Exploring the use of seed coat enhancements in fecal seeding efforts for rangeland restoration and Cheatgrass seed viability post ruminal fermentation
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Authors
Holton, Graham
Issue Date
2024
Type
Thesis
Language
en_US
Keywords
Cattle , Endozoochory , Fecal seeding , Rangelands , Seed coating , Targeted grazing
Alternative Title
Abstract
As cheatgrass (Bromus tectorum) continues to establish itself as a prolific invader across the rangelands of North America, an abundance of fine fuel has resulted in a changing fire cycle. The intensification of these fires has led to the loss of key vegetative species, which destabilizes the landscape, putting ecological processes and rural communities at risk. To combat this destructive cycle, cattle can be utilized to mitigate cheatgrass encroachment by reducing fuel height and the seedbank through targeted grazing. Additionally, by supplementing the seeds of desirable rangeland species in the diet of cattle, the animals may serve as seed dispersal agents of these advantageous plant species through fecal material. The bovine rumen houses a highly adapted microbial consortium specialized in degrading fibrous material. The studies included in this thesis aimed to utilize in vitro and in situ methods to evaluate the effects that seed coat enhancements have on the viability of seed germination post ruminal fermentation. In addition, cheatgrass seeds were subjected to the same fermentation methods to understand how the rumen impacts the germination potential of this invasive annual grass species. The seeds of six target species, Indian ricegrass (Achnatherum hymenoides), crested wheatgrass (Agropyron cristatum), fourwing saltbrush (Atriplex canescens), bottlebrush squirreltail (Elymus elymoides), bluebunch wheatgrass (Pseudoroegneria spicata), and gooseberryleaf globemallow (Sphaeralcea grossulariifolia) were coated with either Polyvinylpyrrolidone (PVP) or PVP + ethyl cellulose (Ethocel). Our findings suggest that while PVP and PVP + Ethocel coating treatments resulted in decreased germination rates at time point 0 hours across most species, they ultimately exhibited greater resistance to microbial degradation through time. This demonstrates the potential compatibility of these coating treatments, specifically PVP + Ethocel, with rangeland species for fecal seeding projects. Additionally, our study found that cheatgrass seed viability was completely inhibited after 36 hours of ruminal fermentation, with fall harvested seeds exhibiting a slight lag in microbial degradation. These findings will play a pivotal role in the development of future land management and livestock grazing strategies for western rangelands.