Gomez, Francisco Ernesto (2015-08). Biomechanics of Bioenergy Sorghum [Sorghum Bicolor (L.) moench]. Master's Thesis.
Stem lodging is a complex and is a limiting factor on bioenergy sorghum yield worldwide. Stem lodging is defined as mechanical failure at the stem caused by external forces due to wind or rain. Current lodging ratings are frequently unreliable because various factors that cause lodging and there is uncertainty about which factors are responsible. Temporal and spatial unpredictability has also hindered progress on the systematic research on this issue. As a result, stem lodging resistance is considered as one of the highest priorities for a bioenergy sorghum breeding program. In this study, a three-point bending (3PBT) test was used to quantify the biomechanical properties of bioenergy sorghum with different lodging ratings. The 3PBT was able to detect significant statistical differences among genotypes and within their stems. Significant genetic effect and variability was identified for a group of 15 bioenergy sorghum genotypes that may allow to identify quantitative trait loci (QTL) related to these geometric, shape, and biomechanical properties toward applying marker assisted recurrent selection (MAS). Geometry, shape, and biomechanical properties are influenced by maturity and developmental stages of a growing sorghum plant. Plant height, internode length, volume and flexural stiffness are particular important traits that that may serve to select for lodging resistance in plants. Future studies should focus on composition, rind thickness and computerized tomography (CT) scan in sorghum stems to develop a better model of the sorghum stem. This will allow sorghum breeders to select for important traits that infer lodging resistance in a bioenergy sorghum breeding program to improve germplasm with lodging resistance characteristics.