Switchgrass Germination and Growth as Affected by Soil Salinity

The use of biofuel has become one of the solutions to face increased oil costs, increased world population growth, and environmental pollution. Switchgrass is a major biofuel grass in North America. To determine the feasibility of growing switchgrass on saline soil and irrigated with saline water, we have completed two greenhouse pot experiments to test two upland switchgrass varieties (Trailblazer and Blackwell) for their germination and growth as affected by irrigation with different saline waters.   The first experiment was conducted in 2011-2012 and the second experiment was conducted from March to September, 2013.  For each cultivar, seventy seeds were planted in forty 2-gallon pots containing sand mixed with 20% organic matter. The 5 salinity levels of irrigation water were 0.1 (control), 4, 8, 12 and 14 dS m^-1. Germination rate reduced with increased salinity level of irrigation water. Germination rate decreased from 100% to 60% as soil salinity increased to 16 dSm^-1 in the first experiment, but in the second experiment germination rate decreased from 100% to 50% as salinity level reached 9.5 dSm^-1.  The first harvest of aboveground biomass started to decrease after salinity level reached 7.7 dSm^-1. The final harvest of aboveground biomass was reduced by 33-40% as soil salinity  increased to 7-9 dSm^-1. Root biomass decreased as salinity level reached  9.5 and 7 dSm^-1  in the first and the second experiment. Our results suggest switchgrass has a moderate level of salinity tolerance.