Seed Priming Increases Germination and Biomass Production of Native Understory Species used in Longleaf Pine Savanna Restoration

Abstract

Restoration of Pinus palustris (longleaf pine) savannas often requires planting native plant species to reestablish the understory, which can involve sowing mixes of understory species such as Aristida stricta and A. beyrichiana (wiregrass). These efforts have faced several challenges, for instance, low A. stricta and A. beyrichiana seed germination and reduced species diversity compared to old-growth sites. This emphasizes the importance of finding restoration methods to promote understory plant establishment. Seed priming enhances restoration in other ecosystems, thus it may aid in P. palustris savanna restoration. We aimed to determine if hydro- (i.e., soaked in water) and bio- (i.e., soaked in water and a commercial mycorrhizal inoculant) priming native understory plant seeds influence germination and biomass production. Experiments were conducted in both laboratory and greenhouse settings as an initial trial on effectiveness, providing a foundation for future field studies. We selected six species (i.e., A. beyrichiana, Muhlenbergia capillaris [hairawn muhly], Eragrostis spectabilis [purple lovegrass], Liatris spicata [dense blazing star], Sericocarpus tortifolius [Dixie whitetop aster], and Carphephorus corymbosus [coastal plain chaffhead]) and divided seeds of each species into three treatments: 1) unprimed 2) hydroprimed 3) bioprimed, then tested seed germination and plant biomass for each treatment. Biopriming increased the likelihood of germination by 2.42-fold for A. beyrichiana and 1.37-fold for L. spicata relative to the unprimed treatment. Aristida beyrichiana, E. spectabilis, and L. spicata showed significantly higher biomass production in bioprimed than hydroprimed seeds. Our study provides crucial insight into previously unexplored seed enhancement methods in an ecosystem frequently undergoing restoration.