Influence of Sorghum Stem Anatomical traits on Industrial biomass properties

Sorghum, a perennial C4 warm-season grass is among the foremost herbaceous species being advanced as a source of biomass for energy but also for biobased materials production. However, expansion of these value chains is currently hampered by a lack of knowledge regarding the relationships of the sorghum stem biological properties and the end use product properties. Two main application sectors have been chosen for sorghum biomass valorisation in the Biomass For the Future project (BFF) funded by the French research agency project:1) the use of lignocellulosic sorghum material in polymeric matrix composites and 2) the use of sorghum as a feedstock for methane production by anaerobic digestion ( a very dynamic sector in Europe : France Germany…). Plant biomass is chiefly composed of cell wall (a supra molecular arrangement of 3 macromolecules cellulose, hemicellulose and lignin) whose thickness and composition vary depending on the tissues type and anatomical traits. Thus the quality of the biomass and the performances of the industrial products resulting from the transformation of the biomass should depend directly on its histochemical composition. In this context, a panel encompassing the stem biochemical diversity of sorghum has been analyzed for their end-use product properties and also for their stem anatomy. As far as biocomposite sorghum based products were considered, their tensile strength, deformation at break, Young’s Modulus, resistance to impact and degree of darkening of the composites due to thermal degradation were analyzed. For methane production the biomethane potential (BMP) was assessed. These end-products properties were compared to the histochemical properties or the raw stem material. A high throughput histochemical phenotyping pipeline was developed in combination with NIRS biochemical predictions. We underline in this study the relationships between stalk related traits and ends use product properties. Our data clearly show how anatomical and histochemical traits can influence the potential methane production, the mechanical properties of the composites and, emphasize the key potential of the genotypic variability available in sorghum to develop varieties fitting the expectations of the different value chains.