No abstract

Recent interest in the possible protective effects of dietary antioxidant compounds against human degenerative disease has prompted investigation of foods such as blueberries (Vaccinium sp.), which have a high antioxidant capacity. Fruit obtained from genotypes of highbush blueberries (Vaccinium corymbosum L.) and lowbush blueberries (Vaccinium angustifolium Aiton) were analyzed for their antioxidant capacity, their content of anthocyanins, and total phenolic compounds, to evaluate the intraspecific and interspecific variation in these parameters. The method of extraction influenced the composition of fruit extracts; the highest anthocyanin and total phenolic contents and antioxidant capacity were found in extracts obtained using a solvent of acidified aqueous methanol. Regardless of the method, lowbush blueberries were consistently higher in anthocyanins, total phenolics, and antioxidant capacity, compared with highbush blueberries. There was no relationship between fruit size and anthocyanin content in either species.

Summary 1The fleshy fruited species of Vaccinium are known for their spatial dispersal ability but have generally been found to have poor representation in soil seed banks. 2 A buried seed experiment was conducted with 28 species of Vaccinium , in which seed lots were exhumed at intervals for up to 17 years. Mean species seed longevity was 8.65 years. For five species that persisted in soil for 15-17 years, regression indicates survival times of more than 20 years. 3 Climatic factors (particularly annual temperature range in the centre of the species' distribution range) alone accounted for 42% of the variation in seed longevity and reproductive variables for 55%. 4 Models of fruit dispersal speed (rapid/tardy) demonstrated the link between spatial and temporal (seed longevity) dispersal and between spatial dispersal and habitat affinity (open/closed) of a species. The majority (87%) of species belonged to two of the four possible syndromes (rapid fruit dispersal/long-term seed persistence or tardy dispersal/ short-term persistence); 84% of the former were open habitat species. 5 Seed bank density is a function of seed potential longevity, seed rain and soil conditions. Regions that support species having greatest potential longevity have the smallest seed banks. Annual temperature range was positively correlated with potential longevity but negatively correlated with actual seed bank densities. 6 Lack of recruitment via seed in Vaccinium species in arctic regions may limit genetic variability in these clonal plants and impede population responses to climate changes.