Many barriers can limit restoration success. In the first chapter of this thesis, the barrier of strong seed dormancy is addressed. While dormancy benefits the species' long-term survival, it can present a challenge within a restoration scenario where rapid establishment is required. Soaking seeds in gibberellic acid (GA3) can overcome dormancy. An easier and potentially more effective method to apply this hormone is to coat seeds with a GA3-impregnated polymer, which provides a slow release of the hormone. Seed dormancy can also be mitigated by creating a favorable microsite with increased soil moisture. We compared the emergence and establishment of penstemon seeds that were coated with GA3 to uncoated seeds planted in shallow drill rows versus deep, U-shaped furrows. These treatments were evaluated in fall and spring plantings at three field sites in the Great Basin Region of the United States. Overall, coating with GA3 improved the emergence and establishment of Palmer's penstemon (Penstemon palmeri; p < 0.01) and thickleaf penstemon (P. pachyphyllus; p < 0.001) but did not improve the emergence or establishment of firecracker penstemon (P. eatonii; p = 1). Between planting seasons, fewer seedlings emerged or established from spring than from fall planting (p < 0.001). Emergence and establishment were higher for all species in deep furrows than in shallow drill rows (p < 0.001). These results indicate that GA3 seed coating and deep, U-shaped furrows may improve the restoration success of some native forbs. Land managers could use these techniques to restore native forbs in dry, disturbed areas. The second chapter of this thesis addresses another barrier to successful restoration, specifically pathogenesis from soil and seed-borne fungus. Survival and growth of native seeds and seedlings can be limited by soil and seed-borne pathogens. Fungicides can combat fungal pathogens, but in some studies, fungicide treatments were ineffective at improving seedling emergence. These studies cite dry conditions leading to low fungal presence as the cause of the ineffectiveness of fungicide treatments for some years and sites. This study tested if fungicide treatment effectiveness is indeed related to the amount of fungus in the soil. We analyzed the emergence and biomass of uncoated, blank-coated, and fungicide-coated bluebunch wheatgrass (Pseudoroegneria spicata) across five soil fungal levels. For both percent emergence and total biomass, uncoated seed performed best in autoclaved soil and declined with increasing level of fungus, but the level of fungus did not impact fungicide-coated seed. When grown in autoclaved, untreated, or low fungal soils, percent emergence and total biomass from fungicide-coated seeds was not different from uncoated seeds. However, in medium and high fungal soils, the percent emergence and total biomass from fungicide-coated seeds were more than two times greater than uncoated seeds (p < 0.05). These results indicate fungicide seed coatings can be effective at increasing restoration success for bluebunch wheatgrass, but the effectiveness of this treatment depends on the microbial environment of the planting site.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-11318 |
| Date | 21 April 2023 |
| Creators | Johnson, Amber Jo |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | https://lib.byu.edu/about/copyright/ |
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