Author(s): Samuel Leigh
Mentor(s): Matt Madsen, April Hulet
Institution BYU
Native early seral forb species are crucial for rangeland restoration, as they rapidly establish ground cover, stabilize soil, and increase plant diversity. Their use helps create favorable conditions for later successional species, promoting overall ecosystem recovery and resilience. This study aimed to evaluate methods for breaking seed dormancy in three Asteraceae forb species—annual sunflower, curlycup gumweed, and prairie coneflower—and assess their growth across three degraded rangeland soil types: mine tailings, rock dumps, and disturbed rangeland soils. In addition to the benefits mentioned, forb species were selected for specific roles: annual sunflower for its potential in mine site phytoremediation, and curlycup gumweed and prairie coneflower for providing habitat and forage for pollinators from late summer to early fall. One challenge with many forbs is non-uniform and slow germination due to seed dormancy. Our research investigated various treatments to break dormancy including soaking seeds in water or gibberellic acid (GA3), scarification with hydrochloric acid (HCl), and treating seeds in boiling water. For annual sunflower, GA3 treatments at 1000ppm, 2500ppm, and 5000ppm were significantly more effective than the control, resulting in germination rates up to 19 times higher (average seed germination of 4% to 76%, respectively). Following treatments, seeds were air-dried under ambient conditions to assess whether seed dormancy was maintained. For annual sunflower, a 30-day storage period reduced germination by an average of 19.3% in GA3 treated seeds. However, these rates remained significantly higher than non-GA3 treatments. These findings suggest that GA3 treated annual sunflower seeds could be effectively included in spring seeding mixes. Research on the germination and growth of curlycup gumweed and prairie coneflower is ongoing. Future studies will evaluate plant growth for all species sown in degraded rangeland soils and investigate phytoremediation capabilities of annual sunflower.