Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/2017
Publication Date: N/A
Technical Abstract: As a species, switchgrass is adapted to an amazingly broad range of environments, spanning hardiness zones ranging from HZ3 to HZ9 (Canada to Mexico), from the mid-grass prairie to the Atlantic Seaboard, from sandy soils to heavy clay soils, from acid to alkaline soils, and from wetland to dryland habitats. Despite this breadth of adaptation, individual genotypes have a considerably narrower range, generally restricted by environmental characteristics such as temperature, photoperiod, rainfall, and soil type. In the 25 years since the U.S. Department of Energy began funding basic biology research on switchgrass, we have learned that temperature and photoperiod are the most important factors limiting the adaptation of individual genotypes or populations of genotypes. However, there appears to be genetic variation for cold or freezing tolerance, creating the possibility of expanding the range of late-flowering southern germplasm. The fact that late-flowering genotypes can survive in HZ4 (much of Minnesota and Wisconsin) where they do not flower until shortly before killing frost, strongly suggests that nutrient recycling may begin long before flowering in northern environments, perhaps triggered by photoperiod, rather than flowering per se. Secondarily, switchgrass genotypes are differentially adapted to moisture availability, with increasingly strong evidence of differential genotype and population performance in dryland habitats of the Great Plains compared to humid environments of the Eastern USA. At current rates of gain, every additional increase in biomass yield of 1 Mg/ha increases nitrogen removal in the biomass by up to 10 kg N/ha. Adjusting breeding strategies to develop higher nitrogen-use efficiency could reduce this by up to 75%, increasing the possibility of developing switchgrass populations with reduced nitrogen requirements and greater ability to utilize soil and atmospheric sources of nitrogen.