented. The Poaceae and Asteraceae families were the most frequent, the most abundant and the richest in species in the altitude zones. Among the three altitudinal studied zones, the mid zone had the highest floristic diversity linked probably to the diversity of habitats. Diversity of plants was affected by parameters such as altitude, rainfall and soil types.Les savanes des Hautes Terres de l'Ouest Cameroun sont exploitées pour des activités agricoles et pastorales. Ces sa-vanes sont peu étudiées et leur gestion durable exige des connaissances floristiques précises. Le présent travail s'est focalisé sur l'analyse de la diversité floristique dans trois zones d'altitude différentes des monts Bambouto (Ouest, Ca-meroun) : la zone basse (1100-1600 m), la zone moyenne (1600-2000 m) et la zone haute (supérieure à 2000 m). Les données sur la composition floristique ont été obtenues à partir d'un inventaire de toutes les espèces présentes dans 54 quadrats de 100 m² échantillonnées dans la zone d'étude. La richesse spécifique ainsi que les indices de diversité biolo-gique ont été utilisés pour exprimer les différences de diversité au sein des trois zones d'altitude différentes. Au total, 209 espèces appartenant à 139 genres et 63 familles, ont été recensées. La zone basse a été la plus riche (128 espèces) suivie de la zone moyenne (107 espèces) et de la zone haute (70 espèces). Les espèces Imperata cylindrica et Aspilia africana ont été les plus représentées. Les familles des Poaceae et des Asteraceae ont été les plus fréquentes, les plus abondantes et les plus riches en espèces dans les trois zones. Parmi les trois zones d'altitude étudiées, la zone d'altitude moyenne a eu la diversité floristique la plus élevée liée probablement à la diversité des habitats. La diversité des plantes a été affectée par les paramètres tels que l'altitude, les précipitations et les types de sols

Influence des aports mod&#233r&#233s d'engrais sur la valeur nutritionnelle de Manihot esculenta Crantz. (Euphorbiaceae)

No Abstract.Cameroon Journal of Experimental Biology Vol. 2 (2) 2006: pp. 62-6

Relationships between algae taxa and physico-chemical characteristics of water in wetlands and waterbodies

A study of algae flora was performed on 16 samples collected in different aquatic environments in Bamenda (Cameroon) in order to evidence the relationships between algae assemblages and physico-chemical parameters of the milieu. A total of 22 algae species were identified, the most represented class being Bacillariophyceae (8 species), followed by the Cyanophyceae (5 species), Zygnemataceae (4 species), Euglenophyceae (3 species) and finally Chlorophyceae (2 species). Physicochemical analyses of water samples suggest evidences of organic pollution related to anthropogenic activities, running waters being less affected than stagnant ones. This organic pollution is inferred from highest values of TDS and conductivity. The Correspondence Analysis (CA) displayed four groups of algae on the two first axes. On axis 1 the discriminating factor is the current, because running water sites are opposed to stagnant water ones. Unfortunately measured values of water current are not available to precise that hypothesis, our interpretations in this paper are based on relative data. The second axis reveals the opposition between oligotrophic and eutrophic waters, and could be considered as a gradient of organic pollution. The species Navicula sp, Gomphonema sp, Ulothrix sp., Nostoc sp., Amphora sp., Pinnularia sp., Tabellaria sp. and Lyngbya sp. are associated to low values of TDS and conductivity while Phacus sp., Closterium sp., Euglena sp. and Trachelomonas sp. thrive better in high polluted waters. The distribution of these algae identified as indicators of high organic pollution, evidenced a spatial variability of organic pollution in accordance with the water physicochemical parameters monitored. This variability is probably modulated by the presence in the sampling sites of macrophytes that are efficient in removing pollutants. Keywords: Bamenda, algae, correspondence analyse, organic pollution, phytoremediationCaJEB Vol. 3 (2) 2007: pp. 70-7

