Agro-ecological Zones Of Cameroon Research Articles

Evaluation of Fungicide against Taro Leaf Blight Disease Caused by Phytophthora colocasiae in Three Agro-Ecological Zones of Cameroon

Globally the taro leaf blight (Phytophthora colocasiae) disease causes between 50 to 70% yield loss. Four taro landraces were planted in three agroecological zones of Cameroon; the Western Highlands (Bambui), Mono-Modal Humid Forest (Ekona), and the Bimodal Humid Forest (Nkolbisson) and evaluated for taro blight severity in four successive growing seasons in March and July, 2018 and 2019. Different concentrations of copper oxide (600 g)–Metalaxyl (120 g) fungicide were applied to control taro blight before and during plant growth. Results showed that, in all the field sites, the disease severity of Phytophthora colocasiae greatly decreased below 1.5 with varying concentrations of copper oxide (600 g)–Metalaxyl (120 g) fungicide applied at two-week intervals. The control field at Ekona recorded the highest taro blight severity of 7.8. There was no significant difference in taro blight severity (P≤0.05) between landraces treated with the different concentrations of copper oxide (600 g)–Metalaxyl (120 g) fungicide. Therefore, lower concentrations (0.33% and 0.27%) of copper oxide (600 g)–Metalaxyl (120 g) can be effectively used in the pre and post control of taro blight in the field. All the landraces in the screen house experiments were susceptible to P. colocasiae. In all the zones, Landrace L2 (red petiole small leaves) was highly resistant to P. colocasiae and should be recommended to farmers for optimum taro production in the three agro-ecological zones and zones with similar characteristics.

Impact of Environment on Callosobruchus maculatus (Coleoptera: Chrysomelidae) Response to Acetone Extract of Gnidia kaussiana Meisn (Thymeleaceae) and Ocimum canum Sims (Lamiaceae) Botanical Insecticides

The response of pests to the effects of a botanical insecticide can vary spatially and temporally. To test whether efficacy of botanicals differed spatially, the insecticidal efficacy of Gnidia kaussiana and Ocimum canum against Callosobruchus maculatus was investigated in two different agro-ecological zones of Cameroon, i.e. Maroua and Ngaoundéré (sudano-sahelian and sudano-guinean zones, respectively). Experiments were, therefore, conducted to determine the insect mortality, progeny production, grain damage and weight loss in cowpea. G. kaussiana was more effective against C. maculatus in Maroua (LD50 = 0.12 g/kg at 6th day of exposure) than in Ngaoundéré (LD50 = 4.35 g/kg at 6th day of exposure). Moreover, it was more toxic than O. canum extract and neem seed oil (reference), irrespective to the agro-ecological zones. Overall, the performance of O. canum did not vary significantly between the two zones, and was slightly more active (LD50 = 4.66 g/kg) than the reference insecticide neem seed oil (LD50 = 4.89 g/kg) in Ngaoundéré in contrast to the results recoded in Maroua (LD50 = 1.44 g/kg and 2.60 g/kg, respectively for neem seed oil and O. canum at 6 days post exposure). In view of the above, there were some discrepancies in extract performance between Maroua and Ngaoundéré. Thus, the establishment of dose rates of insecticidal products formulated from G. kaussiana must be specific to an environment in contrast to those from O. canum.

Impact of legumes on soil microbial activity and C cycle functions in two contrasting Cameroonian agro-ecological zones

Unsustainable farming systems for a growing population in Sub-Saharan Africa stress natural resources and lead to soil degradation. Legume cultivation, however, promotes soil microbial communities and may help reverse soil degradation. The soil properties (pH, texture, C and nutrient contents) of a set of contrasting sites from two agro-ecological zones of Cameroon were determined. This study characterises the microbial activities and functioning in rhizosphere soils of the four legumes Phaseolus vulgaris L., Glycine max L., Arachis hypogea L. and Vigna subterranea L. in a laboratory incubation experiment. Ecological indicators (total respiration, microbial biomass determined as total phospholipid fatty acids, metabolic quotient) of soil health were quantified after microbial activation by 14C-glucose and related to site-specific parameters as well as to the effects of legume cultivation.Microbial activation after glucose addition was frequently site-specific. Cumulative glucose respiration increased over time, and glucose pulses repeatedly boosted glucose respiration and total respiration at all sites. The microbial biomass was lowest after the experiment in the soil from the High Guinean Savannah except for soils under soybean cultivation. Among the four legumes cultivated, only soybeans strongly increased microbial biomass in the High Guinean savannah reaching even the level of microbial biomass in Western Highland soils. The lowest metabolic quotient in soybean rhizosphere soil and lowest glucose respiration compared to the soils of other legumes suggests a high carbon use efficiency, presumably due to C limitation in the High Guinean Savannah. Abiotic soil properties (pH, clay content) strongly influenced microbial habitat properties and thus had a positive effect on the CO2 efflux, irrespective of glucose addition.Within the set of tested legumes, soybean cultivation can, therefore, be strongly recommended as a long-term sustainable crop to boost soil microbial functioning and probably also nutrient cycling, especially under low total organic carbon stocks.

