Agro-ecological Zones Of Cameroon Research Articles

New okra genotypes for the management of aphids (Hemiptera: Aphididae) in the diverse ecological landscapes of Central Africa.

Various aphid species, including Aphis gossypii Glover (Hemiptera: Aphididae), are considered important pests of okra and other vegetables. Previous studies under 1 environment in Cameroon, Central Africa, had found multiple okra genotypes with resistance to A. gossypii. However, the stability and yield performance of the "resistant" genotypes across different environments were unknown. Ten previously identified aphid-resistant okra genotypes along with 1 commercial variety and a local landrace (specific to a given location) were compared during 2 seasons in replicated trials in 4 agro-ecological zones of Cameroon that also represent large areas of Central Africa. Aphid populations and okra yield parameters were evaluated. Breeding values were predicted using a linear mixed model for all data, and genotypes by location interactions were identified. The area under the infestation pressure curve (AUIPC) was calculated using aphid count data and subjected to resistance analysis. The Local-the most susceptible with the highest breeding value (+2.33)-and VI060794-one of the moderately resistant-genotypes had the highest yield per hectare. The only resistant genotype VI036213 had the lowest breeding value (-2.20). Genotype × location interactions were significant for yield, pod width, and plant height, while location variance was significant for all parameters evaluated. When considering that higher aphid densities could lead to greater pesticide use and, therefore higher production and environmental costs, the high-yielding VI060794-with moderate aphid resistance across multiple environments-presents an alternative or substitute for local landraces across multiple agro-ecologies of Cameroon and (by extension) Central Africa.

Investigating smallholder farmers’ practical experiences, perceptions and response to climate change: An empirical analysis in Cameroon

Climate change is constraining rural wellbeing, agriculture and food security. This necessitates adaptive strategies to overcome negative effects especially at the level of low-income tropical farming households. Using survey data from farming households in the Western Highland and the Bimodal Rainfall Humid Forest agro-ecological zones in Cameroon, this study evaluates the socio-economic and institutional factors associated with farmers’ perception and adaptive response to climate variability and change. We employed a logistic regression model to estimate the drivers of farmers’ perception. Our results show that farmers’ experience and land status (ownership) are positively associated with farmers’ ability to perceive climate change in the Western highlands agro-ecological zone. Access to credit, membership in a farmers’ organisation and gender are significant drivers in the Rainforest agro-ecological zone. Our findings show that different socio-economic and institutional factors drive perception and these factors differ between zones. The findings have important implications for short-term adoption of coping strategies and medium-term adaptation planning. We suggest that farmers’ capacity is improved through early-warning climate information and the creation of farmer field school to vulgarise climate smart farming techniques and supplemented with timely technical support from the governmental extension services.

Prevalence of African Mosaic and Morphological Characterization of Cassava (Manihot esculenta Cranz) Varieties in Two Agroecological Zones of Cameroon

The objective of this work is to conduct an epidemiological study of African cassava mosaic and to characterize the diversity of local cultivars in circulation in the monomodal and bimodal rainforest zones of Cameroon. Disease-related parameters (incidence and severity index) were studied as well as morphological parameters (plant height, leaflet color, petiole color, lobe length, number of lobes, number of branches, petiole length). The results show that 96 cassava varieties were identified with 89 local varieties and 07 improved varieties. Diseased plants showed a symptom severity index of 1 to 5, which could reduce production by half in the areas considered. The leaf color was dark green, the number of branches was 3, the lobe and petiole lengths were 16.46 and 22 cm respectively, while the number of lobes was 5 the disease incidence for the two agro-ecological zones as a whole is 57.58% for a symptom severity index of 3. The epidemiological study reveals that the desease incidence of both agro-ecological zones was 57.58 % for a symptom severity index of 2 corresponding to 40 %. In the humid forest zone with monomodal spray the average incidence was 49.74% and a leaf attack rate was 29.03 % in the locality of Njombé (Cameroon's littoral region). At Ekona in southwestern Cameroon, the average incidence was 63% and leaf attack index was 1 corresponding to 20 %. In the bimodal rainforest zone (central Cameroon region), the average incidence was 60 % for a leaf attack rate was 37.11%. The expected results highlight a relatively worrying situation. Principal Component Analysis (PCA) confirms the convergence of tolerance towards the mosaic and grouped the different varieties into more or less homogeneous groups according to the morphological and epidemiological cassava descriptors. The results of the present work show that the introduction of cassava local varieties tolerant to mosaic disease in middling could be an alternative for the control of the cassava mosaic disease.

