This study is conducted in the period 2014-2015 in the experimental field of the
Maize Institute – Knezha by using an agro technique typical for the region. For the
purposes of the study are included four maize hybrids Kn 307, Kn 435, Kn 509
and Kn625М at different degree of maturity - FAO 300-399; 400-499; 500-599
and FAO above 600. The hybrids together with their parental forms are studied in
competitive variety trials under conditions without irrigation at five densities of the
crop 4500pl/da; 5500рl/da and 6500рl/da.
Total leaf area in the hybrids is inherited upon clearly manifested positive heterosis
and overdominance. The year of study and density of the crops influence heterosis
manifestation of the hybrids but do not change their character and direction,
provided that the influence of the year of growth is stronger.
Key words: Maize hybrids at different groups of ripeness, Heterosis, Degrees of
dominance
