LIMITS TO CLONAL SELECTION IN DANISH SOUR CHERRY

An initial investigation into the level of genetic variation that exists within the clones ‘Birgitte’ and ‘Viki’ was undertaken as selections are being made from these with putative commercial benefits. A significant, commercial yield advantage of ‘Viki’ over ‘Birgitte’ was found (2006-2011) together with a consistently higher density of flower buds and better ability to avoid winter bud-freezing. No such benefits have been seen in the clones subsequently selected from either of these original sources. This suggests that little further variation exists within the genetic base spanning ‘Birgitte’ and ‘Viki’ and that an improvement strategy for ‘Stevnsbær’ based on non-mutant selection within them will not be productive. Collection of wild and relict material to expand the genetic base of Danish sour cherry and more conventional breeding approaches, perhaps based on recent advances in seed technology, may prove more valuable.