Submitted to: Southern Nursery Association Research Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/8/2006
Publication Date: 4/5/2006
Citation: Kardos, J.H., Robacker, C.D., Dirr, M.A., Rinehart, T.A. 2006. Production and Verification of Hybrids for Hydrangea Macrophylla x H. angustipetala and H. macrophylla x Dichroa febrifuga. Southern Nursery Association Research Conference, vol 51, pp 570-572. Interpretive Summary: Past breeding efforts in H. macrophylla have focused mainly on the production of cultivars for the pot-plant market. The introduction of remontant (reblooming) cultivars such as Endless Summer™ (‘Bailmer’) has increased the presence of hydrangeas in American commerce and gardens. The genetic diversity among H. macrophylla cultivars is considered small due to the restricted native distribution and multiple breeding programs that utilized the same taxa and employed similar breeding goals (Haworth-Booth, 1984). There are only a few reports of introduction of wild-collected germplasm. Most of the early breeding took place using these introductions, and therefore, the majority of the over 500 extant cultivars originated from these few early introductions. Increasing genetic diversity through interspecific and intergeneric hybridizations will allow development of unique cultivars. Two promising species are H. augustipetala and D. febrifuga. H. angustipetala, also listed as H. scandens subsp. chinensis (Dirr, 2004) and H. scandens subsp. angustipetala (Mallet, 1994), flowers nearly a month before H. macrophylla and has been more resistant to powdery mildew than the latter species.
Technical Abstract: Hydrangea macrophylla is one of the most important flowering shrubs grown in the U.S. Sales of new cultivars such as 'Endless Summer' have surpassed three million plants. New sources of genetic diversity and unique characteristics are needed in future cultivars to sustain the current volume of sales. H. angustipetala and D. febrifuga are two sources of genetic diversity and unique characteristics for incorporation into H. macrophylla.