Aspects of the biology of Rubus chamaemorus L. (bakeapple) in Newfoundland and Labrador

Abstract

Rubus chamaemorus L. (bakeapple), a common species of nutrient-poor peatlands throughout Newfoundland and Labrador, is harvested for its commercially valuable berries. Management practices in Scandinavia are used to increase natural yields in the field; this study in part attempted to determine if similar practices could be applied to the native population in Newfoundland and Labrador. In sites throughout the province the synecology and autecology of R. chamaemorus L. were studied to find the environmental and habitat preferences of the species. Flowering, fruiting and vegetative development were traced through several seasons and found to be particularly sensitive to climate. Although germination can be enhanced by the use of gibberellic acid (GA₃) and kinetin, growth of R. chamaemorus L. from seed remained an ineffective proposition. However, results from greenhouse and field studies showed that yields of existing populations could be greatly improved by ploughing the bog surface, reducing the numbers of competitive species, and providing increased shelter from wind. -- Using the greenhouse population, plant organs were prepared and examined by optical and electron microscopy. General descriptions of root and rhizome anatomy compared well with Resvoll (1929), Bailey (1941) and Taylor (1971). Previous results (Bal, 1975) indicated that certain cells in the root contained dense material. The electron density was subsequently identified as due to the presence of polyphenolics. Ferric chloride was used to localize phenolic deposits within the cells and a variety of staining procedures enabled various classes of phenolics to be identified and their distributions in root and rhizome sections determined. -- Rubus chamaemorus L. also possesses a varied root microflora, consisting of many bacterial and fungal species. Isolation and culture of root bacteria yielded good results and the rhizosphere medium displayed considerable diversity. It appears that phenolic compounds not only protect the root and rhizome from excessive damage by microorganisms but also control and delineate the association between the root microflora and the root tissue themselves. These two factors acting together could play a major role in the ability of R. chamaemorus L. to exploit nutrient-poor environments.