Browsing by Author "Manu-Aduening, J."
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Item Agronomic performance and genotypic diversity for morphological traits among cassava genotypes in the Guinea Savannah Ecology of Ghana(Korean Society of Crop Science, 2016) Adjebeng-Danquah, J.; Gracen, V.E.; Offei, S.K.; Asante, I.K.; Manu-Aduening, J.We evaluated the agronomic performance and diversity for morphological traits among a collection of local and exotic cassava genotypes in the Guinea Savannah agroecology of Ghana. One hundred and fifty cassava genotypes were assessed using 28 agro-morphological (18 qualitative and 10 quantitative) traits recorded from three months after planting until harvesting at 12 months after planting. There was significant genetic variability among the genotypes for most of the traits evaluated. High broad sense heritability was observed for most of the traits. Principal component analyses of the traits indicated that the first three principal component axes which accounted for more than 55% of the variation for 10 quantitative traits included storage root yield, number of leaves, harvest index, height at first branching, and plant height as the most important traits. A greater proportion of the phenotypic variances of plant height, height at branching, and harvest index were accounted for by genetic variances indicating that progress could made with selection. Pearson correlation analysis indicated that a number of traits were related to growth and yield of cassava in the Guinea Savanna ecology, making indirect selection for root yield possible. The study revealed ample genotypic variation in these morphological and agronomic traits to support selection for improved varieties. © Korean Society of Crop Science and Springer 2016.Item AMMI Stability Analysis and Estimation of Genetic Parameters for Growth and Yield Components in Cassava in the Forest and Guinea Savannah Ecologies of Ghana(Hindawi International Journal of Agronomy, 2017-07) Adjebeng-Danquah, J.; Manu-Aduening, J.; Gracen, V.E.; Kwadwo Asante, I.; Offei, S.K.yield stability using the additive main effect andmultiplicative interaction (AMMI) analysis.Highly significant (𝑃 < 0.001) effects of genotype, environment, and genotype ∗ environment interactionwere observed for all traits studied.TheAMMIanalysis of variance indicated that genotype accounted for 51% of the total sum of squares for height at first branching followed by environment (33%) and interaction (15%). For fresh root yield, environment effects accounted for 37% of the total sum of squares, whilst genotype and interaction accounted for 32% and 29%, respectively. Genotypic variances for harvest index (HI), plant height, storage root yield, and dry matter content contributed a greater proportion of the phenotypic variance indicating stronger genetic control. This suggests better chance of progress in the genetic improvement of these traits. Genotype MM96/1751 combined high yield with stability according to the yield stability index ranking across environments. On the other hand genotypes UCC 2001/449 and 96/1708 though high yielding were unstable according to AMMI stability value scores. However they can be tested further in more environments to ascertain their specific adaptability for release to farmers for cultivation to boost cassava production and ensure food security.Item AMMI Stability Analysis and Estimation of Genetic Parameters for Growth and Yield Components in Cassava in the Forest and Guinea Savannah Ecologies of Ghana(International Journal of Agronomy, 2017-07-13) Adjebeng-Danquah, J.; Manu-Aduening, J.; Gracen, V.E.; Asante, I.K.; Offei, S.K.Twenty cassava genotypeswere arranged in a randomised complete block design with three replications and assessed for growth and yield stability using the additive main effect andmultiplicative interaction (AMMI) analysis.Highly significant (𝑃 < 0.001) effects of genotype, environment, and genotype ∗ environment interactionwere observed for all traits studied.TheAMMIanalysis of variance indicated that genotype accounted for 51% of the total sum of squares for height at first branching followed by environment (33%) and interaction (15%). For fresh root yield, environment effects accounted for 37% of the total sum of squares, whilst genotype and interaction accounted for 32% and 29%, respectively. Genotypic variances for harvest index (HI), plant height, storage root yield, and dry matter content contributed a greater proportion of the phenotypic variance indicating stronger genetic control. This suggests better chance of progress in the genetic improvement of these traits. Genotype MM96/1751 combined high yield with stability according to the yield stability index ranking across environments. On the other hand genotypes UCC 2001/449 and 96/1708 though high yielding were unstable according to AMMI stability value scores. However they can be tested further in more environments to ascertain their specific adaptability for release to farmers for cultivation to boost cassava production and ensure food security.Item Development of End-User Preferred Sweetpotato Varieties in Ghana(University of Ghana, 