Shoot and plantlet regeneration from meristems of Dioscorea rotundata Poir and Dioscorea alata L.

In vitro culture media capable of regenerating moderate to high shoots and/or plantlets from meristems of two yam species - Dioscorea rotundata and Dioscorea alata within comparable duration of 10 weeks as commonly obtained in other monocots and root and tuber crops were investigated. The study comprised 125 phytohormone combinations investigated in three factorial experiments each consisting of an auxin (NAA) and a cytokinin (BAP or kinetin), or two cytokinins only. The frequency of direct plantlet regeneration, though significantly (P < 0.05) higher for D. alata than for D. rotundata, was low and ranged from 0 to 10% at 3 weeks after culture (WAC) and 0 to 35% at 8 WAC. At 8 WAC, shoot regeneration of 42-75% was obtained in D. rotundata in MS medium supplemented with 0.1 M NAA + 0.20 M BAP, and shoot + plantlet regeneration of 60-82% obtained in media containing 0.05 M + 0.20 M BAP or 0.46 M BAP + 0.50 M kinetin in D. alata. Both shoot induction and plantlet regeneration were species-dependent. Induced shoots were successfully rooted in MS medium within 3 to 4 weeks, bringing time taken for plantlet regeneration to 11 to 12 weeks. Regenerants were morphologically similar to the mother plants. Results of the present study will facilitate regeneration of plantlets via meristem in D. rotundata and D. alata

Sensory evaluation: The last hurdle in varietal development of yams (Dioscorea rotundata, poir) in Ghana

In variety development, sensory evaluation is not only the most important hurdle after all the necessary agronomic characteristics have been developed but also a major determinant of acceptability of thevariety, as well as a major determinant in the subsequent adoption and use of the variety. Eight yam genotypes out of thirty-six genotypes evaluated for yield, pest and disease tolerance and stability over athree year period, plus 3 farmers’ checks were assessed on parameters such as enzymatic oxidation, colour attractiveness, aroma, taste, texture and overall acceptability in relation to farmers’ checks (Dente,Brass and Dorban). Gender differences existed in the degree of perception of texture and taste of yams. KUP__2000/001 was the overall best genotype with respect to general acceptability in all agroecologiesfollowed by TDr_89/02665, 2000/001, TDr__ 89/02660, TDr__95/19177, Dente, Brass, Dorban, TDr__95/01932, TDr__95/01544 and TDr__98/02877 in that order. The results of this study indicated that accessions KUP_2000/001, TDr_89/02665 and 2000/001 were the most preferred accessions with respect to sensory evaluation. After clearing this all important hurdle of sensory evaluation, genotypes KUP_2000/001, TDr_89/02665 and 2000/001 were release as varieties CRIPona, MankrongPona and CRIKukrupa respectively in 2005

Upscaling cassava processing machines and products in Liberia

Open Access JournalCassava is produced by more than 80% of farming households and is an important contributor to gross domestic product (GDP) in Liberia. It is therefore important to assess the status of cassava processing into food and other products. A total of one hundred and sixty (160) well-structured questionnaires were used for the collection of information from eight counties, with twenty respondents from each county. It was found out that all the counties lack adequate modern cassava processing machines, with almost all cassava processing operations being done with rudimentary equipment. Gari and wet fufu are common products in Liberian markets, with no high-quality cassava flour (HQCF) or derivatives. Consequently, user and gender friendly processing machines were installed in six established modern cassava processing centres, and new cassava products, such as fufu powder, tapioca, and HQCF with its value-added products (10% bread and pastries), were introduced. This upscaling will enhance the cassava value chain in Liberia with improvement in livelihoods, especially for vulnerable women and unemployed youth

Effects of cultivar and agrobotanical storage treatment on organolepetic quality of yam (Dioscorea rotundata)

