Background: The search for promising and renewable sources of carbohydrates for the production of biofuels and other biorenewables has been stimulated by an increase in global energy demand in the face of growing concern over greenhouse gas emissions and fuel security. In particular, interest has focused on non-food lignocellulosic biomass as a potential source of abundant and sustainable feedstock for biorefineries. Here we investigate the potential of three Brazilian grasses (Panicum maximum, Pennisetum purpureum and Brachiaria brizantha), as well as bark residues from the harvesting of two commercial Eucalyptus clones (E. grandis and E. grandis x urophylla) for biofuel production, and compare these to sugarcane bagasse. The effects of hot water, acid, alkaline and sulfite pretreatments (at increasing temperatures) on the chemical composition, morphology and saccharification yields of these different biomass types were evaluated. Results: The average yield (per hectare), availability and general composition of all five biomasses were compared. Compositional analyses indicate a high level of hemicellulose and lignin removal in all grass varieties (including sugarcane bagasse) after acid and alkaline pretreatment with increasing temperatures, whilst the biomasses pretreated with hot water or sulfite showed little variation from the control. For all biomasses, higher cellulose enrichment resulted from treatment with sodium hydroxide at 130°C. At 180°C, a decrease in cellulose content was observed, which is associated with high amorphous cellulose removal and 5-hydroxymethyl-furaldehyde production. Morphological analysis showed the effects of different pretreatments on the biomass surface, revealing a high production of microfibrillated cellulose on grass surfaces, after treatment with 1% sodium hydroxide at 130°C for 30 minutes. This may explain the higher hydrolysis yields resulting from these pretreatments, since these cellulosic nanoparticles can be easily accessed and cleaved by cellulases. Conclusion: Our results show the potential of three Brazilian grasses with high productivity yields as valuable sources of carbohydrates for ethanol production and other biomaterials. Sodium hydroxide at 130°C was found to be the most effective pretreatment for enhanced saccharification yields. It was also efficient in the production of microfibrillated cellulose on grass surfaces, thereby revealing their potential as a source of natural fillers used for bionanocomposites production.

Gamba grass (Andropogon gayanus Kunth) is a promising forage alternative for Brazil’s Cerrado regions, attracting increasing research interest due to its potential to complement or replace widely planted species such as Urochloa and Megathyrsus. Despite the release of three cultivars, significant improvements in dry matter (DM) yield and forage quality are needed to fully realize its agronomic potential. This study aimed to evaluate genetic variability, estimate narrow sense heritability, and predict expected genetic gains for DM yield and key forage quality traits in two gamba grass populations derived from the cultivars BRS Sarandi and Planaltina. Trials were established in spring 2017 in Planaltina, DF, and evaluated during February–March 2018 and January–March 2019. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL), and hemicellulose (HEMIC) were quantified alongside DM yield. BRS Sarandi exhibited higher CP (12.3% vs. 9.8%) and lower NDF (57.1% vs. 63.4%), ADF (36.2% vs. 41.5%), CEL (20.8% vs. 23.7%), and HEMIC (20.9% vs. 21.9%) compared to Planaltina, while DM yield did not differ significantly between populations (4.57 t·ha⁻¹ vs. 4.50 t·ha⁻¹ per harvest, p > 0.05). Heritability estimates for individual harvests ranged from 0.31 to 0.68 for DM yield and 0.28 to 0.62 for quality traits, whereas multi-harvest models across years yielded lower estimates (0.07–0.27). Expected annual genetic gains were modest, with the highest predicted increase for CP (0.45% per year) and the largest decrease for NDF (−0.78% per year), reflecting the quantitative nature of trait inheritance and strong environmental influence. This study provides novel insights by simultaneously comparing two populations for multiple harvests and quantifying both yield and detailed forage quality traits, offering practical guidance for gamba grass breeding strategies. Results indicate that breeding programs should prioritize multiple selection cycles, precise phenotyping, genotypic and potentially genomic selection to accelerate improvement in both DM yield and forage quality, overcoming the constraints of low heritability and multi-trait selection.

Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its release, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba-grass-based farms by presenting a greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars—Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, for 3 years, namely 2018, 2018–2019, and 2020. The experimental design was a completely randomized block design with two treatments and three replicates, each one continuously stocked at three stocking rates (SR)—1.3, 2.6, and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (green leaf, stem, and dead material), and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than that of Planaltina (0.490 kg/bull/d) (p < 0.10). In the subsequent year (2018–2019), there was no effect of cultivar (p > 0.10), while in 2020 the ADG was again affected by cultivar (p < 0.10), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3–6 pp less than for Planaltina (p < 0.10). As well as for stems, Sarandi pastures presented a shorter CH in 2028 and 2020 (6–7%) (p < 0.10). The positive high correlation of leaf:stem ratio with ADG (r = 0.70) probably predisposed the superiority of Sarandi over Planaltina. The distinguishing plant-part composition of Sarandi canopy promotes increasing weight gain of beef cattle when compared to cv. Planaltina.

Stylosanthes scabra Vogel is a tropical legume grown in dry tropical and subtropical environments. The objective of this research was to evaluate the genetic diversity of forage quality traits for 80 accessions of S. scabra. Seven plants from each accession were planted in a single-line plot with no replicates at Embrapa Cerrados, Brazil. All plants were harvested 90 days after planting. Crude protein (CP), in vitro dry matter digestibility (IVDMD), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin (LIG), hemicellulose (HEMIC) and cellulose (CELLU) were estimated. Data were submitted to principal component analysis (PCA) and a cluster analysis was performed to identify groups of similarity. Simpson and Shannon–Weaver diversity indices estimated the genetic diversity. The average values of CP, IVDMD, NDF, ADF, LIG, HEMIC and CELLU were 220g/kg, 560g/kg, 516.8g/kg, 368g/kg, 69.4g/kg, 148.8g/kg and 298.6g/kg, respectively. There was a significant difference among collection sites for IVDMD, ADF and CELLU. The first two principal components accounted for 73% of the total variation. The 80 accessions resulted in four clusters, among which significant differences were observed for CP, IVDMD and ADF. Group IV, with 24 accessions, had the highest CP and IVDMD concentrations and the lowest ADF concentration, being the highest-quality forage group. Diversity indices were 0.78 and 0.81 for Simpson’s and Shannon–Weaver’s, respectively. In conclusion, there is genetic diversity for forage quality traits among S. scabra.