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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Genome and transcriptome sequencing identifies breeding targets in the orphan crop tef (Eragrostis tef)

Cannarozzi, Gina, Plaza-Wuthrich, Sonia, Esfeld, Korinna, Larti, Stephanie, Wilson, Yi, Girma, Dejene, de Castro, Edouard, Chanyalew, Solomon, Blosch, Regula, Farinelli, Laurent, Lyons, Eric, Schneider, Michel, Falquet, Laurent, Kuhlemeier, Cris, Assefa, Kebebew, Tadele, Zerihun January 2014 (has links)
BACKGROUND:Tef (Eragrostis tef), an indigenous cereal critical to food security in the Horn of Africa, is rich in minerals and protein, resistant to many biotic and abiotic stresses and safe for diabetics as well as sufferers of immune reactions to wheat gluten. We present the genome of tef, the first species in the grass subfamily Chloridoideae and the first allotetraploid assembled de novo. We sequenced the tef genome for marker-assisted breeding, to shed light on the molecular mechanisms conferring tef's desirable nutritional and agronomic properties, and to make its genome publicly available as a community resource.RESULTS:The draft genome contains 672 Mbp representing 87% of the genome size estimated from flow cytometry. We also sequenced two transcriptomes, one from a normalized RNA library and another from unnormalized RNASeq data. The normalized RNA library revealed around 38000 transcripts that were then annotated by the SwissProt group. The CoGe comparative genomics platform was used to compare the tef genome to other genomes, notably sorghum. Scaffolds comprising approximately half of the genome size were ordered by syntenic alignment to sorghum producing tef pseudo-chromosomes, which were sorted into A and B genomes as well as compared to the genetic map of tef. The draft genome was used to identify novel SSR markers, investigate target genes for abiotic stress resistance studies, and understand the evolution of the prolamin family of proteins that are responsible for the immune response to gluten.CONCLUSIONS:It is highly plausible that breeding targets previously identified in other cereal crops will also be valuable breeding targets in tef. The draft genome and transcriptome will be of great use for identifying these targets for genetic improvement of this orphan crop that is vital for feeding 50 million people in the Horn of Africa.
2

Studies of lodging, floral biology and breeding techniques in tef (Eragrostis tef )

Ketema, Seyfu January 1983 (has links)
Two aspects of the Ethiopian cereal tef (Eragrostis tef) which relate to its improvement have been studied: lodging and floral biology with special reference to hybridisation. Lodging was examined in a large germplasm collection in Ethiopia. Several types of lodging were recognised. Temporary lodging, from which the plant makes a complete recovery, occurs before heading. Permanent lodging, which occurs after heading, takes one of three forms: bend-lodging, break-lodging and root-lodging. Only bendlodging is widespread and of economic importance: losses are estimated at seventeen per-cent. Lodging resistance is aS80ciated with several interacting morphological characteristics particularly plant height, length of panicle, peduncle and culm and the diameter of culm. The sequence of flowering in tef is a8 follows: flowering commences at the top of the inflorescence and proceeds basipetallYj flowering begins at the bottom of each spikelet and proceeds acropetally. The timing of flowering is complex, making it difficult to predict anthesis for any individual flower. Anthesis is rapid: exsertion of the stamens and shedding of the pollen takes less than five minutes and the pollen starts to germinate on the stigma immediately. In the presence of light, temperatures above 4°C do not prevent flower opening while in the ab8ence of light, temperatures above 4 °c inhibit flower opening and therefore enable the breeder to control anthesis. Warm humid air helps to delay the dehiscence of anthers of opening flowers by up to an hour without affecting pollen viability. Contrary to previous reports ethrel does not prevent fertilization in tef and can be used as a male gametocide; it is most effective when applied at the flag-leaf stage, though it is phytotoxic at high concentrations. Dark treatment and hot water treatment induced male sterility but produced other effects which make them unsuitable for em,asculation. A reliable and rapid method of screening seedlings for hybridity has been developed utilizing anthocyanin production. When pollen carrying the marker gene is used for crossing, only hybrid progeny produce anthocyanin. This technique reduces screening time from about three months (heading time) to less than four days.
3

Adoption of improved tef and wheat production technologies in crop-livestock mixed systems in northern and western Shewa zones of Ethiopia

