Variation in energy sorghum hybrid TX08001 biomass composition and lignin chemistry during development under irrigated and non-irrigated field conditions

Abstract

This study was conducted to document the extent and basis of compositional variation of shoot biomass of the energy Sorghum bicolor hybrid TX08001 during development under field conditions. TX08001 is capable of accumulating ~40 Mg/ha of dry biomass under good growing conditions and this genotype allocates ~80% of its shoot biomass to stems. After 150 days of growth TX08001 stems had a fresh/dry weight ratio of ~3:1 and soluble biomass accounted for ~30% of stem biomass. A panel of diverse energy sorghum genotypes varied ~6-fold in the ratio of stem structural to soluble biomass after 150 days of growth. Near-infrared spectroscopic analysis (NIRS) showed that TX08001 leaves accumulated higher levels of protein, water extractives and ash compared to stems, which have higher sugar, cellulose, and lignin contents. TX08001 stem sucrose content varied during development, whereas the composition of TX08001 stem cell walls, which consisted of ~45–49% cellulose, ~27–30% xylan, and ~15–18% lignin, remained constant after 90 days post emergence until the end of the growing season (180 days). TX08001 and Della stem syringyl (S)/guaiacyl (G) (0.53–0.58) and ferulic acid (FA)/para-coumaric acid (pCA) ratios were similar whereas ratios of pCA/(S+G) differed between these genotypes. Additionally, an analysis of irrigated versus non-irrigated TX08001 revealed that non-irrigated hybrids exhibited a 50% reduction in total cell wall biomass, an ~2-fold increase in stem sugars, and an ~25% increase in water extractives relative to irrigated hybrids. This study provides a baseline of information to help guide further optimization of energy sorghum composition for various end-uses.

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

“…Previous studies reported different extents of relationships between stem size (mainly height) and lignocellulosic composition and suggested they are genetically and/or physiologically linked (Trouche et al, 2014). McKinley et al (2018) and Perrier et al (2017) reported a decrease in stem cell wall content to the benefit of nonstructural carbohydrate in biomass sorghum but they did not evaluate the genotypic variability of this response. Some studies demonstrated, however, in the case of sweet sorghum (characterized by sweet, juicy, and tall stems), that drought did not affect [postflowering stress ] or even increased [preflowering stress (Almodares, Hotjatabady, & Mirniam, 2013;Perrier et al, 2017)] stem soluble sugar content.…”

“…A significant genetic diversity was pointed out for these traits (Kholová et al, 2014;Vadez, Deshpande, et al, 2011;Vadez, Krishnamurthy, Hash, Upadhyaya, and Borrell, 2011). The effect of drought on the production of biomass sorghum was by far less studied, although a few studies reported biomass sorghum is more drought tolerant than other biomass crops as maize (Schittenhelm & Schroetter, 2014) and that drought reduced stem biomass cell wall content (McKinley et al, 2018;Perrier et al, 2017). The quality of biomass sorghum production relies on stem biomass lignocellulosic composition, soluble sugar content, and digestibility (Trouche et al, 2014).…”

“…Some studies demonstrated, however, in the case of sweet sorghum (characterized by sweet, juicy, and tall stems), that drought did not affect [postflowering stress ] or even increased [preflowering stress (Almodares, Hotjatabady, & Mirniam, 2013;Perrier et al, 2017)] stem soluble sugar content. McKinley et al (2018) and Perrier et al (2017) reported a decrease in stem cell wall content to the benefit of nonstructural carbohydrate in biomass sorghum but they did not evaluate the genotypic variability of this response.…”

Sorghum an Important Annual Feedstock for Bioenergy

“…The composition of biomass derived from forage, grain, and sweet sorghums has been well characterized [28]. The research on exploiting forage sorghum as biofuel was initiated in 1980s, which led to the development of photoperiod-sensitiveenergy sorghum hybrids [29].…”

“…Such sorghums exhibit wide variations in biomass composition [34]. Now a days, near-infrared spectroscopic (NIR) analysis is routinely used for high-throughput computation of biomass composition [28].…”