Diverse eastern gamagrass ecotypes: General characteristics, ploidy levels, and biogeography

Authors: Kiniry, James; Williams, Amber; JACOT, JACQUELINE - Oak Ridge Institute For Science And Education (ORISE); MCBRYDE, GARY - Retired Non ARS Employee; SHADOW, ALAN - Natural Resources Conservation Service (NRCS, USDA); BRAKIE, MELINDA - Natural Resources Conservation Service (NRCS, USDA); BURSON, BYRON - Retired ARS Employee; JESSUP, RUSSEL - Texas A&M University; CORDSIEMON, RON - Natural Resources Conservation Service (NRCS, USDA); KIM, SUMIN - Dankook University; AVILA, ANGELA - University Of Texas At Arlington; ELIAS, SABRY - Oregon State University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2023
Publication Date: 9/26/2023
Citation: Kiniry, J.R., Williams, A.S., Jacot, J., Mcbryde, G., Shadow, A., Brakie, M., Burson, B., Jessup, R., Cordsiemon, R., Kim, S., Avila, A., Elias, S. 2023. Diverse eastern gamagrass ecotypes: General characteristics, ploidy levels, and biogeography. Crop Science. https://doi.org/10.1002/csc2.21103.
DOI: https://doi.org/10.1002/csc2.21103

Interpretive Summary: Eastern gamagrass (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, and has an extensive root system. 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 accessions. For this study, we obtained a large assortment of accessions, measured and quantified some of their plant characteristics, and determined how their genetics differed. Accessions were collected from 10 states over five years and planted in a common garden in Temple, TX. Plants measured throughout the growing season. We investigated diversity of 292 accessions. Genetic ploidy was determined to compare accessions to location origin. Genetic 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. Accessions originating in the south experienced reenup before plants originating in the north. This new insights into EG ecology and the collected data are applicable to modeling to better answer producer questions about climate and management operations.

Technical 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, and has an extensive root system. 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 accessions. Study objectives were to obtain a large assortment of accessions, measure and quantify some of their morphological aspects, determine ploidy level for many of these accessions, and develop diverse data for future production simulation modeling. To meet these objectives EG accessions were collected from 10 states over five years and planted in a common garden in Temple, TX. Plant parameters were measured throughout the growing season for species phenological and ecological adaptations important to modeling. We investigated diversity of 292 accessions of EG including: heights of canopies, canopy width, canopy volume, length from the top leaf to the bottom of the spike inflorescence, spike length, number of terminal spikes per tiller, number of spikes per tiller, number of spikes per plant, greenup date, leaf width and structure, and color intensity. Ploidy was determined to compare accessions to location origin, and compare against previous studies. Monovariate analyses results show plant morphology measurements were variable, though none were statistically significantly correlated when compared pairwise 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. Visual 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 phenotypically. This does not correlate univariately, however, with location on the landscape or ploidy. It appears that EG syngameon characteristics extend from the species level to ploidy populations. This new insight into EG ecology and the collected data are applicable to modeling to better answer producer questions about climate and management operations.