Phenotype and Fertility of Intersectional Hybrids between Tetraploid Highbush Blueberry and Colchicine-treated Vaccinium stamineum

Several hundred hybrid seedlings were produced by pollinating flowers of tetraploid highbush blueberry cultivars with pollen from 13 plants of Vaccinium stamineum that were selected as tetraploids following colchicine treatment. The hybrids were intermediate between the parents in many characteristics. They were less vigorous than the parents, but 46 plants flowered when 1.3 years old from seed. The F-1 hybrids produced pollen abundantly, but only 30% of the microspores appeared potentially viable when viewed at 250X. F-1 flowers that were pollinated with pollen from either parent taxon or with pollen from a different F-1 hybrid produced thousands of well developed seeds. The F-1 hybrids were less successful when used as male parents in backcrosses to highbush, but 4790 well-developed seeds were obtained by pollinating 3250 highbush flowers. Flowers on F-1 plants had long peduncles and pedicels, giving an open raceme. The flowers were open in the bud and had anther awns, two characteristics from V. stamineum. Berries on the F-1 plants had black skins, and the ripe berries of 11 F-1 plants had red to purple pulp like their V. stamineum parent. Berries on the hybrids were juicy. They had little or no bitterness typical of V. stamineum, and most had a pleasing balance of sugar and acid.