Climate, agroecology, and farm returns: differential impacts with implications for agricultural progress in the face of climate change

Climate change is expected to have differential impacts on different zones. In this study, we employed the Ricardian technique, estimated through ordinary least squares (OLS) to assess the impact of climate change on farmers’ revenue. We use survey data from two distinct agroecological zones in Cameroon. Our results show that rainfall is the main climatic variable affecting farmers’ revenue. The results are statistically different for the two agroecological zones. While rainfall in the dry season affects revenue in the western highland zone. No climatic variable seems to affect farm revenue in the bimodal forest zone. These results suggest that the abundance of forest in the bimodal zone maybe be shielding the zone from the effects of climate change. We therefore recommend that farmers employ water harvesting and low-cost irrigation methods to cope with changes in rainfall pattern especially in extended dry seasons. Facilitating farmers’ access to climate information particularly with respect to the onset and cessation of rains will improve the planning of farm operations.

Isolation, Characterization, and Selection of Bacterial Endophytes from Soybean (Glycine max) Nodules and Roots in Some Soils of Cameroon for Promoting Growth of Forage Legume Plants

Aim: The present study aimed to isolate, characterize and select the most effective bacterial endophytes to enhance soybean growth, biomass, and yield. Methodology: Seven soil samples were collected from the rhizosphere of forage legumes in fields across three agroecological zones of Cameroon. Bacterial endophytes were isolated from soybean roots and nodules and cultured on nutrient agar. The isolates were screened for the tolerance tests, extracellular enzymatic activity, P-solubilization activity, and IAA production. The best isolates were selected using a two-factor block factorial design. Each treatment was replicated six times. Results: A total of 85 bacterial endophytes were isolated. Characterization results of 22 preselected isolates revealed an optimal growth temperature of 37°C and a pH range between 6 and 7. Furthermore, the 22 isolates solubilized inorganic phosphate, 7 produced IAA, and 8 exhibited amylase activity. PCR analysis of the nifH and nodC genes showed that the isolates possessed the nifH gene as a nitrogen fixation marker and the nodC gene as a nodulation marker. The findings show that, out of the 22 bacterial endophyte isolates, NTT1 and BOSH9 were the most effective in increasing plant height by 26.74% and 31.78%, respectively. Additionally, they resulted in an increase in biomass of 94.24% to 120.48% and an increase of 71.59% to 76.70% in grain yield compared to control treatment. Conclusion: The selected isolates significantly enhance plant growth, increase biomass, and improve soybean grain yield. However, their potential use as biofertilizers in agriculture will require further investigation under real field conditions.

Past and future annual droughts in the five agro-ecological zones of Cameroon

Past and future annual droughts in the five agro-ecological zones of Cameroon

Evaluation of the artemisinin content of Artemisia annua L. grown in different Agro ecological zones of Cameroon

Artemisinin and its derivatives are potent antimalarials that have become essential components of Artemisinin Based Combination Therapies (ACTs) for malaria treatment. Production of artemisinin is less compared to its world demand and access to ACTs is still limited in worst hit countries. Secondary metabolite production in plants depends on a number of factors including agro ecology. This work sought to evaluate the growth characteristics and artemisinin content of Artemisia annua grown in four agro ecological zones of Cameroon. Experimental fields comprising of A annua were set up in the different agro-ecological zones, for growth and artemisinin assessments. Artemisinin detection and quantification was compared in leaves/flowers and stems of Artemisia annua from these agro-ecological zones, using High-Performance Liquid Chromatography. Soil provenance and other agro ecological factors significantly affected the growth parameters of A. annua as there were significant differences (p<0.05) in plant height, leaf area, number of branches, stem girth and number of leaves across the different study areas. There was significant variation (P<0.05) in the content of artemisinin from the plant in the different agro ecological zones. The mean levels of artemisinin in the samples was 0.34-0.80% in stem samples, and 0.18-0.61% for leaves/flowers. The highest artemisinin yield in leaf/flowers samples (0.61%) was recorded in samples from Bamenda, while that of stem samples (0.80%) was recorded in samples from Ngaoundere. The study confirms the effect of agro ecological factors on artemisinin content of A. annua in Cameroon and reveal that A. annua grown in most regions of the country contain commercially viable levels of artemisinin which can further be exploited for pharmaceutical purposes.

