Assessment of Stalk Properties to Predict Juice Yield in Sorghum

Abstract

Sweet sorghum is an outstanding feedstock choice for bioethanol production, but the gap between theoretical and commercial ethanol yields must be reduced to improve economic viability. Extractable juice yield is a primary limiting factor for higher ethanol yield, but current phenotyping techniques to measure juice yield in sorghum can be laborious. Therefore, alternative approaches to measuring juice yield during selection are needed. The objectives of this study were to investigate the relationship between stalk-related traits and juice yield and to assess the ability to predict juice yield using agronomic traits and stalk properties across and within a diverse set of sorghum ideotypes (photoinsensitive, photosensitive, biomass, grain, and sweet types). Stalk weight, stalk volume, stalk diameter, and plant height had significantly strong associations with juice yield, which were consistent across different sorghum ideotypes. The direct and indirect effects of multiple predictive traits on juice yield varied greatly with the distinct sorghum subsets. However, equation modeling demonstrated that juice yield is satisfactorily predicted by jointly assessing stalk weight and stalk moisture. Moreover, alternative prediction models involving distinct combinations of agronomic and stalk-related traits had similarly good prediction accuracy. Altogether, this suggests that several prediction models can be used to accelerate phenotyping for juice yield, which will improve the selection process. Overall, the results indicate that increasing sorghum juice yield via indirect selection is possible, but the choice of prediction model depends on the ideotypes and resources available in a breeding program.

Genotypic covariations of traits underlying sorghum stem biomass production and quality and their regulations by water availability: Insight from studies at organ and tissue levels

“…This positive correlation between stem height and fiber content was previously reported but with an extent largely dependent on the genetic material studied (Carvalho & Rooney, 2017;Maria G. Salas Fernandez, Becraft, Yin, & Lübberstedt, 2009). The eight studied genotypes contrasted for stem biomass accumulation and component traits related to stem growth.…”

“…Recently, El Hage et al (2018) related this phenomenon in maize to the fact that lignin type proportions and extent of p-coumaroylation were different in internode sclerenchyma and parenchyma. Carvalho and Rooney (2017) suggested similar proxies based on stalk volume and weight measurements for estimating juice yield. Interestingly, stem structural density could be explained by lignin content in particular in the inner zone of the internode.…”

Sorghum stem aerenchyma formation is regulated by SbNAC_D during internode development

“…All others were determined by Sanger sequencing. b AER ratings were adapted from Carvalho & Rooney, .…”

“…The extent of aerenchyma (AER) formation was rated by visual inspection of cross sections of internodes taken approximately at the midpoint between nodes. Ratings were based on a scale from 1 to 5 (1, no AER; 5, high AER) in a manner similar to prior studies () (Carvalho & Rooney, ; Nilsen et al., ). Results from visual rating were similar to ratings based on a percent of area calculation when data were used for QTL analysis (Carvalho & Rooney, ).…”

“…Ratings were based on a scale from 1 to 5 (1, no AER; 5, high AER) in a manner similar to prior studies () (Carvalho & Rooney, ; Nilsen et al., ). Results from visual rating were similar to ratings based on a percent of area calculation when data were used for QTL analysis (Carvalho & Rooney, ). All AER ratings are the mean of at least three biological replicates unless otherwise indicated.…”