Morphological Characterization of Arbuscular Mycorrhizal Fungi Associated with the Rhizosphere According to the Age of Xanthosoma sagittifolium L. Schott Plants in the Field

The objective of this work was to carry out a morphological characterization of arbuscular mycorrhizal fungi in the rhizosphere of Xanthosoma sagittifolium L. Schott plants. The plant material used was the white and red cultivars of X. sagittifolium, belonging to age intervals of 3 - 6, 6 - 9, and 9 - 12 months. Three harvest sites were chosen in the Central Region of Cameroon. In each site, soil from the rhizosphere and plant roots was collected in a randomized manner. In the field, the agronomic parameters were evaluated. The physicochemical characteristics of the soils, the mycorrhization index, and the morphological characterization of the mycorrhizal types of each site were carried out. The results obtained show that the agronomic growth parameters varied significantly using the Student Newman and Keuls Test depending on the harvest sites. The soils’ pH in all sites was acidic and ranged between 4.6 and 5.8. The Nkometou site has a loamy texture while the Olembe and Soa sites have loam-clay-sandy and loam-clay textures respectively. The highest mycorrhization frequencies appeared at the Nkometou site, with 75 and 87.33% of the white and red cultivars plant roots at 6 - 9 and 3 - 6 months. The relative abundance of AMF arbuscular mycorrhizal fungal spores in the rhizosphere of X. sagittifolium plants varied with age and cultivar. There were 673 spores between 9 - 12 months in Nkometou in the red cultivar. Six AMF genera were identified in all the different soils collected: Acaulospora sp., Funneliformis sp., Gigaspora sp., Glomus sp., Scutellospora sp., and Septoglomus sp. The genus Glomus sp. was the most present at all age intervals in both cultivars.

Soil Physico-Chemical Properties and Different Altitudes Affect Arbuscular Mycorrhizal Fungi Abundance and Colonization in Cacao Plantations of Cameroon

This study aims to investigate the abundance of AMF according to soil properties and altitudes in different cacao plantations of Cameroon. Physico-chemical analyses were made on soil samples collected from three agro-ecological zones. Soil samples were also used to evaluate directly the AMF abundance following the various altitudes and after trapping by sorghum plant. The results showed that soil properties, AMF spore abundances and colonization fluctuated significantly at different altitudes. The most represented texture was sandy loam. The bimodal zone presented a homogeneous texture (sandy loam) in all its localities. Cacao soil chemical characteristics showed that, the highest nitrogen rate (0.47%;p 0.05, Scott-Knott test) was recorded at Melong in a monomodal zone while Tonga in the Western highlands displayed the lowest rate (0.13%). Soil P concentration was significantly high in monomodal zones (Mbanga and Melong). Soil pH level indicated that the soil from Tonga in the Western highlands was neutral (pH = 6.67), and soils of other localities under study were acidic with the lowest (4.75) pH level recorded at Melong in a monomodal zone. In soil samples, the highest spore density (1.03 spores/g soil) was observed at Ntui in Bimodal zone, while the lowest spore density (0.26 spores/g soil) was observed at Bafang in the Western highlands. Root colonization showed that the sample from Bokito in a bimodal zone displayed the best frequency of mycorrhization (86.11%) while the sample from Bafang in the Western highlands recorded the lowest (27.11%). The PCA analysis highlighted that available phosphorus, pH and altitude all strongly correlated with AMF root colonization ability and can be used as a predictor of AMF colonization ability in cacao rhizosphere.

Assessement of Nutritional Status of Households Using Weighed Food Intake in North West Region of Cameroon

This study determined the nutritional status of households in North western region of Cameroon using weighed food intake. Twenty–two rural and 106 urban households were randomly selected for weighed food intake Descriptive and inferential statistics were used to analyze collected data and significance at p < 0.05 accepted. Corn fufu with huckleberry was the most frequently consumed meal with little or no animal-source protein. Protein and B group vitamins intake of respondents in both communities were below the FAO/WHO recommended values while energy, iron, and vitamins A and C were in excess for most age groups. Adolescents 10 - 19 years and adults 20 years and above failed to meet at least 85% of RNI for calcium.

