F1 hybrid versus 32 selected F7 lines performance of common winter wheat (Triticum aestivum ssp. vulgare).

One F1 common wheat hybrid ('Zlatna Dolina' x 'Primépi') which had exhibited significant heterosis in a previous study was compared with 32 F7 lines selected from the same cross. The yield test was planted in the 1976-1977 season at two locations: Zagreb, Yugoslavia (optimal environment) and Hutchinson, Kansas, USA (stress environment). The purpose of this experiment was to determine if a homozygous segregant superior to the F1 hybrid could be obtained from the same cross combination.Heading date, plant height, disease incidence, grain yield and its components, protein content, and sedimentation value were examined at Zagreb. Germination, winterhardiness and grain yield were determined at Hutchinson.At Zagreb, the F1 hybrid exhibited significant heterosis in grain yield, even though two of the three yield components were intermediate to parent values. Heterotic effects were greater in the stress environment (Hutchinson), mainly due to the poor winterhardiness and lower yield of one parent variety. At Zagreb, grain yield of the f1 hybrid was significantly better than the best F7 line. However at Hutchinson, the two leading F7 Unes outyielded the f1 hybrid, but differences were not significant.It can be concluded that genes involved in heterosis in the hybrid, 'Zlatna Dolina' x 'Primépi', were not fixed in the homozygous lines selected from the same cross.