Dominic Njualem - Academia.edu (original) (raw)

Papers by Dominic Njualem

Journal of Applied Life Sciences International

Aims: This study was aimed at exploring tissue culture technique as a tool for mass propagation o... more Aims: This study was aimed at exploring tissue culture technique as a tool for mass propagation of some Cameroonian cocoyam (Xanthosoma sagittifolium) cultivars/landraces (red, yellow and white skin colour). Study Design: The experiment was laid out in a completely randomized design with three treatments in four replications. Place and Duration of Study: The study was conducted in the tissue culture laboratory of the Institute of Agricultural Research for Development, Bambui, Cameroon, in the first half of 2018. Methodology: Explants were gotten from three Cameroonian cocoyam landraces (red, white and yellow skin colour). Shoot tips were excised and cultured on Murashige and Skoog (MS) medium supplemented with 30 g of sucrose, 5ml of ascorbic acid, 4ml of 6- benzylaminopurine (BAP 1mg/l), 1 ml indole-3- acetic acid (IAA 1 mg/l) and 6 g of agar at pH of 5.8±0.1 for shoot initiation and proliferation. Data was collected after 4 weeks (number dead, num...

American Journal of Agriculture and Forestry

Plant population density in intercropping system is known to directly affect competition among co... more Plant population density in intercropping system is known to directly affect competition among component crop as well as their yields. In a bit to establish appropriate population density in an intercropping system in Bambili, a field experiment was conducted with treatments Sole Potato (33,333 plants/ha), Sole maize (40,000 plants/ha), sole beans (66,666 plants/ha), potato 30 cm/maize 25 cm (73,333 plants/ha), potato 30 cm/maize 50 cm (53333 plants/ha), potato 30 cm/beans 15 cm (99,999 plants/ha), potato 30 cm/beans 30 cm (66,666 plants/ha) and potato 30 cm/Maize 100 cm/Beans 60 cm (59,333 plants/ha) using a Randomized Complete Block Design with four (4) replicates. Data was collected on growth and yield parameters and the analysis of variance (ANOVA) was done using the Statistical Package for Social Sciences (SPSS) version 26. Means were separated using Fischer's least significance difference (LSD). Results obtained showed that intercropping potato, maize and beans had no effect on percentage emergence and percentage plant vigor but significant differences (P≤ 0.05) on plant height and groundcover. Significant differences (P≤ 0.05) between numbers of tubers per potato plants were obtained in both intercropping and sole cropping while the differences in the number of pods per beans plant and number of cobs per maize plant were not significant (P≥ 0.05). Intercropping had a negative effect on the average weight of tubers per potato plant which resulted to lower tuber weights per plant in intercropping as compared to sole cropping. In the case of beans and maize, intercropping had no significant effect (P≥ 0.05) on the average weight of pods, but there was significant (P≤ 0.05) difference in the average weight of maize grains. Overall the yields of potato per hectare, maize per hectare and beans per hectare were significantly (P≤ 0.05) affected by intercropping. Comparing the intercropping treatments, potato/maize at 25 cm had the best maize grain yield (1.7 tons/ha) while potato/beans at 15 cm had the best beans yield (2.4 tons/ha). More research on Potato /beans (99,999 plants/ha), Potato /maize (53333 plants/ha) and Potato /maize (73,333 plants/ha) as appropriate intercropping systems is recommended.

Fundamental and Applied Agriculture, 2021

International Journal of Plant & Soil Science, 2020

The aim of this study was to evaluate the associations of vegetative and reproductive parameters ... more The aim of this study was to evaluate the associations of vegetative and reproductive parameters of Irish potato from different organic and inorganic nutrient sources The study was done in the west region of Cameroon, specifically in Bougham, a village in the western highlands. The seeds were sown on the 4th of May 2016. Harvesting was done in August 2016. A total area of 250m2 was cleared and prepared in to a Randomized Complete Block Design (RCBD). Each block was divided into nine ridges. Eight fertilizer treatments: inorganic (NPK 15:1515, NPK 11:11:22), organic (Pig dropping, Poultry dropping), composite (four bi-combinations of the animal and NPK-based fertilizer) and a control treatment were randomly assigned to each ridge per block. General agronomic practices were adopted from local farmers. Data were collected on vegetative and reproductive parameters. Correlation analysis was also evaluated between parameters. This was followed by principal component analysis with varimax ...