There is current interest in the search and use of agrobotanicals in preference to conventional chemicals in agriculture as plant protectants hence the need to investigate the potential effects of some of the agrobotanicals on yam food after storage. This study was, therefore, conducted to assess the effects of yam cultivar and agrobotanical extracts on the organoleptic quality and acceptability of two yam based food forms: boiled yam and pounded yam. Tubers of four yam cultivars (Nwaopoko,Danacha, Ezakwukpolo and Pepa) were treated with aqueous leaf extracts of Neem (Azadiracta indica), Scent leaf (Occimum gratissimum), pod extracts of ‘Uda’ (Xylopia aethiopica), root extracts of Ginger (Zingibger officinale) and a synthetic phytohomorne (Gibberellic acid) and stored for six months. Thereafter, two food forms (boiled yam and pounded yam) were prepared from the stored yam tubers and a nine-member panel of judges enlisted to perform sensory quality assessment on them. The attributes scored with respect to boiled yam were colour, taste, texture, mealiness and general acceptability while pounded yam was assessed for its aroma, texture, colour and general acceptability. No significant differences were found among the sensory attributes due to the agrobotanical treatments rather, differences were due to yam cultivars. The results obtained and confirmed by the scatter plots and multiple linear regression showed that texture and taste contributed much to the general acceptability of boiled yam while aroma and consistency were the major qualities of pounded yam. Consistency of pounded yam was best with Nwaopoko and Danacha cultivars but significantly less so with other cultivars with or without agrobotanical treatment. The agrobotanical treatments did not affect the culinary quality of the stored yam tubers as no evidence of such treatment was noticed in the prepared yam foods. This result suggests that the constituent active ingredients imparted on the tubers during storage by the plant extracts were either water-soluble and heat labile or that their shelf lives were less than six months of the storage period and therefore had no effects on the quality attributes of food yams

Assessment of the suitability of different cassava varieties for gari and fufu flour production in Liberia

Open Access Article; Published online: 15 Feb 2020Different cassava varieties are available in Liberia, but there is little knowledge of their product suitability. Hence, the need to assess the potentials of these varieties to produce gari and fufu flour. The two products from ten improved and two local cassava varieties were characterized based on their yield and chemical, pasting and functional properties using standard methods. The results showed that TMS 96/0097 (gari 27.54%) and Butter cassava (fufu flour 27.35%) have the highest percentage yields. The starch content was higher in gari produced from TMS98/0505 (92.00%) and lower from TMS95/0289 (82.62%); the fufu flour starch content was higher in TMS98/0505 (90.59%) and lower in Bassa girl (84.75%). Gari and fufu flour produced from TMS96/0097 (507.38 RUV) and TMS00/0357 (506.04 RVU) had the highest final viscosity, and the products from TMS95/0289 (338.46 RVU and 336.80 RVU) had the least. The highest swelling power was found in gari (12.74%) and fufu flour (13.55%) produced from TMS92/0057 and the lowest in TMS91/0416 gari (8.23%) and TMS01/1235 fufu flour (8.31%). All the samples may form a paste below the boiling point of water (100°C) at < 7 min. However, cassava varieties and the interactions between varieties and locations had a significant (P < 0.05) effect on the properties of the products: Chemical (except ash content), pasting (except pasting temperature) and functional. Therefore, all the varieties may be suitable for gari and fufu flour production based on the quality preferred by the consumers

Spatial distribution of N, P and K in major yam soils of southeastern Nigeria

Pedometrics, the application of numerical techniques to describe soil attributes and enhance objectivity in soil-related decision making, was applied to soil samples from 149 geo-referenced locations in yamgrowing area of southeastern Nigeria. Geostatistical technique was applied using Krigin to estimate soil parameters from unsampled sites. Results revealed multi-nutrient deficiencies of N, P, and K in the area. The magnitude of deficiency is N > K > P. Pragmatically, 4.19, 2.59 and 1.76 m ha are deficient in total N, exchangeable K and available P, respectively. This could guide soil nutrient management decision for sustainable yam production in the area

Sensory evaluation of amala from improved water yam (Dioscorea alata) genotypes in Nigeria

