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RISS 인기검색어
- 검색키워드
- 저자 : Kebebew Assefa (검색결과 3 건)
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Brikti Ferede,Firew Mekbib,Kebebew Assefa,Solomon Chanyalew,Eyasu Abraha,Zerihun Tadele 한국작물학회 2020 Journal of crop science and biotechnology Vol.23 No.2
A field experiment was conducted to identify drought tolerant, high yielding and stable tef genotypes using drought tolerance indices. Sixty-four tef genotypes were evaluated under drought and non-stress conditions using “8 x 8 simple lattice design” with two replications at Debre-Zeit Agricultural Research Center. Drought tolerance indices including drought susceptibility index (SSI), drought tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP), yield index (YI), yield stability index (YSI), drought resistance index (DRI), abiotic tolerance index (ATI), stress susceptibility percentage index (SSPI), harmonic mean (HM) were estimated from grain yield under drought (Ys) and non-stress (Yp) conditions. Highest grain yields in both drought and normal watering conditions were recorded for genotype Melko. Based on drought tolerant indices the highest values of STI, GMP, and MP were related to genotypes Melko, Etsub, and Ziquala. Correlation analysis revealed that grain yield was positively and significantly correlated with STI, GMP, MP, YI, DRI, and HM, indicating that these indices were more important for screening stress-tolerant tef genotypes. Principal component analysis indicated that the first two components accounted for more than 98% of the total variations. The first PC contributed for 67.9% of the variation with strong presence of STI, GMP, MP, YI, DRI, HM, Ys, and Yp. Biplot analysis also indicated the STI, GMP, MP, YI, DRI, and HM were more reliable indices to identify drought tolerant tef genotypes. Cluster analysis grouped the 64 tef genotypes into seven clusters. The study showed that selection based on indices which exhibited significant and positive coordination with Ys and Yp are more reliable parameters for breeders to use in the tef improvement program.
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Tsion Fikre,Kassahun Tesfaye,Kebebew Assefa 한국작물학회 2018 Journal of crop science and biotechnology Vol.21 No.4
Knowledge on the extent and pattern of diversity in crop species is a precondition for any crop improvement as it helps breeders in determining apt breeding approaches. The genetic diversity of 49 tef genotypes (36 improved varieties, 10 farmers’ varieties, 3 elite lines) and 2 wild relatives was investigated using nine SSR markers. A total of 52 alleles were amplified with a mean of six alleles per locus, and mean polymorphic information content and gene diversity values of 0.69 and 0.73, respectively. The analysis of molecular variance showed higher percentage of variation within individuals (60%) and the variation among groups was the least (10%).The lowest pair-wise genetic differentiation and highest gene flow were observed among the varieties obtained through hybridization and direct selection. Genetic distance analysis showed the smallest (GD=0.101) between varieties from direct selection and hybridization and the largest (GD= 0.454) between wild Eragrostis accessions and cultivated tef accessions. The dendrogram based on the cluster analysis grouped the tested genotypes into three major clusters. PCoA showed that the first three most informative principal coordinates accounted 29% of the genetic variation. In summary, the farmer’s varieties are distant from the improved varieties and represent more genetic diversity. This finding is of interest to national breeding program to use the farmer’s material as a source of genetic variation for traits of interest. Similarly, wild relatives showed highest genetic distance however, further investigation is required in order to identify useful genes controlling agro-morphological characters.
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Mizan Tesfay Abraha,Shimelis Hussein,Mark Laing,Kebebew Assefa 한국작물학회 2017 Journal of crop science and biotechnology Vol.20 No.5
The extent of genetic variation and heritability of a trait are among the major determinants of selection gains in plant breeding programs. The aim of this study was to determine the magnitude of genetic variation and inheritance of grain yield, and component traits of newly developed tef populations under moisture-stressed and non-stressed conditions for drought tolerance breeding. Seventeen crosses along with the parents were evaluated in the F2 generation under moisture-stressed and non-stressed conditions in northern Ethiopia during 2015 and 2016. There were marked genotypic and phenotypic variation among the crosses in the F2 generation for plant height, panicle length, peduncle length, number of productive tillers per plant, main shoot panicle seed weight, biomass yield, and grain yield under both test conditions, important for successful selection and genetic advancement. The families of DZ-Cr-387 x 207832 and DZ-Cr-387 x 222076 were high grain yielders with early maturity under both test conditions.
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