International Journal of Sciences: Basic and Applied Research, 2017

Introduction: Availability of disease-free, high yielding potato planting material is a major cha... more Introduction: Availability of disease-free, high yielding potato planting material is a major challenge to producers. This study focused on evaluating the ability of locally improved varieties to be introduced for the first time in vitro. Meristem tip culture was used to regenerate in vitro plantlets from improved potato varieties in Cameroon. Materials and methods: Six varieties including Cipira, Mafo, Jacob 2005, Bambui Wonder, Tubira and Irad 2005 were taken from IRAD potato breeding program. Ten meristems were cultured per replicate (4) per variety.The number of meristem tips sprouting, rooting, the number of nodes and shoot length were recorded weekly over a period of 4 weeks. Results and discussion: Meristem tips of all potato varieties regenerated plantlets with vigorous shoots and roots. Sprouting began in the first week and ranged from 40% (Tubira) to 75% (Cipira and Jacob 2005). Rooting began in the 2 nd week and ranged from 7.5 % (Cipira) to 37.5 % (Irad 2005 and Tubira)....

Journal of Applied Biosciences, 2010

Objective : Yam ( Dioscorea spp.) is one of the staple tubers consumed by most households in West... more Objective : Yam ( Dioscorea spp.) is one of the staple tubers consumed by most households in West and Central African countries. It exists in many varieties and forms and could also be consumed in a number of ways. However, the cultivation of this very important crop is limited by several factors, such as the scarcity of high yielding seedlings resulting in low yield, thereby compromising food security. To address some of these problems, the National Agricultural Extension and Research Programs in Cameroon adopted and disseminated the yam minisett seedling technology to yam farmers in Cameroon to improve productivity. This study evaluated the factors influencing the adoption and use intensity of this innovation. Methodology and results : Survey data was collected from 76 farmers chosen randomly in the Western Highland (WHL) and High Guinea Savannah (HGS) agro-ecological zones of Cameroon following a quasi experimental research design. Tobit regression method was used as the main ana...

International Journal of Sciences: Basic and Applied Research, 2018

The cumbersome nature of tissue culture technique contributes to the low adoption of the techniqu... more The cumbersome nature of tissue culture technique contributes to the low adoption of the technique. This work aims at developing an accessible alternative tissue culture medium for potato micro propagation. The inorganic components of the conventional MS medium were replaced with a common source of nitrogen, phosphorus and potassium (NPK) to regenerate in vitro plantlets of six improved Cameroonian potato varieties selected from meristem-derived plantlets. These varieties included: Cipira, Mafo, Bambui wonder, Irad 2005, Jacob 2005 and Tubira. Five (5) nodes each per replicate per variety were cultured on both media and allowed to grow at a temperature of 21 oC and 16hrs/day photoperiod for 28 days. Number of nodes sprouting, number of nodes rooting, plant height, and number of nodes per plantlet were recorded weekly in 4 weeks. Results shows that both media regenerated vigorous plantlets with shoots and roots. Using the Statistical Package for Social Science (SPSS), analysis of var...

