Papers by Prof Emmanuel Otoo
Agricultural and Food Science Journal of Ghana, 2004
The “sawah” technology (bunded and leveled irrigated rice field) was introduced to some farmers w... more The “sawah” technology (bunded and leveled irrigated rice field) was introduced to some farmers within the forest agro-ecology of Ghana. To improve the productivity of their soils and also to minimize expenditure on mineral fertilizers, the effect of three organic amendments on rice yield was evaluated. Poultry manure, cattle manure and rice husk were used either solely or in combination with mineral fertilizer on rice at three different locations within the forest agro-ecological zone at Potrikrom, Biemso No. 1 and Biemso No. 2. Sole organic amendments were applied at a rate of 7.0 t ha -1 and sole mineral fertilizer was applied as N-P-K at 90-60-60 kg ha -1 . The N source was either urea or sulphate of ammonia, P source was triple super phosphate and K source was muriate of potash. Combinations were half rate (organic amendments + mineral fertilizer). Results showed that organic amendments, mineral fertilizer and their combinations significantly contributed to the growth and grain yield of rice. A combination of poultry manure (half rate) and mineral fertilizer (half rate) gave significantly greater grain yield than all the treatments except mineral fertilizer (full rate) at two out of the three locations. Rice grain yields were 6.2, 7.3 and 3.7 t ha -1 for half rate poultry manure + half rate mineral fertilizer at Potrikrom, Biemso No. 1 and Biemso No. 2 respectively, while full rate mineral fertilizer gave 6.6, 7.3 and 3.9 t ha -1 at the three sites respectively. In addition, a combination of organic amendments with mineral fertilizer out-yielded sole organic amendments at all the three sites. Organic amendments applied solely performed in the order: poultry manure > cattle manure > rice husk. Keywords : agro-ecology, forest, organic amendments, “sawah”, sustainability Agricultural and Food Science Journal of Ghana Vol. 3 2004: 237-248
international food research journal, 2012
This study characterized the most cultivated and consumed yam (Dioscorea) cultivars within the Gh... more This study characterized the most cultivated and consumed yam (Dioscorea) cultivars within the Ghanaian yam germplasm based on their chemical composition and anti-nutritional factors. Matured yam cultivars grown under the same climatic and edaphic factors were harvested from the Roots and Tuber Conservatory Division of the Council for Scientific and Industrial Research-Plant Genetic Resources Research Institute, Bunso Ghana. Samples were analyzed for proximate composition, mineral content and levels of tannins, phytates and oxalates using standard analytical methods. Significant differences (p<0.05) existed between the means of the yam varieties based on their chemical characteristics. The moisture content of the fresh tubers ranged between 58.18 to 77.79%. The varieties had low fat (<1.0%), protein (4.0-6.5%) and fibre (1.25-3.47%) with high carbohydrate (77.5-87.3%) and energy (1451.2-1574.7 kJ/100g). The most predominant minerals were potassium (475-1475 mg/100g), phosphorus (158-294.5 mg/100g) and sodium (62.5-102.5 mg/100g). All the studied varieties had low levels of oxalates, tannins and phytates (<15 mg/100g) and could all be safely recommended for food processing applications. D. rotundata, D. praehensalis, D. cayenensis and D. bulbifera differed from the rest by having higher levels of carbohydrate and energy with appreciable levels of minerals that make them nutritious and can be used as reliable food and energy security crops. D. rotundata (Pona) variety distinguishes itself because of low moisture content (high dry matter) that makes it suitable for high yield flour production.
