INTERACTIONS BETWEEN KALMIA AND BLACK SPRUCE - ISOLATION AND IDENTIFICATION OF ALLELOPATHIC COMPOUNDS

Aqueous extracts of fresh leaves and organic soil of northern sheep la urel (Kalmia angustifolia var. angustifolia) were found to be inhibito ry to the growth of black spruce (Picea mariana) germinants. Primary r oot growth of black spruce was mom affected by the extracts than was s hoot growth. The growth inhibition caused by the leaf extract was most pronounced under acidic conditions (pH 3-4). The aqueous extract of K almia leaves contained ferulic, vanillic, syringic, gentisic, m-coumar ic, p-coumaric, o-hydroxyphenylacetic, and p-hydroxybenzoic acids as w ell as some other unknown compounds. These compounds were isolated fro m the aqueous extract of Kalmia leaves by ethyl acetate extraction and identified using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Bioassay indicated that the overall tox icity of the phenolic compounds to black spruce appeared to increase i n the order of o-hydroxyphenylacetic, p-hydroxybenzoic, vanillic, p-co umaric, gentisic, syringic, ferulic, and m-coumaric acids.