IN 2006, THE UNITED STATES DEPARTMENT OF ENERGY (DOE) SET THE GOAL OF REPLACING 30% OF THE NATION'S TRANSPORTATION FUELS WITH RENEWABLE BIOENERGY SOURCES. THIS GOAL WAS BORN OUT OF A DESIRE TO MEET RISING ENERGY DEMANDS, REDUCE AMERICA'S DEPENDENCY ON FOREIGN ENERGY SOURCES, AND STIMULATE ECONOMIC GROWTH, WHILE ALSO REDUCING GREENHOUSE GAS EMISSIONS. HOWEVER, A MAJOR CHALLENGE TO ACHIEVING THIS GOAL IS OUR INSUFFICIENT UNDERSTANDING OF THE FACTORS THAT REGULATE THE PRODUCTIVITY AND SUSTAINABILITY OF BIOENERGY SYSTEMS OVER SPACE AND TIME. THIS IS ESPECIALLY URGENT GIVEN THE LIMITED LAND-BASE FOR BIOENERGY PRODUCTION AND THE ONGOING IMPACTS OF CLIMATE CHANGE ON AGRICULTURAL SYSTEMS. THIS PROJECT WILL DETERMINE HOW GENETIC AND ENVIRONMENTAL VARIATION COMBINE TO INFLUENCE BIOLOGICAL PROCESSES THAT REGULATE THE PRODUCTIVITY AND SUSTAINABILITY OF SWITCHGRASS (PANICUM VIRGATUM L.); ONE OF THE MOST PROMISING BIOENERGY CROPS SELECTED BY THE DOE'S BIOFUELS FEEDSTOCK DEVELOPMENT PROGRAM. SPECIFICALLY, WE WILL DETERMINE THE TEMPERATURE RESPONSE OF PHOTOSYNTHESIS AND RESPIRATION IN SWITCHGRASS ORIGINATING FROM DIVERSE HABITATS/CLIMATES GROWN AT THREE FIELD SITES IN THE CENTRAL U.S (TEXAS, MISSOURI, MICHIGAN). WE WILL TEST WHETHER SWITCHGRASS FROM DIFFERENT CLIMATES DIFFER IN THEIR PHYSIOLOGY, THEIR ABILITY TO ADJUST TO TEMPERATURE CHANGES, AND THEIR PRODUCTIVITY ACROSS SPACE AND TIME. THIS PROJECT WILL IMPROVE OUR FORECASTING OF PRODUCTIVITY IN SWITCHGRASS BIOENERGY SYSTEMS AND WILL HELP IDENTIFY SWITCHGRASS CAPABLE OF MAXIMUM PRODUCTIVITY UNDER CURRENT AND FUTURE CLIMATE CONDITIONS. MOREOVER, THIS PROJECT WILL PROVIDE NEW INSIGHT INTO THE FUNDAMENTAL BIOLOGICAL PROCESSES THAT REGULATE THE PRODUCTIVITY OF BIOENERGY CROPS LIKE SWITCHGRASS. THIS PROJECT ADDRESSES THE NEEDS OF MULTIPLE STAKEHOLDERS INCLUDING (BUT NOT LIMITED TO): THE PUBLIC, LAND OWNERS, AGRICULTURAL SCIENTISTS, MODELERS, PLANT BREEDERS, BIOENERGY RESEARCHERS, AND PLANT SCIENTISTS.