Applying Source Parameter Imaging (SPI) to Aeromagnetic Data to Estimate Depth to Magnetic Sources in the Mamfe Sedimentary Basin

Aeromagnetic data over the Mamfe Basin have been processed. A regional magnetic gridded dataset was obtained from the Total Magnetic Intensity (TMI) data grid using a 3 × 3 convolution (Hanning) filter to remove regional trends. Major similarities in magnetic field orientation and intensities were observed at identical locations on both the regional and TMI data grids. From the regional and TMI gridded datasets, the residual dataset was generated which represents the very shallow geological features of the basin. Processing this residual data grid using the Source Parameter Imaging (SPI) for magnetic depth suggests that the estimated depths to magnetic sources in the basin range from about 271 m to 3552 m. The highest depths are located in two main locations somewhere around the central portion of the study area which correspond to the area with positive magnetic susceptibilities, as well as the areas extending outwards across the eastern boundary of the study area. Shallow magnetic depths are prominent towards the NW portion of the basin and also correspond to areas of negative magnetic susceptibilities. The basin generally exhibits a variation in depth of magnetic sources with high, average and shallow depths. The presence of intrusive igneous rocks was also observed in this basin. This characteristic is a pointer to the existence of geologic resources of interest for exploration in the basin.

Floristic Diversity and Conservation Status of Guineo-Congolese Species in Southeastern Cameroon: The Case of the Gari-Gombo Communal Forest

The conservation of plant biodiversity has become one of the most important objectives in the sustainable management of Guinean-Congolese ecosystems. However, in the south-east zone of Cameroon, there is a lack of rigor in the management of these forests, which can result in the loss of species of high conservation value. The study was carried out in communal forests in the south-east zone of Cameroon. Its aim was to carry out a floristic inventory and then compare the list of species with the IUCN catalog. Twenty-four plots, each with a surface area of 0.2 ha, were set up in the Gari-Gombo communal forest. All timbers with a DBH ≥ 5 cm were systematically counted. A total of 176 species, belonging to 144 genera and 45 families, were surveyed. Fabaceae (42.08%), Malvaceae (39%), Euphorbiaceae (24.64%), Moraceae (20.92%), Apocynaceae (18.64%), Cecropiaceae (16.60%), Ulmaceae (14.76%), Meliaceae (14.61%), Violaceae (14.08%), Combretaceae (12.67%), Theobroma cacao (21.17%), Baphia leptobotrys (18.06%), Rinorea sp. (14.09%), Musanga cecropioides (12.18%), Terminalia superba (10.32%), Neosloetiopsis kamerunensis (10.14%), Celtis zenkeri (8.29%) and Alstonia boonei (7.77%) were the most important taxa. Nearly 90% of the species in this forest are Guinean species, with a dominance of Guinean-Congolese species (66%). Fourteen (14) threatened species have been identified in the FCGG. This study, which highlights the rich biodiversity of communal forests, is important for guiding biodiversity conservation policies in ecosystems used for production.

Higher Order Solitary Wave Solutions of the Standard KdV Equations

Considered under their standard form, the fifth-order KdV equations are a sort of reading table on which new prototypes of higher order solitary waves residing there, have been uncovered and revealed to broad daylight. The mathematical tool that made it possible to explore and analyze this equation is the Bogning-Djeumen Tchaho-Kofané method extended to the new implicit Bogning' functions. The analytical form of the solutions chosen in this manuscript is particular in the sense that it contains within its bosom, a package of solitary waves made up of three solitons, especially, the bright type soliton, the hybrid soliton and the dark type soliton which we estimate capable in their interactions of generating new hybrid or multi-form solitons. Existence conditions of the obtained solitons have been determined. It emerges that, these existence conditions of the chosen ansatz could open the way to other new varieties of fifth-order KdV equations including to which it will be one of the solutions. Some of the obtained solitons are exact solutions. Intense numerical simulations highlighted numerical stability and confirmed the hybrid character of the obtained solutions. These results will help to model new nonlinear wave phenomena, in plasma media and in fluid dynamics, especially, on the shallow water surface.

Dissipation and amplification management in an electrical model of microtubules: Hybrid behavior network

The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series resistance–inductance(R–L) circuit. Through linear dispersion analysis, two features of the network are found, that is, low bandpass and bandpass filter characteristics. The effects of the conductance’s parameter λ on the linear dispersion curve are also analyzed. It appears that an increase of λ induces a decrease(an increase) of the width of the bandpass filter for positive(negative) values of λ. By applying the reductive perturbation method, we derive the equation governing the dynamics of the modulated waves in the system. This equation is the well-known nonlinear Schr?dinger equation extended by a linear term proportional to a hybrid parameter σ, i.e., a dissipation or amplification coefficient. Based on this parameter, we successfully demonstrate the hybrid behavior(dissipation and amplification) of the system. The exact and approximate solitary wave solutions of the obtained equation are derived, and the effects of the coefficient σ on the characteristic parameters of these waves are investigated. Using the analytical solutions found, we show numerically that the waves that are propagated throughout the system can be dissipated, amplified, or remain stable depending on the network parameters. These results are not only in agreement with the analytical predictions, but also with the existing experimental results in the literature.

