Genetic Variability for Biomass Yield, Yield Components, and Ethanol Yield Among Half-Sibs of Switchgrass.

With increasing conflict abroad, inconsistencies in gas prices and the U.S. dependency on foreign oil imports, there has been a push towards creating renewable energy domestically.  A native North American warm-season perennial prairie C₄ bunch grass, switchgrass (Panicum virgatum L.), possesses capability to produce high yields with lower inputs and on marginal lands. This has made it a primary target of current bioenergy research.  The objective of this research is to quantify biomass and ethanol yield performance of F₁ half-sib families from four parental sources that can be utilized in future selections for switchgrass grown as a bioenergy crop.  The four parental lines used in this study were PI 421999 (AR), PI 607837 (TX), PI 421552 (Cimarron), and Exp. # NSL-2001-1 (OK). The polycross nursery consisted of 14 randomly assigned, seed-derived plants of each parent.  Ten half-sib progeny were produced from each of the 14 parent plants for a total of 140 half-sib progeny for each family. The parents and half-sibs were evaluated at the East Tennessee Research and Education Center (ETREC) in Knoxville. Evaluations were based on a 1-cut biomass system versus a fall biomass harvest following a spring forage harvest system. The 1-cut system covered the years 2010 and 2011 and the biomass following forage covered years 2012 and 2013.  The biomass mean yield, number of tillers, and plant height of the half-sib family from the AR parental source were lower than those of the other three parental sources. The distributions of stem diameter, leaf width, leaf angle, and bloom score were similar for all four half-sib families.  Data will be presented on yields as well as heterotic responses and genetic variance parameters for each of the half-sib families.