Sunday, April 29, 2007 - 2:20 PM
1A-03

Characterization and analysis of maize traits contributing to production of lignocellulosic ethanol

James G. Coors1, Aaron J. Lorenz1, Kendall R. Lamkey2, Krystal Kirkpatrick2, M. Paul Scott2, Lisa J. Haney2, and Paul J. Weimer3. (1) Agronomy, University of Wisconsin, 1575 Linden Drive, Madison, WI 53706, (2) Agronomy, Iowa State University, 2101 Agronomy Hall, Ames, IA 50011, (3) U.S. Dairy Forage Research Center, USDA-ARS, 1925 Linden Drive West, Madison, WI 53706

Improvement of lignocellulosic ethanol yield of maize stover is one goal of a multidisciplinary approach to increasing the efficiency of this emerging industry. The University of Wisconsin and Iowa State University corn breeding programs evaluated 75 hybrids that are genetically diverse for many potentially relevant traits. Field trials were conducted in 2005 and 2006 at two Wisconsin and two Iowa locations. Traits measured included stover yield, grain yield, theoretical ethanol potential (TEP), and in vitro ruminal digestibility (IVR). An experimental assay referred to as simultaneous saccharification and catabolism (SSC) was used to rapidly quantify sugars released after acid pretreatment and enzymatic hydrolysis. A range greater than 1900 L ha-1 was found within the tested germplasm for theoretical ethanol yield. Stover yield was much more variable than stover composition. Grain yield and stover yield were largely independent, but later-maturing hybrids tended to yield more stover than earlier maturing hybrids. The IVR assay used in this study was correlated with an SSF (simultaneous saccharification and fermentation) assay, and SSC was designed to mimic SSF. However, no relationship was found between these methods and TEP suggesting that sugar availability may as important as quantity. This is exemplified by the brown-midrib entries (low lignin mutants), which ranked last for TEP, but were highest regarding IVR and SSC. Selecting for conversion efficiency in addition to TEP may be needed to maximize overall stover quality.


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