African Journal of Biotechnology, Apr 9, 2014

Potato seeds degenerate over time due to systemic diseases (viruses and bacteria wilt), whose det... more Potato seeds degenerate over time due to systemic diseases (viruses and bacteria wilt), whose detections are mostly evident during later stages of epidemiology. Potato varieties released by Institute of Agricultural Research for Development (IRAD) Bambui recorded a drop in yields of approximately 50% within 20 years indicating that the varieties had started degenerating and thus required cleaning. A study was conducted in 2012 and 2013 at IRAD Bambui (Cameroon) to evaluate the rate of shooting in four improved IRAD potato varieties: Cipira, Tubira, Mafo and Bambui wonder. Liquid and solid media stocks prepared according to the International Potato Center (CIP)'s protocol were used. A randomized complete block design with four replications was used. Number of shot out nodes and average shoot length were collected after 28 days. The average number of shot out nodes in liquid and solid media in all the varieties ranged from 87.5 to 100, with the solid medium yielding better results, 97.5 to 100% in all the potato varieties as compared to liquid medium, 8.75 to 97.5%. The average shoots length in the liquid and solid media ranged from 4.95 to 10.56 cm. The analysis of variance revealed that there were significant differences at p = 0.05 between potato varieties studied. The liquid medium showed better results (8.49 to 10.5 cm) in all the varieties compared to the solid medium (4.59 to 6.08 cm) but the plantlets suffered from vitrification and asphyxiation forming callus. From the results obtained, the following conclusions may be drawn: shoot proliferation of potato tissues are reduced in stationary liquid medium as a result of vitrification and asphyxiation; potato nodal cuttings have faster growth in liquid medium than in solid medium. It is therefore recommended that solid medium should be used over stationary liquid medium in potato micropropagation because the loss of plant tissues in the liquid medium as a result of vitrification and asphyxiation can be very high.

Journal of Scientific Research and Reports, 2018

Potato production has outstripped and even surpassed that of other staple food crops in Africa in... more Potato production has outstripped and even surpassed that of other staple food crops in Africa in terms of yieldsand cultivated areas. These increases are still very low looking at the existing potentialsdue to a number of restraining factors including high cost of inputs, low productivity of soils and the late blight disease severity. A field experiment was conducted in the Western Highlands of Cameroon to study the effects of Calliandra calothyrsus, sterilizedcompost, non sterilized compost and mineral fertilizers (NPK 11:11:22) on physical characteristics, yield components and late blight disease severity of potato (Solanum tuberosum). A two factorial treatment combination made up of fertilization schemes and sanitary measures were laid out in a Randomized Complete Block Design (RCBD) with four replicates and 10 treatments. Data collected were subjected to a Multivariate ANOVA and means separated with the Dunnett t-test with Calliandra calothyrsus considered as the main treatment. The results revealed that mineral fertilizers and Calliandra calothyrsus treatments significantly augmented potato plants stem diameter, plant height and plant vigor. Plants treated to mineral fertilizer and Calliandra calothyrsus showed statistically similar vigor but were significantly more vigorous that those in the other treatments. The mineral fertilizers and Calliandra calothyrsus treatments consistently gave significant higher total and marketable yields, despite the fact that late blight severity was high in the two treatments. The correlation matrix showed that total yield had significant and positive correlation with stem diameter (r = 0.74), plant height (r = 0.61), plant vigor (r = 0.61) and marketable yield (r = 0.99) and negative correlation (r =-37) with late blight severity. From this study, Calliandra calothyrsus as organic manure was effective in improving potato production and is therefore recommended to potato farmers provided appropriate fungicide treatment is applied.

Journal of Applied Life Sciences International, 2018

Field trials were conducted in seven localities across the Western Highlands of Cameroon from Apr... more Field trials were conducted in seven localities across the Western Highlands of Cameroon from April to September 2015 to evaluate the seed tubers yield performance of some potato varieties. Three improved potato varieties (Cipira, Tubira and Jacob 2005) were used in the experiments in a non-randomized complete block design. Results revealed a significant difference (P=.01) in the total yield of graded potato tubers in the seven localities. However, no significant differences were observed in the yield of grades A, C and D potato tubers in the different sites. The results also showed that there was a significant difference (P=.05) in the yield of grade E with its highest value recorded at Santa (0.6 t ha-1) while the yields of grade B were significantly different (P=.01) with the highest value (8.7 t ha-1) recorded at Batcham. As for the varietal effects on the seed tubers yield of graded potato varieties, there were significant differences (P=.05) among the means of grades A and B with the highest values (1.6 t ha-1 and 5.3 t ha-1 respectively) recorded in Jacob 2005. In the Original Research Article

