ABSTRACT
Diploid hybrids between V. darrowi Camp and V. ar-borewn Marsh, (sparkleberry) were allowed to open-pollinate in the presence of a wide range of blueberry cultivars and species at the Horticultural Research Unit in Gainesville, Florida. Open-pollinated seedlings (MIKs) with high fertility were selected and crossed to let-raploid southern highbush cultivars. Most crosses of this type gave numerous seedlings, indicating that the fertile MIKs were tetraploid or near tetraploid. The vigor of these backcross seedlings varied widely, both within and among crosses of MIK x highbush cultivar. The best seedlings from the best crosses had fruit of cultivar quality. Some seedlings ripened as early as the earliest southern highbush cultivars; others ripened later than the latest southern highbush culti-vars. This study suggests that commercial cultivars could be selected in which one-eighth or more of the pedigree consists of K arboreum, but many seedlings will have to be grown to sample all the plant types that can be derived from this gene pool. The extent to which these seedlings have inherited the superior tolerance of V. arboreum to droughty, low-organic, high pH soils is unknown.