192 research outputs found
Tef Taxonomy, Origin, Distribution and Genetic Resources
No full textThe tef crop has both its center of origin and diversity in Ethiopia. Tef is the product of nature and nurture, and it has co-evolved with Ethiopians in the course of cultivation by the framers over the millennia. The diverse agro-ecologies and sociocultural conditions of the country have also endowed the country with a huge wealth of genetic diversity in phenologic, agronomic and morphological traits as well as traits associated to nutrition and biotic and abiotic stress tolerances. Such diversity offers opportunities to develop suitable varieties for diverse cropping systems, agroecologies and utilization aspects.
However, the physiological mechanisms and the traits and genes associated with the nutritional values and stress tolerances are little known. Collection, characterization, evaluation and conservation of the tef genetic resources have not yet been comprehensively and systematically done. Because of this, some duplication of tef accessions are expected in the Ethiopian gene bank holdings. Hence, rigorous conservation, characterization, and utilization of these resources including its wild relatives are essential for sustainable improvement of the crop.
Various studies based on morphological, cytological, biochemical and molecular markers suggested E. pilosa as the closest relatives to tef. The diploid ancestors of tef are, however, not yet known since E. pilosa is a tetraploid species like tef. Hence, the identification of the diploid progenitors of tef based on genome analysis as well as biochemical and molecular markers is far more than scientific curiosity since the knowledge of the diploid progenitors would open an avenue to resynthesize tef and create de novo variability including important traits like lodging tolerance.
Overall, the most important areas of future research emphasis include: 1) Systematic and comprehensive collections of germplasm including wild relatives so as to mitigate the representation gaps and capture the evolutionary dynamics; 2) Extensive evaluation and characterization of the tef genetic resources including the wild relatives using both phenotypic, biochemical and molecular markers; 3) Establishment of more refined and representative set of “core tef germplasm” and minimization of duplications of germplasm accessions in gene-banks; and 4) Mining of the tef genetic resources with respect to the identification of noble genes and traits associated with abiotic and biotic stress tolerance, quality and metabolites
Tef Breeding
No full textIn summary, whilst the generation of basic scientific information on the genetics, genomics, physiology and other related biosciences is still a fundamental requirement, the overall improvement of tef in Ethiopia requires a concerted and holistic multi-disciplinary approach. This, in turn, calls for enhancement of national, regional and international networking, collaboration and data sharing among research and development, and donor institutions and organizations. Last but not least, in order to see the impact on the genetic progress research on tef, it is imperative to undertake large-scale popularization of the released varieties, where the end-user farmers can see the impact of such improved technologies through demonstrations and scaling up activities involving improved varieties coupled with commensurate management practices
Tef Biotechnology
No full textIn vitro technology has been advancing as a highly valuable pre-breeding tool for achieving better results in germplasm preservation, distant hybridization and genetic transformation approaches. Furtheremore, it has been gaining a growing importance in direct applications in conventional line selection by facilitating asexual multiplication, inducing variations, undertaking site-directed mutagenesis and production of doubled haploids. Because of genetic difference, tissue specificity and culture environment (media) interactions, there are no universally applicable protocols of culture and regeneration pathways. It varies as tissues from different sources and species as well as varieties differ in their response and culture requirements. The challenges are more conspicuous with recalcitrant monocot species such as tef
Morphology, Development and Phenotypic Plasticity in Tef
No full textDue to the large influence of the environment on plant development and morphology, there is a lot of potential to use a variety of crop management processes to improve tef production. A major benefit of this is that these methods can be used to promote development of desirable traits in tef varieties already preferred by farmers. Initiatives such as Sustainable Rice Intensification (SRI), a basic system of crop management practises for rice, are already improving cereal crop performance around the world (Mishra et al., 2006)
Principles and Practices of Tef Improvement
No full textThe Ethiopian farmers are the “master engineers” of tef in domesticating and nurturing the crop, and ther by rendering it among the precious gifts of Ethiopia to the world. In essence, the tef crop is the product of both “nature and nurture”. Tef, owing to its localized importance, has grossly been labeled as one of the various “orphan or neglected or under-utilized” crops since it has been little subjected to research in the international arena. Recently, however, tef is gainingincreased global popularity especially as “health and performance” food due to its gluten-free and highly nutritious grains. Scientific research on tef in Ethiopia began towards the end of the 1950s and specifically in 1957. Ever since commendable research efforts along with commensurate achievements and advances have been made primarily and chiefly through the domestic efforts. This should not be taken as a very stubborn expression as noteworthy contributions have also been made by the external research institutions, donors and researchers. To this end, the book “Principles and Practices of Tef Improvement” has inculcated the science to the art of tef husbandry. It is worth remarking that this book is inevitably “one of the first of its kind when it comes to tef”, whereas volumes after volumes of books have been published by different authors on the globally important crops such as wheat, maize, sorghum, rice, barley and so on. I would, at this juncture, like to appreciate and congratulate the editors and all the contributors there-in for making the publication of such a comprehensive book on tef a success. The book would undoubtedly serve as an invaluable text book and also as a comprehensive reference material for the academia, research, and other interested readers in the subject areas. Apart from issues that have become a common and widely known public knowledge, all ideas and issues taken from other sources have been adequately acknowledged and cited
Tef Physiology
No full textTef and most other orphan crops particularly millets are resilient to marginal environments in which they are extensively cultivated (Tadele, 2016). Compared to most other cereals, tef is relatively tolerant to abiotic and biotic stresses. However, they suffer from low productivity (Tadele, 2019). Crop productivity can be enhanced through intensification (Tadele, 2017).
