Abstract

Estimation of genetic parameters is pertinent as variability within population determines the extent of improvement achieved through crop improvement methods. In view of this, forty-nine coffee (Coffea arabica L.) germplasm accessions, which were collected from Gomma Woreda, were evaluated at Agaro with the objectives of assessing genetic variability, heritability and genetic advance for morphological traits. The experiment was conducted in simple lattice design with two replications. Data on 26 quantitative characters were recorded. The result revealed significant differences (p<0.05) among the accessions for most of the traits studied. The phenotypic coefficients of variation (PCV) was greater than genotypic coefficients of variation (GCV) for all the characters studied, this shows the influence of environmental factors on the characters. Estimates of variability indicated that high phenotypic (PCV) and genotypic coefficients of variation (GCV) were recorded for coffee berry disease (CBD) severity and yield per tree. High heritability was recorded for hundred bean weight (80.21%), number of nodes of primary branches (67.89%), stem diameter (67.16%), height up to first primary branch (66.6%), bean length (62.79%), bean width (61.43%), average inter node length of primary branches (58.33%), angle of primary branches (53.32%), leaf width (52.94%) and canopy diameter (51.95%). The high GAM were recorded for coffee berry disease reaction (88.86%), clean coffee yield per tree (24.03%), number of secondary branches per tree (22.34%), height up to first primary branch (20%) and hundred bean weight (20%). High heritability was coupled with high genetic advance as percent of mean for characters such as hundred bean weight and height up to first primary branch. The high heritability with high genetic advance as percent of mean observed for these characters is due to the lesser influence of environment in expression of the characters and additive gene effects. The present study indicated the presence of variability for some important morphological traits among the accessions. Therefore, the variability observed for yield, disease resistance and other important traits should be utilized to improve Gomma woreda coffee. However, since high morphological variation between accessions is not a guarantee for a high genetic variation, molecular and biochemical studies need to be considered as complementary to morphological variability. On the other hand, as most of the traits exhibited low GCV and/or low GAM, there is no opportunity to improve these traits using simple selection. Therefore, heterosis breeding should be applied to improve these traits.

Key words: Coffee germplasm, genetic variability, disease resistance, simple lattice, hundred bean weight.