Identification of major sources controlling groundwater geochemistry in Mount Makabaï in the Far-North of Cameroon(the northernmost part of the Pan-African Belt)

The present work focuses on the volcanic basement rock geochemistry of Mount Makabaï(MarouaCameroon city)in relation to groundwater geochemistry.Investigations were centered on an approach involving an association of several methods such as geological cartography,hydrogeology,and geochemistry.Three rock samples,four disturbed soil samples,three undisturbed soil samples,and 20 samples of groundwater in 10 wells were collected during fieldwork and prepared for laboratory analyses.Bedrocks exhibit porphyritic,aphyric,and subaphiric textures.The phenocryst phases are mainly olivine,clinopyroxene,and plagioclase.Based on whole rock major element chemical compositions,the Makabaï samples,plotted on Na_(2)O+K_(2)O versus SiO_(2)diagram,are mugearite,hawaiite,and basalt.The ratio of(MgO+CaO)/(Na_(2)O+K_(2)O)exceeds unity and shows dominance of alkaline Earth metals(MgO:2.99-4.48%;CaO:6.19-9.80%)relatively to alkali metals(Na_(2)O:2.27-4.46%;K_(2)O:2.09-2.51%).Exchangeable base contents are high,mostly represented by Ca and Mg,whose contents vary from 14.6 to 35.28 cmol(+)kg^(-1)and from 3.28 to9.48 cmol(+)kg^(-1)respectively.The CECclayis likewise high,fluctuating between 116.80 and181.38 cmol(+)kg^(-1),values in line with the presence of 2:1 clay minerals represented in the study area by montmorillonite.In the water samples,the Ca2+and Na+contents are generally higher than K^(+)and Mg^(2+),reflecting the relative abundance of Na_(2)O and CaO oxides to K_(2)O and MgO oxides in rocks where different waters were sampled.The waters of Makabaï are acidic to neutral(6.3≤pH≤7.4)and weakly to highly mineralized(110.0≤EC≤1190.0μS/cm).Hydro-geochemical classification by using the Piper diagram revealed two water types:(1)CaMg-HCO_(3)(40%)and(2)CaMg-Cl or CaMg-SO4(60%).The average content of ions in all the analyzed samples was HCO_(3)^(-)>>NO_(3)^(-)>SO_(4)^(2-)>Cl-for anions and Ca^(2+)>>Mg^(2+)>Na^(+)>K^(+)for cations.Major mechanisms governing ionic constituents of groundwater in the study area are water-rock interactions,silicate weathering,and ion exchange.

Plants Extracts and a Mycoinsecticide in Cowpea Yield Improvement in Guinean Savanah and Sahelian Savanah Agro-Ecological Zones of Cameroun

Cowpea yield improvement is done by adding agricultural inputs. The use of natural substances as pesticides is being encouraged to fight against cowpea field pests. The pesticidal potentials of Azadirachta indica and Boswellia dalzielii water extracts, Metarhizium anisopliae, alone and in combination with plant extracts, and a commercial synthetic pesticide (Decis®) were tested in field on two varieties of cowpeas, Vigna unguiculata in two agroecological zones (Guinean Savanah and Sahelian Savanah) of Cameroon. The field trials were carried out in a full randomized block design including nine treatments and a control. Four replications were made concerning the different treatments and control. At the flowering stage, the cowpea field was sprayed three times with different pesticidal formulations at the interval of five days. The number of ramifications per plant, and that of pods per block and seed yield were determined. The pesticide formulations considerably (p ®). Bafia variety treated with the combination of M. anisopliae and A. indica recorded the highest ramification rate (37.03 ± 1.59) in Maroua (Sahelian Savanah). The same variety also produced more important pods number (90.50 ± 16.66) in Ngaoundere (Guinean Savanah) with the binary combination of two plants used in this experiment. The highest seed yield (44.23 ± 2.31) was recorded in Ngaoundere with B125 variety treated with the combination of the three pesticidal formulations separately (A. indica, B. dalzielii, M. anisopliae). The plant products used in this work, M. anisopliae and their mixtures could supersede the synthetic pesticides considering environmental issue in cowpea crop protection. Then, such formulations would not only improve crop productivity but also preserve environment from the pollution due to the use of synthetic residual chemicals.

