ABSTRACT
A major contribution to onion breeding has been the development of new open-pollinated varieties using a range of population improvement methods. There is also considerable variation between onion populations available for the breeder to exploit. Special techniques have been used by onion breeders to compare marketable yields of their breeding lines and potential new varieties in countries where the normal practice is to establish the crop by drilling of seed rather than transplanting. Onion breeding in the US owes much to the initial research by H. A. Jones and co-workers on male sterility and their recognition of its potential for use in producing F1 hybrids. It seems likely that F1 hybrids will play an increasing part in future breeding, not least because of the advantages to the breeder of exclusive ownership of the parent lines. The full exploitation of the potential of F1 hybrids is hampered by the difficulties of commercial seed production from relatively weak parent inbreds.
