New hybrid crosses were studied during the period 2010-2012 under non-irrigation conditions in the Experimental field of IASS “Obraztsov Chiflik” – Rousse, as well as their parental lines, at a density of 5,500 plants/da. The expression of a better parent heterosis (BPH) and degree of dominance in F1 generation were determined and analyzed. The following traits were studied: height of the top maize ear formation, length of the maize ear and number of grains in a row, related directly to the mechanized harvesting and the crop yield.
Heterosis was defined after Omarov, 1975, and the degree of dominance in the F1 generation according to Romero and Fray, 1973. Using the method of Romero and Fray, an evaluation was allowed of the dominant gene action in the inheritance of the studied trait and its relation to the expression of heterosis.
The degree of dominance in F1 generation showed that the heterosis in the studied traits was due to positive over dominance. The BG 25 x 139 96 cross showed the highest BPH for the traits height of the top maize ear formation and length of the maize ear. For the trait number of grains in a row, the BG 78 x 139 96 B cross showed the highest BPH. The expression of heterosis in the studied hybrids showed the different genetic basis of the parental lines.