Switchgrass Samples Research Articles

Isolation, Characterization, and Quantification of Steroidal Saponins in Switchgrass (Panicum virgatum L.)

Switchgrass (Panicum virgatum L.) has been identified for development into an efficient and environmentally friendly biomass energy crop. A recent 5 year study demonstrated that switchgrass grown for biofuel production produced 540% more energy than what is needed to grow, harvest, and process it into cellulosic ethanol. If switchgrass is grown on a scale useful for a bioenergy source, some of the material could be used by livestock as hay or pasture. Switchgrass has been reported to cause hepatogenous photosensitization in lambs (Ovis aries) and horses (Equus caballus). In this study, a simple extraction and rapid reversed phase high-performance liquid chromatography-electrospray ionization-mass spectrometry method was developed for quantifying the major saponins in switchgrass samples. Differences in the relative concentrations of different saponins were observed between switchgrass cultivars and plant parts.

Analysis of switchgrass characteristics using near infrared spectroscopy

Switchgrass varieties grown under various environments were investigated by dispersive and Fourier Transform Near-Infrared (NIR) spectrometers. The collected NIR spectra were analyzed using multivariate approaches. More specifically, principal component analysis (PCA) and projection to latent structures (PLS) regression techniques were employed to classify and predict characteristics of the switchgrass samples. The multivariate results were compared to reflectance indices that are commonly used to study the physiological performance of plants. From near infrared spectra, discrimination between the two growth locations was successfully achieved by PCA. Separation based on the ecotype and the rate of fertilizer applied to the field was also possible by the multivariable analysis of the spectral data. For the classification/ discrimination of the switchgrass samples, the near infrared spectra collected by the dispersive and the Fourier Transform spectrometers provided similar results. From the two near infrared data sets robust models were developed to predict non-structural carbohydrates content and the rate of nitrogen applied to the field. However, the spectra collected by the dispersive spectrometer resulted in more accurate models for these samples.

Compositional changes during storage of large round switchgrass bales

‘Alamo’ switchgrass ( Panicum virgatum L.) was harvested in two different years and stored as large round bales, unprotected, outside, for 26 weeks. Fresh and stored switchgrass samples were analyzed for their structural and non-structural constituents. These summative analyses of the switchgrass showed differences in the composition of materials harvested at different times and indicated that the compositions changed during storage. On a dry weight, whole biomass basis, significant differences were observed in the extractives (+3%), ash (+1%), hemicelluloses (−1·4%), and cellulose (−4%) components of the switchgrass harvested in October 1991 relative to August 1992. The bales from the switchgrass harvested in October 1991 were exposed to high rainfall (65 cm) during storage and experienced much greater weathering than bales from the second harvest. The largest change in composition occurred in the ethanol-extractable component. The switchgrass showed a significant loss of extractives in both the weathered outer layer (11%) and the unweathered inner fraction (8%) of the bales prepared from the first harvest. Switchgrass harvested in August 1992 underwent much smaller compositional changes compared to the October 1991 harvest. The extractives in switchgrass and other grasses may contain substantial amounts of fermentable carbohydrates. If so, their loss during storage could have a significant impact on the conversion of switchgrass into ethanol. This is an example of the feedstock assessment research being conducted to determine the influence of harvest and storage conditions on the thermochemical and biochemical conversion of various biomass feedstocks into fuels and chemicals. The results of this research are expected to provide a guide to agricultural practices that optimize production of feedstocks for conversion into fuels.