Yam (Dioscorea sp.) produces a starchy tuber cultivated for human consumption. It is a backbone f... more Yam (Dioscorea sp.) produces a starchy tuber cultivated for human consumption. It is a backbone for food security in tropical countries, especially in West Africa. The most cultivated species, D. rotundata, originated from Africa. However, due to the lack of archaeological data and genetic tools, very little is known about yam domestication. Currently, the wild progenitor of yam is unclear and the geographical origin of yam cultivation has not been elucidated. Here, we took advantage of the recent sequencing of the D. rotundata genome and the development of new powerful analyses to get new insights into the domestication process of African yam. We analyzed a large sampling of cultivated yam and its two closest wild relatives, the savannah species D. abyssinica and the forest species D. praehensilis, collected in West Africa and Cameroon. Whole genome resequencing produced more than 3 million good quality SNPs and revealed a strong genetic structure between the three species, as well as between Cameroon and West African countries. Using coalescent models, we showed that cultivated yam was domesticated from the forest species D. praehensilis. Spatially explicit models inferred an origin of yam culture expansion in the Niger River basin, in a region located in north Benin
Journal of Scientific Research and Reports, Jan 10, 2015
Agricultural and Food Science Journal of Ghana, 2006
The “sawah” technology (bunded and leveled irrigated rice field) was introduced to some farmers w... more The “sawah” technology (bunded and leveled irrigated rice field) was introduced to some farmers within the forest agro-ecology of Ghana. To improve the productivity of their soils and also to minimize expenditure on mineral fertilizers, the effect of three organic amendments on rice yield was evaluated. Poultry manure, cattle manure and rice husk were used either solely or in combination with mineral fertilizer on rice at three different locations within the forest agro-ecological zone at Potrikrom, Biemso No. 1 and Biemso No. 2. Sole organic amendments were applied at a rate of 7.0 t ha-1 and sole mineral fertilizer was applied as N-P-K at 90-60-60 kg ha-1. The N source was either urea or sulphate of ammonia, P source was triple super phosphate and K source was muriate of potash. Combinations were half rate (organic amendments + mineral fertilizer). Results showed that organic amendments, mineral fertilizer and their combinations significantly contributed to the growth and grain yield of rice. A combination of poultry manure (half rate) and mineral fertilizer (half rate) gave significantly greater grain yield than all the treatments except mineral fertilizer (full rate) at two out of the three locations. Rice grain yields were 6.2, 7.3 and 3.7 t ha-1 for half rate poultry manure + half rate mineral fertilizer at Potrikrom, Biemso No. 1 and Biemso No. 2 respectively, while full rate mineral fertilizer gave 6.6, 7.3 and 3.9 t ha-1 at the three sites respectively. In addition, a combination of organic amendments with mineral fertilizer out-yielded sole organic amendments at all the three sites. Organic amendments applied solely performed in the order: poultry manure > cattle manure > rice husk. Keywords: agro-ecology, forest, organic amendments, “sawah”, sustainability Agricultural and Food Science Journal of Ghana Vol. 3 2004: 237-24
Journal of agricultural science, Dec 13, 2017
To determine the effects of environment and genotypic differences on tuber yield and other relate... more To determine the effects of environment and genotypic differences on tuber yield and other related traits, 12 genotypes comprising 9 improved elite clones, two local landraces and 1 improved and released variety were evaluated for tuber yield, response to yam mosaic virus and leaf spot diseases at 16 growing environments. The multi-environment trials were conducted using randomized complete-block design with three blocks for four years in four representative agro-ecological zones (Atebubu, Kintampo, Ejura and Fumesua) in Ghana. The objective was to select high and stable yielding varieties for release as varieties in Ghana. The multi-environment data for the trials collected were subjected to combine analyses of variance using the ANOVA procedure of Statistical Tool for Agricultural Research (STAR) to determine the magnitude of the main effects and interactions. Genotype main effect and genotype by environment interaction effect (GGE) model was used to dissect the genotype by environment interaction (GEI) using the GGE biplot software (GGE biplot, 2007). GGE biplots analysis was applied for visual examination of the GEI pattern in the data set. A highly significant effects (P < 0.001) for Genotype (G), environment (E) and genotype by environment (GEI) interaction were occurred in the data set for highly significant for all the traits studied (P < 0.001), indicating genetic variability between genotypes by changing environments. This indicated changes in ranking order of the genotype performances across the test environments. The partitioning of the GGE effect for tuber yield through in GGE biplot analysis model showed that PC1 and PC2 accounted for 40.47.0% and 19.89.0% of the variation GGE sum of squares respectively for tuber yield, respectively explaining a total of 60.36% variation. Mankrong Pona was the most stable and high yielding (closest to the ideal genotype) followed by TDr95/19177. Genotypes TDr00/02472, TDr00/00539 and TDr98/00933 are desirable genotypes for further assessment on culinary characteristics and end-user assessment for release as varieties. All the four locations used for the study were highly relevant for research and development of yams. Ejura and Fumesua were the most discriminating and most representative for YMV respectively. In terms of yield, Kintampo environment was the most discriminating and Fumesua and Atebubu were the closest to ideal environment for evaluating yield.