Effect of Diet Supplementation with Moringa Oleifera Leaf Meal on Growth and Laying Performances of Female Quail (Coturnix sp.) in Soudano-Guinean Zone of Cameroon

Abstract In order to evaluate the effect of diet supplementation with Moringa oleifera leaf meal (MOLM) on growth and laying performances of quail in soudano-guinean zone of Cameroon, a study has been conducted in Ngaoundéré from May to September 2018. For this purpose, a total of 168 seven weeks old quails were divided into 12 comparable batches of 10 females and 4 males. Each of the four experimental diets (T0, T1, T2 and T3), formulated on the basis of the level (0, 1, 2, and 3% respectively) of diet supplementation with MOLM was randomly assigned to 03 batches in a completely randomized. Data were collected during the 16 weeks of the study on feed intake (FI), body weight (BW), body weight gain and feed conversion ratio. Weekly, after total laid eggs evaluation, 40 eggs per treatment was randomly chosen, weighed and measured. Main findings revealed that FI was not significantly affected by the diet supplementation with MOLM. Significantly higher BW and BW gain was recorded in T1 treatment compared to others treatments while they remains similar between them. The relatively heavier eggs were noted in T2 treatment while the highest (88.57 ± 2.85%) weekly laying rate was recorded with 1% supplementation. It has then been concluded that MOLM could be used as diet supplement during laying phase up to 3% for egg production and 1% of substitution seem to be the most appropriate to increase eggs laying rate while 2% is suitable to obtain heavy eggs in the soudano-guinean agro ecological zone of Cameroon.

English

The objective of this study was to test for appropriate quantity of fertilizer (NPK 12-11-18) required to boost the production of cassava (variety TME 419) in the forest zone of Cameroon. The trial was conducted at the experimental farm of the Institute of Agricultural Research for Development (IRAD) in Mbalmayo. The experimental design was completely randomized block design in three replicates. The treatments were as follows: T0 (Control (No input)); T1 (200 kg.ha-1); T2 (300 kg.ha-1); and T3 (400 kgha-1). The data were analyzed using the IBM SPSS Statistics 20 Software. The results showed that chemical fertilizer improves the growth (number of leaves, plant height, and petiole length) and yield (number of marketable root, yield) of cassava mainly because it enhances soil nutrient availability. Thus, NPK-fertilizer significantly (p<0.001) increased petiole length by 20.71, 27.83, and 31.62% for T1, T2, and T3, respectively at 5 months after planting (MAP). The highest plant height and number of leaves at 4 and 5 MAP was observed with T3 followed by T2 and T1. Similarly, the highest root yield (43.33±10.97 t.ha-1) was observed with treatment T3. Hence, the fertilizer application rate of 400 kgha-1 of NPK 12-11-18 appears most appropriate for intensification of cassava production in the humid forest agro ecological zone of Cameroon. Key words: Cassava, growth, NPK, root yield, soil fertility. &nbsp

A comprehensive survey of the prevalence and spatial distribution of ticks infesting cattle in different agro-ecological zones of Cameroon

