Interspecific blueberry (Vaccinium spp.) progenies were examined to determine combining abilities and genetic variability for seedling root system size and shoot vigor and to establish whether a large root system is correlated with good growth when plants are grown on a mineral soil and exposed to a moderate soil water deficit. General combining ability (GCA) variance components for root system size and shoot vigor and specific combining ability variance components for shoot vigor were significant. US226, a tetraploid hybrid of V. myrtilloides Michaux × V. atrococcum Heller, had the highest GCA effect for root system size and the lowest GCA effect for shoot vigor. US75 (V. darrowi Camp × V. corymbosum L.) had the highest GCA effect for shoot vigor and was second in GCA effect for root system size. Comparison of the crosses containing G111 (V. corymbosum) with those containing G362 (V. corymbosum) indicates that selecting for the best V. corymbosum clone to start a breeding program seems as important as selecting the mineral soil-adapted parent. Root system ratings were highly correlated with total dry weight of field-grown plants (r = 0.89). The method used in this study to evaluate seedlings for root system size and shoot vigor could be used to eliminate the less vigorous plants from a population before field planting and to evaluate mineral soil adaptability.
W.A. Erb, A.D. Draper, and H.J. Swartz
Paul M. Lyrene
number of plump seeds per pollinated flower was calculated when the berries ripened. Crosses between tetraploid Vaccinium myrsinites and tetraploid V. stamineum. Vaccinium myrsinites is an evergreen, rhizomatous lowbush blueberry species native on
Dario J. Chavez and Paul M. Lyrene
relatives have been introgressed into the cultivated gene pool. In the blueberry breeding program at the University of Florida, Vaccinium myrsinites Lam. (4x), Vaccinium darrowii (2x), and V. virgatum (6x), were successfully used as parents to reduce