Ecological risk assessment of pesticides based on earthworms in soils on the southeast slopes of Mount Cameroon

Agrochemicals misuse is common in developing countries with many environmental implications. This work assessed the ecological risk of pesticides, including insecticides, fungicides and herbicides based on earthworms in soils at the lower slopes of Mount Cameroon using the Pesticide Risk in the Tropics to Man, Environment and Trade (PRIMET) model. PRIMET was developed in 2008 in The Netherlands for use in tropical regions. Data on usage scheme and ecotoxicological information were collected and keyed into PRIMET for three main outputs: Predicted Environmental Concentration (PEC), No Effect Concentration (NEC), and Exposure Toxicity Ratio (ETR = PEC/NEC). Pesticides predicted for no acute and no chronic risk to earthworms included fipronil and chlorothalonil. Several pesticides were predicted for an acute risk to earthworms, and they comprised acetamiprid, imidacloprid, lambda-cyhalothrin, and carbendazim when used on maize (PEC ​= ​2.69 ​mg ​kg−1; ETR ​= ​5) and tomato (PEC ​= ​16.15 ​mg ​kg−1; ETR ​= ​30); 2, 4-D and abamectin when used on tomato and ethoprophos. Insecticides exhibiting a possible chronic risk to earthworms comprised acetamiprid, cypermethrin, emamectin benzoate, imidacloprid, indoxacarb, lambda-cyhalothrin, oxamyl, and thiametoxam. The majority of fungicides assessed (83%) posed a possible chronic terrestrial risk, with carbendazim at the top position when applied on tomato (PEC ​= ​16.15 ​mg ​kg−1; ETR ​= ​81). Some herbicides predicted for possible chronic risk based on earthworms included 2, 4-D, diuron, glyphosate, ethoprophos, and metaldehyde. Pesticides with the highest risk to earthworms comprised chlorpyrifos-ethyl, imidacloprid, ethoprophos, and nicosulfuron. The riskiest pesticides should hereby be regulated or replaced by less risky ones. The measurement of pesticide residues in water and food in the various agroecological zones of Cameroon is necessary to shed more light on pesticide ecotoxicology.

SAVOIRS ET USAGES LOCAUX DE SCORODOPHLOEUS ZENKERI HARMS (FABACEAE) ET AFROSTYRAX LEPIDOPHYLLUS MILDBR (HUACEAE) EN ZONE FORESTIERE ET SAVANE HUMIDE AU CAMEROUN

In the forest zone of Central Africa in general and Cameroon in particular, medicinal and food plants constitute the most important category of NTFPs, and many medicinal species contribute to income, cultural identity and improved well-being in rural and peri-urban households. Among these NTFPs, S. zenkeri and A. lepidophyllus, with their multiple uses, remain very useful plants for socio-cultural groups. The aim of this study was to inventory local knowledge and management practices according to ethnic groups and agro-ecological zones in Cameroon. The study was conducted in two agro-ecological zones (Savannah and Forest). Semi-structured individual interviews were conducted with 138 people involved in the S. zenkeri and A. lepidophyllus value chain. The non-parametric Kruskal-Wallis test was used to compare the different variables. Six ethnic groups were surveyed. The organs (S. zenkeri and A. lepidophyllus) used by these ethnic groups were seeds, barks, leaves and roots. Three main categories of use were recorded (food, medicinal, commercial) according to these organs. The seeds were used more for sale and self-consumption, while the barks, leaves and roots of S. zenkeri and A. lepidophyllus were used to treat 17 and 12 illnesses and symptoms respectively, including headaches, stomach ache, toothache, coughs and aches, etc. Despite its many uses by different ethnic groups, the species is subject to various anthropogenic pressures and benefits very little from conservation measures. Previous research should focus on its sylviculture to ensure its domestication.

