Genetic Diversity Analysis of Some Ethiopian Specialty Coffee (Coffea arabica L.) Accessions for Cup Quality Attributing Traits

Abstract

knowledge of nature and extent of genetic variation and diversity available in the germplam or breeding materials helps breeder for planning sound breeding program. Hence, the present investigation was undertaken to evaluate 47 coffee germplam accessions, which were collected from Gomma wereda of Jimma zone and two standard check varieties. The experiment was conducted in simple lattice design with two replications during 2011/12 cropping season. Data on eight organoleptic traits were recorded and the analysis revealed that all organoleptic quality traits showed significant variation among the accessions at (P<0.05). High phenotypic and genotypic coefficients of variation was observed for bitterness and astringency. Organoleptic traits such as flavor, overall standard, acidity and aromatic quality had high heritability. Bitterness and astringency showed moderate heritability coupled with high genetic advance. Similarly, flavor had high heritability and moderate genetic advance as percent of mean. Hence, bitterness, astringency and flavor can be improved through selection. Cluster analysis based on organoleptic traits grouped the accessions into three groups which make them also moderately divergent. Besides, inter-cluster distances were significantly different and crossing coffee accession from these divergent clusters will result in heterosis and recombinant in segregating generation. The principal component analysis showed the variation in first principal component, 63.7%, had been attributed to overall standard, flavor, acidity and aromatic quality. Hence, these traits should be given importance during hybridization and selection in the segregating population. In general , the present study indicated the presence of variability for organoleptic traits among the accessions. Therefore, the observed variability should be exploited in order to improve the quality of Gomma wereda coffee. However, since high quality variation between accessions is not a guarantee for a high genetic variation, biochemical studies need to be considered as complementary to organoleptic studies.