Use of Plant Growth Regulators to Expand Sagebrush Germination Rates for Restoration Efforts

• Published in: Rangeland ecology & management 2021-05, Vol.76 (1), p.48-55
• Main Authors: Keefer, Chelsea E., St. Clair, Samuel B., Radke, Janae, Allen, Phil S., Hoose, Benjamin W., Fahning, Savannah, Hayward, Nicholas K., Stringham, Tamzen K., Madsen, Matthew D.
• Format: Article
• Language: English
• Subjects: Abscisic acid; Arid zones; Artemisia tridentata; Carboxylic acids; Conglomerates; Environmental conditions; Germination; Gibberellic acid; Growth regulators; Hormones; Plant communities; Plant growth; Promoters; Restoration; sagebrush steppe; seed coating; seed enhancement; Seed germination; Seed treatments; Seeding; Seeds; Species; Steppes; Success; Weather
• ISSN: 1550-7424; 1551-5028
• DOI: 10.1016/j.rama.2021.01.009

Seed germination during unhospitable environmental conditions can be a major barrier to direct seeding efforts in dryland systems. In the sagebrush steppe, Wyoming big sagebrush and low sagebrush are important shrub species used in restoration; however, seeding success is highly sporadic due to interannual and intraseasonal weather variability. It may be possible to improve restoration success by expanding the period of seed germination to increase the chances some seeds will germinate within a window that is favorable for plant establishment. Our objective was to determine if we could expand the period of germination using plant growth regulators (PGRs) applied in a conglomerated seed coating to Wyoming big sagebrush and low sagebrush. The seed of each species was 1) left untreated; 2) conglomerated; 3) conglomerated and treated with two concentrations of a germination inhibitor, abscisic acid (ABA); or 4) conglomerated and treated with two different germination promoters, gibberellic acid (GA3) and 1-aminocyclopropane carboxylic acid (ACC) (6 treatments total). Seeds were incubated in a loam soil at five constant temperatures (5–25°C) for approximately 3 mo. Results indicate that seed treatments with PGRs can delay or accelerate germination. For example, at 5°C, which is the temperature most similar to when the seeds germinate in the field, ABA delayed the time for 50% of the seeds to germinate by a maximum of 28 d and 38 d and the germination promoters decreased this time by 9 d and 11 d for Wyoming big sagebrush and low sagebrush, respectively. Field studies are now needed to determine if the bet-hedging strategy developed in this study will increase the likelihood of seeding success. Although our study focused on sagebrush, there is merit to evaluate the use of PGRs on other species, particularly where seed is being sown in highly variable environments.