Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2022
Publication Date: 2/2/2023
Citation: Boerman, N.A., Moffet, C., Gunter, S.A. 2023. Is it feasible to improve stand persistence of eastern gamagrass (Tripsacum dactyloides L.) through breeding? Agrosystems, Geosciences & Environment. 6(1). https://doi.org/10.1002/agg2.20335.
Interpretive Summary: Eastern gamagrass is a warm-season grass native to the central and eastern US. It produces an abundance of nutritious and highly palatable forage that is sought out by livestock when grown in mixed species communities. Many believe this preferential grazing has led to the demise of native eastern gamagrass stands. A collection from native stands, WWGG-003, exhibited 36.3% greater stand persistence than the worst performing germplasm at the end of six years. This indicates breeding has yet to eliminate the stand persistence issue, but native stands may harbor resistance to stress factors contributing to stand persistence. Screening additional collections from native stands using frequent grazing or mowing could provide a germplasm base for breeding eastern gamagrass that has improved stand persistence.
Technical Abstract: Eastern gamagrass is a warm-season perennial grass that has excellent forage nutritional quality and a broad range of adaptation. Despite the favorable forage qualities, agronomic issues persist; most importantly for grazing systems is stand persistence from preferential grazing when growing in mixed species communities. Stand persistence has been studied between two eastern gamagrass cultivars and it has been observed that stands decline under high stocking rates, or low grazing height. The objective of our study was to evaluate if improvement of stand persistence under defoliation to a low-cut height is feasible through targeted breeding efforts. A persistence trial was conducted to evaluate the stand persistence of two commercial cultivars, and three experimental lines when defoliated to a height of 8 cm on multiple occasions over the course of five growing seasons. Stand counts of live plants were taken following the final defoliation of the season. Significant differences between genotypes developed at the end of the second treatment year and increased throughout the subsequent years. One experimental line exhibited significantly greater persistence than either cultivar or the other experimental lines. These results suggest that novel alleles exist for stand persistence under grazing, making it feasible to improve the trait through breeding and selection.