Document: ERI-3-48-7

Emission of volatile compounds by seeds under different environmental conditions.

JORGENSEN, E.E.*

USEPA, Ada, OK 74820 USA ¹

Abstract:
Prior investigators have learned that small mammals locate buried wet seeds with greater efficiency than buried dry seeds. It is hypothesized that this observation may be attributable to emission of volatile compounds by the seeds. To investigate this hypothesis, I measured emission of volatile compounds from seeds of three plant species (Pinus contorta, Pucilla tridentata, and Oryzopsis hymenoides) under both wet and dry conditions using gas chromatography/mass spectrometry headspace analysis. Seeds reponded in two ways to this simple manipulation: 1) Wet seeds released different, generally greater, amounts of volatile gas compared to dry seeds and 2) Wet seeds and dry seeds release different compounds. Pinus contorta releases greater amounts of 3 compounds when wet; Pucilla tridenta release 2 compounds when dry that are not released when wet, and releases 2 compounds at greater levels when wet and 2 compounds at greater levels when dry; Oryzopsis hymenoides releases at least 22 compounds, one of which is released in large concentrations when wet. These data suggest two mechanisms by which small mammals could locate buried seeds. First, small mammals may be sensitive to differing concentrations of volatile compounds being released. Second, small mammals may be sensitive to compounds released by wet seeds that are not released by dry seeds. Ability to survive depredation by granivores may be a niche axis along which seeds from different plant species compete.

Keywords: Seeds, Depredation, Granivory, Volatile Compounds, Gas Chromatography

This abstract is being presented at: 3:30 PM in session:
PLANT-ANIMAL INTERACTIONS