Genetic variation for bioenergy traits within and among lowland switchgrass (Panicum virgatum L.) crosses

Cellulosic biomass derived from switchgrass can be an alternative source to produce renewable bioenergy. However, bioenergy production from switchgrass is not economically viable unless genotypes with high yield potential and acceptable biofuel quality are available. To identify switchgrass genotypes with good biofuel quality, ten high biomass yielding hybrid populations derived from crosses between two lowland cultivars, Alamo (A) and Kanlow (K), were evaluated in this study. The experiment was planted in 2018 in two field environments, the East Tennessee Research and Education Center, Knoxville, and the Plateau Research and Education Center, Crossville, in a randomized complete block design with two replications per location. Tillers were collected in the Fall of 2020 and 2021, and analyzed for bioenergy traits using the near-infrared reflectance spectroscopy technique. The crosses and their parents were different in bioenergy traits across the environments (locations and years) (P < 0.05). The crosses' total ethanol yield (EtOH) ranged from 63.5 to 70.4 mg g-1, and the total sugars yield varied from 725 to 737 mg g-1 across the environments. Average cellulose, hemicellulose, lignin, and ash content were 395.8, 333.9, 178.4, and 49.3 mg g-1, respectively. The estimated non-structural carbohydrates were found as good predictors of EtOH (R2 = 0.67) (P < 0.05). The cross, 12A-259 x 12K-247, exhibited high EtOH, high hemicellulose, low lignin, and low ash. Crosses 12A-261 x 12K-245 and 12A-263 x 12K-250 exhibited high cellulose and sugar. These results indicate significant genetic heterogeneity for bioenergy traits within and between these two lowland switchgrass cultivars.