Evaluation of Root Characteristics of Different Switchgrass Cultivars.

Biofuels that replace fossil fuels have the potential to reduce greenhouse gases in the atmosphere. Switch grass (Panicum virgatum L.), a dedicated biofuel crop has high potential for carbon sequestration from atmosphere as well as for improving soil quality via its root system. Switchgrass cultivars may differ in biomass production and sustainability due to differences in root distribution and biomass, and growth habitat. However, information on switchgrass root growth and its distribution is extremely limited. The objective of this study was to analyze root characteristics and distribution pattern, and evaluate the cultivar differences. The differences in root characteristics of 2 lowland and 11 upland switchgrass cultivar were determined. Measurement of root parameters was carried out with an image analysis system (winRHIZO) with grey level image type with 100 dpi resolution. The cultivar Blackwell had 58% of root biomass in the surface 0-10 cm layer, while Cave-In- Rock had 62% of root biomass below the surface from 10-110cm. Similarly, root length density (RLD) and root weight density (RWD) of Blackwell was found to be greater at a depth of 0-10cm. However, Cave-In- Rock greater root biomass than others in subsequent depth by 23%. In spite of having higher root length, cultivar Southlow had lower RLD than Cave-In-Rock by 46%.  The root length across cultivars during the July harvest was greater (27%) in the top 20 cm, while at second harvest in December the root length was greater by 30% at 20-110 cm depth. Differences between the cultivars suggest that cultivar selection will be an important determinant of C sequestration by its root system.