Glandular hair densities in three perennial Medicago species

Summary Eight triazine resistant (Brassica napus x B. oleracea) x B. oleracea interspecific hybrids with chromosome numbers ranging from 25 to 27 were backcrossed a second time to B. oleracea but no seed was formed. However, in vitro embryo rescue on 77 developing ovules yielded nine BC₂ plants with chromosome numbers between 19 and 25 and in which the herbicide resistance was still strongly expressed. Three of these plants (NOH-8B2B1, 2n=20; NOH-8B2B3 and NOH-8B2B4, 2n=19) were backcrossed again to B. oleracea. Two of the three plants produced seed which germinated to produce triazine resistan BBC₃s with 18, 19 or 20 chromosomes. The triazine resistant B. campestris cytoplasm has now been stabilized in B. oleracea.