Abstract
For assessing the combining ability, the top cross method proved more economical and less laborious compared with the diallel analysis. It also allows the breeder to obtain valuable information about the inbred lines and their hybrids for various traits. In the existing research, determining the combining ability of barley (Hordeum vulgare L.) hybrids took place in two regions of Kazakhstan with contrasting soil and climatic conditions. The additive and non-additive genes played a vital role in determining almost all the traits in barley. Analysis of variance showed varying significance among the barley cultivars and their hybrids and testing sites for the majority of the traits. Analysis of variance also revealed significant differences in general combining ability (GCA) and specific combining ability (SCA) among the parental cultivars and their hybrids in barley. The predominance of additive gene interactions in controlling the traits under environmental conditions of the Aral Sea region indicates the possibility of effective selection already in the F2 generation. However, in the piedmont zone of the Almaty region, the dominant genes managed the traits, and thus, necessary to differentiate the hybrid populations, starting from the first generation, until further selection from several cycles achieved the homozygosis of loci carrying dominant genes. Barley cultivars, Rihane, WI2291/Roho/WI2269 (ICARDA), and the tester, Odessa-100 (Odessa Selection and Genetic Institute, Ukraine), showed greater practical interest and therefore, recommended for use as reliable donors in future breeding programs.