Asian Journal of Soil Science and Plant Nutrition, 2018

divided into raised beds (3 m x 0.4 m x 0.4 m), raised beds within a block were separated by a 40... more divided into raised beds (3 m x 0.4 m x 0.4 m), raised beds within a block were separated by a 40 cm gap. Maize seeds were sown on the 25th of March 2014 after two consecutive heavy rain falls. Two fertilizer applications were made in the experiment; on the day of sowing and five weeks after emergence. On the day of sowing, the fertilizer was applied in shallow trenches mixed with soil and the maize seed 3 cm deep. Five weeks after germination, the second application of fertilizer was made: fertilizer was applied in a ring manner 4 cm away from the plant. Plant spacing and fertilizer application was done based on farmer's practice. Data was collected on growth and yield parameters. Results: Results indicated that different doses (0 g, 4 g, 8 g and 12 g per plant) of NPK fertilizer in two applications influenced agronomic (plant emergence, plant height, stem diameter, leaf area index, plant vigour, and number of plants at harvest) and yield parameters of maize. The highest plant emergence was recorded from with 0 g of NPK application (P = .05). The highest plant height 222.5 cm resulted from treatment with 12 g/plant (P = .05). Maize plants treated with 12 g/plants also gave the highest yield 2.4 kg (P = 0.05). There was also a strong correlation (r = 0.75, P < .01) between plant vigour and yield. Conclusion: From the findings of this experiment, judicious application of NPK fertilizer can improve agronomic and yield parameters of maize. Farmers are recommended to use 12 g of NPK for optimal growth and maximum yield. Other implications are discussed.

Symposium on Tropical Root Crops in a Developping Economy, 1994

African Crop Science Journal, 2001

... DK Njulaem, P. Demo, HA Mendoza, JT Koi and SF Nana Cameroon Potato Programme, PO Box 80, Bam... more ... DK Njulaem, P. Demo, HA Mendoza, JT Koi and SF Nana Cameroon Potato Programme, PO Box 80, Bamenda, Cameroon. Code Number: CS01050. ... Il y avaient des différences variétales significatives pour le rendement des tubercules, les cotes du mildiou et la précocité. ...

Cameroon Journal of Agricultural Science, 2009

ABSTRACT Virus diseases present major constraints to production of okra (Abelmoschus esculentus) ... more ABSTRACT Virus diseases present major constraints to production of okra (Abelmoschus esculentus) in Cameroon. However, the identity of these viruses had not been determined prior to this study. Detection of begomoviruses in okra using polymerase chain reaction (PCR) has been problematic because of interfering polysaccharides and phenolics. We report the use of FTA® Classic Cards as an effective means of collecting, extracting, storing, and retrieving begomovirus DNA from okra leaf samples. Leaves presenting symptoms of virus attack were collected from okra plants in the south-western rain forest region of Cameroon and pressed onto FTA® Classic Cards. Using PCR and universal begomovirus primers, all 10 symptomatic samples were positive. In contrast, two of 10 samples were positive using extracted total DNA. The virus species were provisionally identified by sequencing 536 nt of the viral coat protein gene (V1). Okra yellow crinkle virus (OkYCV) was detected in all okra samples, with a nucleotide identity of 96-99% to two OkYCV isolates from Mali. Onesample contained a mixed infection with OkYCV and Cotton leaf curl Gezira virus (CLCuGV). A phylogenetic analysis showed close grouping of OkYCV isolates from Cameroon and Mali and of CLCuGV isolates from Cameroon, Egypt and the Sudan.

