|Washburn, J -|
|Whitmire, D -|
|Murray, S -|
|Wickersham, T -|
|Heitholt, J -|
|Jessup, R -|
Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2013
Publication Date: May 1, 2013
Citation: Washburn, J.D., Whitmire, D.K., Murray, S.C., Burson, B.L., Wickersham, T.A., Heitholt, J.J., Jessup, R.W. 2013. Estimation of rhizome composition and overwintering ability in perennial Sorghum spp. using near-infrared spectroscopy (NIRS). BioEnergy Research. 6:822-829. Interpretive Summary: Sorghum is grown for food, feed, and forage; however, during the past decade the crop has received considerable attention as a bioenergy feedstock. Essentially all sorghum types grown for biomass are annuals, but there would be advantages if they were perennials. A perennial would not require replanting every year; whereas, an annual has to be replanted each year. This would be a significant economic savings to the farmer because it would eliminate the expenses of preparing a seed bed, purchasing seed, and planting the seed every year. Another economic benefit of perennial sorghum is it can serve as dual purpose crop by providing forage for livestock and biomass for biofuel feedstocks. Perennials also offer ecological and environmental benefits over annuals in that they increase organic carbon in the soil, reduce soil erosion, and reduce fertilizer inputs. Only sorghum plants with underground stems (rhizomes) have the ability to survive the winter and produce new growth the following spring. We conducted a study to evaluate the winter hardiness of 11 different sorghum lines at College Station and Commerce, TX. The chemical composition of the underground stems was also determined before and after the winter conditions. The underground stems of some lines produced new shoots the following spring after the winter, and it was determined these structures had more carbohydrates and sugars and less fat and starch than those that did not survive the winter. Determining the amount of these compounds in underground shoots may be a rapid way to screen for a plant's ability to survive the winter. This is of importance in the selection of perennial plant material to use in a breeding program.
Technical Abstract: Temperately-adapted perennial sorghum feedstocks have recently begun to receive increasing interest as candidate energy crops, producing significant biomass and contributing agroecological benefits including increased soil organic carbon, reduced soil erosion, reduced input requirements, and higher net energy return. Rhizomes are the primary morphological feature facilitating over-wintering in sorghum species; however, underlying physiological mechanisms governing rhizome over-wintering remain poorly characterized. In this study, we investigated the composition of rhizomes from diverse germplasm before and after over-wintering at two locations and three experimental environments. Significant positive correlations were found between rhizome over-wintering and water soluble carbohydrates (WSC), ethanol soluble carbohydrates (ESC), and fructan concentrations, while significant negative correlations were found between rhizome over-wintering and both crude fat and starch. Near infrared spectroscopy (NIRS) calibration equations were developed to quickly and efficiently predict the concentrations of each of these assimilates in rhizomes, except for crude fat.