Highly productive perennial bunchgrasses are among the most promising candidate species for developing low-input cropping systems for biomass energy production. There is potential for developing multi-functional systems where senesced plants are left in the field to provide wildlife habitat. Economically, species must maintain high biomass yields even after over-wintering. We compared three candidate biofuel crops grown under the same, minimal input conditions in
Results/Conclusions
Data from July 2007 do not support our hypotheses: the exotic C3 grass (A. donax) produced 13% and 54% more biomass than the native C4 grass (P. virgatum) and exotic C4 grass (M. × giganteus), respectively. However, September 2007 data support our first hypothesis; the native C4 grass produced 30% more biomass (2512.7 ± 498 g-1m-2) than either the exotic C4 grass(1949.2 ± 487.4 g-1m-2) or the exotic C3 species (1905.7 ± 455.6 g-1m-2). Our second hypothesis regarding the advantage of the C4 pathway was not supported by performance of the exotic C3 and C4 species, which produced biomass yields within 2% of each other. In February 2008, the C4 grasses had retained 74% (P. virgatum) and 71% (M. × giganteus) of their September 2007 biomass, while the C3 species (A. donax) retained 95% of its September 2007 biomass, making February 2008 yields of A. donax (1819.5 ± 410.4 g-1m-2) and P. virgatum (1852.05 ± 534.1 g-1m-2) comparable. Based on these observations, we conclude that P. virgatum is capable of producing more biomass than M. × giganteus or A. donax under low nutrient, high light and temperature conditions typical of Central Texas. However, A. donax may be an important species in multi-functional systems designed to provide wintertime wildlife cover.