Olsen, Jacob , Goad, Rachel , Mendola, Meredith , Tetreault, Hannah , Johnson, Loretta , Baer, Sara , Maricle, Brian .
Photosynthetic gas exchange of big bluestem (Andropogon gerardii) ecotypes across a precipitation gradient of the Great Plains.
Phenotypes of big bluestem and sand bluestem vary throughout the central grasslands of North America as a result of ecotypes within the species. This study sought to discriminate between genetic and environmental variation of big bluestem and sand bluestem ecotypes. Gas exchange was measured in four ecotypes of big bluestem and one ecotype of sand bluestem in common gardens at four sites ranging from western Kansas to southern Illinois. Plots contained single plants isolated by landscape fabric. Additional plots contained seeded assemblages to represent native communities. Photosynthesis rates were measured three times in each of the 2010 and 2011 growing seasons. The role of precipitation was assessed in 2011 with the addition of rainout shelters. In single plants, big bluestem ecotypes from drier environments had higher photosynthesis compared to mesic ecotypes across all sites. Sand bluestem had similar photosynthesis compared to the big bluestem ecotype native to the driest environment. In seeded plots, differences were not detected among ecotypes, indicating high-competition conditions in a community reduced expression of genetic differences among ecotypes. Compared to xeric sites, mesic sites had higher photosynthesis across all ecotypes. Similarly, rainout shelters reduced photosynthesis across sites. Ecotypes of A. gerardii across the Great Plains are adapted to low water availability. Drought-adapted ecotypes of A. gerardii were shorter in stature and had smaller, narrower leaves, which reduced evaporative surface area. This allows drought-adapted ecotypes to have higher photosynthetic rates, stomatal conductances, and transpiration in both mesic and xeric environments compared to ecotypes native to mesic environments.
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Big Bluestem Ecotype Project
1 - Fort Hays State University, Department Of Biological Sciences, 600 Park St., Hays, KS, 67601-4099, USA
2 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, IL, 62901, USA
3 - Kansas State University, Division of Biology, Manhattan, KS, 66506, USA
4 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan, KS, 66506-4901, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, July 10th, 2012
Time: 10:00 AM