1,720,957 research outputs found
Comparative analysis of phenotypic characterization of Kenya and Pacific Islands tarogen germplasm collections Colocasia esculenta L. (Schott)
Get PDFFifty accessions of taro germplasm collections Colocasia esculenta L.
Received: 15 November, 2014
(Schott) were collected from Kenya and Pacific Islands tarogen germplasm
collections. Twenty five accessions of Kenyan taro germplasm were
Accepted: 17 December, 2014
collected from Western, Nyanza and Rift valley province. The taro
germplasm were planted at Masinde Muliro University of Science and
Published: 20 February, 2015
Technology main campus farm field station at Kakamega county (00O
17.30’ and 34o45’East GPS receiver) in western province of Kenya. The
phenotypic characterization was based on the International Plant Genetic
Citation
Resources Institute's (IPGRI) descriptors for Colocasia esculenta. The data
Akwee PE, Netondo G, Palapala VA. 2015. Comparative
was collected from both qualitative and quantitative traits. The phenotypic
analysis of phenotypic characterization of Kenya and
characteristics were classified into leaf and petiole characteristics. From
Pacific Islands tarogen germplasm collections Colocasia
the research study, the phenotype characters such as plant height, presence
esculenta L. (Schott). Scientia Agriculturae, 9 (2), 113-119.
or absence of stolons, number of sucker holds the highest criteria to be
Retrieved
from
www.pscipub.com
(DOI:
selected towards improving the taro crop. These phenotypic characters are
10.15192/PSCP.SA.2015.9.2.113119)
vital diagnostic features for distinguishing taro genotypes and they may
serve as genetic bench markers that could facilitate selection of suitable
germplasm variety for crop improvement in the country. Comparative
assessment on the phenotypic characterization of the germplasm is a key
guide to search for desirable traits that are important in crop productivity
and breeding. This could lead to an increased understanding of the
adaptation potential of taro in various ecological zones to e
Evaluation of Polymorphism Generated By Single Sequence Repeat Markers in Selected Taro Populations
Get PDFGenetic structure of Kenya and Secretariat of Pacific Community’s Tarogen taro germplasm was investigated. Fifty cultivars were evaluated using six SSR primer combinations. Significant polymorphic variations within the Kenyan and Tarogen taro sub-populations were revealed. A total of 64 alleles were detected with sizes from 99 to 294 bp. Kenyan germplasm generated 30 alleles and averaged 5.0 alleles/ locus while the Tarogen revealed 34 alleles with an average of 5.70 alleles/ locus. Primers generated a higher polymorphism information content (PIC) in Tarogen (0.6508) compared to Kenyan (0.6108) genotypes and genetic diversity index mean in Tarogen (0.6989) than Kenyan (0.6530) genotypes. Genetic diversity ranged between 0.25 to 0.6218 and 0.25 to 0.06204
for Kenyan and Tarogen genotypes. Allele frequency ranged from 42.52 to 75% across the populations. Generally, observed mean heterozygosity was lower than the expected mean genetic diversity indexes of 0.6530 and 0.6989 for Kenyan and Tarogen. Kenya recorded the highest mean genetic diversity (0.4735) and richness (3.04), allele frequency (0.62) and PIC (0.412) while Tarogen recorded 2.0, 0.4527, 0.5988 and 0.3917, respectively. Observed genetic diversity was significantly greater than the expected diversity. All the evaluated primers displayed distinct polymorphisms among the taro accessions studied indicating the robust nature of microsatellites in revealing polymorphism variability
Genetic Structure and Geographical Relationship of Selected Colocasia esculenta [L. Schott] Germplasm Using SSRs
Get PDFAims: SSR markers were used to infer population genetic structure variability in taro cultivars with
the objective of characterizing the allelic diversity of each geographical population.
