Biomass crops have potential as a source of renewable CO2-neutral energy to ease concerns about fossil fuel consumption. Therefore, there is an increasing interest in high biomass crops such as switchgrass (Panicum virgatum L.). Switchgrass is a perennial C4 grass that requires low cost for biomass production. In the previous study, we evaluated forty switchgrass germplasms for biomass yield and classified the germplasms into the high-, medium-, and low-yielding groups. In this experiment, we evaluated response of switchgrass accessions to fertilizer applications. A recommended level of fertilizer was applied to the field and responses of morphological and agronomic characteristics affecting biomass productivity (panicle length, clum length, leaf width, thickness, tiller numbers, effective tiller numbers, seed weight, plant weight) were analyzed. Also, the composition of organic compounds (crude protein, crude fat, ash, glucose, xylose) and mineral elements were analyzed for the two selected lines from each biomass yield group by the levels of exchangeable cations in the soil. Positive correlations were found between biomass yield and content of crude protein, crude fat, ash, T-N, glucose, and xylose. However, no relations were found between biomass yield and mineral elements such as Na, P, K, Fe and Zn. Biomass yield was increased by 1.9-fold by the fertilizer application and the traits most significantly affected by fertilizer application were effective tiller number and plant weight. The accessions that showed less than 10% increase in biomass productivity by the fertilizer application were accession 26, 29, 13, and 18. This study was supported by Technology Development Program for New Bioenergy (subject number-20070301030016), Rural Development Adiministration, Republic of Korea.

Biomass crops have potential as a source of renewable CO2-neutral energy to ease concerns about fossil fuel consumption. Therefore, there is an increasing interest in high biomass crops such as switchgrass (Panicum virgatum L.). Switchgrass is a perennial C4 grass that requires low cost for biomass production. In the previous study, we evaluated forty-six switchgrass germplasms for biomass yield and classified the germplasms into the high-, medium-, and low-yielding groups. In this experiment, we analyze physiological characteristics affecting biomass productivity and composition of organic compounds for the two selected lines from each biomass yield group. Among the characteristics related to carbon assimilation, photosynthetic rate, real CO2 absorption rate(Delta CO2(CO2 reference - CO2 analysis(corrected for dilution))), P.A.R incident on leaf surface, and chlorophyll content were positively related to biomass yield of the selected lines. Positive correlation was found between biomass yield and ash content but no relations were found between biomass yield and content of organic compounds such as lignin, glucose, crude protein, cellulose, holocellulose, hemicellulose, ADF, and NDF. This study was supported by Technology Development Program for New Bioenergy(subject number-20070301030016), Rural Development Adiministration, Republic of Korea.