Nitrogen Use Efficiency and N-Remobilization In Switchgrass Cultivars.

The inclusion of switchgrass into conventional production systems will mostly depends on its productivity and profitability for the farmer. Information on nitrogen use of switchgrass cultivars is useful to aid farmers’ decisions in cultivar selection.   The objective of the study was to evaluate the nitrogen use efficiency (NUE) of 13 switchgrass cultivars; 2 low lands (Alamo and Kanlow) and 11 uplands (Carthage , Southlow , Cave-In-Rock , Forestburg , Blackwell, Nebraska , Shelter , Shawnee , Dacotah , Sunburst , WI Ecotype).  Plants were grown in 12 L pots, with pure fine sand as growing medium. Automatic drip irrigation system was used to supply Hoagland nutrient solution for each treatment. Three nitrogen treatments, control (100% N; 81 mg N L-1), 20% N; 16.2 mg N L-1 and 0% N, were imposed starting at 74 days after sowing. Leaf samples were collected at weekly intervals, oven dried, ground and analyzed for N concentration. Total biomass and biomass components of all cultivars were measured at final harvest. In control treatment, leaf N started to decline in August and was considered as N-remobilization. Results showed that NUE and N-remobilization of cultivars differed in response to N treatments. Declined leaf nitrogen concentration was observed across all treatments. The N-remobilization varied between 0 and 0.78% N concentration.