Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 26, 2008
Publication Date: March 31, 2009
Citation: El Nashaar, H.M., Banowetz, G.M., Griffith, S.M., Casler, M.D., Vogel, K.P. 2009. Genotypic Variability in Mineral Composition of Switchgrass. Bioresource Technology. 100:1809-1814. Interpretive Summary: Switchgrass is a warm season perennial grass with great potential as a U.S. energy crop. It is widely adapted to many regions of the U.S., produces large amounts of biomass, and serves as a useful forage grass. Potential technologies to convert this grass to energy include fermentation, similar to that used for corn-to-ethanol, and thermochemical (pyrolysis/gasification). This study compared the mineral composition of six different populations of switchgrass when grown at five different locations to evaluate the potential for breeding new populations that are more suitable for thermochemical conversion. Mineral composition is important because certain minerals like silica, potassium and chlorine react with thermal reactors to form corrosive compounds and slag which reduce the lifetime of the reactor. We found differences among populations at each location, and these differences suggested that complex environmental factors affected mineral accumulation in these populations. The chlorine content of plant tissues varied approximately five-fold between locations while silicon accumulation varied approximately three-fold. Population X Location was the primary determinant of this apparent genetic variability. Further work is needed to understand how environment impacts mineral uptake in switchgrass.
Technical Abstract: Switchgrass (Panicum virgatum L.) is a warm season perennial grass with great potential as a U.S. energy crop. It is widely adapted to many regions of the country, produces large amounts of biomass, and serves as a useful forage grass. Technologies to convert this grass to energy are currently in development and include biological (fermentation) and thermochemical (pyrolysis/gasification) approaches. The objective of this research was to determine whether genotypic variability existed in the accumulation of minerals that impact the suitability of switchgrass for thermochemical technologies. Above-ground biomass samples from six populations grown at five diverse locations were analyzed for a range of minerals including aluminum (Al), silicon (Si), chloride (Cl), potassium (K), phosphorus (P), sulfur (S), and calcium (Ca) and others associated with undesirable combustion characteristics. Differences among populations across locations were complex and suggested that significant environmental factors affected mineral accumulation in these genotypes. The Cl and P content of plant tissues varied approximately five-fold between locations while silicon accumulation varied approximately three-fold. Upland and lowland cytotype explained some of the observed differences, but Population X Location was the primary determinant of variability.