Date of this Version
Bioenerg. Res. (2013) 6:711–718 DOI 10.1007/s12155-012-9285-0
This study presents results from a 2-year evaluation of biomass and cellulosic ethanol (EtOH) production potential of forage sorghum (Sorghum bicolor L. Moench) cultivars differing in brown midrib trait (i.e., bmr12) under dryland (no irrigation) and limited irrigation (2.88 mm day−1; subsurface drip) in the semiarid Southern High Plains of the USA. Commercial cultivar Sorghum Partners 1990 (SP 1990, conventional non-bmr) produced significantly more biomass (29–62 %) than a bmr12 cultivar PaceSetter bmr (PS bmr) under irrigated and dryland conditions during both years of this study. However, PS bmr biomass had higher cellulosic EtOH conversion efficiency than SP 1990 in both years according to simultaneous saccharification and fermentation analysis. Irrigation resulted in 26–49 % more biomass and 28–72 % more cellulosic EtOH production during both growing seasons, indicating that limited irrigation had favorable effects on both biomass and biofuel production. In the first year, when precipitation was below average, both cultivars produced similar amounts of cellulosic EtOH. During the second year, when precipitation was above average, higher biomass production of SP 1990 resulted in 28 % higher cellulosic EtOH production than PS bmr when averaged across both irrigated and dryland conditions. The large range of cellulosic EtOH production (1,600 to 3,380 L ha−1) during the 2 years of this study was primarily driven by differences in water availability that resulted from precipitation and irrigation. Our findings indicates that chemical composition and biomass yield potential of sorghum cultivars are critical factors that affect biomass and biofuel production under limited water conditions.