Assessment of Sweet Sorghum Genotypes for Bioethanol Production Potential and Bagasse Combustion Characteristics in a Semi-Arid Mediterranean Climate

The study aimed to evaluate the genetic diversity of 41 sweet sorghum genotypes from seven countries for key biofuel-related traits over two sorghum growing seasons (2020 and 2021) in a semi-arid Mediterranean environment. Genotypes were assessed for key bioethanol production traits such as fresh stalk yield (FSY), juice yield (JY), Brix, dry biomass yield (DBY), theoretical juice ethanol yield (JEY), theoretical lignocellulosic ethanol yield (LEY), theoretical total ethanol yield (TEY), as well as their potential for solid biofuel production, measured through bagasse ash, nitrogen, and moisture content. Significant variations were observed among genotypes across most traits, analyzed using analysis of variance, principal component analysis, and hierarchical cluster analysis, identifying DBY, LEY, and TEY as the primary contributors to overall genetic variation. Cluster analysis grouped the genotypes into five distinct clusters, highlighting the diversity in biofuel-related traits. The correlation analysis revealed significant positive relationships between traits such as FSY, DBY, and TEY, indicating that higher biomass production directly enhances ethanol output. Strong positive correlations between FSY and TEY underscore the importance of biomass yield in maximizing ethanol production. However, traits like bagasse ash and nitrogen contents, which were negatively correlated with JEY, LEY, and TEY, present challenges in improving biomass combustion quality. The study concludes that certain genotypes, particularly ‘Yellow Bonnet’ and ‘IS 3556’, exhibited strong potential for biofuel production in semi-arid Mediterranean climates where water scarcity and high temperature favor genotypes with high biomass and sugar yields. These genotypes demonstrated high JEYs, LEYs, and TEYs, suggesting their adaptability to the unique environmental stresses of this region, making them good candidates for sustainable biofuel production in similar climates.