Changes in Phenolic Inhibitors in Seeds ofAcer saccharumduring Stratification

Abstract

Phenolics in sugar maple seeds were identified by colour reactions, u.v. spectroscopy and gas-liquid chromatography. Changes in their inhibitory activity during stratification were also followed using several bioassays. p-Coumaric, o-coumaric, and ferulic acids were found in all tissues. The highest concentrations were noted in the embryonic axis and testa, but total amounts per fruit were highest in cotyledons and pericarp. p-Coumaric acid was the principal phenolic in dry seeds, and it declined substantially in all tissues during the first half of stratification with little subsequent change thereafter. Decreases in o-coumaric and ferulic acids per seed were small by comparison, nevertheless losses ranged between 36 and 68% of the original concentrations. Bioassays confirmed that the three endogenous phenolics possessed marked inhibitory properties that diminished with the progress of stratilication, but only the compound identified as p-coumaric acid showed major inhibition in seed germination tests.