Browsing by Author "Oduro, V."
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Item Comparative study of 2,4-D and Picloram on friable embryogenic calli and somatic embryos development in cassava (Manihot esculenta Crantz)(International Journal of Integrative Biology, 2010-01) Danso, K.E.; Elegba, W.; Oduro, V.; Kpentey, P.A comparative study on the effect of 2,4-D and Picloram on primary and cyclic embryo production as well as plant conversion in three local accessions of cassava was conducted. Leaf lobe explants cultured on MS medium supplemented with 8 mg/l (2,4-D) or 16 mg/l (Picloram) induced the highest percentage embryogenic calli. On transfer to maturation medium (MS plus 0.1mg/l BAP), Picloram enhanced early embryo maturation (9 days), highest mean number of primary and cyclic embryo production (two-fold) than 2,4-D except in Wenchi and ADI 001 where leaf lobe explants cultured on MS medium supplemented with 20 mg/l Picloram did not develop embryogenic calli. Somatic embryos produced by Picloram induced calli had thick and elongated hypocotyls which were oriented horizontally on the adaxial surface of the calli while most of the 2,4-D induced embryos mostly had fascinated hypocotyls vertically on the uppers surface. Desiccation of Picloram-induced somatic embryos significantly (P≤0.05) improved plant conversion than 2,4-D- induced embryos. Also, pretreatment of 2,4-D or Picloram- induced embryos with low concentrations of abscisic acid (ABA) prior to desiccation enhanced higher frequency of germination of somatic embryos. This study has shown that Picloram enhances early maturation, high frequency embryo production as well as plant conversion, thus providing an alternative auxin for cassava somatic embryogenesis. © IJIB, All rights reserved.Item Genetic Control of Sugars, Cry Matter, and Beta-Carotene in Sweetpotato (Ipomoea batatas [L.] Lam)(University of Ghana, 2013-12) Oduro, V.; Blay, E.T.; Asante, I.K.; Offei, S.K.; Carey, E.E.Sweetpotato has immense potential for food and nutrition security in Ghana. It is however, infrequently used in local cuisines. Breeders have attributed this low utilization to the fact that sweetpotato lacks quality characteristics that make it amenable to local food preparation. The present study was carried out to develop varieties that combine high dry matter, low sugar and high β-carotene traits, to meet the needs of Ghanaian consumers. A Participatory Rural Appraisal (PRA) and a survey were conducted to assess farmers‟ production constraints and quality characteristics that would enhance utilization of sweetpotato. Subsequently, 130 accessions were assembled and evaluated to assess variation and identify parental genotypes. Ten of these clones with good yield potential and desirable quality attributes were evaluated with a local check variety in four environments to assess genotype x environment interaction effect on expression of the quality traits under study. Eleven parental genotypes were identified as cross compatible and were used in a North Carolina mating design II for development of populations and to estimate genetic parameters for the desired traits. The production constraints listed by farmers during the PRA included, drought, pests and diseases, labour cost, declining soil fertility, low utilization, cost of vines, low market prices and lack of ready markets. Drought was ranked highest among the constraints. Farmer preferred quality attributes included low-sugar, high dry matter, and poundable varieties, with 70% of respondents indicating that the high sugar levels is a limiting factor to regular usage. The PRA also revealed farmers‟ willingness to use orange- fleshed sweetpotato with the desired quality attributes. A high diversity index of 0.85 was obtained for morphological traits using Rogers Tanimoto index while an index of 7.41 was obtained for quality traits using mean Euclidean dissimilarity index, indicating the presence of high diversity among the 130 genotypes. The G x E study revealed that genotype and environmental main effects and their interactions were significant for most traits. Regarding yield traits, G x E was more important while genotype main effects were more important than G x E for quality traits. The AMMI biplot and regression analysis revealed stable and specific adaptation for yield, dry matter, sugars, and β-carotene. Low broad sense heritability (H 2 ) of 27% was recorded for yield but high estimates between 70% and 86% were obtained for quality traits. Narrow sense heritability (h 2 ) estimates for yield was 27% and 51% using parent-offspring analysis and variance components respectively. Parent-offspring regression gave moderate estimates of 0.38, 0.40, 0.39, 0.24 and 0.36 respectively, for dry matter, starch, fructose maltose and total sugars respectively while relatively high estimates of 0.56, 0.53, 0.45, 0.59, and 0.48 respectively were obtained with variance component method. Very high h 2 estimate of 0.80 was