BackgroundTicks and tick-borne diseases are a major impediment to livestock production worldwide. Cattle trade and transnational transhumance create risks for the spread of ticks and tick-borne diseases and threaten cattle production in the absence of an effective tick control program. Few studies have been undertaken on cattle ticks in the Central African region; therefore, the need to assess the occurrence and the spatial distribution of tick vectors with the aim of establishing a baseline for monitoring future spread of tick borne-diseases in the region is urgent.ResultsA total of 7091 ixodid ticks were collected during a countrywide cross-sectional field survey and identified using morphological criteria. Of these, 4210 (59.4%) ticks were Amblyomma variegatum, 1112 (15.6%) Rhipicephalus (Boophilus) microplus, 708 (10.0%) Rhipicephalus (Boophilus) decoloratus, 28 (0.4%) Rhipicephalus (Boophilus) annulatus, 210 (3.0%) Hyalomma rufipes, 768 (10.8%) Hyalomma truncatum, and 19 (0.3%) Rhipicephalus sanguineus. Three ticks of the genus Hyalomma spp. and 33 of the genus Rhipicephalus spp. were not identified to the species level. Cytochrome c oxidase subunit 1 (cox1) gene sequencing supported the data from morphological examination and led to identification of three additional species, namely Hyalomma dromedarii, Rhipicephalus sulcatus and Rhipicephalus pusillus. The finding of the invasive tick species R. microplus in such large numbers and the apparent displacement of the indigenous R. decoloratus is highly significant since R. microplus is a highly efficient vector of Babesia bovis.ConclusionsThis study reports the occurrence and current geographical distribution of important tick vectors associated with cattle in Cameroon. It appears that R. microplus is now well established and may be displacing native Rhipicephalus (Boophilus) species, such as R. decoloratus. This calls for an urgent response to safeguard the livestock sector in western central Africa.

Mycotoxin Contamination of Edible Non-Timber Forest Products in Cameroon.

The prevalence and concentrations of three major mycotoxins, total aflatoxin (AFs), fumonisin (F), and zearalenone (ZEN), were determined on seven edible non-timber forest products (ENTFP) in Cameroon. A total of 210 samples consiting of 30 samples from each ENTFP commodity was collected from farmers and local markets in three agroecological zones of Cameroon and analyzed for moisture content and mycotoxins. Mycotoxins were analyzed using commercial enzyme-linked immunosorbent assay (ELISA) kits and results were validated using the VICAM fluorometric method. The European Union regulation of mycotoxins for human consumption (N°1881/2006) was adopted as reference. The moisture content of samples varied from 5.0% to 22.6%. Aflatoxin contamination was detected in 84.3% samples and only 5.7% exceeded the legal limit (10 ppb). Similarly, 53% of samples were contaminated with fumonisin and 5% of samples exceeded the legal limit (1000 ppb). Zearalenone contamination was detected in 92% of samples and 21% of samples exceeded the legal limit (100 ppb). This is the first report on mycotoxin contamination of ENTFP in the Congo Basin forest. The findings of this study will form a basis for educating farmers and other stakeholders of ENTFP values chain on mycotoxins and mycotoxin mitigation measures to produce safe ENTFP for local and international markets.

Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in Cameroon: Case study on its distribution, damage, pesticide use, genetic differentiation and host plants.

Maize farmers in sub-Saharan Africa recently experienced unusual damage in their farms, attributed to the fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith). This pest was first recorded in Africa in 2016, but detailed information on its distribution and damage and farmer’s response in invaded areas are largely lacking. In this study, we determined FAW distribution, genetic diversity, host plants, crop damage, and farmers’ responses. S. frugiperda was recorded in the 10 regions of Cameroon. Average percentage of infested plants and damage severity (on a scale of 1 to 5) were lowest—20.7 ± 7.4% and 2.1 ± 0.1 respectively—in the Sahelian regions and greatest—69.0 ± 4.3% and 3.1 ± 0.1 respectively—in the Western Highlands. Altitude did not influence FAW incidence and severity and its larvae infrequently co-occurred with maize stemborers on the same plants, suggesting possible direct and/or indirect competition between the two groups of maize pests. In response to this new threat to maize production, farmers have opted for the application of synthetic pesticides. Although our experiments were not designed to determine pesticide efficacy, as parameters such as time since application were not considered, our observations suggest lack of a drastic effect on S. frugiperda infestations on maize. There were two haplotypes of FAW co-occurring in Cameroon corresponding to the rice and corn strains and separated by 1.7% sequence divergence, which does not support the existence of cryptic species. S. frugiperda larvae were also recorded on Sorghum bicolor (L.) Moench (10.6%), Solanum tuberosum L. (2.8%), Ipomoea batatas (L.) Lam. (1.9%), Saccharum officinarum L (0.8%), Phaseolus vulgaris L. (0.4%) and Gossypium hirsutum L. (1.9%). This study show that two strains are present in all agroecological zones in Cameroon, and probably in neighboring countries of central Africa sharing the same agroecologies. Management options should therefore consider the use of specific natural enemies and an informed decision of intervention based on strain capture and damage threshold, to avoid pesticide resistance that may arise from inadequate use of chemicals. Further studies should also be undertaken to assess the response of the two S. frugiperda strains to biopesticides and botanical insecticides.

