Ethiopia is the homeland and center of genetic diversity of Arabica coffee (Coffea arabica L., Rubiaceae). Getting more information on genetic variability is a prerequisite for further improvement of coffee (Coffea arabica L.).A field experiment was conducted at Awada Agricultural Research Sub-Center, Ethiopia, to study the magnitude of phenotypic diversity among southern coffee (Coffea arabica L.) germplasm accessions based on quantitative traits. A total of 104 entries consisting of 100 accessions from southern parts of Ethiopia and four standard cultivars were evaluated using augmented design. The main objective of the study was to estimate phenotypic and genotypic variances, the broad sense heritability, genetic advance and estimate the correlation among various quantitative characters. Data on 24 quantitative traits were recorded from five representative trees per row for each accession. One hundred and four Arabica coffee accessions were grouped into seven distinct groups by cluster analysis indicating a wide genetic diversity of coffee genotypes. Cluster I, II, III, IV, V, VI and VII contained 37 (35.58%), 45 (43.27%), 09 (8.66%), 05 (4.81%), 03(2.88%), 02 (1.92%) and 3 (2.88%) of the accessions, respectively. The X2 test showed that inter cluster squared distances were significant at p<0.01 and p<0.05.Maximum inter-cluster distance (D2) was found between cluster IV and V (D2 =147.47), while the minimum inter-cluster distance (D2) was obtained between cluster II and V (14.08). Generally, the present study revealed the existence of immense genetic variability among coffee germplasm for various important morphological traits. Hence, there is a chance to exploit these traits to develop genotypes that perform better than the existing varieties for the upcoming coffee improvement program.

Keywords: Coffea arabica, genetic variability, the broad sense heritability, genetic advance, cluster analysis, yield and yield components, correlation, germplasm.