Abera, Hailu Beyene 09 June 2008 (has links)
Since adoption is a dynamic process that involves learning about new technologies, static adoption models fail to adequately explore the effects of changes in farmers’ perception and attitudes over time. This study analyzed the influences of farmers’ learning and risk on the likelihood and intensity of adoption of improved tef and wheat technologies in Northern and Western Shewa zones of Ethiopia. The study employed Xtprobit and Xttobit and random effect models and panel data of the same farmers from 1997 to 2001. Separate samples were selected for wheat and tef and the study covers the same farmers from 1997-2001. Panel data are better suited to study dynamic changes and the random effect models control for unobserved variability and potential endogeniety. Comparison of the main features of tef and wheat farmers revealed that wheat farmers are slightly younger, more educated, have slightly higher family size and significantly higher family labour than tef farmers. While average farm size is similar for tef and wheat farmers, farmers cultivated 60% and 30% of their land to tef and wheat, respectively. However, tef farmers allocated only 20% of their tef area to improved varieties due to shortage of desirable varieties whereas wheat farmers allocated 90% of their land to improved varieties from 1997 to 2001. Only three improved varieties were demonstrated and limited quantities of improved seeds were distributed to tef farmers whereas six improved wheat varieties were demonstrated and relatively sufficient quantities of improved seeds were distributed to wheat farmers during the study. Besides, similar levels of fertilizers and herbicide were used on tef and wheat. Wheat and tef were mainly grown for own consumption as less than half of the produce (48% of all wheat and 46% of all tef) was sold in the market. The study provided evidence of the importance of learning in the adoption decision and area allocation to improved varieties. As farmer’s gained more experience from growing the new varieties in previous years, they continued adoption and increased areas under these varieties. The study also revealed that adopters of wheat and tef technologies have increased their production by 20% and 39%, respectively, than non-adopters. Results of the analyses indicate that awareness, availability and profitability of the new improved tef and wheat varieties enhanced farmer’s learning and farmer’s experience had positive influence on the likelihood and intensity of improved seed adoption. Improved tef and wheat varieties were found more risky than the local varieties. The study further revealed that younger age of farmer, farmers’ learning from previous experience, availability of family labour and credit are key determinants of the likelihood and intensity of adoption of improved seed. Policies and strategies that contribute to timely availability of improved inputs and provision of credit enhance farmers learning from their own experience on adoption. Policies and strategies that focus on farmers’ education and provision of insurance for crop failure to reduce risk would help the new extension program (NEP) achieve its objectives which give emphasis to raising smallholders’ production and productivity. / Thesis (PhD (Agricultural Economics))--University of Pretoria, 2008. / Agricultural Economics, Extension and Rural Development / unrestricted
4

TEF Text Editor and Formatter

Maveety, Stephen 02 1900 (has links)
<p> A survey of the main features and characteristics of text editors and formatters is given. An implementation of a text editing and formatting system is discussed. The Text Editor and Formatter (TEF) was designed to be easy to learn and use and to allow extensions of the present version with little modification to the existing system. TEF is a content (or context) oriented editing system with line organization and text formatting capabilities. </p> / Thesis / Master of Science (MSc)
5

Molekulární fylogeneze rodu Geosmithia / Molecular phylogeny of the genus Geosmithia

Korittová, Celie January 2013 (has links)
The genus Geosmithia contains 11 described and several tens of undescribed species of fungi living nearly exclusively in galleries of subcorticolous insects, especially bark beetles. In this work, a phylogenetic analysis of the genus was made using DNA sequences of four protein-coding genes, namely TEF-1, RPB2, Mcm7 and Tsr1. The analysis has confirmed that ecological strategies of these fungi (such as association with conifers or broad leaved trees or symbiosis with ambrosia beetles) have evolved several times in this genus. 51 species are recognized based on the obtained phylogenetic tree according to Genealogical Concordance Phylogenetic Species Recognition. I have also tested utility of the above mentioned genes to serve as "barcode" for identification of closely related Geosmithia species.
6

Calculo de la tasa TEF en empresas acogidas al régimen B) y sus efectos tributarios frente a los impuestos finales

