Genetic variability and character association of Amaro coffee (coffea arabica l.) Accessions at awada, Southern Ethiopia

Abstract

Fifty eight Amaro coffee (Coffea arabica L.) accessions and six standard check were evaluated for genetic variability and character association at Awada Agricultural Research Sub-Center, Southern Ethiopia using morphological traits. The experiment was laid out in an 8x8 simple lattice design with eight coffee accessions per each incomplete block. Analysis of variance for 19 quantitative characters revealed significant difference (P<0.05) among the accessions in coffee bean yield, plant height, height up to first primary branch, main stem diameter, canopy diameter, number of bearing primary branches, fruit width, fruit length, bean thickness, bean width, leaf width, 100-coffee beans weight, coffee berry disease and coffee leaf, average inter nodes length of main stem, length of first longest primary branch, number of primary branches, bean length, leaf size. High phenotypic and genotypic coefficient of variation was recorded for coffee bean yield, coffee berry disease and coffee leaf rust disease severity. Genotypic coefficients of variation were very close to their corresponding estimates of phenotypic coefficient of variation suggesting greater role of the genotype in the expression of these traits. High estimates of heritability and genetic advance as percent of mean observed for coffee berry disease, coffee leaf rust and bean yield. Coffee yield has positive and significant genotypic association with number of primary branches (rg=0.704), number of bearing primary branch (rg=0.613), number of main stem node (rg=0.619), stem diameter (rg=0.335) and canopy diameter (rg=0.376), whereas average inter node length of main stem (1.083), number of main stem nodes (0.427), canopy diameter (0.414), height up to first primary branch (0.300) and number of bearing primary branch (0.294) had maximum direct effect on yield. Cluster means analysis revealed appreciable variation for quantitative characters. The distances between most of these clusters were highly significant at (P<0.01), suggesting the possibility of getting genetically divergent accessions for hybridization. The first six principal components exhibited more than one Eigen value and accounted for 77.7% of the total variation. The first two principal components with values of 23.32% and 18.85%, contributed more to the total variation. Shannon- diversity indices for the traits fruit shape, young leaf tip color and growth habit were high. This indicates that these qualitative traits contributed more to genetic variation in this study. Coefficient of variation, heritability estimates, correlation analysis, path analysis and multivariate analysis confirmed presence of variation among tested accessions. However, additional traits of interest should be studied over year and locations including physiological, quality and biochemical analysis with the support of advanced molecular techniques