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Forty-seven Coffea arabica L. germplasm accessions collected from Limmu district were field evaluated from 2004/5 to 2013/14 with two commercial check varieties at Agaro Agricultural Research sub-center in a single plot. The objective of the experiment was to assess the variability among the accessions using quantitative traits. Data for about eight quantitative traits were recorded only once in the experimental period, while the yield data were recorded for six consecutive cropping seasons. Cluster, genetic divergence, and principal component analysis were used to assess the variability among the genotypes. The results revealed that average linkage cluster analysis for nine traits grouped the germplasm accessions into three clusters. The number of accessions per cluster ranged from three in cluster III to 25 in cluster II. The clustering pattern of the coffee accessions revealed that the prevalence of moderate genetic diversity in Limmu coffee for the characters studied. The maximum inter-cluster distance was observed between clusters II and III; whereas the minimum inter-cluster distance was observed between clusters I and II. The study highlighted the possibility of using accessions of the distant clusters as potential candidates for the genetic improvement of Limmu coffee through hybridization. Moreover, the principal component analysis showed that the first four PCs extracted about 82% of the total variance of the 49 coffee germplasm accessions and also confirmed moderate diversity among the germplasm accessions since the entire variation cannot be explained in terms of few PCs. This, in turn, indicates that the involvement of a number of traits in contributing towards the overall diversity.
Forty-nine Coffea arabica. L. germplasm accessions,which were collected from Gomma district, were evaluated at Agaro research sub center with the objective of assessing the variability among the accessions using qualitative traits. The experiment was conducted in simple lattice design with two replications. Data on13 qualitative traits were recorded and frequency distribution and Shannon- weaver diversity index were estimated. The frequency distribution results revealed that the majority of the accessions were dominated by intermediate canopy nature (61.22%), stiff stem (51.1 %), dropping angle of insertion of primaries (38.78%), green young leaf color (73.47%), elliptic leaf shape (91.84),acuminate leaf apex shape (80%), ovate stipule shape (51.02%), roundish fruit shape (48.98%), red fruit color (44.90%), with calyx limb persistence (53.06), obolong bean shape (63%), uniform seed (57%) and medium bean size (96%). Moreover, the existence of variability among these accessions was further confirmed by Shannon-Weaver Diversity index (H') analysis. The highest H' values were recorded for angle of insertion of primaries (1.08), fruit color (1.04), stipule shape (0.83) and fruit shape (0.83) as compared to the other traits, indicating the presence of adequate variability for qualitative traits among the evaluated coffee accessions. Ingeneral, as considerable variability was observed among the accessions for most these traits, it recommended that these accessions should be properly conserved for future breeding work. However, the morphological diversity observed in this study must be further confirmed using molecular characterization techniques. Keywords: Fruit C
Variability for coffee bean biochemical composition among the coffee accessions is vital for further quality improvement. However, lack of this information has been one of the major bottlenecks for any coffee quality improvement program. The current study was, therefore, conducted to evaluate the level of variability in green bean biochemical composition of coffee accessions collected from east Wollega coffee growing areas. Four standard checks and 101 Arabica coffee accessions were used for the study. The study was conducted using augmented design and data were collected on trigonelline, total chlorogenic acid, caffeine, crude protein, crude fat, crude ash and dry matter contents. Both univariate and multivariate analyses were employed to see the variability of biochemical constituents among the accessions. Analysis of variance showed significant differences (P<0.01) among the accessions for all biochemical attributes except for bean dry matter content. Principal component analysis revealed that the first four principal components accounted for 96.9 % of the total variability. The first PC, with Eigenvalue greater than one, alone accounted for 47.9% of the total variation mainly due to the variation in total chlorogenic acid and crude fat content, suggesting that these traits are the major contributors for the observed variability. Besides, clustering grouped the accessions in to six distinct clusters and two solitary regardless of the collection sites indicating the existence of variability among the accessions. Genetic divergence analyses based on Mahalanobis statistics (D2 ) showed significant inter cluster distance, implying that there is a chance to improve these biochemical compounds through hybridization. In general, the observed variability for bean biochemical compounds indicating a great opportunity for genetic improvement of east Wollega coffee for biochemical contents through selection and hybridization. However, the variability observed in this study should be further confirmed by conducting the experiment in different locations as well as using molecular techniques
Abstract: Coffee is the world’s most widely traded tropical agricultural commodity next to oil and is the back bone to the Ethiopian economy. The associations between yield and its components offer important information for plant breeders. Hence, this experiment was conducted at Agaro research station, southwest Ethiopia, to determine the extent of correlations among yield and its related traits of 49 coffee accessions and to assess the direct and indirect effects of these traits on coffee yield. The experiment was conducted in simple lattice design with two replications. Data on yield and its components were recorded and analysis of variance, correlation and path coefficient analysis were performed. The result revealed that significant (P<0.05) differences among the coffee accessions for all traits except for percent of bearing primary branches, leaf area, bean thickness and rust incidence. All traits showed non significant correlation with coffee yield at phenotypic level. However, morphological traits, namely, average inter node length on stem, stem diameter, angle of primary branches, fruit length, fruit width and fruit thickness exhibited positive and significant (P<0.05) correlation with coffee yield at genotypic level and are important components to improve it. Besides, path coefficient analysis showed that average-inter nodes length on main stem, stem diameter, angle of primary branches, fruit length and fruit thickness having positive direct effects, exhibited positive significant genotypic correlation with coffee yield and these traits are important for direct selection to improve coffee yield. On the other hand, fruit width showed negative direct effect but positive and significant genotypic correlation with coffee yield and can be used for indirect selection. In conclusion, average inter node length of main stem, stem diameter, angle of primary branches, fruit length, fruit thickness and fruit width can be used as direct and indirect selection criteria to improve coffee yield. Keywords: Accessions, Agaro, Correlation, Direct effect and Stem diameter