Virus Research, 2012

Ageratum conyzoides (goat weed) is a widespread uncultivated species in Cameroon that exhibits le... more Ageratum conyzoides (goat weed) is a widespread uncultivated species in Cameroon that exhibits leaf curl disease (LCD) symptoms suggestive of begomovirus infection. In Asia, different begomovirus-satellite complexes have been identified in A. conyzoides. The objective of this study was to determine the identity of the suspect begomoviruses and their associated satellites in A. conyzoides in Cameroon. The results indicated that all three symptomatic A. conyzoides plants examined were infected with a new begomovirus species, herein named Ageratum leaf curl Cameroon virus (ALCCMV). The ALCCMV genome sequences shared their highest identity, at 84.3-88.5%, with a group of tomato-infecting begomoviruses from West Africa. In addition, a betasatellite and an alphasatellite were cloned from the same symptomatic A. conyzoides plants. The betasatellite sequences shared limited sequence identity at 37% or less with the betasatellite Cotton leaf curl Gezira betasatellite, and the new betasatellite species is herein named Ageratum leaf curl Cameroon betasatellite (ALCCMB). The alphasatellite shared 80% nt identity with Tomato leaf curl Cameroon alphasatellite (ToLCCMA), and the new alphasatellite species is herein named Ageratum leaf curl Cameroon alphasatellite (ALCCMA). In addition, two fragments containing begomovirus-alphasatellite sequences were cloned from sample AGLI4, and they were related to the defecting interfering molecule (Y14167) associated with Ageratum yellow vein virus from Asia. These results suggest that the begomoviral-satellite complexes infecting A. conyzoides in Cameroon may be as complex or more so, to species and strains reported thus far from Asia.

American Journal of Potato Research, 2003

In 1988, the IRA-CIP potato project was created in Bambui, Cameroon, with the major objective of ... more In 1988, the IRA-CIP potato project was created in Bambui, Cameroon, with the major objective of improving potato production in the country. In 1992, two potato cultivars, Cipira and Tubira, were released by the project. In 1998, a socioeconomic impact study of Cipira and Tubira was carried out in the main potato-producing region of Cameroon to determine the reaction of the farmers, the effect of the new potato cultivars on the farmers’ standard of living, and the level of achievement of the project’s objectives.Data were collected on-farm using questionnaires and direct observations. An impact survey was carried out in the region with a sample of 297 farmers selected among the potato farmers using stratified random sampling. The survey indicated that 98.6% of the potato farmers were aware of the new potato cultivars. Their main source of information was other farmers (51.5% of farmers informed). Seventy-eight percent of the farmers were still using Cipira and 62% had adopted it as part of their production system. These farmers (62.6%) reported that the resistance of Cipira to late blight was higher than that of local and European cultivars used in their production system. More than 44% of the farmers believed that their standard of living had improved due to Cipira and Tubira, since they had generated more revenue to improve their family education and nutrition, build more houses, buy more farms, purchase more farm inputs, and open new businesses. In addition, the farmers’ average yearly potato production increased from 1.6 to 3.1 tons during the period when these varieties were being adopted.ResumenEn 1988, se creó en Bambui, Camerún el IRAD-Proyecto de Papa del CIP con el objetivo principal de mejorar la producción de papa en el país. En 1992, el proyecto liberó dos cultivares de papa, Cipira y Tubira. En 1998, en la principal región productora de papa de Camerún se realizó un estudio acerca del impacto socio económico de ambas variedades para determinar la reacción de los agricultores, los efectos de los nuevos cultivares en el estandar de vida de los productores y el nivel de objetivos alcanzados por el proyecto.Los datos fueron recogidos mediante encuestas en campo y observaciones directas. Se realizó una encuesta de impacto entre 297 agricultores de la región, quienes fueron seleccionados usando muestreos estratificados al azar. La encuesta arrojó que el 98.6% de los agricultores de papa estaban enterados de los nuevos cultivares. Su prinipal fuente de información eran otros agricultores (51.5% de los encuestados). Setenta y ocho por ciento de los agricultores todavía seguían usando Cipira y 62% la habían adoptado como parte de su sistema de producción. Esos agricultores (62.6%) señalaron que la resistencia de Cipira al tizón tardío era más alta que los cultivares locales y europeos usados en sus sistemas de producción. Más del 44% de los entrevistados creían que sus estándares de vida se habían elevado gracias al uso de Cipira y Tubira, debido a que les habían generado mayores ingresos para mejorar la nutrición y educación de sus familias, construir más casas, comprar más tierras, adquirir más insumos agrícolas y abrir nuevos negocios. Además, el rendimiento promedio de la producción de papa de los agricultores se había incrementado de 1.6 a 3.1 t durante el período de adopción de esas nuevas variedades.

