The expression of heterosis in the F1 generation of a diallel cross of diverse hard red winter wheat genotypes

Yielding ability in wheat can be increased by breeding genotypes that make better use of heterosis. A full diallel cross was made with five genetically diverse red winter wheats to determine the expression of heterosis, and specific combining ability (SCA) effects. Very low or negative levels of heterosis were expressed for yield and characteristics significantly correlated with yield. This was probably due to unsuitable environmental conditions for the expression of heterosis. This reaffirmed that the expression of heterosis should be tested over a number of seasons and environments. Average SCA effects were negative or low for measured characteristics, and did not seem to be related to the expression of heterosis.