|ECKBERG, JAMES - University Of Minnesota|
|SHAW, RUTH - University Of Minnesota|
|JOHNSON, GREGG - University Of Minnesota|
|SEEFELDT, LAURA - University Of Minnesota|
|BLAEDOW, KAREN - University Of Minnesota|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2015
Publication Date: N/A
Publication URL: http://handle.nal.usda.gov/10113/62466
Interpretive Summary: Switchgrass is undergoing development as a bioenergy crop. Low germination, caused by seed dormancy, is one of the major factors limiting the economic sustainability of switchgrass for biomass production. This is the first study to document the difference in seed germination and dormancy between cultivated and wild populations of switchgrass. Cultivated populations were much higher in germination and lower in dormancy than wild populations, even though wild populations were highly variable. Cold-moist stratification was very successful for enhancing the germination of wild populations, but this procedure is not practical on a commercial scale. Seed size plays a role in enhancing germination, with larger seeds expressing higher germination rates. Both natural variation in seed size and plant breeders' efforts to select for larger seeds and reduced dormancy are responsible for the genetic improvements that have been achieved. These results will be of value to switchgrass breeders, agronomists, and producers who want to grow switchgrass for biofuel production.
Technical Abstract: Switchgrass breeding and selection has improved the agronomic qualities of this crop for forage and bioenergy applications. Previous work has characterized variation in phenotypic traits (e.g. survival, biomass yield, cell wall carbohydrates) among wild and cultivated populations. Despite the importance of germination rate to the establishment of a productive switchgrass stand, there is little information to characterize the variation in germination for selected cultivars versus wild populations of switchgrass. The objectives of this study were to quantify the germination of 12 switchgrass populations, compare wild versus cultivated populations with a history of selection, and evaluate the relationship between seed size and germination in a growth chamber. While cultivars generally showed higher germination than wild populations, there was marked variation in germination of wild populations. These data led us to perform a subsequent experiment testing the application of a seed treatment, cold-moist stratification, on a subset of eight populations representing the wide variation in germination observed in the first experiment. Cold-moist stratification substantially increased germination but the magnitude of the effect varied among populations. Populations with higher dormancy showed a much larger increase in germination after cold-moist stratification. These data clearly show that marked variation in the germination of wild populations can be easily overcome by cold-moist stratification in the short-term and breeding and selection in the long-term.