Care Cárdenas, Luis Orlando 03 1900 (has links)
TESIS/AFE PARA OPTAR AL GRADO DE MAGISTER EN TRIBUTACIÓN / La Ley Nº20.780, publicada con fecha 29 de septiembre de 2014, constituye la mayor modificación que ha afectado a nuestro sistema tributario en los últimos treinta años, cambiando el paradigma basado en un sistema totalmente integrado que propiciaba el ahorro e inversión, por uno basado en la tributación con los impuestos finales en el mismo ejercicio en que se generan las rentas, independiente de si estas han sido distribuidas o retiradas por los contribuyentes de los impuestos finales y, otro parcialmente integrado, en donde si bien se tributa en base a retiros o distribuciones, parte del impuesto de primera categoría pagado por la empresa no puede ser utilizado como crédito en contra de los impuestos finales. El objetivo principal de este nuevo sistema tributario es el financiamiento de políticas sociales según los compromisos adquiridos por el gobierno encabezado por la presidenta, Sra. Michelle Bachellet. En cuanto a los regímenes generales de tributación, esta modificación sustituyó el régimen tributario de las rentas empresariales de los dueños, contenidas en el artículo 14 de la LIR, vigente al 31 de diciembre de 2016 y que se basaba en los retiros de utilidades tributarias imputadas al Fondo de Utilidades Tributables (en adelante FUT), por dos nuevos regímenes opcionales de tributación, Régimen de renta atribuida o Régimen del artículo 14 letra A) de la LIR, y Régimen de retiros o dividendos conocido también como Régimen del artículo 14 letra B) de la LIR. Debido a la complejidad que implicaba su implementación, costo operativo para los contribuyentes y la aparición de nuevos focos de elusión, se hizo necesaria una “reforma a la reforma” consistente en una serie de correcciones y cambios tendientes a simplificar su operatividad y con ello disminuir los costos de su implementación, principalmente, para la pequeña y mediana empresa. Es así como, con fecha 8 de febrero de 2016 se publica la Ley Nº20.899 que “Simplifica el sistema de tributación a la renta y perfecciona otras disposiciones legales tributarias”.
7

Phenotypic and molecular diversity in the Ethiopian cereal, tef [Eragrostis tef (Zucc.) Trotter] : implications on conservation and breeding /

Assefa, Kebebew. January 2003 (has links)
Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 7 uppsatser.
8

Evaluating teff grass as a summer forage

Davidson, Jeremy M. January 1900 (has links)
Master of Science / Department of Agronomy / Robert M. Aiken / Doohong Min / Finding a high-value forage crop with limited water requirements to produce livestock feed is becoming increasingly important as producers adapt to restricted water supply conditions. Our objectives were to determine the forage yield, nutritive values, and crop water productivity (CWP) of teff grass (Eragrostis tef [Zucc.] Trotter) under field conditions when compared to sorghum sudangrass (SS, S. x drummondii[(Nees ex. Steud.) Millsp. & Chase]) and pearl millet (PM, P. glaucum [L.]R.Br.). Crop water productivity was determined by dividing above-ground biomass by crop water use. Crop water use was determined by the summation of soil water depletion, precipitation, and irrigation. Yield was determined by quadrat area clippings of above-ground biomass. Nutritive value was determined using wet chemical analysis. Cultivars showed significant differences in biomass production and CWP in both years. Excalibur teff grass variety had the greatest CWP (418 kg ha-1 cm-1) 40 days after planting (DAP) in 2016, and was similar to SS and PM for the rest of the season until 58 DAP. Pearl millet had the greatest overall CWP (443 kg ha-1 cm-1) at 44 DAP. In 2017, sorghum sudangrass had significantly greater CWP than teff grass and pearl millet throughout most of the season. Among the teff varieties, Haymore had the greatest CWP (239 kg ha-1 cm-1) when harvested 10 days after boot stage (DAB). Crude protein values of teff grass varieties ranged from 9.3% to 21.3%, depending on the harvest date and year. Teff grass showed equivalent or greater nitrogen use efficiency (27.8 – 88.8 kg biomass kg-1 N applied) in our study than previously reported. Teff grass demonstrated potential to provide producers with a fast-growing and competitive forage crop with less overall water use due to a shortened growing season.
9

Manipulation of gibberellin biosynthesis for the control of plant height in Eragrostis tef for lodging resistance

Kedisso, Endale Gebre 01 September 2012 (has links)
Lodging is a key agronomic problem in E. tef. due to morpho-physiological features, such tall and slender phenotype of the plant. Gibberellins metabolic genes are key targets in the control of plant height. Plant growth regulators (PGRs) that inhibit GA biosynthesis are used to shorten stem length thereby increasing lodging resistance. E. tef responded to treatment with PGRs such as GA, chlormequat chloride (CCC) and paclobutrazol (PBZ). Both PGRs reduced E. tef plant height but CCC treatment did not affect grain yield. Stem diameter was not affected by PGR treatment and also not the poor tapering (acropitally increasing diameter). Putatively transformed E. tef plants carrying a bean GA 2-oxidase (PcGA2ox) coding sequence were further produced via embryogenic callus after Agrobacterium-mediated transformation and plants were successfully grown into mature fertile plants. Eight putative transformed plants were finally generated carrying the insert (PcGA20 ox or nptII gene sequence) at the T0 generation. Constitutive expression of the GA 2-oxidase (PcGA2ox) coding sequence in E. tef resulted in phenotypic changes such as reduction in culm height, change in biomass, reduction in amount of GA in putative transformant semi-dwarf plants. The challenges found in the transgene detection in the T1 generation has been highlighted. Pheno-morphic changes occurred with little or no effect on yield. Genes involved in height control (orthologs to the rice sd-1 gene) and signaling (Rht) in E. tef were also identified and characterized. Activity of the protein for the putative rice sd-1 orthologs was further confirmed by heterologous expression. The three putative sequences in E. tef were named EtGA20ox1a, EtGA20ox1b and EtGA20ox2. Expression analysis showed that EtGA20ox2 were much less transcribed compared to the others and EtGA20ox1b could be the functional equivalent to the rice sd-1 (OsGA20ox2) gene in E. tef. Further, E. tef mutants with a semi-dwarf phenotype could be developed through mutagenesis and TILLING. However, regardless of height, grain yield was severely reduced in all mutants except in the semi-dwarf mutant GA-10. This line also had significantly higher diameter in most internodes which might contribute to the stiffness of stem. G-10 is therefore a promising line for further investigations. / Thesis (PhD)--University of Pretoria, 2012. / Plant Science / unrestricted
10

