Full-season corn ( Zea mays L.) hybrids take advantage of more of the growing season than shorter-season hybrids often leading to greater grain and biomass yield. Many agronomic experiments aimed at corn stover production have been performed at forage harvest rather than later when stover is normally harvested for biofuel measurements. The objective of this research was to evaluate the influence of hybrid relative maturity (days RM) on stover ethanol production, ruminant digestibility, and biomass composition. Hybrids selected were high-yielding commercial grain hybrids grown throughout Wisconsin and ranged from 85 to 115 d RM in 10 d RM increments during 2009, and in 5 d RM increments during 2010. Hybrids were harvested at physiological maturity or after a killing frost. Overall, stover and theoretical ethanol yields increased as RM increased at a linear rate of 0.211 Mg ha -1 RM -1 and 67.1 L ha -1 RM -1. Stover nutritional and biomass composition improved as RM increased, but yield variability was greater than nutritional and biomass compositional variability. Increasing ethanol yields will likely occur by increasing stover yields rather than by altering stover composition. Therefore, until price premiums for stover composition are made available to farmers for ethanol production, the adoption of full-season or longer maturing hybrids should be implemented for increased stover and ethanol yields.
