Phenolic Growth Inhibitors Isolated from Dormant Buds of Sugar Maple (Acer saccharumMarsh)

Phenolic growth-inhibiting substances were isolated from dormant buds of sugar maple (Acer saccharurn Marsh) by paper chromatography of their aqueous methanolic extracts. Inhibition was determined in germination bioassays using lettuce (Lactuca sativa var. Grand Rapids) seeds. An inhibition of some 20% was attributed to four major phenolics identified as ferulic, vanillic, p-coumaric, and caffeic acids. Quercetm was also present and caused a weak stimulation of growth. Fractionation of the extract with acidic, neutral, and basic groups indicated that more phenolic compounds were in the acidic group than in the neutral, while none were in the basic group. On a seasonal basis, autumn buds had a higher phenolic content than winter and spring buds. The results presented are not inconsistent with the view that growth-inhibitory phenolic compounds could contribute to dormancy in sugar maple buds.