Mung bean (Phaseolus aureus Roxb.) cuttings and cucumber (Cucumis sativus L. cv. Marketer) seedlings were cultured in water extracts of bark from silver maple (Acer saccharinum L.) hackberry (Celtis occidentalis L.), sycamore (Platanus occidentalis L.) and cottonwood (Populus deltoides Marsh.). Extracts of fresh silver maple bark inhibited root elongation of cucumbers and the adventitious rooting of mung bean. Composting the silver maple bark for 30 days prior to preparing the water extracts reduced inhibition. Pretreatment of fresh silver maple bark extracts with insoluble polyvinylpyrrolidone (PVP) reduced inhibition and indicated that the inhibitory compound was phenolic in nature. Chromatography and spectral analysis of common phenolic compounds and silver maple bark extracts revealed the toxic substance was similar to tannic acid.
Received for publication April 14, 1975. Illinois Agr. Expt. Sta., Univ. of Illinois at Urbana-Champaign. This study was supported in part by funds from Hiram Walker and Sons Distillery, the Mead Corporation and the Weston Paper and Manufacturing Co.
The authors are respectively, Assistant Professor of Horticulture and Forestry, Kansas State University, Manhattan; Assistant Professor and Professor of Horticulture, University of Illinois, Urbana-Champaign.