Production of improved water yam (Dioscorea alata) genotypes that are suitable for the preparation of amala (a popular darkish Nigerian food) would likely enhance the economic importance of the crop inNigeria. Fermented flour (oven dried and sun dried) made from tubers of eight improved D. alata genotypes (TDa 00/00364, TDa 00/00194, TDa 00/00103, TDa 00/00104, TDa 99/00240, TDa 99/01176, TDa98/01166, Um 680) and two landraces (TDa 92-2, Ominelu) were reconstituted into amala, and organoleptically evaluated. Relevant characteristics of the experimental yam tubers, and theirintermediate products (chips and flour), were also evaluated for desirable qualities. Results showed that the tubers shape could affect the percentage peel loss of the tubers during processing. The drymatter content of the experimental fresh tubers varied from 20.05 to 45.63%, while the moisture content of the oven dried fermented (pH 5 - 6) yam flour (elubo) samples (used for the amala preparation)ranged from 8.30 to 9.80%. The colour observed in the amala samples varied from light brown to black. Though most of the experimental genotypes could be used in preparing amala, only TDa 00/00194 andTDa 00/0364 were highly rated (in relevant sensory parameters) for the preparation of the foodstuff (which is traditionally made from processed tubers of some Diosocrea rotundata cultivars)

Search for Scutellonema bradys resistance in yams (Dioscorea spp.)

A study to examine variability in susceptibility of yams to Scutellonema bradys and to identify possible sources of resistance in Ghanaian yam germplasm (Dioscorea spp.) for use in yam improvement programmes, particularly, in West Africa was undertaken. Pot and field screening methodologies were used. In general, S. bradys and dry rot of tuber symptoms as well as tuber cracking increased during the storage period. The study showed a positive correlation between visual nematode damage and population densities in yam tubers. There was also a linear relationship between dry rot disease and tuber cracking at harvest and during storage. This confirms that S. bradys causes dry rot of tubers resulting in external cracking of yam tubers. Positive linear relationship was also observed between yam tuber weight loss and dry rot disease indicating that dry rot disease may have contributed to the tuber weight loss. Therefore, tuber dry rot symptoms caused by S. bradys of yams could be used to discard susceptible yams at harvest and after a period of storage. However, there was no linear relationship between nematode population densities in yam tubers and roots, therefore, a root protocol cannot be used for assessing resistance in yams as it could lead to misclassification. The yam germplasm screened, reaffirmed resistance to S. bradys in Dioscorea dumetorum var. Nkanfo and D. cayenensis var. Afun

Genomic resources for water yam (Dioscorea alata L.): analyses of EST sequences, De Novo sequencing and GBS libraries

Published online: 29 July 201

The impact of climate change on household food security in the Bongo District of the Upper East Region of Ghana

The study determined the impact of climate change on household food security, investigated awareness level and identified coping strategies used to mitigate negative impact of climate change in the Bongo District with emphasis on women. It was a cross-sectional survey conducted in four purposively selected farming communities in the District in the Upper East Region of Ghana. A sample size of 246 women participated in the study. Using a structured questionnaire, data were collected on socio-demographic characteristics of the participants, awareness of climate change, food consumption patterns, coping strategies and household food security. Data on rainfall and temperature for the past 30 years period in the District were obtained from the Ghana Meteorological Service. Crop yields data over a period of 21 years in the District was also obtained from the Ministry of Food and Agriculture (MOFA). The results revealed that rainfall in the Bongo District has been decreasing at - 0.3 mm per annum and maximum temperature has been increasing at 0.005 °C. More than half (62.6%) of the participants were aware of climate change in their communities. Majority (89.4%) of the participants reduced the quality and quantity of diets as coping strategy method during food shortage periods and almost all (97.2%) of the households were food insecure. Participants who reported to have observed decrease in rainfall were more likely to be food insecure (OR = 3.96; CI = 0.56 – 27.81). Participants were aware of climate change and employed reduction in the quality and quantity of diet as coping mechanism. Almost all households were food insecure. There is the need to intensify climate resistant agriculture technology such as irrigation methods to offset the negative impact of climate change on food security in the District.