Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2013
Publication Date: 4/18/2013
Publication URL: http://handle.nal.usda.gov/10113/56240
Citation: Vogel, K.P., Mitchell, R., Sarath, G., Jung, H.G., Dien, B.S., Casler, M.D. 2013. Switchgrass biomass composition altered by six generations of divergent breeding for digestibility. Crop Science. 53:853-862. DOI 10.2135/cropsci2012.09.0542 Interpretive Summary: Biomass composition of perennial grasses such as switchgrass can affect its utilization by ruminants and its conversion to liquid fuels in a biorefinery. Switchgrass populations developed by six generations of breeding to improve its digestibility by beef cattle were evaluated for changes in chemical composition. The breeding work to increase forage digestibility altered almost all plant biomass constituent concentrations and also improved potential conversion efficiency to ethanol in a biorefinery. When breeding selections were based only on forage digestibility without any attention to yield or other fitness traits, winter survival was adversely affected in the advanced generation populations. Both feedstock quality and plant agricultural fitness traits need to be considered when developing perennial grasses for use as biomass energy crops.
Technical Abstract: Biomass composition of perennial grasses such as switchgrass can affect its utilization by ruminants and its conversion to liquid fuels in a biorefinery. The objective of this study was to evaluate the effects of six generations of divergent breeding for forage in vitro dry matter digestibility (IVDMD) on switchgrass biomass composition, forage quality traits, and ethanol yield. Initially there was one cycle of selection for both low (C-1) and high IVDMD (C1= cv Trailblazer) followed by four additional breeding cycles for high IVDMD. In cycles 4 and 5, winter survival was included as a selection criterion because of decreased winter survival of the C3 population. The experimental populations that were produced by these breeding generations and nine half-sib families from cycle 5 were evaluated for two post-establishment years at the research station in eastern Nebraska, USA where all the breeding work was conducted. The six breeding generations resulted in significant differences among the populations for all of the 28 cell wall and non-cell wall composition variables measured, forage quality, and ethanol yield traits measured except for total biomass C, cell wall concentration, soluble glucose, and etherified ferulates. The compositional traits included all cell wall and non-structural carbohydrates. Breeding for the heritable complex trait IVDMD affected a large number of plant biomass characteristics and also adversely affected plant biomass yield and winter survival. Selection for a fitness trait such as biomass yield should be practiced when breeding to modify plant biomass composition of perennial grasses such as switchgrass.