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.

在不适宜的环境条件下，种子发芽可能成为直接在旱地系统播种的主要障碍。在鼠尾草草原中，怀俄明州的大鼠尾草和低鼠尾草是用于恢复的重要灌木树种。但是，由于年际和季节内的天气变化，播种成功非常零星。通过延长种子发芽时间，增加某些种子在有利于植物生长的窗口内发芽的机会，可能可以提高恢复成功率。我们的目标是确定是否可以使用植物生长调节剂（PGR）来延长发芽期，PGR应用于大种子鼠尾草和怀俄明州大鼠尾草的混合种子包衣中。每个物种的种子都是1）未经处理的；2）团聚；3）团聚并用两种浓度的发芽抑制剂脱落酸（ABA）处理；或4）团聚并用两种不同的发芽促进剂赤霉素（GA₃）和1-氨基环丙烷羧酸（ACC）（共6种处理）。种子在五个恒定温度（5-25°C）的壤土中孵育约3 mo。结果表明，用PGRs处理种子可以延迟或加速发芽。例如，在5°C（最接近种子在田间发芽的温度）下，ABA将50％种子发芽的时间最多延迟了28 d和38 d，发芽促进剂降低了发芽时间。怀俄明州的大鼠尾草和低鼠尾草分别为9 d和11 d。现在需要进行实地研究，以确定本研究中开发的对冲策略是否会增加播种成功的可能性。尽管我们的研究重点是鼠尾草，但仍有必要评估PGR在其他物种上的使用，