Parasitism of the whitefly Bemisia tabaci by aphelinid parasitoids on cassava across five agro-ecological zones of Cameroon

The whitefly Bemisia tabaci (Gennadius) is the vector of cassava mosaic viruses causing cassava viral diseases, which are the most important biotic constraints of cassava production in sub-Saharan Africa (SSA). Presently, B. tabaci management in cassava fields calls for the development of an integrated approach that relies on host plant resistance and biological control. Data on B. tabaci's natural enemies, particularly parasitoids, in Central Africa are limited. Field surveys were conducted from 2015 to 2017 to identify parasitoids associated with B. tabaci in 5 Cameroon agro-ecological zones. Additionally, population dynamics studies were conducted in replicated fields experiments were conducted from 2016 to 2018 to identify cassava genotypes that can best promote B. tabaci parasitism. Two parasitoids, Encarsia sophia (Girault & Dodd) and Encarsia lutea (Masi) were found parasitizing B. tabaci nymphs with higher parasitism by E. lutea compared with E. sophia. The average parasitism rate during the survey was 33.4% for E. lutea and 8.4% for E. Sophia, regardless of AEZ. The highest parasitism rates by E. lutea (48.2% and 24.2% from field trials and surveys, respectively) were observed in the Western Highlands (AEZ 3) while parasitism by E. sophia was less than 12.4%. Four cassava genotypes (I090590, I011797, I090574, and I070593) promoted higher parasitism rates of B. tabaci by E. lutea and E sophia. The contributions of the two parasitoids and their integration with cassava genotypes for the management of B. tabaci in cassava fields are discussed.

Antifungal Potential of Acetone and Ethyl Acetate Extracts of Thevetia peruviana on Development of Phytophthora colocasiae, Causal Agent of Late Blight of Taro (Colocasia esculenta (L.) Schott) from Three Agro-Ecological Zones of Cameroon

Aims: This study was aimed to evaluate the antifungal activities of acetone and ethyl acetate extracts of Thevetia peruviana seeds on the in vitro growth of the fungus.
 Study Design: A randomized sample block design containing four treatments (T- = Negative control; T2= Ethyl acetate extract; T3= Acetone extract; T+=Callomil Plus) with three repetitions was used. Plant extracts were used at three concentrations: C1: 12.5 µl/ml; C2: 25 µl/ml and C3: 50 µl/ml; the chemical fungicide at the dose of 12.5 μL/ml.
 Place and Duration of Study: The study was conducted in the University of Yaoundé 1, Faculty of Sciences, Department of Plant Biology, Laboratory of Phytopathology and Crop Protection, and in the Institute of Agricultural Research for Development (IARD) of Yaoundé, Laboratory of Phytopathology, during the year 2019-2020.
 Methodology: acetone and ethyl acetate extracts of T. peruviana were prepared and used at concentrations of 12.5, 25 and 50 µl/ml. P. colocasiae was isolated from infected taro leaf cultivars "Macumba or Ibo coco" located in three different regions: west, Littoral and Centre. The various explants were were put in V8 agar medium and maintained in pure culture. Mycelial fragments of P. colocasiae of about 0.8 cm in diameter were cut and placed in sterile Petri dishes containing Potato Dextrose Agar (PDA) medium supplemented with different concentrations of plant extracts and incubated at 23±1°C for seven days for the evaluation of the radial growth.
 Results: The results obtained showed that the acetone and ethyl acetate extracts have completely inhibited the growth of the strain of West at 25 μ/ml while total inhibition of the pathogen was not obtained with strain of Centre region. The lowest inhibition was obtained with the strain of Littoral region: 93.88 % for acetone extract and 90.78 % for ethyl acetate extract compare to 100 % for west and Centre region at highest concentration.
 Conclusion: The acetone and ethyl acetate extracts at the concentration of 25 μ/ml totally inhibited the in vitro radial growth of some strains of P. colocasiae. These extracts, which are effective against P. colocasiae, may substitute fungicides in the fight against taro leaf blight.

