Plant Breeders Increase Switchgrass Yield by 40%

Susan Harlow
Newsletter Issue: 
January 2017

Dr. Michael Casler
Above: Dr. Michael Casler, Plant Breeder USDA ARS in his switchgrass research test plots. 
Photo credit: Wolfgang Hoffman

Researchers in CenUSA’s Feedstock Development team made exciting new discoveries important in the successful production of switchgrass for biofuels.

Team members worked to develop new switchgrass varieties and ways to produce more biomass. Their goal: doubling switchgrass yields by 2020, primarily through boosting the rate of annual gain. 

One of their most notable successes was the creation of ‘Liberty,’ a new switchgrass variety that yields 40% more than other varieties and is widely adapted throughout the Midwest.

By using new methods such as hybridization, delayed flowering, and genomics, the team worked to generate new switchgrass varieties for both bioenergy and forage that are more vigorous and better adapted to marginal lands. They also studied how to better manage switchgrass plants.

Researchers and graduate students scoured fields and prairies for switchgrass plants of many varieties. They brought hundreds of leaf and seed samples back to their laboratories and spent many more hours studying and sequencing plant DNA. Other team members sampled switchgrass plants to discover how they are threatened by insects and diseases.

Team members were project directors were Mike Casler, of the U.S. Dairy Forage Research Center and Rob Mitchell of the USDA Agricultural Research Service (Northern Plains). Former co-director, Ken Vogel, USDA ARS recently retired. 

Collaborators on the team were Akwasi Boateng, USDA Agricultural Research Service; Bruce Dien, USDA Agricultural Research Service; Tiffany Heng-Moss, University of Nebraska – Lincoln; Ken Moore, Iowa State University; and Gary Yuen, University of Nebraska – Lincoln.

Their achievements ranged widely. In addition to creating ‘Liberty,’ the researchers:

Developed a system for classifying gene pools of switchgrass that could provide germplasm to improve varieties used for biofuels and ecosystems services.

Identified eight gene pools of switchgrass across the United States that could be a rich source of germplasm to improve commercial switchgrass varieties for biofuels, and in restoration and conservation work. 

Identified the origins and the genetic diversity of the two switchgrass ecotypes, upland and lowland, in their native habitats. 

Identified switchgrass pests. Entomologists found that insects such as aphids could threaten switchgrass production. But they also discovered that some varieties are resistant to these pests.

Identified the Panicum mosaic virus as a significant pathogen that could stymie production of switchgrass. 

Developed a method of NIR calibration to measure more plant properties in switchgrass. This will be valuable in breeding better bioenergy crop lines and can eventually be used by commercial biorefiners. A rapid and inexpensive method for analyzing chemical composition of switchgrass and other warm-season grasses will speed effective plant breeding. It is already being adopted by other perennial grass researchers. Commercial biorefiners cabn also use it to efficiently and accurately grade biomass delivered to their factory gates.

The work of CenUSA’s Feedstock Development Team is a cornerstone in creating a flourishing biofuels industry. It’s valuable to perennial-grass producers, to processors and refineries, and to geneticists and plant breeders who will create the varieties of the future.

By identifying and classifying switchgrass gene pools, then employing them to develop new varieties, the team opens up more possibilities for successful switchgrass production. For example, introduction of the new variety, ‘Liberty,’ gives potential switchgrass producers in the Midwest an excellent choice that is well adapted to their area, so they have a greater opportunity for success.

The team’s work also provides a foundation for future work, including:

  • Developing varieties with unique traits: those that are better adapted to marginal lands, later flowering, and higher yielding
  • Employing new genomic technologies to improve winter survival in southern types of switchgrass.
  • Developing more efficient fermentation of biomass, a plus for producing either animal products from forage or liquid fuels from biomass.
  • Improving the plant’s capacity to recycle more nitrogen (N) back into its roots before it is harvested, so growers need apply less N fertilizer.