Value of various taxa in breeding tetraploid blueberries in Florida

Many species and races of blueberries native to the southeastern United States have been used in the University of Florida breeding program. Highbush blueberry cultivars from a program started in 1908 in the northern United States were used at the start of the Florida program as a source of early ripening, large fruit size and high fruit quality. Vaccinium species native to Florida were used to obtain adaptation to the Florida environment, which is characterized by a long growing season, mild winters interrupted by killing freezes, low number of chill hours, and warm, moist conditions that favor fungal pathogens. The Florida species that have proved most useful in breeding have been southern races of Vaccinium corymbosum, which produce hybrids with high vigor and upright growth habit, and V. darrowi, which produces hybrids that retain their leaves late into the winter and have a very low chilling requirement. Species that have been less useful in breeding are V. elliottii and V. myrsinites. V. arboreum, in Vaccinium section Batodendron, is the only species outside of section Cyanococcus that has been used in breeding Florida blueberries, and has been a good source of vigor and tolerance to soils low in organic matter and high in bicarbonates. Although the gene pool available for improving low-chill highbush blueberries is large and diverse, progress is slowed by the need to improve simultaneously a large number of traits.