Sorghumis emerging as an excellent genetic model for the design of C4 grass bioenergy crops. Annual energySorghumhybrids also serve as a source of biomass for bioenergy production. Elucidation ofSorghum's flowering time gene regulatory network, and identification of complementary alleles for photoperiod sensitivity, enabled large-scale generation of energySorghumhybrids for testing and commercial use. EnergySorghumhybrids with long vegetative growth phases were found to accumulate more than twice as much biomass as grainSorghum, owing to extended growing seasons, greater light interception, and higher radiation use efficiency. High biomass yield, efficient nitrogen recycling, and preferential accumulation of stem biomass with low nitrogen content contributed to energySorghum's elevated nitrogen use efficiency.Sorghum's integrated genetics-genomics-breeding platform, diverse germplasm, and the opportunity for annual testing of new genetic designs in controlled environments and in multiple field locations is aiding fundamental discovery, and accelerating the improvement of biomass yield and optimization of composition for biofuels production. Recent advances in wide hybridization betweenSorghumand other C4 grasses could allow the deployment of improved genetic designs of annual energySorghums in the form of wide-hybrid perennial crops. The current trajectory of energySorghumgenetic improvement indicates that it will be possible to sustainably produce biofuels from C4 grass bioenergy crops that are cost competitive with petroleum-based transportation fuels.
The current trajectory of drought resilient energy sorghum improvement indicates it will be possible to sustainably produce cost competitive biofuels from C4 grass bioenergy crops.