VOLATILE CONSTITUENTS IN HEADSPACE OF BLACK SPRUCESEED CONES: IN SITU VS EX SITU.

Jean Turgeon, Eckehard G. Brockerhoff and Gary G. Grant
Canadian Forest Service, Great Lakes Forestry Centre, P.O. Box 490,Sault Ste. Marie, Ontario, Canada P6A 5M7

The headspace of black spruce seed cones still attached to a live tree(in situ) was compared to that of seed cones from the same treethat had been severed (ex situ) to determine whether differencesin cone condition during sampling influenced the profile of volatile emissions. Seed cone emissions were collected with a manifold headspace sampling system,adsorbed on Porapak® Q and analysed by capillary gas chromatographyand gas chromatography-mass spectrometry. The headspace constituentsof black spruce seed cones were tricyclene, a- and b-pinene, camphene,sabinene, b-myrcene, D-3-carene, p-cymene, b-phellandrene, limonene,g-terpinene,a-terpinolene, camphor, borneol and bornyl acetate. The relativeabundance of the constituents in in situ extracts differed quantitatively,almost qualitatively, from that found in ex situ samples. Camphene and bornyl acetate were significantly more abundant in the headspaceof in situ seed cones than in that of ex situ seed cones. Conversely, b-phellandrene was consistently less abundant in extracts ofin situ collections than in those of ex situ. Furthermore,the release rate of total monoterpenes from in situ seed cones wasapproximately twice as high as that from ex situ.