Abstract
Dryland ecosystems face widespread degradation from historical mismanagement, climate change, and invasive species proliferation. Although herbicides effectively control invasive annual weeds, they often suppress the establishment of desirable perennial species, limiting restoration success. Legumes enhanced with rhizobia inoculants offer a promising approach to overcome these challenges by facilitating nitrogen fixation, improving soil microbial communities, and potentially mitigating herbicide stress. We conducted paired greenhouse and field experiments to evaluate whether rhizobia seed coatings improve the establishment of three legume species Astragalus cicer (Cicer Milkvetch), Onobrychis viciifolia (Sainfoin), and Medicago sativa (Alfalfa), in soils treated with imazapic and glyphosate. In the greenhouse, rhizobia-coated seeds exhibited significantly higher plant density, nodule formation, and biomass under herbicide exposure compared to uncoated seeds, with species-specific responses reflecting differences in inherent stress tolerance. Cicer milkvetch benefited most proportionally from coating despite being the most herbicide-sensitive, while sainfoin maintained the highest overall performance. Field trials demonstrated that rhizobia seed coatings provided consistent but modest improvements in seedling emergence under both herbicide-treated and untreated conditions. Importantly, the effects of seed coating, furrowing, and in-furrow mulch application were strictly additive, indicating that these interventions address distinct establishment barriers. Together, furrowing increased emergence approximately five-fold under herbicide, mulch increased emergence two- to three-fold, and seed coating provided an additional ~30% improvement. These results demonstrate that integrating biological seed enhancements with microsite modifications can meaningfully improve legume establishment in herbicide-dominated restoration contexts, offering land managers a practical strategy for reestablishing nitrogen-fixing species on degraded rangelands.
Degree
MS
College and Department
Life Sciences; Plant and Wildlife Sciences
Rights
https://lib.byu.edu/about/copyright/
BYU ScholarsArchive Citation
Glover, Ryan Matthew, "Using Rhizobia Seed Coatings and Soil Amendments to Combat Herbicide Toxicity for Native Legume Establishment" (2025). Theses and Dissertations. 11082.
https://scholarsarchive.byu.edu/etd/11082
Date Submitted
2025-12-17
Document Type
Thesis
Keywords
rhizobia, legumes, seed coatings, rangeland restoration, herbicide stress, soild amendments
Language
english