Abstract

The sagebrush (Artemisia spp.) steppe is undergoing rapid ecological change. The degradation of sagebrush steppe rangelands has resulted in the listing of more than 350 animals and plants as species of conservation concern. In addition, there has been a decrease in recreational values, reduced forage production, degraded water resources, and an increase in fire frequency. In the sagebrush steppe, success rates for seeding sagebrush after wildfire are notoriously low. Not only are sagebrush seeds hard to sow due to their small size and associated flower parts, but seedlings are exposed to numerous stresses that lowers their survivability. To improve sowing efficiency and reduce the associated stresses to seedling development we use seed enhancement technologies. In Chapter 1, we explain how a rotary seed coater can be used to agglomerate and apply enhancements to Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis) seed. Using a mix of compost and clay we used a rotary seed coater to create small uniform agglomerates that allowed for enhancements to be applied to the seed. Our study demonstrated that agglomerates have no negative effects on seed germination and increased the overall flow of seed. In Chapter 2, we analyzed the addition of the plant hormone abscisic acid (ABA) in seed coatings. This hormone may delay seed germination and allow seedlings to avoid mortality due to over-winter freezing. We determined effects of different concentrations of ABA on total germination and timing of germination. Using a wet-thermal accumulation model, we estimated germination timing of seeds using soil temperature and water potential data for six different sites in the Great Basin. These models illustrate the variation in germination timing across the Great Basin. From our results we proposed the idea of using ABA to create a bet- hedging strategy in seed mixes to increase the probability that some seeds would germinate when conditions are favorable for seedling success.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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