Atmospheric Environment, 2014
ABSTRACT This study characterized the most cultivated and consumed yam (Dioscorea) cultivars with... more ABSTRACT This study characterized the most cultivated and consumed yam (Dioscorea) cultivars within the Ghanaian yam germplasm based on their chemical composition and anti-nutritional factors. Matured yam cultivars grown under the same climatic and edaphic factors were harvested from the Roots and Tuber Conservatory Division of the Council for Scientific and Industrial Research-Plant Genetic Resources Research Institute, Bunso Ghana. Samples were analyzed for proximate composition, mineral content and levels of tannins, phytates and oxalates using standard analytical methods. Significant differences (p&lt;0.05) existed between the means of the yam varieties based on their chemical characteristics. The moisture content of the fresh tubers ranged between 58.18 to 77.79%. The varieties had low fat (&lt;1.0%), protein (4.0-6.5%) and fibre (1.25-3.47%) with high carbohydrate (77.5-87.3%) and energy (1451.2-1574.7 kJ/100g). The most predominant minerals were potassium (475-1475 mg/100g), phosphorus (158-294.5 mg/100g) and sodium (62.5-102.5 mg/100g). All the studied varieties had low levels of oxalates, tannins and phytates (&lt;15 mg/100g) and could all be safely recommended for food processing applications. D. rotundata, D. praehensalis, D. cayenensis and D. bulbifera differed from the rest by having higher levels of carbohydrate and energy with appreciable levels of minerals that make them nutritious and can be used as reliable food and energy security crops. D. rotundata (Pona) variety distinguishes itself because of low moisture content (high dry matter) that makes it suitable for high yield flour production.
A trial was conducted on-station with farmer participation at Fumesua (Forest zone), Wenchi (Fore... more A trial was conducted on-station with farmer participation at Fumesua (Forest zone), Wenchi (Forest-Savannah transition zone) and Bodwease (Coastal Savannah zone) from 2000 to 2003 and on-farm during 2002-2003. Two factors, staking and species, with two levels each were assessed using the Augmented RCB design. The objective of this study was to identify genotypes capable of producing high and stable yields under staking and non-staking condition. No significant differences (P&gt;0.05) were observed in disease severity, frequency of hand weeding and yield of D. alata genotypes. Among the D. rotundata genotypes, leaf spot severity was more severe on non-staked genotypes except in TDr95/19177 where no significant differences were observed between the staked and non-staked genotypes. Tuber yield of the genotypes were significantly increased by staking. In Punjo the increase in yield of staked over non-staked plants ranged between 51.3 and 56.5%. Similarly, the yield of non-staked Dorban was increased by staking by 48.1-55.9% and Tela by 44.9-47.6%. Non-staked TDr95/19177 was technically and economically the more efficient system for production followed both staked and non-staked Punjo, Dente and Tela. Generally, cost of yam production was greater in the coastal savannah than the forest and the forest-savannah transition, due to the largest cost of labour and staking. Link of the paper : https://www.wflpublisher.com/Abstract/1360
Twenty-two genotypes of D. rotundata cultivar Dorban consisting of 19 botanically developed seeds... more Twenty-two genotypes of D. rotundata cultivar Dorban consisting of 19 botanically developed seeds and 3 vegetative checks were evaluated in 15 environments from 2000 to 2004 using CRD to assess the effect of genotype and genotype x environment interaction on the tuber yield of 22 white yam (D. rotundata L. cv. Dorban) genotypes via GGE (genotype plus genotype x environment) biplot methodology. The GGE biplot procedure was used to determine the yield potential and stability of the genotypes. Significant differences (p&lt;0.001) were observed in all cultivars with respect to genotype, environment and genotype by environment interactions. Biplot analysis identified three mega-environments corresponding to the three agroecologies – Fumesua (Forest) was the most representative and discriminating environment followed by Bodwease (Coastal Savannah) and Wenchi (Forest-Savannah Transition). Genotypes Gdo02, Gdo03, Gdo20 and Gdo01 including the three checks were identified as superior. Genotype Gdo016 was the worst genotype. Link of the paper : https://www.wflpublisher.com/Abstract/1455
