Is it feasible to improve stand persistence of eastern gamagrass (Tripsacum dactyloides L.) through breeding?

Eastern gamagrass is a warm-season perennial grass that has excellent forage nutritional quality and a broad range of adaptations. Despite the favorable forage qualities, agronomic issues persist; most important for grazing systems is stand persistence from preferential grazing when growing in mixed species communities. Stand persistence when monoculture stands are grazed has been previously studied, 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 an improvement of stand persistence under defoliation to a low-cut height is feasible through the breeding of improved lines. A persistence trial was conducted using a completely random design and eight replications to evaluate the stand persistence of two commercial cultivars, two experimental lines, and an ecotype selection. Defoliation occurred by grazing and mowing to a height of 8 cm three-to-four times over the course of five growing seasons. Stand counts of live plants were taken following the final defoliation of the season. Mixed linear regression modeling indicates significant differences between genotypes developed in years where no grazing occurred. An ecotype selection from Northwest Oklahoma exhibited significantly greater persistence than the cultivar Pete and the other experimental lines. These results suggest that different alleles exist for critical persistence genes, indicating it may be feasible to improve the trait through breeding and selection.