Impact of Pretreatment on the Germinative Characters of Seeds of Stereospermum kunthianum Cham. (Bignonaceae) for Its Domestication in Chad

The objective of this research is to lift the dormancy of seeds of S. kunthianum in with a view to domesticating them. In this experiment, we used the soaking of seeds in sulfuric acid for different durations (10 min, 30 min and 1 h). The treated seeds were sown in transparent germinators. The explants obtained were then transplanted into pots containing five types of substrate (black earth, fine sand, sawdust, mixtures 1/1 of sawdust/black earth and 1/1 of sawdust/fine sand). This second test made it possible to determine the rate of germination on the substrate. The results obtained compared to those of the control showed a clear reduction in the latency time or germination time (62 hours) instead of 6 days (control), in the germination time 3 days/7 days (control) and a very high germination rate (100%). At the 5% threshold, soaking for 10 min and 30 min (100%) is the best result on the germination of S. kunthianum seeds. Soaking for 1 hour gives (7%) very low. After transplantation of the explants, the percentages obtained independently of the treatments show that the 1/1 mixtures of sawdust/black earth (75.19%), black earth (73.33%) and sawdust/fine sand (66.30%) have a higher performance than the others. The type of germination is epigeal. This work makes it possible to domesticate S. kunthianum in Chad.

Study of the Effect of Plastic Aggregates on Drying Shrinkage and Expansion of Concrete

The aim of this work was to propose a possibility of using plastic aggregates from waste to reduce the shrinkage and expansion observed in concrete. The process of obtaining plastic aggregates was presented. Natural aggregates were partially substituted by plastic aggregates in the percentages: 0%, 5%, 10%, 20% and 30%. Drying shrinkage, water absorption and expansion tests were carried out on three families of concrete: control concrete (BT), concrete with addition of BAgP-PEHD high-density polyethylene plastic aggregate and with polyvinyl chloride BAgP-PVC. Given the slow appearance of the internal sulfate attack (ISA), an experimental technique was proposed to accelerate the appearance of this pathology. This technique involves heat treatment which stimulates the heating of the concrete at a young age, followed by a cycle of drying and cooling and ends with total immersion in water. The method of measuring expansions through sample image correlation was also proposed. The results showed an increased skrinkage of BAgP-HDPE compared to BT. On the other hand, a significant decrease in shrinkage was observed in BAgP-PVC samples. Water absorption increased in BAgP-HDPE and BAgP-PVC compared to BT. Greater expansion was observed at the cement paste-plastic aggregate interface than at the cement paste-natural aggregate interface. Given these properties, BAgP-PVC can be recommended for paving surfaces exposed to the hard weather conditions.

Influence of Harvest Periods on Cassava (Manihot esculenta Crantz) Agronomic Traits and Physiological Response to Post-Harvest Physiological Deterioration

Cassava (Manihot esculenta Crantz) is the third largest source of calories in tropical countries and the sixth most important food crop in the World. However, the short shelf life of its storage roots after harvest due to a rapid post-harvest physiological deterioration (PPD) makes the roots to be considered as a risky product to market. The objectives of this work were to investigate the influence of two harvest periods on cassava agronomic parameters and their physiological response to PPD. Three cassava cultivars 96/1414, I070593 and LMR were selected for the experiment and harvested at 10 and 12 months after planting (MAP). The response to PPD was assessed during storage at 0, 3, 8 and 15 days after harvest (DAH). Total proteins content, soluble sugars and starch, total polyphenols compounds, polyphenoloxidase and peroxidase activities were recorded during storage. Results showed large variation among the parameters at the two harvest periods across the cultivars. High number of tubers was recorded in all the cultivars at 12 MAP and a significant increase in storage roots length was observed in 96/1414 and LMR from 10 MAP to 12 MAP (25 ± 5.1 to 41.3 ± 5.9 and 22.6 ± 3.3 to 27.9 ± 4.8) respectively. A reduction of about 49% of tubers weight was observed in I070593 from 10 to 12 MAP while an increase of about 36% and 11% were recorded in LMR and 96/1414 respectively. Tubers from I070593 showed less susceptibility to PPD when harvested at 10 MAP compared to those from LMR and 96/1414 where less susceptibility to PPD were recorded at 12 MAP. An increase in soluble sugars content, total proteins content and peroxidase activity subsequently to a decrease in starch content were recorded during storage from 8 to 15 days after harvest especially at 10 MAP in I070593 and at 12 MAP in LMR and 96/1414. High content of total phenolic compounds and less activity of polyphenol oxidase were correlated to PPD susceptibility. This work opens a new insight issue of the consideration of the appropriate harvest time of the cultivars as a tool to better control the onset of postharvest physiological deterioration.

