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Abstract Detail

Ecological Section

Sabates, Sofia [1], Galliart, Matthew [1], Baer, Sara [2], Bello, Nora [3], Caudle, Keri [4], Maricle, Brian [4], McCrea, Evan [2], Gibson, David [2], Wilson, Laurel [2], Johnson, Loretta [5].

How does phenology and seed production of big bluestem (Andropogon gerardii) vary across the climate gradient of the Great Plains? A reciprocal garden approach to distinguish roles of site and ecotype.

Midwest grasslands are dominated by the perennial C4 grass big bluestem, Andropogon gerardii that persists across a strong precipitation gradient (500 to 1200 mm/yr rainfall from western Kansas to Illinois). These grasslands have recently experienced severe drought, which is predicted to continue with climate change. Better knowledge of how grasslands will respond to drought is critical for planning conservation plantings and agricultural rangeland sustainability. We used a reciprocal garden platform to investigate ecotype-specific seed production and phenology across a precipitation gradient. Three ecotypes (each comprised of four populations from central KS, eastern KS, and southern Illinois) were reciprocally planted as individual plants in 10 replicated blocks in Colby, Hays, and Manhattan, KS, and Carbondale, IL in 2009. In 2012, we recorded phenological stage from leaf emergence to seed set. At the end of the 2012 growing season, we collected and weighed seed from each site. We aimed to determine whether there is ecotypic variation or an interaction between ecotype and environment (differential variation among sites) in emergence, seed production, phenology, and time to flowering. We predicted ecotypes would have the greatest seed production in the home environment and the presumably most drought-adapted central KS ecotype would show advanced flowering as an adaptation to shorter growing season and drought. Leaf emergence varied significantly by planting site, but not ecotype. Plants in eastern sites emerged earlier than western sites. In Colby, Hays, Manhattan, and Illinois, mean emergence occurred at Julian day 91, 84, 83, and 79, respectively. In contrast, time to flowering varied by both site and ecotype. The central KS ecotype flowered on average 20 days earlier than eastern KS and southern Illinois ecotypes, independent of planting site. Moreover, when planted in Colby, the central KS ecotype was the only one that flowered. Seed production showed strong ecotype, site, and site x ecotype effects. As hypothesized, the central Kansas ecotype showed greater seed production in Hays, KS (‘home site’ advantage). In contrast, the southern IL ecotype in Hays produced 1/5 the amount of seed relative to the central KS ecotype. Furthermore, when southern IL and eastern KS ecotypes were planted even farther west in Colby, they did not flower and so could not produce seed. Our results provide insight into how adaptable A. gerardii might be in response to drier climates and will also help to identify which ecotypes are best suited to restore grassland in the central US.

Broader Impacts:

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Related Links:

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

Big bluestem
common gardens
seed production.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Number: PEC018
Abstract ID:538
Candidate for Awards:None

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