In general, little is known on the mechanisms of tolerance of tef to abiotic stresses in particular as this pertains to the physiology aspects. Physiological studies on tef will benefit from recent omics on tef. For instance, the whole genome sequence of tef (Cannarozzi et al., 2014; VanBuren et al., 2020) and related Eragrostis species with desirable properties (Pardo et al., 2020; Carballo et al., 2019) can be used to relate physiologically important traits to genes and genomic regions. Similarly, the recent proteomic study from drought affected tef plants (Kamies et al., 2017) and miRNAs from moisture limited tef plants (Martinelli et al., 2018) provide valuable findings. The recent completion of the genome sequence of extremely drought tolerant or resurrection E. nindensis (Pardo et al., 2020) and lodging tolerant E. curvula (Carballo et al., 2019) will play key role in advancing our knowledge on tef. Future research on tef improvement requires strong partnership among stakeholders which include donors, policy makers, research institutions, and farmers (Cannarozzi et al., 2018a)
Molecular Breeding of Tef
No full textTef is the most important food security crop in Ethiopia. As a result, a dedicated national tef improvement program has been established to facilitate its improvement using conventional breeding. However, the inherent limitations of this breeding method and the continuous progress in crop genomics necessitated its complementation by molecular tools. Modern plant breeding approaches involving molecular markers, such as marker assisted breeding, QTL mapping, gene mining and genetic transformation including gene editing have been used to develop new varieties in several crop species
Tef Agronomy
No full textTef production has expanded from time to time. However, the national average yield is still low due to several constraints including the use of poor crop management practices by farmers. Tef is cultivated with intensive seedbed preparations involving 3 to 5 passes in semi-arid and 5 to 8 passes in humid areas of the country. Planting of tef requires a firm and moist seedbed. The optimum sowing time for tef ranges from early-July to mid-August based on the soil type and the onset the rainfall as well as the length of growing period. Early sowing is the common practice on light soils, while late sowing is practiced on heavy black soils. However, calendar-based sowing date has not been working very well particularly in recent years due to climate change. Hence, it is important to adjust the sowing date based on the onset and cessation of the rainfall and moisture content of the soil
Tef, Eragrostis tef (Zucc.) Trotter
No full text9.1 Introduction 226
9.2 Origin and Taxonomy 227
9.3 Genetic Resources and Utilisation 232
9.4 Genetics and Cytogenetics 236
9.5 Reproductive Biology 240
9.6 Constraints in Tef Production 242
9.7 Genetic Improvement of Tef 245
9.8 Crop and Pest Management 256
9.9 Future Prospects 259
References 26
Grain yield variation and association of major traits in brown-seeded genotypes of tef [Eragrostis tef (Zucc.)Trotter]
No full textBackground
Tef [Eragrostis tef (Zucc.) Trotter] is the major cereal crop of Ethiopia where it is annually cultivated on more than three million hectares of land by over six million small-scale farmers. It is broadly grouped into white and brown-seeded type depending on grain color, although some intermediate color grains also exist. Earlier breeding experiments focused on white-seeded tef, and a number of improved varieties were released to the farming community. Thirty-six brown-seeded tef genotypes were evaluated using a 6 × 6 simple lattice design at three locations in the central highlands of Ethiopia to assess the productivity, heritability, and association among major pheno-morphic traits.
Results
The mean square due to genotypes, locations, and genotype by locations were significant (P < 0.01) for all traits studied. Genotypic and phenotypic coefficients of variations ranged from 2.5 to 20.3 % and from 4.3 to 21.7 %, respectively. Grain yield showed significant (P < 0.01) genotypic correlation with shoot biomass and harvest index, while it had highly significant (P < 0.01) phenotypic correlation with all the traits evaluated. Besides, association of lodging index with biomass and grain yield was negative and significant at phenotypic level while it was not significant at genotypic level. Cluster analysis grouped the 36 test genotypes into seven distinct classes. Furthermore, the first three principal components with eigenvalues greater than unity extracted 78.3 % of the total variation.
Conclusion
The current study, generally, revealed the identification of genotypes with superior grain yield and other desirable traits for further evaluation and eventual release to the farming community
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