Switchgrass cultivars and germplasm for biomass feedstock production in Texas

Switchgrass (Panicum virgatum L.) is a warm-season perennial grass indigenous to North America with excellent potential as a bioenergy crop. Our objective was to determine the yield potential and adaptability of switchgrass cultivars and germplasms in diverse Texas environments where the species might be used as a bioenergy crop. We determined the adaptability of several switchgrass cultivars and germplasms at five ecologically different locations (Beeville, College Station, Dallas, Stephenville, and Temple) in Texas in two experiments during 1992 to 1996. Alamo switchgrass was the best adapted commercially available switchgrass cultivar for biomass feedstock production in Texas in these trials with yields of 8 to 20 Mg ha(-1). A single harvest in the fall maximized biomass yield and maintained switchgrass stands. Although very tolerant of moderate or even severe drought, switchgrass failed to yield under chronic extreme drought. At Beeville in 1996, there was no harvestable switchgrass growth because of extreme drought. Upland cultivars from the midwest matured early and did not produce as much biomass as lowland cultivars from the southern U.S. The predominant factor affecting switchgrass productivity in these Texas locations seemed to be rainfall amount. The highest biomass yield at each location generally occurred in years of greatest April to September rainfall. Soil type did not appear to have much influence on biomass production. Soil organic carbon increased from 11.1 to 15.8 g kg(-1) in the upper 30 cm of soil (average of four locations) during 1992 to 1996. These increases in organic carbon indicate a good potential for sequestering carbon through biomass production. (C) 1998 Elsevier Science Ltd. All rights reserved.