Date of Award

2009

Type

Thesis

Major

Biology

Department

Biology

First Advisor

Julie Ballenger

Abstract

It is hypothesized that global warming is at least partially due to increased greenhouse gases, one of which is carbon dioxide. An increase in atmospheric carbon dioxide has been shown to stimulate higher rates of plant productivity, including the production of plant toxins like urushiol. Urushiol, a secondary plant compound produced in members of the Anacardiaceae family, causes dermatitis in sensitive individuals. An increase in urushiol production could increase the reactivity of certain individuals to plants like poison oak and poison ivy. To determine how elevated levels of atmospheric carbon dioxide would effect urushiol production, 16 samples of poison ivy and poison oak were grown in environmental chambers. One chamber was maintained at ambient carbon dioxide levels (0.037%) and the second was held at an increased level of 0.057%. Urushiol was extracted and analyzed through thin layer chromatography and ultraviolet spectroscopy to determine the amount present in each plant after sixteen weeks of exposure in the two growth chambers. The overall urushiol production and the average weight of the leaves decreased as time elapsed in both chambers. Poison ivy urushiol absorbance showed a decrease over all 16 weeks of exposure. Poison oak showed a drop in urushiol absorbance through 8 weeks then increased back towards initial levels, indicating that poison oak is a hardier species when dealing with the stress of being transplanted and placed in a new environment. Decreases in both overall leaf size and urushiol production may be due to the lack of grow lights in the chambers and plant stress. In addition, the presence of chlorophyll pigments in early extractions influenced the ultraviolet absorption and may have compromised our results.

Comments

Honors Thesis

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