Place and Duration of Study: Masinde Muliro University of Science and Technology and Beca
Hub, ILRI, Nairobi. Methodology: Six highly polymorphic SSR markers widely distributed in taro population genome were used in genotype 50 cultivars collected from Kenya and a taro genebank (SPC Tarogen). Results: The average polymorphic loci was 87.88%. The highest Shannon information index was observed in the germplasm from Nyanza (1.04), Western (1.2) and Hawaii (1.11) and Malaysia (1.36). Only Malaysia and Thailand germplasm had allele unique to a single locus. The analysis of molecular variance (AMOVA) revealed that 70% of the variations found within individual taro accessions, 6% of variations among the taro populations and only 24% amongst individual taro genotypes and they were statistically significant (p<0.001). Principal component analysis clustered the taro germplam into different groups. In total 50.06% and 51.82% of the variation was explained by the first three principal components of the taro germplasm. Some of the Kenyan taro cultivars clustered together with the Tarogen germplasm.
Conclusion: The determination of genetic diversity is core function towards understanding taro
genetic resources for varietal identification to rationalize its collection and safeguarding the existing
genetic diversity for taro germplasm conservation, management and for potential utilization for food
security
Genetic diversity analysis of Kenyan taro [Colocasia esculenta (L.) Schott] accessions using SSR markers
Get PDFSix SSR primer pairs were used to characterize 25 taro genotypes of Kenya. A total of 30 polymorphic alleles were generated. The number of alleles per locus ranged from 1 to 6 alleles, with an average of 3.0425 alleles across 18 loci obtained in the study. The polymorphic information content values ranged from 0.1875 to 0.5731 in all 18 loci with an average of 0.4120. Genetic diversity ranged from 0.25 to 0.6218. Genetic richness ranged between 1.5 and 4.67. The frequency of most common allele at each locus ranged from 51.21% to 75%. The pair wise genetic dissimilarity co-efficient indicated that the highest genetic distance was obtained between the Rift Valley and Nyanza taro germplasm populations (0.794). The closest allele similarity was between Western and Nyanza (83.1%) taro populations while the widest dissimilarity was between Rift Valley and Nyanza populations (45.2%). Being grouped into a distant cluster KK12 could be exploited as probable parental for the development of variant taro varieties. The SSR markers are comprehensive source for the identification of genetically distant taro accessions as well as in the replica sorting of the phenotypically close germplasm
A critical review of the role of taro Colocasia esculenta L. (Schott) to food security: A comparative analysis of Kenya and Pacific Island taro germplasm
Get PDFThe many threats to global food security in Sub Sahara Africa include poverty, unsustainable cultivation practices and climate change. Increasing poverty and decreasing food security have been exacerbated by continued low food crop productivity by smallholder farmers, constrained by several factors. Taro (Colocasia esculenta L. (Schott.) is a amongst the category of plant species that farmers and researchers have neglected or underutilized crops considered as orphan crops yet they can have the potentials to ameliorate malnutrition and food paucity in developing nations. In Kenya, taro production has suffered low crop productivity leading to underexploitation in terms of popularity of the crop, food security, nutritional aspects and economical contribution to the country earnings. In terms of food production, it does not translate into improved yields for sustained food security and as a result of this; its agricultural production is extremely low. The agronomic potential and importance of taro remains unknown because it has remained as underutilized crop in the country due to little attention attached to the crop. As a result, it has led to dangerous levels of
reduced economic livelihoods and loss of its genetic diversity. This paper review interest in neglected taro food crop stems from a variety of factors that could lead to an increased understanding of the adaptation potential of taro to enhance development of efficient and sustainable taro cultivation practices. The review could be a major breakthrough in understanding various biotechnological approaches towards integrating the taro crop into mainstream research for crop improvement and intervention programs. © 201 5 PSCI Publisher All rights reserved.
Key words: Taro as a food crop; Under-exploitation; Commercial production; Agronomic potential; Low crop productivity; Undesirable impacts;
Economic livelihoods; Genetic diversity; Smallholders farmers
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
