A comprehensive method to select energy sorghum hybrids for bioethanol production

Breeding dedicated energy sorghum [Sorghum bicolor (L.) Moench] hybrids is an effective way to provide highquality biomass feedstock for bioethanol production. However, there exist very limited energy sorghum cultivars/hybrids suitable for bioethanol production with different bioconversions, which require a comprehensive evaluation method that can select elite sorghum germplasms effectively. Here, an integrated approach (combing cluster analysis, principal component analysis, and grey relational analysis) was applied to evaluate the bioethanol potential of 96 sorghum hybrids at two locations with distinct environmental conditions in North China based on 10 energy-related traits. Results showed that 96 hybrids present extensive genetic diversity as reflected by a high coefficient of variation of theoretical ethanol yield and chemical components including soluble sugars, cellulose, hemicellulose, lignin, and ash content at two locations. The 96 sorghum hybrids can be consistently sorted into 4 groups targeted for different bioconversions for both locations, namely Cluster I (unsuitable sorghum type for bioethanol production), Cluster II (ideal sorghum type for bioethanol production), Cluster III (sweet sorghum type) and Cluster IV (biomass sorghum type). Hybrids No. 28 and 30, hybrids No. 64 and 33, and hybrid No. 10 were identified as optimal candidates for ideal sorghum type, sweet sorghum type, and biomass sorghum type for bioethanol production, respectively. Those results highlight that our comprehensive evaluation method can be effective to select elite sorghum hybrids targeted for different bioethanol bioconversions, which can facilitate the breeding process of high-quality energy sorghum hybrids.