English

The papaya tree is not very exploitable on the international market because of the post-harvest decline of the fruits. In this study, we identified arbuscular mycorrhizal fungi (AMF) from the rhizosphere of papaya in two agroecological zones of Cameroon (Njombe-Pendja: NP and Yaounde: Y). Morphological studies on the density, the rate of root colonization, the diversity of AMF species were evaluated. Molecular identification of AMF was performed by sequencing the small subunit (SSU) 18S rDNA gene region from soil samples. These genes were amplified from the AML and NS2 primers. The total number of spores per 100 g of dry soil was significantly different (P<0.05) depending on the sites, ranging from 391 in NP to 790 in Y sites. The frequency and intensity of root colonization was not significantly different in the two sites. Eleven (11) AMF belonging to seven (7) genera (Scutellospora, Gigaspora, Acaulospora, Entrophospora, Funneliformis, Glomus and Racocetra) were recorded. Two AMF species (T1: Scutellospora rosa and T6: Racocetra gregaria) were recorded at NP and absent at Y. The Shannon-Wiener index revealed a low diversity of AMF species. Homogeneity of species was recorded. Molecular analysis reveals that the AMF species obtained have sizes of 250 bp. Key words: Arbuscular mycorrhizal fungi, Carica papaya L., fungal, molecular and morphological identification, rhizosphere.

Seroprevalence and Risk Factors of African Horse Sickness in Three Agroecological Zones of Cameroon.

African horse sickness (AHS), a highly fatal arbovirosis of equines is endemic in sub-Saharan Africa. However, its epidemiology is poorly known in Cameroon. This study aimed to investigate the prevalence profile and risk factors of African horse sickness in Cameroon. Horse sera were subjected to the ELISA blocking test for the determination of antibodies against African horse sickness virus, and positive samples were submitted to capture ELISA to determine the presence of antigens. Potential risk factors associated with AHS were assessed based on the information collected in the field. The chi-square test and the odd ratio (OR) were used to test the association between serology and the different variables. Of the 336 sera obtained, 198 were positive for antibodies with a prevalence of 58.93% (CI: 53.67–64.19). From the 198 positive sera to antibodies, only one revealed positivity to antigens with a prevalence of 0.51% (CI: 0–1.5). Agroecological zone I (94.31%, CI: 91.83–96.79, OR: 34.92) was significantly (p < 0.05) associated with the higher risk of disease dissemination than agroecological zone II (66.67%, CI: 61.63–71.71, OR: 4.21) and agroecological zone III (32.18%, CI: 27.18–37.18; OR: 1). Males (63.59%, CI: 58.44–68.74, OR: 1) were significantly (p < 0.05) affected than females (50.42%, CI: 45.07–55.77; OR: 0.58). Horses of more than 8 years (76.00%, CI: 71.43–80.57) were significantly (p < 0.05) at risk than young animals of less than 3 years old (32.14%, CI: 27.15–37.13, OR: 0.15). This study highlights a high seroprevalence of antibodies of African horse sickness in Cameroon. Agroecological zone, age, and the importation of horses were highly associated with the distribution of disease at the national level.

Agroforestry for Climate Change Adaptation, Resilience Enhancement and Vulnerability Attenuation in Smallholder Farming Systems in Cameroon

