LEVEL OF SELF-FERTILITY AND CROSS-FERTILITY OF DERIVATIVES OF VACCINIUM-ARBOREUM X VACCINIUM SECTION CYANOCOCCUS HYBRIDS

The extent of self-fertility and self-fruitfulness was studied in Vacc inium arboreum Marsh, V. darrowi Camp, and in seedlings, termed MIKs, from open-pollination of V. darrowi (section Cyanococcus) x V. arboreu m (section Batodendron) F-1 hybrids. The open pollinations that produc ed the MIKs occurred in a field containing tetraploid southern highbus h selections (based largely on V. corymbosum L.), and the pollen paren ts of the MIKs are believed to be southern highbush selections. The MI Ks that were studied had been selected for high fruit set after open p ollination in the field, Both V. arborenin and V. darrowi exhibited ve ry low self-fruitfulness and self-fertility when hand-pollinated in a greenhouse; the former produced no seedlings from more than 600 selfed flowers, and the latter produced only 13, By contrast, southern highb ush clones averaged 70 seedlings per 100 pollinated flowers when selfe d and 230 when crossed. Self-fertility and self-fruitfulness of the MI Ks were higher than those of V. arboreum and V. darrowi but lower than those of southern highbush selections. MIK x MIK crosses gave fewer s eedlings per 100 pollinated flowers (84) than highbush x highbush cros ses (230), probably reflecting their ha brid ancestry. Although introd uction of V. arboreum genes into southern highbush blueberry gives pla nts of excellent vigor and adaptation to north Florida, several genera tions of breeding will be needed to obtain cultivars with high fertili ty and berry quality.