In allogamous rye selfing results in strong inbreeding depression, i.e., hybrid genotypes display heterosis. Major
heterotic effects are found for grain yield, sometimes up to 210%. As hybrid breeding in rye progressed, line performance increased and relative midparent heterosis for grain yield decreased to about 140 %.
Presently, more than 20 hybrid varieties are on the commercial list in Germany , occupying about 60% of the total rye acreage. Some of these hybrids are registered and distributed in Austria, Denmark, France,
UK, Scandinavia, Netherlands, and Australia.
For hybrid seed production genotypes are needed showing cytoplasmatically male sterility and restoration effects: