Distribution of Structural Carbohydrates in Corn Plants Across the Southeastern USA

Quantifying lignin and carbohydrate composition of corn (Zea mays L.) is important to support the emerging cellulosic biofuels industry. Therefore, field studies with 0 or 100 % stover removal were established in Alabama and South Carolina as part of the Sun Grant Regional Partnership Corn Stover Project. In Alabama, cereal rye (Secale cereale L.) was also included as an additional experimental factor, serving as a winter cover crop. Plots were located on major soil types representative of their respective states: Compass and Decatur soils in Alabama and a Coxville/Rains-Goldsboro-Lynchburg soil association in South Carolina. Lignin and structural carbohydrate concentrations in the whole (above-ground) plant, cobs, vegetation excluding cobs above the primary ear (top), vegetation below the primary ear (bottom), and vegetation from above the primary ear including cobs (above-ear fraction) were determined using near-infrared spectroscopy (NIRS). The distribution of lignin, ash, and structural carbohydrates varied among plant fractions, but neither inclusion of a rye cover crop nor the stover harvest treatments consistently affected carbohydrate concentrations within locations. Total precipitation and average air temperature during the growing season were strongly correlated with stover composition indicating that weather conditions may have multiple effects on potential biofuel production (i.e., not only yield but also stover quality). When compared to the above-ear fractions, bottom plant partitions contained greater lignin concentrations. Holocellulose concentration was consistently greater in the above-ear fractions at all three locations. Data from this study suggests that the above-ear plant portions have the most desirable characteristics for cellulosic ethanol production via fermentation in the southeastern USA.