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Articles by Taye Kufa
Total Records ( 6 ) for Taye Kufa
  Olika Kitila , Sentayehu Alamerew , Taye Kufa and Weyessa Garedew
  The aim of this study was to estimate the extent of genetic variation and association among yield and yield-related traits. Forty nine Coffea arabica accessions from Limu (Jimma, Ethiopia) were tested at Agaro Agricultural Research Sub Center, Ethiopia from 2004 to 2009 in simple lattice design with two replications. Variances component method was used to estimate genetic variation, broad sense heritability and genetic advance. Association of traits was also estimated using standard method. The germplasm accessions differ significantly for most of the traits. Relatively high phenotypic (45.11 and 30.18%) and genotypic coefficient of variation (25 and 24.90%) were observed for yield and number of secondary branches in the order of magnitude. Hundred bean weight (81.13%) showed the highest heritability. Yield per plant showed significant positive phenotypic correlation with percentage of bearing primary branches (r = 0.53) while it revealed significant positive genotypic correlation with bean width (r = 0.47), fruit length (r = 0.61), hundred bean weight (r = 0.59), plant height (r = 0.28), canopy diameter (r = 0.29), leaf length (r = 0.30) and percent of bearing primary branches (r = 0.62). Over all, the study confirmed the presence of trait diversity in Limu coffee accessions and this could be exploited in the genetic improvement of the crop through hybridization and selection.
  Olika Kitila , Sentayehu Alamerew , Taye Kufa and Weyessa Garedew
  To estimate the extent of genetic diversity among Limmu Coffee collection, Coffea arabica accessions from Limu (Jimma) were planted in simple lattice design with two replications. Clustering of the 49 accessions for 22 quantitative characters was performed using the method of average linkage clustering strategy of observations. Genetic divergence between clusters was determined using the generalized Mahalanobis D2 statistics Analysis of variance indicated the presence of significant (p<0.05) variability for most of quantitative traits. However, non significant variation was observed for stem diameter, canopy diameter, internode length of stem, average length of primary branch, internode length of primary branch, number of primary branch and percentage of bearing primary branches. Moreover, clustering analysis grouped the accessions in to four genetic divergent classes. The smallest inter cluster distance (D2 = 5.24) was observed between clusters I and III while the highest and highly significant inter cluster distance (D2 = 93.74) was between cluster III and cluster IV suggesting the coffee materials among clusters were divergent from each other. Furthermore, principal component analysis indicated that about 85.74% of the variation present among accessions was explained by ten principal components. Over all, the study confirmed the presence of trait diversity in Limu coffee accessions and this could be exploited in the genetic improvement of the crop through hybridization and selection.
  Olika Kitila , Sentayehu Alamerew , Taye Kufa and Weyessa Garedew
  The aim of this study was to characterized and to estimate the extent of genetic variation and character association of organoleptic quality attributes of Coffea arabica accessions from Limu (Jimma, Ethiopia). Forty nine coffee germplasm accessions which have little or no information about their genetic variability together with two checks were planted in the field at Agaro Agricultural Research Sub Center, Ethiopia from 2004 to 2009. Simple lattice design with two replications was used in this particular study. Variances component method was used to estimate genetic variation, heritability and genetic advance. Relationship among traits was also estimated using standard method. The germplasm accessions differ significantly for most of the traits. Analysis of variance, variance components, phenotypic and genotypic associations, cluster analysis and principal components were computed for the sensorial quality attributes studied. The results depicted significant variations among coffee accessions for cup quality attributes studied, except aromatic intensity, bitterness, astringency and body. There was high phenotypic coefficient of variation for astringency and bitterness. This is in contrast to the low phenotypic coefficients of variation recorded for aromatic intensity and body. In principal component analysis, the first three principal components with eigen values greater than one explained 81.4% of the total variation. The first two principal components accounted with percent variability of 52.87 and 17.77%, respectively explained 70.64% of the total variability among the coffee germplasm. These were grouped into three genetically divergent clusters and three uncorrelated principal components. In general, our findings show that more than half percent of the Limu accessions had similar quality attributes with the standard checks. The results also confirmed the presence of variability in most quality attributes among the Limu coffee accessions and this could be exploited in the future genetic improvements.