observed for β-carotene using variance method, while a moderate estimate of 0.40 was obtained using regression of offspring values on mid-parent values. The moderate h 2 estimates for yield was associated with a moderate genetic advance implying that progress can be made through selection. With the exception of dry matter, starch sucrose and glucose were associated with low h 2 and low genetic advance. All other quality traits including total sugars and β-carotene, had moderate to high h 2 that also associated with moderate genetic advance indicating that progress could be made through selection. General combining ability (GCA) for males and females were highly significant (P < 0.001) for most agronomic and quality traits. The presence of more significant GCA than Specific Combining Ability (SCA) effects and the substantially greater GCA than SCA (σ gca2 / σ sca2 ; between 2.7 – 21.8) confirm the preponderance of additive over non-additive gene action in the expression of the traits. Twenty-eight F 1 clones with desired characteristics have been selected for further evaluation.Item Incidence of sweet potato viruses in the coastal savannah agro-ecological zone of Ghana(Journal of Plant Pathology, 2015-05) Sossah, F.L.; Appiah, A.S.; Oduro, V.; Amoatey, H.M.; Owusu, G.K.; Oppong, A.; Lamptey, J.N.L.; Carey, E.E.; Fuentes, S.An experiment was conducted under field conditions to assess the incidence of viral diseases in 20 accessions of sweet potato [Ipomoea batatas (L.) Lam.]. Using symptomatology, biological indexing, nitrocellulose membrane ELISA (NCM-ELISA) and PCR, the accessions were assessed for disease incidence and symptom severity. Symptom expression varied among the accessions with severity index ranging from 2.24 in UK/BNARI at eight weeks after planting (wap) to 3.63 in US029 at 12 wap. Mean disease incidence varied significantly among the accessions, ranging from 43.2% to 96.3%. Using NCM-ELISA, 85% of the sweet potato plants tested positive to Sweet potato feathery mottle virus (SPFMV), Sweet potato mild speckling virus (SPMSV, 55%), Sweet potato collusive virus (SPCV, 45%), Sweet potato chlorotic fleck virus (SPCFV, 30%), Sweet potato virus G (SPVG, 20%), Sweet potato mild mottle virus (SPMMV, 5%), Sweet potato chlorotic stunt virus (SPCSV, 1.67%) and Cucumber mosaic virus (CMV, 1.67%). PCR detected Sweet potato leaf curl virus (SPLCV) in accessions UK/BNARI and CRI054. Biological indexing resulted in characteristic symptoms, commonly vein-clearing with eventual death of plants grafted with scions mix-infected with SPCSV and SPFMV. This work provides the first detailed report on sweet potato virus diseases in Ghana correlating symptoms, grafting, serology as well as PCR. It emphasizes the importance of selecting resistant cultivars as planting materials and the enforcement of quarantine measures to minimise the introduction of viruses into Ghana and their subsequent spread. © 2015, Journal of Plant Pathology. All rights reserved.Item Study of the reproductive characteristics of nine cassava accessions(West African Journal of Applied Ecology, 2013) Nunekpeku, W.; Amoatey, H.M.; Oduro, V.; Klu, G.Y.P.; Asare, D.K.; Danso, K.E.Reproductive behaviour of two cultivars (AF and AN) and seven breeding lines (BA, AS, LA, BS-1, HO-008, ME and SE) of cassava (Manihot esculenta Crantz) was studied to obtain information pertaining to flowering habits and other reproductive characteristics of these potential parents required for future hybridization programmes. The accessions were grown on the Research Farm of the Biotechnology and Nuclear Agriculture Research Institute in the coastal savanna agro-ecological zone of Ghana between April 2008 and December 2009. For each accession, 40 stem cuttings, each bearing five to eight nodes, were prepared from the mid-section of healthy cassava stems and planted at a spacing of 1.5 m x 1.0 m while accessions were separated by a distance of 2 m. Ten plants were tagged per accession for the collection of data on key reproductive characteristics. All accessions flowered, suggesting that flower production may not be a limiting factor under the prevailing climatic conditions. Light microscopy revealed that one accession (BA) produced dysfunctional male flowers which were devoid of pollen. Mean days to flowering and fruiting varied significantly (P < 0.05) among the accessions, indicating the need to use different planting dates for different accessions to ensure synchronization of flowering. The accessions also differed significantly (P < 0.05) with respect to plant height at various levels of branching, as well as number of inflorescences, staminate and pistillate flowers, and fruit produced per branching level. There was also variation in percent seed set, embryo formation and fruit drop. The extensive variability observed among the accessions provides breeders with immense opportunities for carrying out cross combinations to generate new genotypes to meet specific objectives.