Effects of general and specific combining value of several winter lines were determined basing on the F₁ hybrids. In the yield structure traits under study a prevalence of additive over nonadditive action of genes has been found. Hybrids of Oregon 394, Marksman and Liwilla lines inherited highly significant values of the number of grains per ear, 1000 grain weight and weight of grains per an average ear. Hybrids of Atlas 66 and Kr 118/78 lines can constitute an interesting breeding material, of which both the SCA effects obtained and the variance estimates can bear evidence.