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The methods by which FI hybrid swedes can be produced are discussed. The use of self-incompatibility is considered preferable to the use of cytoplasmic male sterility. Several ways of utilising self-incompatibility are available and the integration of self-compatible lines into these methods should simplify their use.

The interactions of nine S-gene lines of Brassica napus were examined . Seven different S-genes were involved in the crosses, with three lines of different origin having the same S-gene . In general, the reactions on selfing the heterozygotes were as expected from the results of test crosses with the homozygous parent lines . All types of dominance relationships were found, including reversal of dominance in pollen and pistil .Weakening of activity of one or both genes was found in several cases . Background genotype was found have to some effect and reciprocal differences in reactions were also observed .

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