2014-12) Baafi, E.; Gracen, V. E.; Blay, E. T.; Manu-Aduening, J.; Carey, T.; University of Ghana, College of Basic and Applied Sciences , West Africa Centre for Crop ImprovementStudies were undertaken to identify the constraints to increase sweetpotato utilization in Ghana and to develop end-user preferred varieties that would increase utilization in Ghana and beyond. A survey was conducted using Focus Group Discussion (FGD) followed by administration of Semi-Structured Questionnaire. This was done in some selected communities in Ghana where sweetpotato is popular in February 2012. Sweetpotato germplasm was also collected from farmers’ field in these areas, and from National Agricultural Research Stations of Ghana as well as the International Potato Centre (CIP) research station at Fumesua, Ghana in 2010. The germplasm was evaluated at two locations in the major and minor cropping seasons in 2011 for beta-carotene, dry matter and sugar contents as well as other agronomic and quality traits. Crosses among four genotypes, two with low sugar, high dry matter, low beta-carotene contents, and the other two with high sugar, low dry matter and high beta-carotene contents, were made to determine gene action influencing these three traits and other quality traits from 2012 to 2013. Four superior genotypes with low sugar content and five with high beta-carotene content were selected as parents for the development of low sugar and high beta-carotene populations, respectively, from 2012 to 2013. The survey showed that consumers in Ghana desire non-sweet, high dry matter sweetpotatoes with low or moderate beta-carotene content. Agro-morphological and physico-chemical descriptors revealed high variation among the sweetpotato accessions and it was confirmed by the SSR markers. Much of the genetic variation identified among the sweetpotato genotypes was additive in nature. Sufficient useful genetic variation was present in the germplasm and was exploited for improvement on beta-carotene, dry matter and sugar contents. There was significant heterosis for beta-carotene, dry matter and sugar contents. Fifteen percent of the low sugar population developed had sugar content less than 12% (non-sweet staple types) whilst the remaining 85% had sugar content of 12 – 20% (low sugar). Fourteen percent of the high beta-carotene population developed were low sugar (12 – 20%) genotypes. Seven non-sweet (preferred staple types) hybrids, 30 low sugar hybrids, 16 high beta-carotene and moderate dry matter content hybrids, and 18 high yielding hybrids were identified. There is a high potential for identifying hybrids that combine all the preferred traits and so further testing needs to be done multi-locational for potential release to farmers.Item Genetic diversity and population structure analysis of Ghanaian and exotic cassava accessions using simple sequence repeat (SSR) markers(Heliyon, 2020-01-31) Asante, I.K.; Adjebeng-Danquah, J.; Manu-Aduening, J.; Agyare, R.Y.; Gracen, V.; Offei, S.K.Genetic diversity is fundamentally important in crop improvement and provides plants with the capacity to meet the demands of changing environments. This work was carried out to assess the diversity and the extent of genetic relatedness among a number of assembled cassava (Manihot esculenta Crantz) accessions. We conducted a microsatellite marker analysis of 89 cassava accessions collected from Ghanaian and exotic sources. These accessions were assayed using 35 simple sequence repeat (SSR) markers. A total of 167 alleles were detected from 35 polymorphic markers with an average of 4.77 alleles per locus. High allelic frequency was detected across the accessions, ranging from 0.32 to 0.99 with an average of 0.62 per marker. Observed heterozygosity ranged from 0.03 - 0.97 across the accessions. Polymorphism information content (PIC) ranged from 0.03 to 0.78 with a mean of 0.45, indicating high level of polymorphism across the accessions. Comparatively, higher number of alleles, gene diversity and observed heterozygosity were detected among the local accessions compared with the exotic accessions indicating rich genetic diversity among them. Population structure analysis based on STRUCTURE identified two subpopulations and a large number of admixtures. Cluster analysis based on the neighbour joining algorithim further separated the collection into seven sub-groupings irrespective of geographical origin. This indicates the possible sharing of common genomic regions occurring across the accessions. High allelic frequency differences and levels of heterozygosity were observed among the germplasm. These findings indicated significant genetic variability in the germplasm to warrant selection.Item Genetic incompatibilities in sweetpotato and implications for breeding end-user preferred traits(Southern Cross Publishing and Printing Pty Ltd, 2016) Baafi, E.; Carey, E.E.; Blay, E.T.; Ofori, K.; Gracen, V.E.; Manu-Aduening, J.Sweetpotatoes utilization is low in Ghana due to lack of farmer and consumer preferred cultivars. Poor flowering and incompatibilities among genotypes limit breeding progress in its improvement. The objective was to assess compatibilities among sweetpotato genotypes to select good parents