In Vitro Evaluation of the Antifungal Activity of Essential Oils of Thymus vulgaris and Cymbopogon citratus on Some Strains of Sclerotinia sclerotiorum, Agent Responsible for White Rot of Beans

The present work was aimed to the study of the antifungal activity of essential oils of two aromatic plants against three strains of Sclerotinia sclerotiorum responsible for white rot of bean. The two essential oils (EO) of the studied plants: Thymus vulgaris (HET) and Cymbopogon citratrus (HEC), used at different concentrations: C1 (0.75 ml/ml), C2 (1.5 ml/ml) and C3 (3 ml/ml) presented significant inhibitory activities on the three tested fungal strains namely Bia 1, Bia 2, and Njo 2. Two control treatments (T-: containing no antifungal substance and T+: synthetic fungicide) were also used. The antifungal activity here is related to the inhibition of mycelial growth especially with high concentrations of essential oils. Thus, against S. sclerotiorum, HET showed the highest activity comparable to that of T+ (100% inhibition) at all concentrations on the Bia 1 and Bia 2 strains and at concentration C3 on the Njo 2 strain compared to that of HEC, which certainly inhibited the mycelial growth of the different strains considerably (with a maximum of 78.15% on the Njo 2 strain) but not completely. According to their sensitivity, the Bia 2 strain showed a higher sensitivity to essential oils than the others while the Njo 2 strain was more aggressive. On the basis of MIC50 and MIC90 obtained on the Njo 2 strain, the HET turns out to be the most efficient with respective lower values of (1.73 and 23.34 ml/ml) against (4.76 and 26.03 ml/ml) for the HEC. These EO could thus be exploited as biodegradable antifungal substances, likely to control white rot of bean.

Regional Intrusive Signature from the Cameroon Coastal Basins to Bioko Island in Equatorial Guinea (Gulf of Guinea) Using Gravity Studies

The Gulf of Guinea constitutes an area of great petroleum potential yet with very limited geophysical research information. Consequently in this study, a Bouguer anomaly map has been computed from gravity data covering regions stretching from the Cameroon coastal basins to Bioko island (formerly Fernando Po) which is part of Equatorial Guinea. The data were further processed for Source Edge Detection (SED), Euler 3D deconvolution, 3D surface oriented models and 3D voxel solutions. The results confirmed the presence of previously identified intrusive bodies around the Douala and Kribi/Campo sedimentary sub-basins and went ahead to suggest a probable continuity between these two. A possible extension of this body offshore the Gulf of Guinea right up to Bioko island with very striking similarities was also highlighted and it shows characteristic variations in the depth to the surface of the body at different locations.

Evolution of Floristic Composition and Structural Parameters between Two Management Inventories in a Tropical Forest in the East Cameroon Region

The realization of two management inventories in 2003 and 2020 on the same forest concession made it possible to characterize the floristic composition and to describe some structural parameters on three sites established according to the period of exploitation. Due to the change in the orientation of the lines, it was noted that respectively 82 and 85 species from the first inventory are not found in the second and inversely. A total of 311 species were identified in 2003, compared to 314 in 2020. The density varies from 111 to 140 stems/ha for all the individuals, 19 to 25 for the main species and 15 to 20 for the most exploited species. The decrease in the basal area between the two phases of 12% for all the species and 13% for the main species on the site exploited before the first inventory indicates a persistence of the disturbance for years after logging. It is proposed to supplement the management plans decisions with annual measures based on more complete inventories and to ensure the application of reduced impact logging measures.

Soil Seed Bank Characteristics in Congolese Rainforests and Implications for Post-Logging Plots Reforestation

The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m2 and 1742 seedlings/m2. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m2 and 4 seedlings/m2, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.

