Date of Completion

Fall 12-6-2019

Thesis Advisor(s)

Robert Bagchi; Valerie Milici; Cora Lynn Deibler; Bernard Goffinet; Virge Kask

Honors Major

Individualized Major

Disciplines

Biodiversity | Botany | Illustration | Interdisciplinary Arts and Media | Plant Biology | Terrestrial and Aquatic Ecology

Abstract

Vesicular-arbuscular mycorrhizae (VAM) are an ancient mutualism in which soil-dwelling fungi enhance plant absorption of phosphorus and nitrogen in exchange for photosynthates. VAM are sensitive to changes in soil moisture and nutrient content, fluctuating between mutualism and parasitism depending on conditions of drought stress and nutrient deficiency. Understanding how VAM respond to precipitation changes is crucial for both conservation and agricultural purposes. To test how soil moisture changes the effects of VAM colonization and growth in little bluestem (Schizachyrium scoparium), a common prairie grass, I planted 300 seeds in a greenhouse in sterilized soil and soil inoculated with VAM fungi spores. I applied five watering treatments for 13 weeks and then harvested the seedlings. Increasing soil moisture had a negative effect on biomass and shoot height, but no significant effect on number of leaves or root length. Soil inoculation did not have a significant effect on plant growth, and the fungi did not colonize any of the 15 root samples examined. Results suggest that little bluestem grows taller in dry soil, and may benefit from mild drought conditions. The phosphorus content of the potting soil may have been too high to incentivize young seedlings to recruit VAM fungi. As a precaution, future greenhouse studies involving VAM fungi should incorporate nutrient-poor soil to encourage colonization.

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