Crossing a winter B. napus line with a rapid-cycle B. rapa line has been discovered to provide an unexpectedly simple and efficient way to create a modified B. napus with a spring flowering habit. In one implementation, such a modified B. napus or its progeny is crossed with a second winter B. napus line to produce at plant having a winter flowering habit. This allows one to significantly shorten the development cycle for winter-flowering B. napus lines by conducting part of the breeding program with spring-flowering time cycles, then migrating the resultant germplasm back into a winter-flowering line.