A implanta??o do emissor de cupom fiscal no Estado do Rio Grande do Norte e sua repercuss?o na arrecada??o do ICMS

Souza, Adneide Maria Ribeiro de 24 September 2007 (has links)
Made available in DSpace on 2014-12-17T13:53:16Z (GMT). No. of bitstreams: 1 AdneideMRS.pdf: 669164 bytes, checksum: 2bf5f8400bafdb6fa8d8e052ea6d7c45 (MD5) Previous issue date: 2007-09-24 / The present paper has aimed the analysis of a real instrument which offers great impact in the ICMS revenue: The Fiscal Voucher Emitting Equipment (ECF). In this sense, the effects of the commercial automation process in Rio Grande do Norte s ICMS revenue between 2000 and 2006 were investigated. Based on this goal, the methodology adopted was characterized as a study of quantitative, exploratory-qualitative nature, through the collecting of secondary data, provided by the State Taxation Bureau (SET). In the absence of a statistic model in the existing literature about the approached theme, we decided for the elaboration of a suitable model, with tables and graphics. As a way to observe the effects of these programs on the revenue, the comparison between the ECF users and non users, in the same period, has proved to be of great importance. We reached the conclusion that even though the growth rates amongst the activities that use the ECF had ascended in tributary revenue in the related years, from 2004 on, with the introduction of TEF, this participation presented a higher growth, which leads us to suppose that the use of this recent instrument provides a significant impact in the State effective revenue. We stand out that the collected amounts could have been even higher, if the level of adhesion to the instrument had not been so low, mainly amongst the minor entrepreneurs, which may mean a rooted defraudation in the system. In short, through the set of data obtained, it is possible to conclude that the ECF and the recent TEF have significantly influenced the ICMS revenue in the entire State all over the period that was analyzed / O presente estudo concentrou-se em analisar um instrumento atual de grande impacto na arrecada??o estadual do ICMS: o Equipamento Emissor de Cupom Fiscal (ECF). Nesse sentido, procurou-se investigar os efeitos do processo de automa??o comercial na arrecada??o do ICMS do Estado do Rio Grande do Norte, no per?odo de 2000 a 2006. Para tanto, trabalhou-se com o Com?rcio Varejista, exceto a atividade de combust?veis, por ser um dos grupos de contribuintes obrigados a usar o equipamento ECF. Baseado nesse objetivo, a metodologia adotada caracterizou-se como um estudo de natureza quantitativa, explorat?rio-descritiva, atrav?s da coleta de dados secund?rios, fornecidos pela Secretaria de Estado da Tributa??o (SET). Na aus?ncia de um modelo estat?stico na literatura existente sobre o tema abordado, optamos pela elabora??o de um modelo pr?prio com a constru??o de tabelas e gr?ficos. Constatou-se que embora as taxas de crescimento entre as atividades usu?rias do ECF tenham tido participa??o ascendente na receita tribut?ria nos anos em quest?o, a partir de 2004, com a implanta??o da Transfer?ncia Eletr?nica de Fundos (TEF), essa participa??o apresenta maior crescimento, o que leva a supor que o uso desse recente instrumento proporciona um impacto significativo na arrecada??o efetiva do Estado. Ressalta-se ainda que os montantes arrecadados poderiam ser ainda maiores, se o n?vel de ades?o ao instrumento n?o fosse t?o baixo, principalmente em rela??o aos pequenos empres?rios, o que pode indicar sonega??o enraizada no sistema. Em resumo, pelo conjunto de dados obtidos, ? poss?vel concluir que o ECF e o recente TEF tem influenciado de forma significativa a arrecada??o do ICMS no Estado em todo o per?odo analisado

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