Genetic diversity of Arabica coffee genotypes in south Ethiopia using quantitative agro-morphological traits

The investigation was conducted to assess the extent of genetic diversity of South Ethiopian Arabica coffee genotypes for agro-morphological characters. Seventeen Arabica coffee genotypes were evaluated at Awada, Shebedino, and Wonago in south Ethiopia. Analysis of variance revealed significant variation among genotypes, environments, and genotype by environment interaction(GEI) for most of the characters investigated. Mean performance analysis confirmed the presence of genotypes superior for yield. Moderately high-to-high broad-sense heritability along with moderate-to-high genetic advance values were found for 15 traits, thereby indicating the possibilities of improvement through selection. Most agro-morphological traits were positively associated among themselves and with yield. Path coefficient analysis showed a positive direct effect of 11 characters on yield, indicating the significance of those traits for direct selection to increase coffee yield. Cluster analysis grouped genotypes into two main clusters and four sub-clusters. The first five principal components explained 74.05% of the total variation. The highest yield was recorded for genotypes AW7705 and AW105 which could be promoted as promising candidates for the release of a new cultivar for Arabica coffee growing regions in South Ethiopia and other similar agro-ecologies. Genotype, environment, and GEI have a significant effect on yield performance. Hence, the coffee yield improvement program should pay careful attention to a multi-location and season testing strategy to develop high-yielding cultivars. Investigation of management options after the high-yielding season is also advised to minimize high-seasonal yield oscillation.