for breeding end-user preferred varieties for increased utilization. Twenty-one genotypes selected from 115 accessions evaluated across three contrasting environments were crossed using full diallel mating scheme. In all, 6388 crosses were carried out and 3214 seeds produced. This study sought to understand the genetic incompatibilities based on the number of seeds set per capsule after self- or cross-fertilization. Lack of flowering or poor flowering, and self- and cross-incompatibilities were major constraints to sweetpotato improvement found. Four genotypes (Histarch, Apomuden, Beauregard, and Ogyefo) were the best parents based on cross compatibilities and they can be used to determine the genetic control of beta-carotene, dry matter and sugar contents in sweetpotato. Histarch and Ogyefo are recommended as parents for the development of non-sweet, high dry matter sweetpotato varieties that are the preferred cultivars in Ghana because of their low sugar content. Use of many genotypes in hybridization and establishment of crossing blocks Hybridization in the minor cropping season is highly recommended.Item Genetic Studies of Physiological and Morphological Traits Associated with Drought Tolerance in Cassava Genotypes(University of Ghana, 2014-12) Adjebeng-Danquah, J.; Gracen, V.; Offei, K. S.; Asante, K. I.; Manu-Aduening, J.This study was undertaken to identify key traits that are closely related to cassava yield under drought stress and also identify stable high yielding cassava genotypes under varying environments. A survey was conducted using in semi-structured questionnaire in three districts in the Northern Region involving 120 farmers to identify farmers’ perception on drought in cassava cultivation, production constraints, mitigation strategies and preferences for improved cassava genotypes. To identify ideal genotypes that meet farmers’ preferences, 150 cassava genotypes from local and exotic sources were assembled and assessed for diversity using morphological traits and simple sequence repeat markers. Subsequently 20 genotypes were selected and evaluated under irrigation and no irrigation to assess genetic variability in abscisic acid content, carbon isotope ratio, stomatal conductance, leaf temperature and root yield. Stability of genotypes for physiological and yield traits were also assessed using the additive main effect and multiplicative interaction (AMMI) and GGE biplot analyses. The survey indicated lack of credit as the most important constraint facing cassava cultivation in the region. Drought was the second most important constraint and the intensity was observed to be increasing. Majority of the farmers also preferred early maturing cassava varieties that are high yielding with good plant type and marketability. Factorial analysis of the morphological traits grouped the genotypes based on their origin with few exceptions. Principal component analysis further identified plant height, branching habit, distance between leaf scars, colour of end branches, root yield, harvest index and number of roots per plant as the traits contributing most of the variability in the groups. High level of heterozygosity was revealed by the simple sequence repeat markers which grouped the genotypes into seven distinct clusters irrespective of sources. Genetic variability was established for abscisic acid content which was higher under stress than irrigation. ABA content was negatively correlated with root yield, harvest index and above ground biomass yield meaning it can be used as indirect selection criteria against unproductive genotypes. Narrow genetic variation was observed for carbon isotope ratio which was higher under irrigation than no irrigation. Carbon isotope ratio was positively correlated with above ground biomass yield but not root yield. Stomatal conductance and leaf temperature were significantly different among genotypes and environments but genotype x environment interaction was not significant. Broad sense heritability estimates were high for most of the traits except stomatal conductance, above ground biomass yield, root number and stem diameter. AMMI analysis of plant height, severity of cassava mosaic disease, root yield, root length/girth ratio, above ground biomass yield and harvest index indicated stronger effect of environment than genotypes for all traits except CMD. The study established for the first time relationship between ABA content and cassava root yield on the field. Extension of roots to lower soil depts (L/G ratio) was also found to be detrimental to storage root yield. It was also found from this study that carbon isotope ratio influence above ground biomass and not storage root yield under stress conditions. Based on AMMI selections and the GGE biplot analysis, three genotypes, MM96/1751, UCC2001/449 and 00/0203 were identified as high yielding and stable across environments. These can be used as donor parents in improving local farmer-preferred varieties. Six genotypes (UCC2001/449, 96/1708, MM96/1751, 00/0203, 96/409 and I91934) had significantly higher root yield than the best local farmer preferred variety. These can be tested on-farm for official release to farmers for cultivation.