Evaluation of Sweet Sorghum Genotypes for Biofuel Production in Missouri.

Sweet sorghum (Sorghum bicolor), a highly productive C4 grass, has garnered attention in recent years as ethanol  mandates have required the use of more plant based fuels.  The species requires less N fertilizer and is more drought tolerant than corn, and may be particularly suited for double-cropping with wheat.  In Missouri, few researchers have addressed the potential of sweet sorghum as a biofuel crop.  This study evaluated productivity of 12 diverse sweet sorghum cultivars when planted mid-late June corresponding to planting after early wheat harvest in the region.  The effect of harvest timing on biomass production, stem juice yield, and juice sugar content (brix) of the cultivars was compared.  Growth stage at harvest differed among cultivars and varied from head emergence to soft dough at the first harvest date and milk to hard seed at the final harvest date. Stem biomass ranged from 8.2 to 14.0 Mg ha^-1 and was unaffected by harvest timing.  Juice yield ranged from 12.6 to 23.2 kL ha^-1 and generally increased at later harvest dates.  Mean brix among cultivars ranged from 10.8 to 16.8 across harvest dates and was generally greatest in cultivars harvested at dough stage.