Summary
Energy content and fruiting patterns were examined for eight species in the genus Vaccinium Section Cyanococcus, the blueberries. Blueberries varied in both seed and berry production. Fresh fruit contained approximately 85 % moisture. A mg of dried pulp yielded 4.02 ± 0.08 cal; a mg of dried seed 5.15 ± 0.12 cal. The ratio of seed energy to pulp energy was 1:6.33 for small berries, 1:2.61 for large berries.
Whole-berry energy content was higher and seed energy lower in fruit from northern populations. Mean seed and pulp caloric values were 33 and 136 cal, respectively, for spring (southern) fruiting lowbush blueberries, compared to 15 and 168 cal respectively for summer (northern) fruiting species. Significant differences in seed and pulp energy also were found among three geographic populations of highbush blueberry, Vaccinium corymbosum. Blueberry fruiting patterns show a latitudinal gradient wherein sporadic fruiting occurs in spring when avian dispersal agents are few and territorial. Mass fruiting occurs in summer when avian dispersers are numerous. Further studies are needed to examine avian nutrition, foraging behavior and movements in relation to Vaccinium fruit production.
Methodology
Blueberry fruits for analyses came from 33 greenhouse populations which represented eight of the nine species currently recognized in Vaccinium (Vander Kloet, 1983): V. darrowii Camp, V. myrsinites Lamarck, V. tenellum Aiton, V. pallidum Aiton, V. myrtilloides Michaux, V. angustifolium Aiton, V. boreale Hall and Aalders and V. corymbosum Linnaeus. Only the rare V. hirsutum Buckley, a species endemic to the southern Appalachian Highlands, was omitted from the analysis. Provenance of these 33 populations is described in Vander Kloet (1977, 1978 and 1980). Vouchers are at ACAD.
Blueberry plants were grown in 1:1 (by volume) sand-peat soil mixture under a 14 hr light and 30 ± 4/15 ± 3 C day/night temperature regime to minimize the effects of environmental variables. Berries were produced by hand-pollinating plants within populations during January and February 1976, 1977 and 1978. Twenty-five ripe berries were collected from each of the 33 populations.
Ripe wild berries were collected from tagged Vaccinium corymbosum shrubs on the Archbold Biological Station, Lake Placid, Florida (n = 126); Herbert Bog, Upper Rock Lake, Frontenac Co., Ontario (n = 50), and Lake George, Yarmouth Co., Nova Scotia (n = 50). A pilot study in 1981 showed no significant difference in caloric value from berries gathered in the wild and greenhouse-grown berries (Student's t = 1.114, NS).