Evaluation of genotypes for association traits contributing to grain yield and generation of genetic information on complex traits were the key steps in plant breeding to develop varieties for the targeted area of production. Hence, this research was conducted at Adami Tulu Agricultural Research Center in Mid Rift Valley of Ethiopia where twenty-five food barley genotypes were tested in 5 x 5 lattice design with three replications. Breeding for high grain yield supposes an understanding of associations among yield and yield contributing traits as well as the identification of traits that have great direct and indirect effects on grain yield. Fifteen quantitative traits were subjected to an analysis of variance which revealed differences between genotypes for twelve out of 15 quantitative traits considered including grain yield. The study of relationships between yield and yield contributing characters indicated that grain yield had highly significant and positive phenotypic and genotypic correlation with thousand kernel weight, biological yield and harvest index. This implied that the three traits had similar genetic influence on grain yield and that grain yield could be improved directly by improving these traits. The association between yield and yield related characters determined by phenotypic and genotypic path coefficients analysis revealed that biological yield, 1000-kernel weight, number of kernel per spike and plant height exerted highest positive direct effect on grain yield and suggested that grain yield would be improved by imposing direct selection on these traits. Days to first heading and days to heading exerted negative direct effect on both phenotypic and genotypic path analysis showing that the direct selection of these characters would not be dependable for grain yield improvement. Yet, this study should be conducted in different locations and seasons to develop countrywide high yielding varieties.
Keywords: Genotypic, Phenotypic, Grain yield, Direct and Indirect effects