Corn Stover and Cobs Ethanol Yield As Affected By Hybrid, Bt Trait, and Environment.

A recent publication from Banerjee et al. 2010, reported differences in corn stover glucose release ranging from 95 to 64%.  These significant differences in fermentable glucose levels would likely result in tremendous variability in bio-refinery ethanol yield from corn stover feedstock.  Preliminary GLBRC analyses of corn stover (cultivar Pioneer 36H56) showed year to year (2008-2009) variability in ethanol precursors, glucose and free sugars, suggesting a significant environmental effect on stover quality.   Additionally, work published by Saxena and Stotzky (2001) showed that the lignin content, an anti-quality agent for ethanol production, was significantly higher (33-97% higher) for Bt lines compared to their respective non-Bt isoline.

The objectives of this project are 1. Evaluate the effect of the Bt trait on corn stover and cob ethanol yield. 2. Evaluate the effect of environment (location) on corn stover and cob ethanol yield. 3. Evaluate hybrid differences on corn stover and cob ethanol yield.

For the experimental design, 2 hybrid pairs (one Bt and one near-isoline relative) were analyzed giving a total of 4 hybrids.  Each hybrid pair were grown at two latitudinal differing locations at the MSU Hybrid trials in four replicated plots at each location.  One hybrid pair was grown in Saginaw and Mason Counties (Zones 2 & 3) and the second hybrid pair was grown in Mason and Menominee Counties (Zones 3 & 4).  Total samples to process = 2 hybrids x 4 locations x 4 reps = 32 samples. At each location, the entire corn plants were harvested. Then the ears were removed from the plants and the grain was shelled from the cob. Wet and dry weights were recorded from all three fractions for each plot (stover, cob, and grain). This experiment was repeated in the years 2010 and 2011. Samples were ground and were submitted for AFEX pretreatment. Samples will be analyzed for glucose, sugar profile, cellulose, and IVTD. Samples will be fermented and analyzed for ethanol yield.

To better visualize the relationships among compositions of Bt and Non BT isolines, SigmaPlot 10.0 (SYSTAT Software, 2007) will be used. Principle component analysis (PCA) of glucan, xylan, arabinan, acid-insoluble lignin, and ash content in corn fractions will be conducted by PROC PRIN- COMP in SAS 9.1.3 (SAS Institute, 2006). Multiple linear regression will be used to build a prediction model for ethanol production from sugar concentrations in hydrolysate using PROC GLM in SAS.