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Influence of Plant Growth Regulators on Turfgrass Growth, Antioxidant Status, and Drought Tolerance

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dc.contributor.authorZhang, Xunzhongen
dc.contributor.committeechairSchmidt, Richard E.en
dc.contributor.committeememberParrish, David J.en
dc.contributor.committeememberHess, John L.en
dc.contributor.committeememberHall, John R.en
dc.contributor.committeememberAllen, Vivien G.en
dc.contributor.departmentCrop and Soil Environmental Sciencesen
dc.date.accessioned2014-03-14T20:22:38Zen
dc.date.adate1997-09-05en
dc.date.available2014-03-14T20:22:38Zen
dc.date.issued1997-07-01en
dc.date.rdate1997-09-05en
dc.date.sdate1997-07-01en
dc.description.abstractA series of studies were conducted to examine the antioxidant status, drought and disease tolerance, and growth response to foliar application of soluble seaweed (Ascophyllum nodosum) extracts (SE) and humic acid (HA; 25% active HA or 2.9% active HA) in tall fescue (Festuca arundinacea Schreb), Kentucky bluegrass (Poa pratensis L.) and creeping bentgrass (Agrostis palusttis Huds.) grown under low (-0.5 MPa) and high (-0.03 MPa) soil moisture environments. Foliar application of humic acid (2.9 % active HA) at 23.7 and 47.4 l/ha improved leaf water status, shoot and root development in tall fescue, Kentucky bluegrass and creeping bentgrass grown under drought. Humic acid (2.9% active HA) at 15.5 l/ha or SE at 326 g/ha significantly reduced dollarspot incidence and improved turf quality in creeping bentgrass. Drought stress induced an increase of antioxidants alpha-tocopherol and ascorbic acid concentrations in the three turfgrass species. In the experiment with Kentucky bluegrass, drought stress increased beta-carotene concentration, but did not significantly influence superoxide dismutase (SOD) activity. Foliar application of humic acid (25% active HA) at 5 l/ha and/or SE at 326 g/ha consistently enhanced alpha-tocopherol and ascorbic acid concentrations, leaf water status, and growth in the three cool-season turfgrass species grown under low and high soil moisture environments. In the experiment with Kentucky bluegrass, application of HA at 5 l/ha plus SE at 326 g/ha also increased beta-carotene content and SOD activity under low and high soil moisture environments. There were close positive correlations between the antioxidant status and shoot or root growth in the three turfgrass species regardless of soil moisture levels. The antioxidant SOD activity, photosynthetic capacity in terms of Fvm690, and chlorophyll content in terms of Fm730/Fm690 exhibited a seasonal fluctuation in endophyte [Neotiphodium coenophialum (Morgan Jones and Gams) Glenn, Bacon, Price and Hanlin] -free and endophyte-infected tall fescue. Application of SE enhanced SOD activity, photosynthetic capacity, and chlorophyll content in tall fescue, especially at 4 weeks after SE treatment. The SOD activity, photosynthetic capacity and chlorophyll content were not significantly influenced by the endophyte infection. A close positive correlation between SOD and photosynthetic capacity during the summer was found in endophyte-free and endophyte-infected tall fescue.en
dc.description.degreePh. D.en
dc.identifier.otheretd-8597-161835en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-8597-161835/en
dc.identifier.urihttp://hdl.handle.net/10919/30739en
dc.publisherVirginia Techen
dc.relation.haspartdissert.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectDroughten
dc.subjectFluorescenceen
dc.subjectFree Radicalsen
dc.subjectAntioxidantsen
dc.subjectTurfgrassen
dc.subjectHormonesen
dc.titleInfluence of Plant Growth Regulators on Turfgrass Growth, Antioxidant Status, and Drought Toleranceen
dc.typeDissertationen
thesis.degree.disciplineCrop and Soil Environmental Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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