The adverse impacts of climate variability and change are felt mostly by smallholder farmers and smallholder farming systems where rainfed agriculture is predominant. Continuous dependence on rain-fed agriculture has led to declining crop productivity and crop failure in most cases as weather patterns shift which is very problematic for crop growth. Agroforestry which is one of the climate-smart, environmentally benign and agroecological practices has been found to mitigate climate change adversities while fostering adaptation, enhancing resilience and attenuating vulnerability especially in smallholder farming systems. However, in Cameroon, limited empirical research has been done to ascertain the role played by agroforestry in climate change adaptation, resilience enhancement and vulnerability attenuation. This paper which is based on an in-depth review of literature was undertaken to uncover what has been done so far in terms of empirical studies tackling the role played by agroforestry in climate change adaptation, resilience and vulnerability attenuation in Cameroon. It was found that most of the empirical studies have been carried out in one agroecological zone – the western highlands of Cameroon, showing that smallholder farmers adopt different agroforestry practices in the face of climate change with the most common being home gardens with livestock, home gardens without livestock, scattered trees on croplands, improved fallows, live fences/hedges and windbreaks, coffeebased agroforestry, cocoa-based agroforestry, apiculture-based agroforestry, fodder banks, and plantation crop-based agroforestry practices. These agroforestry practices provide a plethora of ecosystem services categorized into provisioning, supporting, regulating and cultural which play an important role towards fostering climate change adaptation, enhancing resilience and attenuating vulnerability in smallholder farming systems. From the findings uncovered by this study, it is imperative for more empirical studies to be carried out in the other four agroecological zones of Cameroon where there is a paucity of information regarding the role played by agroforestry towards fostering climate change adaptation, enhancing resilience and attenuating vulnerability in smallholder farming systems.

Farmers’ Knowledge and Perception on Beans Postharvest Constraints and Their Mitigation Methods in the Humid Rainforest and Highland Ecozones of Cameroon

Aims: This study sought to assess farmers’ awareness and knowledge about bean postharvest constraints and their indigenous methods to mitigate them. Cameroon.&#x0D; Study Design: Random interviewing of bean farmers.&#x0D; Place and Duration of study: Interviewed farmers of the highland savanna and humid rainforest ecological zones which are two agro-ecological zones of Cameroon respectively from January 2017 to October 2018.&#x0D; Methodology: A structured questionnaire was randomly distributed to 519 bean farmers in order to document their perceptions on various constraints hampering beans postharvest handling/storage and their indigenous methods of mitigating these constraints. Of these, 356 were from the highland savanna and 163 from the humid rainforest ecozones&#x0D; Results: Most postharvest losses in beans are caused by insects and mold/rot. Insect pests were reported by 251 (69.5%) of farmers in the highland savanna and 134 (84.8%) in the humid rain forest, while mold/rot was reported by 108 (29.9%) of the farmers in the highland savanna and 11 (6.9%) in the humid rainforest. Farmers in both agro-ecological zones lacked adequate storage facilities, as reported by 147 (40.7%) in the highland savanna and 43% (275) in the humid rainforest. Most farmers in the highland savanna 118 (39.20%) and humid rainforest 67 (43.22%) stored bean grains for 1-3 months, though farmers in the highland savanna generally stored beans longer than those in the humid rainforest. The insect infestations were controlled mainly by using conventional pesticides and local plant materials while mold was mainly managed by proper drying of the produce.&#x0D; Conclusions: To mitigate these constraints, an integrated approach of storing appropriately dried insect-free grains in moisture proof storage containers/facilities and judicious use of synthetic pesticides and/or proven effective botanicals should be adopted. Thus, farmers should be trained on good bean preservation methods and effective plant-based products.

Infection coefficient of Maize streak virus, leafhoppers composition and control using biopesticids and some cultural practices in agro-ecological zones of Cameroon

Infection coefficient of Maize streak virus, leafhoppers composition and control using biopesticids and some cultural practices in agro-ecological zones of Cameroon

Indigenous Knowledge of Bamboo Products and uses in the Western Highlands of Cameroon

Introduction: Today, bamboo is a resource frequently used by local people for their wellbeing and rural development in poor localities.&#x0D; Aims: This study aimed at identifying the ecosystem services offered by bamboo to the local population for their wellbeing.&#x0D; Duration and Place of Study: The study was carried out in January to February 2021 in Western highlands Agro ecological zone of Cameroon; more precisely in areas with high bamboo density according to literature review.&#x0D; Methodology: Three hundred and ten (310) questionnaires were administered to persons involved in bamboo activities including a direct observation in the field. This was complemented with key informant interviews.&#x0D; Results: The results showed that bamboo is highly utilized for subsistence purposes in many households in the Western Highlands of Cameroon, with at least 97 bamboo uses and products identified. These uses/products were grouped into 11 sectors/domains making use of bamboo. Agriculture, silviculture, handicrafts, furniture and house construction are the sectors using more bamboo products. Only 5% of respondents used bamboo in more than 10 sectors/domains.&#x0D; Conclusion: This baseline survey presents results which could orientate decisions of Policymakers and Development planners on how bamboo products could be valorized in the Western Highlands.