Morphological Characterization of Four Leguminous Crops Cultivated in Two Agro Ecological Zone: Western and Guinean Savannah Highlands of Cameroon

In 2014, quarter (¼) of Africa populations were estimated to be suffering from hunger. In Cameroon, the demand for food is increasing while productivity was decreasing subsequently the food insufficiency. To solve this problem, leguminous crops were valorized in Cameroon. They represent a major source of protein especially among the poorest population, and are rich in essential amino acidssuch as lysine, supplementing thusthe nutritional value of cereal and tuber diets. Nevertheless, their production faced the problem of soil degradation and loss of soil fertility. The main objective of this work was to characterize leguminous crops cultivated in two agro ecological zones of Cameroon. Investigations based on farmer’s knowledge on leguminous crops cultivation were done in Western highlands and High Guinean savannah zones of Cameroon. During this survey, leguminous crops were collected for qualitative and quantitative analysis. Farmers which were mostly women have at least 10 years of experience on these leguminous crops cultivation. They kept their seed for next cultivation season and did not use fertilizers in their field. Based on color of seeds, nine, seven, six and four ecotypes of representing beans, peanuts, Bambara groundnuts and soybeans respectively were found from study sites. Quantitative analysis of these ecotypes presents the diversity of beans, peanuts and soybeans (p = 0.00) according to their biometric parameters. Except the weight of Bambara groundnuts which were different (p = 0.00) their size was similar among ecotypes.

Agro-ecological distribution of the phenotypic diversity of aerial yam (Dioscorea bulbifera L.) in Cameroon using multivariate analysis: prospect for germplasm conservation and improvement

Abstract Aerial yam (Dioscorea bulbifera L.) is a crop of great economic importance and an excellent candidate for improving food security in developing countries. Understanding the genetic variability of any crop species is a decisive step for its improvement and requires characterization and evaluation of available germplasm. The objectives of this study were to determine the extent of genetic variability, estimate the association between agromorphological traits and clustering among 57 genotypes of aerial yam from three distinct agro-ecological zones in Cameroon using multivariate analysis. Thirty nine characters (23 qualitative and 16 quantitative) were used for the study. Significant differences in genetic diversity indices were found. Accessions from the bimodal humid forest zone (Na = 2.08, He = 0.27) showed significantly lower diversity compared to both western highland (Na = 2.30, He = 0.34) and humid monomodal forest zones (Na = 2.57, He = 0.32). Means values of most quantitative traits also showed significant differences between agro-ecological zones. Batingla-3 and Bawouwoua-1 had important bulbil yield, reaching 3500 g / plant. Significant associations were found between many traits. The use of the Unweighted Pair Group Method with Arithmetic Mean allowed the distribution of the 57 genotypes into six distinct clusters with the clustering pattern not showing any parallelism with location sites or agro-ecological zones. Mahalanobis D2 statistics revealed the highest inter-cluster distance between cluster II and VI. Accessions of these clusters are potential parents for future breeding programs. This study showed that aerial yam from Cameroon has an enormous wealth of traits variation, indicating huge potential for its genetic improvement through selection and hybridization.

A Pilot Study in Cameroon to Understand Safe Uses of Pesticides in Agriculture, Risk Factors for Farmers' Exposure and Management of Accidental Cases.

