The Role of Interspecific Hybridization in Blueberry Improvement

Interspecific hybridization has played a significant role in blueberry improvement from its beginnings early in the Twentieth Century and continues to be important today. With the tetraploid highbush blueberry, Vaccinium corymbosum (2n=4x=48), interspecific hybridization has primarily involved species in the secondary genepool, i.e., other species in Vaccinium section Cyanococcus. The species used in interspecific hybridization for improvement of highbush blueberry types up to the present time are V. angustifolium (lowbush blueberry, 2n=4x=48), V. darrowii (Darrow's evergreen blueberry, 2n=2x=24), V. virgatum (rabbiteye blueberry, 2n=6x=72), V. tenellum (southern lowbush blueberry, 2n=2x=24), V. elliottii (Mayberry, 2n=2x=24) and V. constablaei (Constable's blueberry, 2n=6x=72). One or more generations of backcrossing are most commonly involved where interspecific hybridization has been utilized successfully in highbush blueberry improvement. Interspecific hybridization has played a minor role in improvement of cultivated hexaploid rabbiteye blueberries (V. virgatum) up to the present time. Where it has been utilized it has only involved V. constablaei in the secondary genepool. Only one F-1 and one BC1 interspecific hybrid hexaploid cultivar have been named to date. Cultivar improvement in tetraploid lowbush blueberries has been confined exclusively to the primary genepool of V. angustifolium to date. Vaccinium pallidum holds promise for contributing to future highbush and halfhigh blueberry improvement. Vaccinium constablaei and hexaploid southern highbush will probably contribute significantly to rabbiteye blueberry improvement in the future. Intersectional crosses among tetraploid species also may be promising for future blueberry cultivar improvement.