Study: Miscanthus More Than Twice as Productive as Switchgrass for Energy Crop
11 July 2007
|Miscanthus. Standing next to the grass is Dr. Emily Heaton (now with Ceres), who is 5' 4" (163 cm) tall. Source: UIUC|
Researchers at the University of Illinois at Urbana-Champaign have made the first direct comparisons of the biomass productivity of two C4 perennial grasses: switchgrass (Panicum virgatum) and Miscanthus (Miscanthus x giganteus). The two have been widely trialed as low-input bioenergy crops in the US and EU, respectively.
Results from the trials throughout Illinois show that Miscanthus is more than twice as productive as switchgrass. Its efficiency of conversion of sunlight into biomass is amongst the highest ever recorded. The research team presented their results at Plant Biology and Botany 2007, a joint congress including the American Fern Society (AFS); the American Society of Plant Biologists (ASPB); the American Society of Plant Taxonomists (ASPT); and the Botanical Society of America (BSA).
The team, led by Frank Dohleman of the Plant Biology Department, theorized that Miscanthus produces more usable biomass than switchgrass because of these three key attributes:
Miscanthus can gain greater amounts of photosynthetic carbon per unit of leaf area;
Miscanthus has a greater leaf area; and
Miscanthus has a longer growing season.
The research team measured the amount of gas exchanged on the upper canopy of Miscanthus leaves from pre-dawn to post-dusk on 20 dates in the 2005 and 2006 growing seasons. The averages from two years’ data showed that Miscanthus gained 33% more carbon than switchgrass.
Integrated measurements also showed that the Miscanthus leaf area was 45% greater than switchgrass and that Miscanthus plants grew an average of eleven days longer than switchgrass. This extended growing season and accompanying lower temperatures proved to further boost the photosynthetic activity of Miscanthus. Specifically, pyruvate Pi dikinase was found to be expressed at higher rates when ambient temperatures are lower. This enzyme supports C4 photosynthesis in Miscanthus.
The University of Illinois at Urbana-Champaign is working with the University of California at Berkeley and the Lawrence Berkeley National Laboratory in forming the new $500-million Energy Biosciences Institute (EBI) funded by BP, with UC Berkeley taking the lead. (Earlier post.)
As part of the EBI, some 340 acres of farmland at the Urbana campus will be devoted to the study and production of feedstock for biofuel production. Researchers will explore the potential benefits of using corn crop residues, switchgrass, Miscanthus and other herbaceous perennials as fuel sources. The initiative will explore how adequate supplies of high quality plant biomass can be sustainably produced and utilized in facilities that convert the biomass to fuels.
Feedstock development is one of five research areas at the EBI. The others are biomass depolymerization; fossil fuel bioprocessing (converting heavy hydrocarbons to cleaner fuels) and carbon sequestration; socio-economic systems; and biofuels production. In addition to feedstock development and socio-economic research, Illinois will work with the other research institutions on biofuels production. UC Berkeley will lead this part of the project, with Illinois joining the search for the most efficient use of microbes to harvest the energy in plants for biofuels.
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