636 research outputs found
Evaluation of genetic diversity in barley (Hordeum vulgare L.) from Wollo high land areas using agromorphological traits and hordein
This study aimed to determine the genetic diversity and relationships among barley varieties (Hordeum vulgare L.) growing at Wollo Highland areas by using hordein and agro-morphological traits. Twenty (20) varieties were laid down in randomized complete block design (RCBD) design with three replications; they were planted by irrigation at Wollo University, Dessie Campus from January to May 2014. The genetic analysis using hordein was done in the laboratory of Ethiopian Biodiversity Institute (EBI) in July 2014. Ten (10) competitive random plants from the rows of the experimental plots were taken for recording their agromorphological characters. Electrophoretic separation of barley storage proteins or hordeins was done using acid polyacrylamide gel electrophoresis (A-PAGE). The traits: day of heading, day of maturity, grain yield (kg/ha), plant height, spike length, number of spiklet per spike, kernel number per spike, weight of seed per spike and biomass yield (g/plot) were highly significant for the diversity of barely, whereas thousand seed weight was less significant. The results reveal positive correlation between spike length and number of spiklet per spike (the highest correlations from the agro morphological traits); the next highly correlated traits were kernel weight per spike and thousand seed weight. The A-PAGE analysis showed limited variation among the analysed accessions. The Neiâs genetic distance for all varieties of barely varied from 0.0000 to 1.6094. It is found that the 20 genotypes of barely investigated in this research were having a gene diversity (h) of overall populations (0.138) using hordein. The cluster analysis grouped the 20 barely genotypes into three different clusters using agro-morphological traits and into four clusters using hordein. This indicates the presence of wide diversity among the tested genotypes. From cluster mean values of agro-morphological traits, genotypes in cluster III deserve consideration for directly developing high yielding barely varieties. The result of the principal components analysis revealed that the first three principal components having greater than 1 eigenvalue contributed 84.22% of the total variation. From this study, it can be concluded that the presence of high morphological variation indicated the potential of Wollo Highland areas in contributing to barley improvement and conservation activities of land areas.Key words: Acid polyacrylamide gel electrophoresis, agro-morphological traits, hordein, genetic distance, hordeum vulgare, variability
Exploring the genetic diversity of Ethiopian grass pea (Lathyrus sativus) using EST-SSR markers
Expressed sequence tags (ESTs) in public databases and cross-species transferable markers are considered to be a cost-effective means for developing sequence-based markers for less-studied species. In this study, EST-simple sequence repeat (SSR) markers developed from Lathyrus sativus L. EST sequences and cross-transferable EST-SSRs derived from Medicago truncatula L. were utilized to investigate the genetic diversity among grass pea populations from Ethiopia. A total of 45 alleles were detected using eleven EST-SSRs with an average of four alleles per locus. The average polymorphism information content for all primers was 0.416. The average gene diversity was 0.477, ranging from 0.205 for marker Ls942 to 0.804 for MtBA32F05. F(ST) values estimated by analysis of molecular variance were 0.01, 0.15, and 0.84 for among regions, among accessions and within accessions respectively, indicating that most of the variation (84%) resides within accessions. Model-based cluster analysis grouped the accessions into three clusters, grouping accessions irrespective of their collection regions. Among the regions, high levels of diversity were observed in Gojam, Gonder, Shewa and Welo regions, with Gonder region showing a higher number of different alleles. From breeding and conservation aspects, conducting a close study on a specific population would be advisable for genetic improvement in the crop, and it would be appropriate if future collection and conservation plans give due attention to under-represented regions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11032-011-9662-y) contains supplementary material, which is available to authorized users
Analysis of production costs, market opportunities and competitiveness of Desi and Kabuli chickpeas in Ethiopia
This study was conducted to examine the existing conditions of chickpeas in relation to production and marketing and outlines the major technological and institutional constraints for harnessing market opportunities in the chickpea sub-sector. The study determines variety introduction, market conditions and seed delivery systems in Ada'a-Liben woreda. This district is one of the major chickpea growing areas in which new market-preferred and high-value Kabuli types are being tested and promoted. Section two of this paper presents the research process and methods. This is followed by discussion of production trends, available technologies, costs and opportunities for chickpeas. An overview of the structure and organization of the chickpea marketing system is given in section four. Section five presents market conditions with emphasis on opportunities for Kabuli exports, quality requirements, grading systems, competitiveness of smallholder producers, and existing potentials in domestic markets. The final section summarizes the key findings and highlights issues for policy and future research
Food Security in the Drylands of South Asia and Sub-saharan Africa: Research Challenges and Opportunities
Despite the significant agricultural research achievement that led to the
green revolution, South Asia (SA) and Sub-Saharan Africa (SSA) remain the hotspots
of food and nutrition insecurity in the world. One of the reasons behind this challenge
is the failure of the green revolution to increase dramatically rainfed crop and
livestock productivity in SA. The green revolution achievement has also generally
eluded SSA despite the increased availability of high-yielding and risk-reducing
cultivars and agricultural innovations. Many factors are attributable to the lack of
productivity growth. This paper investigates the major factors that have contributed
to the food insecurity in SA and SSA and forecasts the future of the food production
and consumption and their effect on food and nutrition security to the year 2020.