Journal of Food Agriculture and Environment
Three yam species (Dioscorea rotundata, D. alata and D. cayenensis) were used in three separate s... more Three yam species (Dioscorea rotundata, D. alata and D. cayenensis) were used in three separate studies to investigate the effect of gibberellin- inhibitors uniconazole-P (UP) and prohexadione-Ca (PC) on sprouting and initial growth of yams. A 3 x 2 factorial experiment involving 2 factors with 3 levels of chemicals (250 g/l of uniconazole-P (UP), prohexadione-Ca (PC) and water) and two varieties of yams was used in each study which was conducted at Crops Research Institute of Ghana's on-station facility at Fumesua in 2007. The varieties of Dioscorea rotundata were Mankrong Pona and CRI Kukrupa. Matches and Akaba were the two varieties of D. alata, and TDc_01/018 and TDc_01/023 were the two D. cayenensis varieties. The experimental design was RCBD with 3 replications. There were 10 tubers/treatment/variety/rep. Variable varietal response was observed. UP and PC suppressed sprouting and shoot development in D. alata and D. rotundata with greater suppression of sprouting by PC. Th...
Journal of Agricultural Science, 2015
The yam species, Dioscorea alata has an advantage for sustainable cultivation due to its comparat... more The yam species, Dioscorea alata has an advantage for sustainable cultivation due to its comparatively good agronomic characteristics. Breeders are therefore keen to improve the food quality of the species. Nevertheless, published data on molecular classification and genetic diversity of this crop are scanty. This research therefore investigated genetic variability and relationships among some collected Ghanaian D. alata accessions (35) together with 14 introductions from IITA in Nigeria. The true genetic identity and population structure of the accessions were determined using 14 Simple Sequence Repeats primer pairs available for yams. Dimensional scatter diagram of the principal coordinates showed a wide dispersion among the accessions. Cluster analysis using unweighted neighbour-joining method clearly separated the 49 accessions into five main groupings. From the allele frequency analysis, the size of amplified alleles ranged from 100 to 510 bp. The mean polymorphic information content (PIC) values for all markers used was 0.91 and ranged between 0.86 and 0.94 in loci YM13 and YM30 respectively. Gene diversity was high and the average observed heterozygosity was 0.77. Gene diversity was high ranging from 0.87 in YM13 to 0.94 in YM30 with a mean of 0.92. Generally, the allele frequency of all the primers was below 0.95 indicating that they were all polymorphic in character. The findings of this study confirm that SSR molecular markers are able to identify closely related materials within species.
Journal of Agricultural Science, 2015
Dioscorea alata (L) is growing in importance in Ghana due to its long shelf life and its demonstr... more Dioscorea alata (L) is growing in importance in Ghana due to its long shelf life and its demonstrated potential use as a functional food to supplement the fiber and mineral needs of consumers. Research and development efforts on D. alata in Ghana are therefore on the ascendency. To exploit the genetic diversity of the crop, 49 genotypes of D. alata including 14 from IITA were evaluated on-station for three years. Using a selection pressure of 90%, the 4 best lines were evaluated on-farm under farmer-managed conditions in 12 environments in the Forest Savannah Transition agroecology of Ghana. The experimental design used was RCB with 3 replications in 3 locations for 4 years in the Forest-Savannah Transition agroecology. A local variety D. alata cv Matches was used as check. Highly significant (p < 0.01) differences were observed in pre-harvest factors such as virus and anthracnose tolerance. Postharvest factors such as yield, tuber texture, taste, aroma, and after-taste were also highly significant with texture being a very important in choice of materials by farmers. Genotypes TDa_00/0046 was the best genotype amongst the four genotypes evaluated, followed by TDa_01/0029, TDa_01/0004 and TDa_00/0003. The local check had good sensory attributes than some of the improved genotypes. Genotype TDa_00/0046, however, had sensory similar attribute to the local check. It is therefore the best candidate for release as a variety in Ghana.
