Seed enhancement technologies such as seed priming and seed coating, developed by the agricultural seed industry, are standard procedures for the majority of crop and horticultural seeds. However, such technologies are only just being evaluated for native plant seeds despite the potential benefits of such treatments for improving restoration effectiveness. Key approaches applicable to native seed include: (1) seed priming, where seeds are hydrated under controlled conditions, and (2) seed coating, in which external materials and compounds are applied onto seeds through a diversity of treatments. These technologies are commonly employed to accelerate and synchronize germination and to improve seed vigor, seedling emergence, establishment, and to facilitate mechanized seed delivery to site, through standardizing seed size and shape. Seed enhancement technologies have now been tested on native seeds to overcome logistical and ecological barriers in restoration. However, further research is needed to extend the application of seed enhancements to a broader array of species, ecosystems, and regions as well as to evaluate new and innovative approaches such as the incorporation of beneficial soil microorganisms and plant growth regulators in the coatings. As techniques in native seed enhancement develop, these approaches need to be capable of being scaled‐up to provide the tonnages of seed required for global restoration.

Small or low-vigor species can be susceptible to being planted at depths that prevent seedling emergence. As an example, sagebrush (Artemisia spp. L. [Anthemideae]) seed is often prone to being planted at depths where the seedlings cannot emerge from the soil. We evaluated a potential solution to this problem that incorporates seed within an extruded pellet that is designed to enhance seedling emergence through the swelling action of the pellet creating conduits for the emerging seedlings to follow. We quantified the swelling capacity of the extruded pellet and evaluated how the technology improves seedling emergence and plant growth of Wyoming big sagebrush (Artemisia tridentate Nutt. ssp. wyomingensis Beetle & Young), over a range of seeding depths (5, 10, and 15 mm [0.2, 0.4, and 0.6 in]), within silt-loam and sandy-loam soils. Swelling capacity of the pellets in the silt-loam soil was approximately twice that of the sandy-loam soil. At all planting depths, pellets improved seedling emergence between 2.3- to 10.0-fold in the silt-loam soil. In the sandy-loam soil, no treatment effect occurred for seedling emergence at the 5 mm and 15 mm depths, but pellets enhanced emergence at the 10 mm depth by 3.1-fold. Some indications suggest that seedlings produced from the extruded pellets had greater growth than untreated seed. This technology opens up the possibility for sagebrush (and potentially other small-seeded species) to be seeded at deeper soil depths where soil water potential levels are more conducive for seed germination and seedling survival. Future development and field testing are merited.

There is a need to develop effective techniques for establishing native vegetation in dryland ecosystems. We developed a novel treatment that primes (hydrates) seeds in a matrix of absorbent materials and bio-stimulants and then forms the mixture into pods for planting. In the development process, we determined optimal conditions for priming seeds and then compared seedling emergence from non-treated seeds, non-primed-seed pods, and primed-seed pods. Emergence trials were conducted on soils collected from a hillslope and ridgetop location on the Kaibab Plateau, Arizona, USA. Poa fendleriana and Pseudoroegneria spicata were used as test species. Seeds were primed from -0.5 to -2.5 MPa for up to 12 d. Seeds primed under drier conditions (-1.5 to -2.5 MPa) tended to have quicker germination. Days to 50% emergence for primed-seed pods was between 66.2 to 82.4% faster (5.2 to 14.5 d fewer) than non-treated seeds. Seedling emergence from primed-seed pods for P. fendleriana was 3.8-fold higher than non-treated seeds on the ridgetop soil, but no difference was found on the other soil. Final density of P. spicata primed-seed pods were 2.9 to 3.8-fold higher than non-treated seeds. Overall, primed-seed pods show promise for enhancing germination and seedling emergence, which could aid in native plant establishment.