Caudle, Keri , Hilt, Christina , Smart, Cera , Urban, Adam , Kramer, Diedre , Martin, Nicole , Baer, Sara , Johnson, Loretta , Maricle, Brian .
Does environment or genetics influence leaf level physiology? Measuring photosynthetic rates of native big bluestem (Andropogon gerardii) grown in common gardens across a precipitation gradient.
Big bluestem (Andropogon gerardii) is a native tallgrass species that has a wide west to east geographic distribution. There are several putative ecotypes within big bluestem, each hypothesized to be locally adapted to their native climatic regions, largely distinguished by precipitation. This study sought to determine if genetics (ecotype) or environment influenced photosynthetic rates, a useful tool in detecting water stress, in big bluestem ecotypes. Photosynthetic measures were made with a LI-6400XT portable photosynthesis system during June and July of 2014 at four sites including Colby, Hays, and Manhattan, KS, as well as Carbondale, IL across a range in mean annual precipitation from 500-1200 mm/yr. Reciprocal gardens at each site contained five ecotypes of big bluestem ranging in tolerances to water availability. When comparing sites, Hays, KS (582 mm/yr) had the highest photosynthetic rates among sites, potentially in response to rainfall during the early 2014 growing season. Manhattan, KS (872 mm/yr) had the lowest photosynthetic rates, likely due to poor nutrient availability in soil. When comparing photosynthetic performance among big bluestem ecotypes, the Central Kansas ecotype (originating from Hays, KS) and the drought tolerant variety Sand bluestem had the highest photosynthetic rates across sites. Drought tolerance in A. gerardii is potentially related to nitrogen assimilation; increased nitrogen content manifested in several results, including increased photosynthetic rates. Knowing which ecotypes of big bluestem are adapted to decreased water availability could help shape understanding of how native tallgrass vegetation could respond to increased aridity.
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1 - Fort Hays State University, Department of Biological Sciences, 600 Park St., Hays, KS, 67601, United States
2 - Fort Hays State University, Department of Biological Sciences, 600 Park St., Hays, Kansas, 67601, United States
3 - Southern Illinois University, Department of Plant Biology, 1263 Lincoln Drive, Carbondale, IL, 62901, United States
4 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan, KS, 66506-4901, USA
5 - Fort Hays State University, Department Of Biological Sciences, 600 Park St., Hays, KS, 67601-4099, USA
Presentation Type: Oral Paper
Session: 3, Ecophysiology
Location: 104/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 8:45 AM
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize