Developing New Sorghum Based Value Chains for Biomaterials and Energy: Process Optimization and Ideotype Definition

Sorghum is expected to contribute significantly to the growing needs of ligno cellulosic biomass that will support the productions of renewable energy, biomaterials and innovative biorefinery approaches. The agronomic and genetic assets of sorghum will facilitate these contributions. Nevertheless, in order to fine tune the varieties to the expectations of the growers (agronomic behavior) and of the different value chains (quality parameters) there is a crucial need to i) optimize the production process of sorghum based derived products and ii) to accurately define the target ideotypes to consider in breeding programs depending on the end-products and contexts considered. As a first step, we considered three end products: methane, biocomposite and feed. For the first two targets, we optimized the process of production by adjusting the pre-treatments and fine tuning-the different steps of the processes. As a second step we aimed at identifying the sorghum traits that contributed to the final properties of the end products. To reach this objective, we characterized at the biochemical, histological and physical levels a panel of diversity that encompassed most of the chemical variability of sorghum biomass. This panel was also characterized for its feed and biocomposite properties and for its biomethane production potential. This allowed the identification of the sets of biomass properties to target for the different end-products. As a last step, specifically for the energy targets (methane and second generation ethanol), we performed a spatially based multicriteria analysis at the regional level (anchoring the analysis on the French Midi Pyrenees region) to assess the relevance of different types of crop management and end product value chains in accordance with the local constraints (i.e. water availability, technical context). These three steps provided us with a decision tool to orientate breeding efforts depending on the targeted end-product, the environmental and technical contexts.