Date of Graduation

5-2023

Document Type

Thesis

Degree Name

Master of Science in Horticulture (MS)

Degree Level

Graduate

Department

Horticulture

Advisor/Mentor

Richardson, Michael D.

Committee Member

Bertucci, Matthew B.

Second Committee Member

Philipp, Dirk

Keywords

Seed germination; Seed source; Tallgrass prairie

Abstract

American tallgrass prairie has faced losses estimated at 87-98% of original land area since European settlement. Native seeds are often used to supplement struggling or extinct plant populations in tallgrass prairie restoration and establishment sites. Two main considerations in restoration and establishment are from where to source seed and how to obtain high germination rates. In order to determine the effect of seed source, a common garden experiment was performed in Fayetteville, Arkansas in 2022 with five prairie species: Andropogon gerardii (big bluestem), Bouteloua curtipendula (sideoats grama), Panicum virgatum (switchgrass), Schizachyrium scoparium (little bluestem), and Sorghastrum nutans (Indiangrass). Seed was sourced from Oklahoma, Kentucky, Illinois, South Dakota, North Dakota, Minnesota, and Ontario, Canada. These sources represented a variety of latitudinal distances from the common garden. Differences in date of anthesis of first culm, mature height of tallest growing point, annual aboveground biomass production, and annual seed production of the individuals were analyzed among sources. The preliminary conclusion was that seed source does not affect success of a restoration or establishment, as there were very few significant differences in the measured characteristics among sources, and only one instance of the closer source being significantly taller with more biomass than the further source. Germination trials were conducted to investigate how germination pretreatments would affect germination rate for tallgrass prairie species, including fourteen common grasses and forbs found in Arkansas prairies. Seeds for each species were obtained from multiple sources across the USA and Canada. Pretreatments in the study included sterilization with hydrogen peroxide, dry and moist stratification of varying durations (1, 2, or 3 months), mechanical scarification with sandpaper, thermal scarification with boiling water, chemical scarification with hydrogen peroxide, and hormonal treatment with gibberellic acid. Across all species, there were minimal instances where a pretreatment significantly improved germination rate. One consistent finding was that thermal scarification with boiling water should be avoided unless specifically prescribed.

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