Abstract: A process for the production of high purity hybrid Brassica seed, comprising (a) selecting a heterozygous, maximally self-incompatible parent plant, (b) cloning said selected plant to produce a first cloned parental line, the plants of which are both maximally self-incompatible and maximally clonal-incompatible, (c) crossing plants of said parental line with plants of a second parental line, and (d) collecting high purity hybrid seed from said first cloned parental line. The second parental line may also have been obtained by cloning a second maximally self-incompatible plant to obtain a second cloned parental line, the plants of which are both maximally self-incompatible and maximally clonal-incompatible. The second parent plant may be homozygous or heterozygous. The high purity hybrid seed may be collected from said second maximally self-incompatible cloned parental line or alternatively from both first and second maximally self-incompatible cloned parental lines.

Abstract: A process for commercially producing high purity hybrid cabbage seed. One (or both) of the parental lines is rendered sib-incompatible by cloning a maximally self-incompatible parent plant so that the resulting line (or lines), consisting of cloned plants, is sib-as well as self-incompatible. The two parental lines, one or both of which is clonally derived, may then be crossed by natural pollination without encountering inbreeding of the cloned parental line (or lines). Prior difficulties in maintaining the parental inbred breeding lines are eliminated.

Abstract: New hybrid seed varieties and plants therefrom are rapidly developed and commercially produced. New hybrid seeds can be readied for market in as little as three years, compared to the conventional eight to twelve years required for preexisting techniques of hybrid seed production. Plant breeders are no longer limited to homozygous parents in the production of new hybrids.