Chemical pesticides are widely used in Cameroon for agricultural production. In 2015, more than 600 pesticide products were approved for use in various foodstuffs. Much misuse of these chemicals by farmers has been documented in rural and urban settings. This pilot study aims to contribute to the improvement of the health of the population and the environmental preservation by identifying pesticide-poisoning cases, the most incriminated products and critical risk factors of exposure. Questionnaires were administered to pesticide vendors, farmers and health personnel, and observations made on farmers’ practices at their work places. From July to September 2016, 24 villages from five sites, representing the most important agricultural production areas of the five agro-ecological zones of Cameroon, were visited. In total, 519 people were interviewed: 412 farmers, 69 pesticide vendors and 38 health personnel. A total of 180 pesticide formulations out of 610 registered in 2015 were said to be used by farmers. In the 38 health centers visited, 56 cases of pesticide poisonings and intoxications were reported between 2011 and 2016. Paraquat-, glyphosate-, cypermethrin- and metalaxyl-formulated pesticides were the most incriminated. In total, 78% of poisoning cases were accidental, 12% suicide attempts, 4% criminal. Entry of pesticide products from neighboring countries needs to be better regulated, and the quality of pesticides sold on the market should be monitored periodically. Empty pesticide containers should be recuperated from smallholder farmers. Authorities should set up a harmonized pesticide-poisoning management procedure, and create a toxico-vigilance system for surveillance cases and preventive actions.

Potentials of Arbuscular Mycorrhiza Fungi (AMF) and Neem (Azadirachta indica A. Juss.) Leaves Extract as Biological Control Agents against the Sweet Potato Weevil (Cylas puncticollis Boh.) in Two Agro-ecological Zones of Cameroon

Potentials of Arbuscular Mycorrhiza Fungi (AMF) and Neem (Azadirachta indica A. Juss.) Leaves Extract as Biological Control Agents against the Sweet Potato Weevil (Cylas puncticollis Boh.) in Two Agro-ecological Zones of Cameroon

Biodiversity of the phosphate solubilizing microorganisms (PSMs) population from the rice rhizosphere soils of the two agro-ecological zones of Cameroon

The plant rhizosphere microorganisms having the phosphate solubilizing capacity can convert the insoluble soil organic and inorganic phosphates into a soluble form and make the phosphorus (P) available to the plant. With the objective of evaluating the phosphate solubilizing microorganism populations under the rice rhizosphere, soils samples were collected in three locations of two agro ecological zones of Cameroon and analyzed for their PSMs diversity. Isolation of microorganisms was made on non selective nutrient agar plates and the phosphate solubilizing activity of isolates was tested on National Botanical Research Institute’s Phosphate growth medium (NBRIP) amended with sparingly soluble rock phosphates of different origins. The morphological description of isolates allowed evaluating the phosphate solubilizing microorganism’s diversity under the rice rhizospheric soil. The most probable number of PSMs ranged between 22 and 53% with an average of 48%, 52.80% and 22.44% for Nkolbisson, Nyokon and Santchou respectively. The 65 isolates obtained from all locations were distributed in four diverse groups. The index of solubilization ranged between 2.70 and 7.24 depending on isolate. From a total of 65 isolates obtained from the three sampling sites, 46 were phosphate solubilizing isolates among which: 20 were of low solubilization, 16 of medium and 10 of high solubilization. This is the first work reporting phosphate solubilizing microorganisms on rice rhizosphere in Cameroon. However, the selection of phosphate solubilizing microorganisms as possible inoculation tools for phosphate-deficient soils should focus on the integral interpretation of laboratory assays, greenhouse experiments as well as field trials. © 2015 International Formulae Group. All rights reserved. Keywords: Diversity, index of solubilization, isolates, rice, rock phosphates

