Cranberry Hybridization

Domesticated American cranberry, Vaccinium macrocarpon Ait., sect. Oxycoccus, has been successfully crossed with both intrasectional and intersectional species. Intersectional hybrids have been recovered from crosses with species from Vaccinium sections Vitis-idaea, Macropelma, and Cyanococcus. The intersectional hybrids are largely sterile as is typical with most Vaccinium intersectional hybrids. It has been reported that colchicine-doubled V. macrocarpon clones were successfully crossed with tetraploid V. oxycoccus, but the materials are not available for study. Among intrasectional crosses, a population of V. macrocarpon x V. oxycoccus hybrids have been produced between various cultivars of American cranberry and diploid V. oxycoccus representatives from Alaska. The hybrids were largely intermediate morphologically for both flower and vegetative traits, with flowering phenology skewed towards V. oxycoccus earlier flowering period. Three large F₂ (n > 100) families and numerous BC₁ (to V. macrocarpon) populations have exhibited considerable segregation for phenological, morphological, fruit chemistry, and fertility traits. Segregation for fruit and leaf anthocyanin glycosylation pattern in these families indicates a single major locus determining carbohydrate attachment at the 3-O position. Both F₂ and BC₁ populations exhibit ‘second bloom’ during mid-summer under New Jersey conditions, resulting in two crops offset in fruit development and maturation. These V. macrocarpon x V. oxycoccus F₂ populations offer the greatest opportunity for the genetic mapping and study of phenological, morphological, physiological, climatic adaptation, biochemical, and other traits in cranberry.