Evaluation of physical and chemical characteristics of bean and cup quality of arabica coffee genotypes grown in Southern Ethiopia.

The study aimed to investigate physical characteristics, cup quality, and biochemical content variability among thirty South Ethiopian Arabica coffee genotypes over three locations. The results revealed the existence of statistically significant variation among genotype, location, and GEI effects for all studied traits. The overall coffee quality score for most of the tested genotypes in three locations was above 80 %. Therefore, in terms of quality, most of the tested genotypes can be used to produce specialty coffee in the study areas. A wider range of caffeine (0.52 % dwb to 1.53 % dwb) was recorded among the studied genotypes. Accordingly, the low caffeine contenting genotypes could be a promising candidate for the development of low caffeine varieties through selection and hybridization. Cluster analysis grouped genotypes into different clusters based on quality trait variation and similarity among genotypes. According to the PCA, caffeine content (0.35), chlorogenic acid (0.34), aromatic quality (0.31), trigonelline (0.29), acidity (0.28), astringency (0.28), color (0.27) in the first PCA, flavor (-0.48), and screen size (0.46) in the second PCA were the important variables contributing more to the variation, and these traits could be considered for effective parent selection in quality improvement programs. Genotype AW9648 achieved the highest score in overall quality attributes at all three locations and could be promoted as a promising candidate and best parent for hybridization in terms of quality. Hence, genotype by environment interaction was significant, the coffee quality improvement program should give due attention to incorporating genetic and environmental influences by using a multi-locational selection strategy.