English

Rock phosphate is an alternative strategy for less expensive natural sources of plant nutrients. However, this can be efficiently used by plants only when associated with phosphate solubilising microorganisms. Phosphate solubilising bacteria (PSB) from soils of two agro ecological zones of Cameroon were screened for their phosphate solubilising ability on plates and in liquid cultures supplemented with Malian, Moroccan or Mexican rock phosphates. They were subsequently tested on maize grown in pots filled with unsterile soil amended with Malian rock phosphate for their aptitude in promoting maize growth. Under in vitro condition, Enterobacter sp. showed halo zone on plates supplemented with the different rock phosphates with an index of solubilization (IS) varying between 2.10 and 2.71. This strain also showed the highest concentration of mobilized P with all rock phosphates: 1075.17, 1161.04, 862.57 µg P/g for Malian, Moroccan and Mexican rock phosphates, respectively, followed by Klebsiella sp. with the concentrations of 862.57, 615.19, 426.29 µg P/g, respectively. The Malian (402.5 µg P/g) and Moroccan (403.7 µg P/g) rock phosphates appeared to be the easiest phosphates to be solubilised by the different strains. However, the Mexican rock phosphate (345.3 µg P/g) was less solubilised in broth. In general, all the strains in single and in consortia significantly increased the number of leaves, stem base diameter, total dry mass, shoot dry mass and root dry mass as compared to non-inoculated control. The effect of inoculation with single strain varied between 27.5 and 59.3% growth increase, while the effect of inoculation with consortia varied between 54.1 and 109.3% as compared to non-inoculated control. The findings of the current study suggest the potential use of rock phosphate and PSB that would enhance maize productivity in economically profitable and environmentally friendly ways. Key words: Maize growth, phosphate solubilising bacteria, plant nutrient, rock phosphate.

Rock Phosphate Solubilisation by Strains of Penicillium Spp. Isolated from Farm and Forest Soils of three Agro Ecological Zones of Cameroon

Rock Phosphate (RP) is theoretically the cheapest fertilizer and most abundant, but its direct application in the soils is not always agronomically effective due to its low phosphorus (P) availability. An environmentally friendly and economically alternative to traditional processing of these deposits is the use of Phosphate Solubilising Microorganisms (PSM). Three Penicillium strains were screened for their aptitude in solubilising sparingly soluble phosphates as well as phosphate rock on plates and in broth supplemented with the different phosphate types. The three strains show the ability in solubilising at least two from the sparingly soluble phosphates types, with the solubilisation index (SI) varying from 1.44 to 4.74. All the strains were able to show halo zone on plates supplemented with Malian and Algerian rock phosphates with solubilisation index ranging from 1.2 to 1.8. No halo zone was detected on plates with Moroccan rock phosphate as sole phosphate source. However, significant amount of phosphorus were mobilised by all strains in broth with the different rock phosphates, including the Moroccan rock phosphate. The amount of solved P varied from 257.46 mgP.L-1 (Penicillium sp. 43) to 326.65 mgP.L-1 (Penicillium sp. 109) for Malian rock phosphate, from 152.61 mgP.L-1 (Penicillium sp. 43) to 337.56 mgP.L-1 (Penicillium sp. 27) for Algerian rock phosphate, and from 283.79 mgP.L-1 (Penicillium sp. 43) to 347.16 mgP.L-1 (Penicillium sp. 109) for Moroccan rock phosphate. The rock phosphate solubilisation was associated with pH media drop and both parameters were strongly correlated.

Prevalence of Six Viruses in Potato Seed Tubers Produced in Informal Seed System in the North West Region of Cameroon

Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent in small size tubers (71%) and least in large size potato tubers (63%). Our results suggest that tuber size can serve as a guide to identify healthy (virus-free) tubers. Farmers could therefore use large size potato tubers for planting.

Assessment of Aflatoxin Contamination of Maize, Peanut Meal and Poultry Feed Mixtures from Different Agroecological Zones in Cameroon

Mycotoxins affect poultry production by being present in the feed and directly causing a negative impact on bird performance. Carry-over rates of mycotoxins in animal products are, in general, small (except for aflatoxins in milk and eggs) therefore representing a small source of mycotoxins for humans. Mycotoxins present directly in human food represent a much higher risk. The contamination of poultry feed by aflatoxins was determined as a first assessment of this risk in Cameroon. A total of 201 samples of maize, peanut meal, broiler and layer feeds were collected directly at poultry farms, poultry production sites and poultry feed dealers in three agroecological zones (AEZs) of Cameroon and analyzed for moisture content and aflatoxin levels. The results indicate that the mean of the moisture content of maize (14.1%) was significantly (P < 0.05) higher than all other commodities (10.0%–12.7%). Approximately 9% of maize samples were positive for aflatoxin, with concentrations overall ranging from <2 to 42 µg/kg. Most of the samples of peanut meal (100%), broiler (93.3%) and layer feeds (83.0%) were positive with concentrations of positive samples ranging from 39 to 950 µg/kg for peanut meal, 2 to 52 µg/kg for broiler feed and 2 to 23 µg/kg for layer feed. The aflatoxin content of layer feed did not vary by AEZ, while the highest (16.8 µg/kg) and the lowest (8.2 µg/kg) aflatoxin content of broiler feed were respectively recorded in Western High Plateau and in Rainforest agroecological zones. These results suggest that peanut meal is likely to be a high risk feed, and further investigation is needed to guide promotion of safe feeds for poultry in Cameroon.