Our projections of food production and consumption show that child malnutrition
in SA is decreasing much faster than the case in SSA, due to increase in per
capita income, female education and female life expectancy. Fast reduction in child
malnutrition is also possible in SSA if the countries invest significantly in improvement
in agricultural production and in addressing the constraints that impede access to
food. The demand for livestock products has been increasing dramatically mainly
due to increasing income and urban population. The livestock sector also has a
large potential to achieve food and nutrition security in the drylands. Unfortunately,
past research and development investments in livestock have not reflected the potential
and opportunities offered by the sector. Harnessing the potential of livestock would
require developing suitable crop-livestock innovations to improve productivity. Even
though returns to agricultural research investments have been high and have shown
a great potential to increase food security in both SA and SSA, government and
donor research funding has generally decreased in the SSA region where national
capacity is weak and underdeveloped. There is an urgent need to increase availability
of funds to address the research challenges and harness the opportunities in the
two regions. Returns to the research investment will also have multiplier effect
on reducing food and nutrition insecurity if the support services â such as extension
services, market services, etc. â are developed. Research also need to take seriously
farmer innovations which have shown great potential in developing technologies
well adapted to the drylands
Solvable model of a polymer in random media with long ranged disorder correlations
We present an exactly solvable model of a Gaussian (flexible) polymer chain
in a quenched random medium. This is the case when the random medium obeys very
long range quadratic correlations. The model is solved in spatial
dimensions using the replica method, and practically all the physical
properties of the chain can be found. In particular the difference between the
behavior of a chain that is free to move and a chain with one end fixed is
elucidated. The interesting finding is that a chain that is free to move in a
quadratically correlated random potential behaves like a free chain with , where is the end to end distance and is the length of the
chain, whereas for a chain anchored at one end . The exact
results are found to agree with an alternative numerical solution in
dimensions. The crossover from long ranged to short ranged correlations of the
disorder is also explored.Comment: REVTeX, 28 pages, 12 figures in eps forma
Localization of a polymer in random media: Relation to the localization of a quantum particle
In this paper we consider in detail the connection between the problem of a
polymer in a random medium and that of a quantum particle in a random
potential. We are interested in a system of finite volume where the polymer is
known to be {\it localized} inside a low minimum of the potential. We show how
the end-to-end distance of a polymer which is free to move can be obtained from
the density of states of the quantum particle using extreme value statistics.
We give a physical interpretation to the recently discovered one-step
replica-symmetry-breaking solution for the polymer (Phys. Rev. E{\bf 61}, 1729
(2000)) in terms of the statistics of localized tail states. Numerical
solutions of the variational equations for chains of different length are
performed and compared with quenched averages computed directly by using the
eigenfunctions and eigenenergies of the Schr\"odinger equation for a particle
in a one-dimensional random potential. The quantities investigated are the
radius of gyration of a free gaussian chain, its mean square distance from the
origin and the end-to-end distance of a tethered chain. The probability
distribution for the position of the chain is also investigated. The glassiness
of the system is explained and is estimated from the variance of the measured
quantities.Comment: RevTex, 44 pages, 13 figure
Relationship between Prosopis juliflora invasion and livelihood diversification in the South Afar region, Northeast Ethiopia
This study assessed the effects of Prosopis juliflora invasion on livelihood diversification and evaluated the determinants of livelihood diversification in two districts in the South Afar region of Northeast Ethiopia. Using random sampling method, 154 households and 2 focus groups composed of 10 individuals were selected from four sites in the two districts. The relationship between P. juliflora invasion and incomes obtained from P. juliflora varied across the study sites. In Awash Fentale District and Amibara District, 11.0% and 3.2% of households, respectively, earned income from P. juliflora charcoal production. In total, 14.3% of households were involved in charcoal production. In addition, 19.9% of households earned income from selling P. juliflora pods and wood materials in the two districts. With the exception of income from P. juliflora charcoal production, the sex of households did not affect incomes from other livelihood activities. Moreover, household educational attainment significantly affected income obtained from vegetables, fruits, and cereal crops. Male householders were engaged in more diverse livelihood activities than female householders. Reversing the severe invasion of P. juliflora on grazing and woodlands in the region is advisable through integrated natural resources, pastoralist participation, and multidisciplinary research strategies
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