Comparative Experimental Effects of Intercropping and Cypermethrin on Insect Pest Infestation and Yield of Maize, Cowpea and Okra in Two Cameroonian Agro-Ecological Zones

The present study investigates the effect of intercropping (maize-cowpea, maize-okra, maize-okra-cowpea, okra-cowpea) compared to insecticide application on the level of infestation of insect pests and the final yield of maize, cowpea and okra. Field experiments were conducted during the 2016 and 2017 cropping seasons in the Guinean Savannah (Dang-Ngaoundere) and Sudano Sahelian (Gouna-Garoua) agro-ecological zones in Cameroon. Our experimental design was a split plot arrangement in a randomized complete block with four replications. The main factor was assigned to the use of insecticide (Cypermethrin) and sub plots were devoted for cropping systems. We compared the efficiency of intercropping to that of Cypermethrin application on the Yield of maize, cowpea and okra as influenced by insect pest damages. The comparison of monocropped sprayed by Cypermethrin to unsprayed showed that, in Dang, insect pests reduced maize yield by 37% and 24% in 2016 and 2017, respectively, whereas in Gouna, it was lower than 8% during the both years. Reduction in seed yield by insect pests on cowpea in Dang represented 47% and 50% in 2016 and 2017, respectively, whereas in Gouna, it was 55% and 63% in 2016 and 2017, respectively. For okra, insect pests reduced okra fruit yield by 25% and 44% in Dang and 23% and 28% in Gouna, respectively, in 2016 and 2017. Crop yield was lower in intercropping compared to monoculture due to competition of plants in association on different resources. Considering the total yields obtained from each intercropping, intercropping trials resulted generally in higher yields compared to mono-culture (LER &gt; 1) in both sites and years but the respective yields were quite different. On the basis of the results obtained, we recommend maize-cowpea intercropping as a sustainable solution to reduce the infestation level of their pest insects.

Morphological and Physiological Responses of Arachis hypogea L. to Salinity and Irrigation Regimes in Screen House

Aims: The K3237-80 groundnut variety from IRAD Nkolbisson is widely preferred in the Central African sub region for its sizable seeds and high yields, thus its contribution to livelihoods and food security. Apart from yield rating studies, responses to abiotic stress have not been done for this variety. The aim of this research was to investigate the responses of K3237-80 groundnut variety to salinity and water stress in screen house, in order to predict growth and yield performance under predicted conditions of soil salinity and rainfall variability.&#x0D; Materials and Methods: The experimental design was a 4 by 3 factorial design. There were three levels of irrigation corresponding to 1100 mm, 2200 mm and 3300 mm crossed with four salinity levels of 0, 4, 8 and 12 ppt. Treatments were maintained till maturity and growth, yield and physiological parameters measured. Data were subjected to Factorial Analysis of Variance through the GLM approach, in the MINITAB Version 17 statistical package, followed by Spearman Rank Correlation and Factor analyses, all at α = 0.05.&#x0D; Results: It was found that this variety is mildly tolerant to salinity, as growth and yield decreased at salinity levels above 4 ppt. It is however resistant to irrigation water variability which explains why it does well in all five agroecological zones of Cameroon. Both salinity and irrigation treatments significantly influenced WUE, transpiration rate and TUE (p&lt;0.05). Water use efficiency decreased from 3.23 g/l in plants irrigated with freshwater to 1.76 g/l in plants treated with water of 12 ppt salinity. Transpiration rate increased from 0.04 l/hr/plant at 0ppt to 0.06 l/hr/plant at higher salinities, while transpiration use efficiency correspondingly decreased significantly. Correlation analysis revealed that growth, yield and biomass parameters of A. hypogea are highly salinity-driven, while transpiration and water use efficiency are highly irrigation-dependent.&#x0D; Conclusion: Therefore groundnut can be grown to maturity at salinity of up to 12 ppt, the trade-off is reduced growth and yield, caused by disruptions in photosynthesis and water relations.

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.