title: Identification of volatile allelochemicals fromAmaranthus palmeri S. Wats.
abstract: Allelopathic volatiles associated with the weed Palmer amaranth (Amaranthus palmeri S. Wats.; AMAPA) were trapped on Tenax GC, thermally desorbed, and identified by gas chromatography-mass spectroscopy. Methyl ketones and alcohols (C4-C11) were the principal components of the volatiles mixture. Seedheads, stems, or roots were placed in a glass container and incubated at 31 °C (10 hr)/21 °C (14 hr) for three days prior to trapping the volatiles. Seedheads were rich in 2-heptanone which was consistently found, together with 2-heptanol, in all AMAPA tissues. Vapors of authentic 2-heptanone and (±)-2-heptanol at concentrations of 1 ppm or higher strongly inhibited the germination of onion and carrot and almost completely suppressed the germination of tomato and AMAPA seeds.
authors.affiliation: Southern Regional Research Center, USDA, ARS, P.O. Box 19687, 70179, New Orleans, Louisiana.
authors.forename: W J
authors.initials: WJ
authors.lastname: Connick
authors.forename: J M
authors.initials: JM
authors.lastname: Bradow
authors.forename: M G
authors.initials: MG
authors.lastname: Legendre
authors.forename: S L
authors.initials: SL
authors.lastname: Vail
authors.forename: R M
authors.initials: RM
authors.lastname: Menges