  Taye Kufa and Jurgen Burkhardt
  The montane rainforests of Ethiopia are the only known centres of origin and genetic diversity for Coffea arabica. However, the remnant coffee forest environments with the spontaneously grown wild coffee populations are under continuous threat of genetic erosion, largely due to anthropogenic activities. The study was conducted with the objective to investigate stomatal characteristics in Arabica coffee accessions under contrasting shade regimes at Jimma (7°46’ N and 36°0’ E, 1750 m), southwestern Ethiopia. For this, two shade levels (full sunlight and moderate shading) and twelve-coffee germplasm accessions were arranged as main and sub-plot treatments in a split-plot design with three replicates. The results depicted that stomata were sparsely distributed and had elliptical guard cells with pores randomly oriented pattern in Arabica coffee leaf. Maximum and minimum average stomatal densities were determined in full sunlight and moderate shade conditions, respectively. In addition, the stomatal area index was significantly higher in sun-exposed than in shaded leaves. The lowest and highest values were determined for the Harenna and Yayu accessions, respectively. The interaction between season and radiation was significant (p<0.05) on the frequency of stomata. The contrasting shade levels had significant influence on the density of stomata in both wet (p<0.05) and dry (p<0.001) seasons. Accordingly, higher stomatal frequency was recorded in dry as compared with wet season, though the range differed among the genotypes. Overall, stomatal size values followed the rainfall gradient with the order: Harenna>Bonga>Berhane-Kontir>Yayu coffee genotypes. The results would demonstrate that coffee accessions in drier Harenna areas may be more productive under higher radiation when soil moisture is sufficient. This underlines the need to consider stomata traits in identifying and developing suitable coffee cultivars against the changing environments.
  Taye Kufa and Jurgen Burkhardt
  The study was conducted with the aim to compare the variability among the wild coffee germplasm accessions in diurnal leaf water potential (LWP, ΨL) under contrasting shading and irrigation environments. Twelve coffee accessions were evaluated under two shading (moderate shading and full sun radiation) and irrigation (well watered and water stressed) regimes at nursery site. The diurnal leaf water potential was measured with a pump-up pressure chamber twice a day (predawn and midday) at every 4-day intervals for a two week drought stress imposed period. The results depicted significantly maximum predawn (ΨL = -0.66±0.43 MPa) and midday (ΨL = -1.35±0.24 MPa) leaf water potential in shaded seedlings as compared with those in full sunlight conditions. Likewise, significant (p<0.05) variation in midday LWP was measured on the 4th day after irrigation (4-DAI). The lowest (ΨL = -1.54 MPa) and highest (ΨL = -1.32 MPa) midday LWP were recorded for the Bonga and Berhane-Kontir coffee germplasm accessions, respectively. Moreover, relatively low (ΨL = -0.87 MPa) and high (ΨL = -0.73 MPa) predawn LWP were recorded for the Bonga and Berhane-Kontir coffee germplasm accessions with the lowest change in diurnal ΨL of -0.75 and -0.73 MPa, respectively. The two-way interaction effects revealed significant (p<0.0001) variations in LWP due to shading by irrigation, shading by time of the day as well as irrigation by time of the day. Accordingly, coffee seedlings exposed to moisture deficits in full sun conditions exhibited minimum LWP on the 8th DAI, particularly in Harenna genotypes. Overall, the present findings demonstrated a two-fold advantage of shading coffee nurseries in optimizing water application and extending the occurrence of severe drought to damage coffee seedlings. However, the precipitation gradient of the geographical origins was not reflected in the LWP dynamics in coffee germplasm accessions, indicating the need for further research in understanding the underlying mechanisms involved in drought tolerance among the immense Arabica coffee genetic resources with the views to promote irrigated coffee farming and thus contribute to sustainable preservation and use of coffee gene pools at its original place of origin in Ethiopia.
  Abeyot Tessema , Sentayehu Alamerew , Taye Kufa and Weyessa Garedew
  The study was carried out to determine the magnitude of genetic diversity among Coffea arabica germplasm accessions. For this, twenty-one native coffee germplasm collections of six geographical areas were used for the study. The coffee genotypes were field, established in 2002 at the Jimma Agricultural Research Center, southwestern using a randomized complete block design of three replications. Ripe red coffee cherries were handpicked and prepared for laboratory determinations on quality and biochemical attributes. Analysis of variance, clusters, principal component and divergence analyses were computed. The results indicated significant (p<0.01) variations for the most coffee quality and biochemical attributes due to coffee genotypes. Cluster analysis grouped the entries into 4 different clusters. The clusters also demonstrated maximum inter- and minimum intra-variances for all the quality attributes. Moreover, the distances among the clusters were highly significant, indicating the possible superiority of heterosis from the highly divergent parents. The analysis of principal component showed four PC1, PC2, PC3 and PC4 with the respective eigenvalue of 5.11, 1.92, 1.73 and 1.16, explaining 84.41% of the total variance. This underlines that coffee breeding strategy within and among geographical areas may provide quality improvement with known origin quality profile. It can be concluded that the promising coffee germplasm collections were diverse in terms of most quality traits and biochemical constituents due to genetic factors. Thus, selection of superior coffee cultivars requires careful evaluations and characterizations for quality attributes and other desirable traits under various field management and processing techniques across locations.
 
 
 
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