Traditional maintenance breeding of landraces: 2. Practical and theoretical considerations on maintenance of variation of landraces by farmers and gardeners

Maintenance breeding of landraces is discussed. Various practical and theoretical advices, presented in the literature to collectors of genebanks have been used to compare these with the methods applied by farmers. Although most farmers realize the utmost importance of yield stability, they and their ancestors experienced that maintenance breeding, could better be replaced by seed replacement. A few crops such as rootstock rose and especially maize, form exceptions. In these crops the farmers actually collect 'hips', or ears for the next generation. However, they also apply seed replacement from time to time. More research is needed to obtain better knowledge about the level of variation of a landrace grown for various generations before and after seed replacement.