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Water relations, growth and survival of root-wrenched Douglas-fir seedlings

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dc.contributor.advisor Lavender, Denis P.
dc.creator Duryea, Mary L.
dc.date.accessioned 2009-02-16T17:25:25Z
dc.date.available 2009-02-16T17:25:25Z
dc.date.issued 1981-04-15
dc.identifier.uri http://hdl.handle.net/1957/10508
dc.description Graduation date: 1981 en_US
dc.description.abstract Chapter 1 Growth and Survival of Root-Wrenched Douglas-fir Seedlings Root wrenching of seedlings (severing the roots 15 cm below the soil surface) was investigated as a nursery practice to improve growth and survival of field-planted Douglas-fir from six local seed sources in the Pacific Northwest. At lifting, shoots of wrenched seedlings were shorter, lighter, and had smaller diameters than those of unwrenched seedlings. Among seedlings from four of the seed sources, wrenching resulted in significantly lighter taproots but did not significantly affect lateral root and total root weights. There were no significant differences between these measurements among wrenched and unwrenched seedlings from the other two sources. Mainly because of lighter shoots, shoot-root ratios were smaller for wrenched than for unwrenched seedlings. In no case did root wrenching improve field height growth or survival after one year, and among four of the sources shoot growth was significantly less than that of unwrenched seedlings. Chapter 2 Water Relations of Root-wrenched Douglas-fir Seedlings Root wrenching was investigated as a nursery practice to precondition Douglas-fir seedlings to droughty field conditions. Wrenching shocked the seedlings while in the nursery, lowering plant water potential and transpiration rate. After planting, however, wrenched and unwrenched seedlings transpired at equal rates when exposed to stress with osmotic solutions of Polyethylene Glycol 1000 and under field conditions. Throughout exposure in pots to a drought simulating the Pacific Northwest summer drought, wrenched and unwrenched seedlings did not differ in plant water potential, leaf relative water content, or seedling condition. However, all wrenched seedlings of four seed sources reflushed in the middle of the drought and had significantly fewer active roots than unwrenched seedlings. Among the four seed sources used, differences in ability to withstand drought were apparent. en_US
dc.language.iso en_US en_US
dc.subject.lcsh Douglas fir en_US
dc.subject.lcsh Roots (Botany) en_US
dc.title Water relations, growth and survival of root-wrenched Douglas-fir seedlings en_US
dc.type Thesis en_US
dc.degree.name Doctor of Philosophy (Ph. D.) in Forest Science en_US
dc.degree.level Doctoral en_US
dc.degree.discipline Forestry en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Boersni, Larry
dc.contributor.committeemember Waring, Richard
dc.contributor.committeemember Zaerr, Joe
dc.description.digitization PDF derivative scanned at 300 ppi (256 B+W), using Capture Perfect 3.0, on a Canon DR-9080C. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR. en_US

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