Thesis
The effects of suppressive bacteria on the germination and growth of cheatgrass (Bromus tectorum L.)
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/102860
Abstract
Cheatgrass is a problematic invasive annual species that is a major factor in the deterioration of our native shrub steppe communities and has substantially increased the frequency of costly wildfires across the western states. We tested the effects of the bacterium, Pseudomonas fluorescens strain D7, on the germination and long-term growth of cheatgrass (Bromus tectorum L.) seedlings in a greenhouse experiment conducted at Washington State University. The D7 inoculum treatment reduced early germination of seeds over approximately the first 7 days of growth, but long-term germination across 35 days was not significantly reduced. Germination varied significantly by seed accession as well as by interaction effects with time and inoculum treatment, indicating a potentially complicated series of ecological and environmental interactions. Cheatgrass seedlings grown in pots treated with D7 had lower total root weights, but higher shoot weights per pot, which may represent compensatory and adaptive growth responses to the stress of the D7 bacterium. However, variation in different seedling characteristics (i.e., root weight, total root and shoot weights, and longest root measurements) among seed accessions was significant and differences among accessions had the largest explanatory power in statistical models and the greatest influence on germination and seedling characteristics. These presumed ecological variations by geographic location may represent differences in adaptations to local environmental conditions. The resulting ecological variations in response to D7 should be considered in future greenhouse and field trials to more precisely determine the potential for using D7 to control cheatgrass in natural settings over a wide geographic expanse.
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Details
- Title
- The effects of suppressive bacteria on the germination and growth of cheatgrass (Bromus tectorum L.)
- Creators
- Amanda Kay Hohnhorst
- Contributors
- Rodney D. Sayler (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Agricultural, Human, and Natural Resource Sciences, College of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525086001842
- Language
- English
- Resource Type
- Thesis