Grisť, David J. , Thompson, Sean M. , Loya, Karla K. , Overath, R. Deborah .
Soil Fidelity in Gulf Coast Helianthus species (Nueces County, Texas).
WE surveyed 46 sites in Nueces County, Texas to determine if the local Helianthus species segregate by soil type. Local species include Helianthus annuus, H. argophyllus, H. ciliaris, and H. praecox. Soils in Nueces County can be roughly classified as clay-based soils or sand-based soils. We drove roads in the southern and eastern portions of Nueces County in relative proximity to the dividing line between clay and sand soils. At each site containing sunflowers, we determined the species of Helianthus, marked the site with a GPS receiver, and collected vouchers if plants were flowering. At a few locations, we collected seeds for germination studies. In our initial surveys, H. annuus and H. argophyllus were common, H. praecox was rare, and H. ciliaris was absent. Helianthus annuus and H. argophyllus had remarkable fidelity to soil type. All clay sites contained only H. annuus. Of the sand sites, 25 of 26 contained H. argophyllus . Of those, only two also contained a few H. annuus plants. The remaining sand site contained only H. praecox. In a growth room, we germinated H. annuus and H. argophyllus on both sand and clay soils. Over the 30 day course of the experiment, H. annuus had higher germination on both soil types; however, this result may have been due to differences in seed quality. Consequently, the underlying cause of soil fidelity in these species is unclear.
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1 - Texas A&M-Corpus Christi, Physical and Life Sciences, 6300 Ocean Drive, Unit 5800, Corpus Christi, Texas, 78412, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM