Graduation date: 2007
In recent years, there has been renewed interest in black raspberry (Rubus
occidentalis L.) breeding. This has been spurred by an increase in black raspberry
consumption due to studies that have shown them to be particularly high in
anthocyanin content indicating high levels of antioxidants. Present cultivars are ill
adapted to the biotic and abiotic stresses of the Pacific Northwest, where the
commercial black raspberry industry is centered, and fields must be replanted after 3-5 seasons. An incomplete, partial diallel, consisting of 10 parents (eight cultivars, a
wild selection, and a bulk pollen sample from R. leucodermis Dougl. ex Torr. &
Gray) and 26 sibling families, was constructed for the study of variation and
inheritance of vegetative, reproductive and fruit chemistry traits in black raspberry.
Sibling families of one to eight plants were established at the Oregon State
University Lewis Brown Farm in Corvallis, Oregon, and were arranged as a
randomized complete block design with four blocks. Phenological development and
vegetative measurements were recorded for each plant in 2005 and 2006. In addition,
25 berry samples of ripe fruit were collected from each plant, and pooled by family within blocks, to study variation in fruit chemistry properties including pH, titratable acidity, soluble solids, anthocyanin profiles, and total anthocyanins. Although there were many striking similarities, strong trends in phenotype based on pedigree were observed for most traits indicating a strong genetic component. For all traits, except for fruit mass, general combining ability effects were significant and larger than specific combining ability effects. Narrow-sense heritability estimates were generally
moderate to high when year effects were excluded from the analysis, indicating the
potential for progress from careful breeding and selection within the population of
plants studied. Most of the observed variability, however, was limited to a small
number of the studied genotypes, suggesting a degree of limitation for selection in
the present germplasm base.