Heterosis and Combining Ability of Coffee Quality Traits in Southwestern Ethiopian Origin Coffee Hybrids

Abstract

Agriculture in Ethiopia is the foundation of the country's economy playing an important role in gross domestic product (GDP), exports, and employment. Large parts of commodity exports are provided by the small agricultural cashcrop sector; principal crops being coffee. The current productivity per hectare is lower than many growing countries. Exploitation of hybrid vigor through selection of best parental lines and hybridization has been one of the most important strategies of improving productivity in some of the most economically important crops, such as Coffee. However, study for quality traits is generally over looked. Hence, this study was objectively designed to understand and estimate the nature and extent of heterosis and combining ability in selected Southwestern Ethiopian origin coffee genotypes for some of the most important coffee quality traits. Half diallel mating design using five parental lines, ten F1 hybrids and one hybrid check variety were laid out in a Randomized Complete Block Design (RCBD) with three replications across three locations Jimma, Metu and Tepi. The study locations represent the major coffee growing areas of the southwestern part of country. Some of the most important quality traits considered for this study includes: flavor, body, aromatic intensity, overall standard, shape and make. The better parent (BP) and mid-parent (MP) heterosis for the majority of quality traits was negative. This might indicate that these quality traits controlled by recessive genes. Some of the F1’s revealed quality nearly similar value with that of maternal parent having better quality character. This might indicate cytoplasmic inheritance of quality characters. This calls for the need to further study the inheritance of these quality traits by crossing the best quality parents with known poor quality parents. The study also revealed highly significant and positive general combining ability (GCA) effect for the parental line74148: for traits flavor and overall quality. It also showed higher positive value for body and physical quality character like shape and make. This shows the importance of this parent for the contribution of additive genes in improving the quality traits in the future coffee quality breeding program.