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Abstract Detail


Maricle, Brian [1], Caudle, Keri [2], Lindsey, Katelyn [3], Baer, Sara [4], Johnson, Loretta [5].

Effects of extreme drought on photosynthesis and water potential of Andropogon gerardii (big bluestem) ecotypes in common gardens across Kansas.

Phenotypes of big bluestem (Andropogon gerardii) vary throughout the central grasslands of North America, giving rise to genetically-distinct ecotypes within the species. This study sought to distinguish between genetic and environmental variation of big bluestem ecotypes. Photosynthesis and water potential were measured in four ecotypes of big bluestem in common gardens in western, central, and eastern Kansas. Plots contained seeded assemblages to provide interspecific interactions that would occur in natural communities. The role of precipitation was assessed with rainout shelters that reduced ambient rainfall by 50%. Photosynthesis rates and water potential were measured three times during the 2012 growing season. There were differences in photosynthesis among sites that correlated with available soil moisture. The more mesic site in Manhattan, KS had higher photosynthesis and water potentials compared to drier sites in Colby and Hays, KS. Photosynthesis rates decreased in all sites as the growing season progressed. Extreme drought in Colby and Hays reduced photosynthesis rates to near zero by late summer, whereas photosynthesis in Manhattan remained above 6 μmol CO2 m-2 s-1 in late summer. Big bluestem ecotypes from drier environments had higher photosynthesis compared to mesic ecotypes across sites, particularly evident at the mesic site in Manhattan. Similarly, rainout shelters reduced photosynthesis across sites. Plant water potentials followed soil moisture across sites. Mean water potentials were as low as -7 MPa in Hays and Colby, but were never lower than -1.3 MPa in Manhattan. This study demonstrate ecotypic variation in leaf-level physiology of A. gerardii, potentially related to morphological adaptations or differences in nitrogen assimilation.

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Related Links:

1 - Fort Hays State University, Department of Biological Sciences, 600 Park St., Hays, KS, 67601-4099, USA
2 - Fort Hays State University, Department of Biological Sciences, 600 Park Street, Hays, KS, 67601-4099, USA
3 - Fort Hays State University, Department of Biological Sciences
4 - Southern Illinois University, Department of Plant Biology
5 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan, KS, 66506-4901, USA

none specified

Presentation Type: Oral Paper:Papers for Topics
Session: 27
Location: Elmwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 11:15 AM
Number: 27005
Abstract ID:532
Candidate for Awards:None


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