Predicting Stem Strength in Diverse Bioenergy Sorghum Genotypes

Abstract

Stem biomechanical properties dictate the mechanical stability of crop plants and ultimately their lodging resistance. This study evaluated stem mechanical, morphological, anatomical, and composition traits to assess their association with historical lodging ratings and developed new approaches to predict stem strength. Significant genotypic variation for stem strength, rigidity, and stiffness existed among 15 bioenergy Sorghum bicolor (L.) Moench genotypes that were selected to represent a range of stem lodging tendencies. Repeatabilities for the mechanical traits ranged from moderate to high across environments (0.58–0.92), high within environments (0.81–0.89), and low to high for maturity groups (0.31–0.89). Lodging rating was moderately correlated with internode density (r = 0.60, P < 0.01), length (r = 0.61, P < 0.01), and rigidity (r = 0.60, P < 0.05). Mechanical traits were highly correlated with morphological traits; correlations with anatomical or composition traits were lower. Using this information, two predictive models were developed. In Model 1, stiffness explained 69% of the total variation for stem strength. In Model 2, a combination of internode density, volume, and stiffness explained 75% of the total variation. Both prediction models were robust and were not confounded by internode number, cultivar type, maturity group, or environment. The results indicate that indirect selection of lodging‐related traits may be possible with the specific use of stiffness as a selective breeding tool to improve lodging resistance.

Large scale genome-wide association study reveals that drought induced lodging in grain sorghum is associated with plant height and traits linked to carbon remobilisation

“…This study also detected a significant positive association between lodging score and plant height regardless of the environments and genetic background of testers (Figure 1; Supplemental Figure S2B). A positive association between lodging and plant height has also been reported by earlier studies (Esechie et al , 1977; Gomez et al , 2017, 2018; Henzell et al , 1984; Srinivasa Reddy et al , 2008). In agreement with the phenotypic association between plant height and lodging score, the haplotype ANOVA results revealed that 66% of the 213 lodging QTL identified in this study significantly affected lodging susceptibility with taller plants being more susceptible to lodging (Supplemental Table S2).…”

“…S2B). A positive association between lodging and plant height has also been reported by earlier studies (Esechie et al 1977; Henzell et al 1984; Srinivasa Reddy et al 2008; Gomez et al 2017, 2018). In agreement with the phenotypic association between plant height and lodging score, the haplotype ANOVA results revealed that 66% of the 213 lodging QTL identified in this study significantly affected lodging susceptibility with taller plants being more susceptible to lodging (Supplemental Table S2).…”

“…Lodging is also affected by stem mechanical properties. Associations between stem lodging and stem strength, rigidity, and chemical composition including lignin density have been observed (Bashford et al 1976; Esechie et al 1977; Murray et al 2008; Gomez et al 2017, 2018). Lignin is one of the key biomolecules in vascular plants and its functions include structural support and water transport (Boerjan et al 2003; Higuchi 2006).…”

High throughput phenotyping of morpho-anatomical stem properties using X-ray computed tomography in sorghum

“…Intensity as used in this study, is a new method to quantify stem density in sorghum or other grass stems. Furthermore, in a recent study by the authors, it was found that internode density, volume, and stiffness can predict strength and can explain 75% of the variation [ 42 ]. Therefore, using the methods developed in this study in combination with biomechanics can be used to apply selective breeding tools to improve lodging resistance.…”

The genetic architecture of biomechanical traits in sorghum

“…Principal component analysis and trait correlations show that mechanical traits are consistently correlated with morphological traits across populations (see also Gomez et al, 2017Gomez et al, , 2018bGomez et al, , 2018Von Forell, Robertson, Lee, & Cook, 2015a). These correlations are not surprising, because the theory of elastic mechanics shows that the geometry, shape, and size of any structure influence its responses to externally applied forces (Gere & Timoshenko, 1984).…”