Self-fertility evaluations of northern-adapted rabbiteye blueberry hybrids

Authors: Ehlenfeldt, Mark; Kramer, Matthew

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2012
Publication Date: 12/1/2012
Citation: Ehlenfeldt, M.K., Kramer, M.H. 2012. Self-fertility evaluations of northern-adapted rabbiteye blueberry hybrids. HortScience. 47:1837-1842.

Interpretive Summary: Rabbiteye blueberry plants are heat tolerant and well adapted to the southern U.S. The USDA is developing new rabbiteye plants adapted to the northern U.S. Before growers can effectively establish rabbiteye blueberry production in the north, additional information is needed on the fertility of new northern-adapted rabbiteye blueberry plants. If plants are not sufficiently fertile, fruit yield is reduced. In this study, we measured the fertility of these new rabbiteye blueberry plants. The results indicated that rabbiteye blueberry plants adapted to the northern U.S. are generally less fertile than highbush blueberry commonly grown in the north and may require measures to ensure adequate pollination for fruit production. However, among the northern-adapted rabbiteye plants we tested, one hybrid was as fertile as highbush blueberry, suggesting that it might be possible to select plants that are well adapted to current northern blueberry production practices. This information is useful to researchers developing northern-adapted rabbiteye blueberry varieties and to growers that may plant these new varieties.

Technical Abstract: Rabbiteye blueberry hybrids that the USDA-ARS program has bred for northern adaptation are combinations of 6x V. ashei Reade, 6x V. constablaei Gray, 4x V. corymbosum L., and 2x V. darrowii Camp germplasm at the hexaploid level, and are generally composed of 50% or greater V. ashei (rabbiteye) germplasm. Four northern-adapted rabbiteye (NRE) selections (US 1043, US 1045, US 1056, US 1057), four rabbiteye cultivar standards (‘Brightwell’, ‘Climax’, ‘Tifblue’, ‘Woodard’), two rabbiteye x V. constablaei hybrid cultivars (‘Little Giant’, ‘Snowflake’), and two highbush cultivars (‘Duke’, ‘Bluecrop’) were pollinated, under greenhouse conditions, with either self-pollen or a multi-cultivar, bulk-pollen mixture (appropriate to ploidy level and species) to determine the relative requirements for cross-pollination among NRE types. Fruit set, berry weight, and seed set were subsequently evaluated. The results suggest that NRE, in general, exhibit cross-pollination needs intermediate to the parent types such that: rabbiteye > northern rabbiteye > highbush (i.e. rabbiteye has the lowest self-fertility and the greatest need for cross-pollination). Considerable variation existed among the NRE selections tested, which suggests that it might be possible to select clones with good levels of self-fertility, potentially equivalent to that of highbush blueberry.