Three popular yam varieties; Pona, Dente and Afebetua were evaluated for their reaction to plant ... more Three popular yam varieties; Pona, Dente and Afebetua were evaluated for their reaction to plant parasitic nematodes infestation in three districts (Atebubu, Kintampo and Wenchi) of Ghana where yam is intensively cultivated. Plant population/12 m 2 plot, nematode population/200 cm 3 rhizosphere soil, nematode population/5g tuber peels, tuber gall index and yield were analyzed using the mixed model (REML) approach in GenStat. Plant establishment of Pona at Wenchi was 63% higher than at Atebubu. Three nematodes; Meloidogyne spp., Pratylenchus coffeae and Scutellonema bradys were isolated from rhizosphere soils across the locations. Meloidogyne spp. population on Afebetua was 41 and 61% higher than on Dente at Kintampo and Wenchi respectively. Similarly, 64 and 89% more Pratylenchus coffeae were found on Afebetua than on Dente at Atebubu and Wenchi, respectively. Significantly higher (P < 0.05) populations of Meloidogyne spp. juveniles were extracted from tuber peels in Pona, Dente ...
African Journal of Food, Agriculture, Nutrition and Development
This work characterized the most cultivated and consumed yam (Dioscorea) cultivars within the Gha... more This work characterized the most cultivated and consumed yam (Dioscorea) cultivars within the Ghanaian yam germplasm based on their biochemical and cell wall constituents to assess their potential alternative food and industrial processing applications. Samples were analyzed for their biochemical composition - starch, amylose, amylopectin, total sugars, reducing sugars and non-reducing sugars along the head, middle and tail regions of each tuber using standard analytical methods. Cell wall constituents - acid detergent fibre, neutral detergent fibre, acid detergent lignin, cellulose and hemicellulose of each tuber were also determined using standard analytical methods. The results showed no significant differences at p<0.05 in biochemical compositions along the length of the studied cultivars. D. cayenensis (Pure-yellow), D. rotundata (Pona) and D. alata (Matches) were found to have high starch contents (63.16-65.69%, 63.54-65.30% and 63.24-65.17% respectively). Amylose content w...
Preliminary investigations of the potentials of five clones of water yam, Dioscorea alata to resi... more Preliminary investigations of the potentials of five clones of water yam, Dioscorea alata to resist plant parasitic nematodes infection was conducted at two locations during 2010. TDa 01/0004, TDa 01/00029, TDa 00/0003, TDa 01/00046 and a local check Matches were planted on ridges in a randomized complete block design and replicated three times at Fumesua and Ejura. Nematode population density/200 cm 3 soil at harvest, tuber galling and yield of yam were analyzed. At harvest at Fumesua, Matches was heavily infected with J2 Meloidogyne spp. (202 /200 cm 3) soil. However, TDa 01/00029 significantly (P=0.05) inhibited infection of the pest (14 /200 cm 3) soil. At Ejura TDa 01/0004 was not infected by Tylenchulus semipenetrans whilst infection of the pest on the local check Matches was significant (162/200 cm 3) soil. Tuber galling symptom was identified only on the tubers of the local check at both locations. TDa 01/00046 yielded the highest 42.6 t/ha and 4 t/ha whilst TDa 01/00029 yie...
Journal of Agricultural Science, 2015
Yam production is characterized by low fertilizer input and annual shifting in search for fertile... more Yam production is characterized by low fertilizer input and annual shifting in search for fertile lands. This practice usually leads to reduction in the yield potential of the crop and destruction of the environment. Biochar additions through its ability to improve soil fertility and increase crop yields could be used to solve these problems. This study therefore investigated the effect of biochar and inorganic fertilizer application on yam production in a forest agro ecological zone in Ghana. A 4×3 factorial experiment in a randomised complete block design with three replications was used. The treatments consisted of four application rates of wood shaving biochar (0 t ha-1 , 5 t ha-1 , 10 t ha-1 and 15 t ha-1) and three inorganic fertilizer rates (0-0-0 N-P 2 O 5-K 2 O kg ha-1 , 30-30-30 N-P 2 O 5-K 2 O kg ha-1 and 60-60-60 N-P 2 O 5-K 2 O kg ha-1). No significant differences in soil parameters in response to the treatment were observed, with the exception of total N, where a decline was observed for all the treatments compared to the controls after harvest. Vegetative growth parameters of yam were not significantly influenced by biochar and inorganic fertilizer application. The number of seed yams per hectare was the only yield parameter that was significantly (p = 0.05) decreased by biochar application. Dry matter, production was also significantly (p = 0.05) increased by fertilizer application at 24 weeks after planting and at harvest. It is suggested that aged and higher rates of biochar would efficiently support yam production.
