COS 110-2 - CANCELLED - Eastern gamagrass diversity: relationships between site origin, morphology, and ploidy

Abstract: Eastern gamagrass (Tripsacum dactyloides) (EG) is a warm season, perennial bunchgrass, with the potential to have multiple applications in ecosystem services and agriculture. This resilient native is drought and flood tolerant, highly productive, thrives without fertilizer, has an extensive root system, and its high palatability has led to its disappearance over much of its range due to overgrazing. EG is widespread in the eastern half of the United States and has highly diverse ecotypes. Objectives of this study were to obtain a large diverse set of ecotypes, measure and quantify some of their morphological aspects, and determine ploidy level for many of these ecotypes. This diverse set of EG ecotypes was collected from 10 states over five years and planted in a common garden in Temple, TX. Morphological aspects were measured throughout the growing seasons to develop plant parameters important for modeling this diverse species. We investigated morphological diversity of 292 ecotypes of EG. Ploidy was determined to compare ecotypes to location origin, and test against previous studies’ conclusions on smaller collections of this grass. Plant morphology measurements were variable, though monovariate analyses showed none were statistically significantly correlated when compared to ploidy levels, origin, landform, precipitation, or temperature. In contrast, multivariate analyses showed that ploidy was significantly correlated with plant volume, plant height, and leaf width. Likewise, mean annual precipitation was correlated with plant height and leaf width. Landform (wet vs. dry) for collection sites was significantly correlated with plant volume in the multivariate analysis. Trends were seen for greenup date versus location when mapped, with accessions originating in the south experiencing greenup before plants originating in the north. When grouped by landform, mapped trends were also observed for ploidy, height, and volume. EG is ecologically spread over much of the eastern US and is highly diverse morphologically. However, this does not correlate with location on the landscape or ploidy. Morphologic differences must be caused by more subtle genetics than ploidy, or a more complicated combined effect from the environmental and genetic interactions. This new insight into EG ecology and measured data is applicable to modeling to help answer producer questions about fertilizer, climate, and management operations.