Variation De La Reponse Au Stress Salin Chez Cinq Especes De Legumineuses

Les effets de la salinité sur la croissance des organes de cinq espèces légumineuses ont été évalués afin d\'identifier celles susceptibles d\'être cultivées sur des terres plus ou moins salées. 4 niveaux de salinité (0, 50, 100 et 200 mM de NaCl) ont été testés. Ainsi, l\'augmentation de la salinité entraîne chez Glycine max et Phaseolus vulgaris (glycophytes sensibles) la baisse de la biomasse sèche dès 50 mM de NaCl. Chez Mucuna poggei (halophyte facultative) et Vigna unguiculata (glycophyte moyennement tolérante) cette baisse s\'observe dès 100 mM de NaCl. L\'inhibition de la croissance des glycophytes sensibles est liée à une diminution de la consommation d\'eau en milieu salé. Le blocage de Na+ dans les racines représente le principal facteur responsable du déficit hydrique des feuilles. Chez Phaseolus adenanthus (halophyte), la production de matière sèche foliaire est peu affectée par la salinité. La résistance de cette espèce à NaCl s\'explique par un bon cheminement du flux hydrique vers les feuilles, facilité par une augmentation des teneurs en Na+ et K+ dans le sens racines, tiges et feuilles. Par ailleurs, au niveau des feuilles la déficience en K+ est liée à la salinité du milieu, qui limite la croissance chez les espèces étudiées. La tolérance de V. unguiculata, M. poggei, et P. adenanthus vis-à-vis du sel permet d\'envisager leur utilisation sur des terres marginales plus ou moins saléesIn order to determine leguminous plants able to be used as pioneer plant species on more or less saline areas, effects of NaCl concentrations on the growth of organs of five leguminous wild or cultivated plants were evaluated. Plants were submitted to 4 levels of salt stress at the roots (0, 50, 100 and 200 mM of NaCl). The increase in salt concentration greatly reduces the production of dry mater at 50 mM of NaCl in Glycine max and Phaseolus vulgaris (sensitive glycophytes). In Mucuna poggei (facultative halophyte) and Vigna unguiculata (moderately tolerant glycophyte) effect of salinity is observed for at least 100 mM of NaCl. Growth inhibition in the sensitive glycophytes is due to the decrease in water consumption within saline medium. The storage of Na+ in roots can be responsible of the water deficit in leaves. In the natural halophyte Phaseolus adenanthus, the presence of salt does not affect the leaves\' production of dry mater. This water flux is due to the significant storage of monovalent cation in leaves, facilitated by the increase in Na+ and K+ from roots to leaves. Moreover, the supply of K+ in leaves is decreased because of the medium variation of the salt rate and therefore can be responsible of the limitation of the plant growth. The adapted behaviour of the glycophyte (V. unguiculata) and of the two natural halophytes (M. poggei and P. adenanthus) suggest that they can be used as pioneer plant species able to grow on more or less saline medium Keywords: stress salin, légumineuses, croissance, distribution ionique, Cameroun; salt stress, leguminous plants, plant growth, ionic distribution, Cameroon.Agronomie Africaine Vol. 16 (1) 2004: pp. 33-4

Evolution paléohydrologique du marais Paurosa au centre du Gabon au cours des deux derniers millénaires : contribution des diatomées

Cet article présente les résultats d'analyses de la variation des assemblages de diatomées le long de la carotte prélevée dans le marais Paurosa (0°12'47,4'S; 11°35'19,3' E) qui se trouve dans une mosaïque forêt-savane au Nord du Parc National de la Lopé au Gabon. Les données obtenues ont permis de reconstruire l'histoire paléohydrologique de ce marais depuis 2000 ans. La microflore des diatomées bien diversifiée montre d'importants changements pendant cette tranche de temps. A la base de la carotte (2000-1700 ans cal. BP), la dominance des assemblages à Pinnularia viridiformis, benthiques, indique une phase de bas niveau palustre avec probablement des eaux claires. L'épisode qui s'ensuit entre 1700-700 ans cal BP montre une évolution vers des conditions plus humides marquées par l'abondance de diatomées tychoplanctoniques acidophiles et oligotrophes. Entre 700 et 500 ans BP, les assemblages de diatomées montrent une baisse du niveau d'eau marquée par l'abondance de benthiques oligotrophes alcaliphiles. L'épisode 4 (500-200 ans cal BP) est comparable à l'épisode 2 et indique aussi des conditions plus humides. Les conditions actuelles se mettent en place sur les 200 dernières années, avec un développement de diatomées benthiques et épiphytes, typiques des mares inondées durant la saison des pluies. Les variations d'humidité de ce marais au cours de ces deux millénaires peuvent s'expliquer par des modifications de la saisonnalité et des quantités de précipitations régionales mais aussi par les conditions hydrologiques locales