American Potato Journal, 1995

In October 1992 the first three late blight resistant varieties developed under local conditions ... more In October 1992 the first three late blight resistant varieties developed under local conditions were officially released in Cameroon. This resulted from the first four years of research collaboration between the Institute of Agricultural Research (IRA) of Cameroon and the International Potato Center (CIP). The three varieties were selected from a group of 95 advanced clones sent by CIP in early 1988. The new varieties are well adapted to the highlands of the country, where late blight is the main pathological constraint on potato production. CIPIRA (CIP 381381.13) is a variety with white skin, as compared to TUBIRA (CIP 381406.6) and BAMIRA (CIP 720055) which have a red skin. These varieties have shown a consistent late blight reaction between 1-3 (scale of 1-immune to 9=highly susceptible) during the four years of field trial evaluations, a growing cycle of 90-125 days at elevations between 1,000-2,000 m, and an average potential yield of 30-40 ton/ha under low fertilizer inputs (60/60/40 kg NPK/ha). Seed will be available for distribution to farmers in late 1994, utilizing a basic seed production scheme based on mass production of rooted stem cuttings developed by the IRA/CIP Project in Cameroon. Compendio En Octubre de 1992 las tres primeras variedades resistentes a tizon tardio, desarrolladas bajo condiciones locales, fueron oficialmente lanzadas en Camerun. Esto ha sido como resultado de los primeros cuatro anos de colaboracion entre el Instituto de Investigaciones Agricolas de Camerun (IRA) y el centro Internacional de la Papa (CIP). Las tres variedades fueron selecionadas inicialmente de un grupo de 95 clones avanzados enviados por el CIP a Camerun en 1988. Estas variedades estan bien adaptadas alas zonas montanosas del pais, donde el tizon tardio es la principal enfermedad que reduce los rendimientos. CIPIRA (CIP 381381.13) es una variedad de piel blanca, en comparacion a TUBIRA (CIP 381406.6) y BAMIRA (CIP

International Journal of Plant & Soil Science, 2019

The aim of this study was to investigate the morpho-physiological and yield response of maize (Ze... more The aim of this study was to investigate the morpho-physiological and yield response of maize (Zea mays L.) variety as influenced by different plant density in Bali Nyonga, North West Region of Cameroon. The fives treatments (intra-row spacing) were: Treatment 1 (T1 = 15 cm ≈ 95200 plants/ha), Treatment 2 (T2 = 20 cm ≈ 71400 plants/ha), Treatment 3 (T3 = 25 cm ≈ 57100 plants/ha), Treatment 4 (T4 = 30 cm ≈ 47600 plants/ha) and Treatment 5 (T5 = 35 cm ≈ 40100 plants/ha). The treatments were arranged in a Randomized Complete Block Design. Commercial NPK (20:10:10) fertilizer was used twice in the course of the study. This experiment was done in Bali Nyonga, a village located in Bali sub- Division, North West Region of Cameroon. This research was conducted in 2014 from March to July. There were four blocks, each with a surface area of 38.2 m2. Each block was divided into five raised beds. Each bed measured 300 cm x 40 cm. The peak of each bed was separated from the adjacent bed by 70 cm...