Yadav/Crop Adaptation to Climate Change, 2011
ABSTRACT Climate change is eminent, and Africa is one of the most vulnerable regions in the world... more ABSTRACT Climate change is eminent, and Africa is one of the most vulnerable regions in the world to this change and variability. This is a situation that is aggravated by the interaction of ‘multiple stresses’, occurring at various levels, with low adaptive capacity. The vulnerability and limitations of poor countries to adapt to the emerging challenges of climate change have been highlighted in the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Although the exact direction of climate change in not known however, there is a general agreement that the continent will experience a projected increase in temperature between 1.5° - 6°C by 2100, and this warming will be greatest over the interior of semiarid margins of the Sahara and central southern Africa. The impact of such a change will lead to drought, increasing poor and degraded soils, shortening of rainfall season and growing season among others. All crops therefore must adapt to this changing environment or be wiped out. Strategic and novel approach by all stakeholders&#39; are needed to counter the numerous effects of climate change. The Governments and individuals should realize the huge challenge climate change poses and adapt more innovative approaches to research, management and conservation of the environments.
Journal of Development and Agricultural Economics, 2011
Yam is a vital crop in Ghana both at the domestic and export markets. It contributes about 17% of... more Yam is a vital crop in Ghana both at the domestic and export markets. It contributes about 17% of agricultural gross domestic product (GDP) and plays a key role in household food security with more than 2 million tons harvested each year. However, the inadequacy of planting materials is a major constraint in yam production. The cost of planting materials alone constitutes about 50% of total cost of production. The newly developed technique of propagating yam through vine cuttings (vine multiplication technique) has been introduced by Council for Scientific and Industrial Research-Crops Research Institute (CSIR-CRI) and its partners to farmers. To assess the willingness of farmers to adopt the vine technology, a study was conducted in the forest-savannah transition zone of Ghana in 2010 involving a total of 375 yam farmers (324 males and 51 females). The study used the probit model to assess framers' willingness to adopt the vine technique. The results show that age, farm size, experience, yield, cost of adoption, ease of adoption, visits to a demonstration field and the expectation of obtaining more seed yams influenced farmers' willingness to adopt the vine technique. It is recommended that the technology should be promoted targeting younger experienced farmers with larger farm sizes and higher yields
Agricultural and Food Science Journal of Ghana, 2006
West African Journal of Applied Ecology, 2010
A cassava seedbed preparation field study was established at Fumesua in the forest and Ejura in t... more A cassava seedbed preparation field study was established at Fumesua in the forest and Ejura in the forest-savanna transition agroecologies of Ghana in 2004/2005. The experimental design was split plot with three seed bed preparation methods as the main plots and three nitrogen rates as sub plots, with basal application of 45-90 kg ha-1 P 2 0 5-K 2 0 on the fertilized plots. A similar study was conducted on yam seedbed preparation in 2003/2004, with a 2 3 factorial design. Cassava and yams on ridges resulted in highest root and tuber yields, on both Lixisols in the coastal and forest-savanna transition and Acrisols in the forest agro-ecologies. However, yam tuber yield on mounds was not statistically different from yields on ridges. Number of roots per plant was identified as a major contributory factor to the yield increase of cassava on ridges. Seed bed preparation method was, however, not an important determinant of cassava root yield at high rates of fertilizer application of 90-45-90 kg ha-1 N-P 2 0 5-K 2 0. Planting on mounds resulted in slender, cylindrically shaped cassava roots and yam tubers, while ridging produced oblong shaped roots and tubers. Weeding and fertilizer application were easier on manual ridging than on manual mounds. The study points to ridging as a potential option to mounding for cassava and yam production, with the feasibility of mechanization of ridges to reduce drudgery associated with roots and tuber crop production in the West African sub-region.
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Papers by Prof Emmanuel Otoo