Background and Purpose: The purpose of this research was to estimate general (GCA) and specific combining ability (SCA) for grain yield, oil content and oil yield of sunflower inbred lines, to estimate the portion of genetic and additive component of variance, to determine relationships between inbred lines, two-line (SC) and three-line hybrids (TWC), and to determine perspective parental lines and hybrids. Materials and Methods: Six inbred lines were used in the research, 15 experimental SC (male sterile) hybrids, 15 experimental TWC hybrids and 3 recognized hybrids. Obtained results were processed by analysis of variance, linear correlation analysis, Griffing's diallel analysis, and estimation of genetic and additive variance. Results: OS-1 line had the largest GCA effect for grain yield, oil content and oil yield. OS-1 A x OS-6 B combination had the highest SCA effect for grain yield, as well as for oil content and oil yield. Genetic variance was larger than environmental variance, and additive variance was larger than dominant for all traits. High significant positive correlations were found for oil content among SC and their TWC hybrids. Line OS-1 transferred its positive effects for oil content and yield in TWC hybrids. Conclusions: Line OS-1 has desirable agronomic traits and could be used in future breeding process aimed at genetic improvement of sunflower. Additive variance was greater for all investigation traits. Lines with the best GCA for oil content kept retained these characteristics in SC and TWC hybrids. Lines with the best GCA did not produce hybrids of the best SCA and opposite. In the case of grain and oil yield a significant correlation between SC and their TWC hybrids did not exist, although it did for oil content. The best hybrid for commercial production was (OS-1A x OS-5B) x RF-28.
