Perennial Grasses for Bioenergy: Not Only Switchgrass!.

Many crop species will be required to meet goals for energy production from biomass and biofuels. Perennial grasses will be one of the more important categories of crops, partly due to high biomass yield potential, the native status of many species, and their potential to serve multiple functions that include soil and water conservation, wildlife habitat, and landscape diversification. In the USA, switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), bermudagrass (Cynodon dactylon), napiergrass (Pennisetum purpureum), eastern gamagrass (Tripsacum dactyloides), Miscanthus (Miscanthus spp.), reed canarygrass (Phalaris arundinacea), and wildryes (Leymus triticoides and L. cinerus) are currently undergoing germplasm assemblage, pre-breeding, advanced breeding, and/or cultivar development efforts for bioenergy production. Switchgrass represents the most advanced of these species, largely because the US DOE chose switchgrass as its herbaceous model species in the early 1990s, supporting existing programs and creating new programs with funding infusions through 2002. The remainder of these breeding programs are just beginning or are developing as spin-offs from existing breeding programs aimed at the livestock industry. Breeding objectives for these species include, first-and-foremost, increased biomass yield, followed by increased stress tolerances, improved biomass quality (conversion efficiency), and other agronomic traits, depending on the species and region.