SWITCHGRASS CULTIVARS AND GERMPLASM FOR BIOMASS FEEDSTOCK PRODUCTION IN TEXAS

Switchgrass (Panicum virgatum L.) is a warm-season perennial grass ind igenous to North America with excellent potential as a bioenergy crop. Our objective was to determine the yield potential and adaptability o f switchgrass cultivars and germplasms in diverse Texas environments w here the species might be used as a bioenergy crop. We determined the adaptability of several switchgrass cultivars and germplasms at five e cologically different locations (Beeville, College Station, Dallas, St ephenville, and Temple) in Texas in two experiments during 1992 to 199 6. Alamo switchgrass was the best adapted commercially available switc hgrass cultivar for biomass feedstock production in Texas in these tri als with yields of 8 to 20 Mg ha(-1). A single harvest in the fall max imized biomass yield and maintained switchgrass stands. Although very tolerant of moderate or even severe drought, switchgrass failed to yie ld under chronic extreme drought. At Beeville in 1996, there was no ha rvestable switchgrass growth because of extreme drought. Upland cultiv ars from the midwest matured early and did not produce as much biomass as lowland cultivars from the southern U.S. The predominant factor af fecting 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 orga nic 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 th rough biomass production. (C) 1998 Elsevier Science Ltd. All rights re served.