Waste Recovery and Sustainable Development. A Case Study of Material Development from Used Tires in Africa

This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for the manufacture of O-rings has been developed, with properties close to those found on the market. The process includes an experimental methodology of a sulfur vulcanization system choice and the quantification of ingredients, as well as the experimental determination of cure parameters. Mechanical tests on the samples completed the work by providing the mechanical characteristics of both unaged and aged (thermo-oxidative ageing) novel material. This process has a high potential for sustainable development and industrialization, making it a valuable contribution to the recycling of rubber in African developing countries.

Baossi–Warack monogenetic volcanoes, Adamawa Plateau,Cameroon: petrography, mineralogy and geochemistry

Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these vents and restricted volcaniclastic deposits were emplaced by Hawaiian and mild strombolian style eruptions. The lavas are porphyritic, mainly composed of olivine(chrysolite) and clinopyroxene(diopside and augite) phenocrysts and plagioclase(andesine) microphenocrysts. Accessory minerals include titano-magnetite and titano-hematite, nepheline,apatite and amphibole xenocrysts. Sanidine occurs in some samples and sodi-potassic albite in others. Some olivines and clinopyroxenes exhibit resorbed margins and thin reaction rims while plagioclase displays oscillatory zoning, and sieved textures as a result of magma mixing. Whole-rock geochemistry data indicates that the lavas are silica-undersaturated, composed of basanites and basalts, showing little compositional variations(SiO_2: 39.20 wt.%–48.01 wt.%,MgO: 5.29 wt.%–9.70 wt.%). Trace elements patterns of these lavas suggest they are enriched in LILE including Pb,probably due to crustal contamination. REE patterns suggest cogenetic magmas below Baossi 1 and Baossi 2 volcanoes,and distinct sources below Warack volcano and nearby lavas.The lavas studied show affinity to high-μ(HIMU), enriched type Ⅰ(EM1) and Oceanic Island Basalt(OIB)-like mantle signatures and thus indicate a heterogeneous mantle source underneath the vents as noted at other monogenetic and polygenetic volcanoes along the CVL. Primary melts derived from low degrees of partial melting(0.5%–2%) and encountered low rates of fractionation, and crustal contamination coupled with magma mixing. These melts evolved independently through structural weaknesses in the basement.

Improved germination of threatened medicinal Prunus africana for better domestication: effects of temperature, growth regulators and salts

Prunus africana is an endangered medicinal species and has been classified as a priority for domestication in Cameroon.However,the seeds rapidly lose their viability during storage at room temperature after 2–3 months.This study aimed to improve seed germination of P.africana by germinating at different temperatures(4℃,28℃)using different concentrations of growth stimulators(sodium nitrate and gibberellic acid)and different concentrations of salts.P.africana seeds had 91.7%germination at 4C after 1 month of storage.Growth regulators considerably influenced germination after 6 months and reached 66.0%with 10 mM gibberellic acid and 100%with 10 mM sodium nitrate.Approximately three shoots per seed were developed,an indication of polyembryony.Histochemical analyses revealed the presence of protein-like bodies close to the embryo axis and accumulations of starch after 7 days of germination.After 14 days,amyloplasts and dark protein bodies of various sizes were observed.The outcome of this study will contribute to improve the germination of P.africana for better domestication and conservation.

Community-Based Approach in the Prevention and Management of Flood Disasters in Babessi Sub-Division (Ndop Plain, North West Cameroon)

Flood is a recurrent natural disaster that has caused enormous human and material damage in many places and continues to hit local committees at an alarming rate. The need to setup permanent committees to prevent and manage flood disasters by local communities is therefore indispensable. In rural areas, the creation of such a structure is always a welcome relief to flood victims but it is often marred by numerous management problems. This study aimed to analyze the community-based approach in the prevention and management of flood disasters in Babessi Subdivision (North West Cameroon), to identify the causes of flood disasters and the preventive strategies used by this local community. A total number of 300 questionnaires as well as structured interviews were used to collect data in the field and the data were analyzed by simple descriptive statistics. The main results revealed that the main cause of flood disasters is heavy and consistent rainfall. Also, poor refuse disposal and drainage system management contribute to floods. The identification of areas likely to be affected by floods and preventing the riparian population from constructing houses along these areas especially beside the main rivers are the flood preventive measures adopted by the local flood management committee. The flood victims are reluctant to relocate to the settlement site earmarked by the Government, meanwhile, the local flood committee do not have the legal tools to forcefully relocate them. The population of Babessi needs to be sensitized on the impending dangers of flood hazard and be encouraged to participate in implementing the adopted strategies to prevent and manage subsequent flood disasters.