Cowpea Quality Seed Indicators as Influenced by Field Application of Selected Biofertilizers and Mycoinsecticide in Three Agroecological Zones of Cameroon

Inoculation of cowpea with biofertilizers (rhizobia + mycorrhiza), and spraying them with the mycoinsecticide Metarhizium anisoplae has been shown to improve growth and grain yield. However, the treatment may impair the technological properties of the grains, which have not yet been investigated. This study is a followup to our recent study on the effect of selected biofertilizers and mycoinsecticide in three agroecological zones of Cameroon, aimed at evaluating the physical properties and the protein content of cowpea seeds as affected by these bio-inoculants. Spraying cowpea plants at flowering with the mycoinsecticide M. anisopliae and/or inoculating cowpea seeds at sowing with biofertilizers (rhizobia, mycorrhizae) had no significant effect on the protein content, water absorption capacity, and the percentage of seed coat. They instead significantly affected the physical properties of seeds, such as the seed weight, length, geometric diameter, and sphericity, but this varied from one agroecological zone to another. Whereas the seed weight was increased in agroecological zone V, a significant decrease was observed in zones I and II. The changes in weight reflected those of diameter and volume as confirmed by the correlation analysis. Application of biofertilizers had no significant effect on the water absorption capacity, protein, and coating percentage of cowpea seeds, suggesting that the main qualities of cowpea seeds for industrial utilization remained the same. The increased yield generally associated with these treatments may result from changes in the geometric size, which depends on the agroecological zone.

Agro-ecological Differentials in Soybean Crop Evapotranspiration and Implications for Adaptation to Climate Change

This study estimated soybean crop evapotranspiration from weather data using the cropwat model. The effects of reference evapotranspiration, crop coefficients, and yield response factor were quantified for three different agroecological zones in Cameroon. The evapotranspiration of soybean was observed to be 281.03 mm in the farming district of Ambam, 387.7 mm in Bamenda and 605.3 mm in Garoua, indicating pronounced differences in the agro-ecologies. Across the three regions studied, rainfall pattern determines soil water reserves and crop water uptake. In the farming zones of Bamenda and Ambam, water requirement for soybean are met by the rainfall. In the northern region of the country, irrigation needs are high. As a consequence, actual crop evapotranspiration is greatest in the hot dry zone of Garoua and lowest in the cool humid region of Bamenda. From this study it could be concluded that coping with climatic variations and future climate change will require complementary irrigation as well as improved crop management practices.Keywords: soybean, climate variation, crop water requirements, Cameroon

Pseudomonads and symbiotic micro-organisms as biocontrol agents against fungal disease caused by Pythium aphanidermatum

Experiments were undertaken to assess the antagonistic aptitude of Pseudomonas spp. alone or associated with mycorrhizal fungi on Pythium aphanidermaturm, the causal agent of seedlings damping-off and stem rot of cowpea (Vigna unguiculata L. Walp). Evaluation was made using selected strains of pseudomonad (Pseudomonas fluorescens, P. putida and Pseudomonas sp.) isolated from V. unguiculata andSolanum tuberosum rhizospheric soils collected in three agroecological zones of Cameroon. Cultures were conducted on agar plates and in liquid media to evaluate the antagonistic capacity of those strains against Pythium aphanidermaturm and to evaluate their biocontrol activity in protecting cowpea plants. The results showed a direct inhibition of the pathogenic fungus by these bacteria. P. fluorescens used alone against Pythium aphanidermaturm, provided a reduction of the disease index from 3.44 to 1.06. When the arbuscular mycorrhizal fungi Glomus deserticola is associated to P. fluorescens, the disease index dropped to 0.13, confirming the synergistic effect of those beneficial micro-organisms. Key words: antagonism, beneficial micro-organisms, biological control, Glomus deserticola, Pseudomonas spp., Pythium aphanidermaturm.