Thesis (Ph. D.)--University of Wisconsin--Madison, 1951. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 100-107).

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Thesis documentation sheet and errata sheet inserted. Appendix reprints five manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on June 12, 2006). Thesis advisor: Jennifer A. Franklin. Vita. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 1973. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.) in Forest Resources--University of Maine, 2000. / Includes vita. Includes bibliographical references (leaves 149-167).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (Ph.D.)--University of Edinburgh, 1987.

Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on July 13, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Systematics and Evolution, Department of Biological Sciences, University of Alberta. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 143-148).

Clonal propagation of white spruce (Picea glauca (Moench) Voss) through somatic embryogenesis (SE) has important applications in tree improvement programs and will help the forest industry to achieve maximum sustainable yield. The level of induction of embryogenic tissue and the yield of mature embryos through SE has reached acceptable levels using current protocols. However, a large percentage of these embryos produce abnormal seedlings. This problem needs to be assessed and this was done in the work described in this thesis. Empirically derived, uncontrolled partial desiccation procedures are currently used to improve germinaton. No systematic study has previously been done to correlate the effects of controlled desiccation on germinant quality. My study looked at the effects of controlled partial and complete desiccation of white spruce somatic embryos at four stages of development on subsequent germinant quality. Both slow desiccation at 5°C and flash desiccation at ambient temperature were examined. The effect of temperature treatments as an alternate means of improving germinant quality and its effect on desiccation tolerance were also examined. Dried somatic embryos are likely to suffer imbibitional damage as they (unlike zygotic embryos) have no protective structures surrounding them to regulate water uptake during imbibition. Therefore, the effects of various rehydration methods were also examined. Large numbers of mature embryos were required for our desiccation experiments. Therefore, a method of squashing the embryogenic tissue into a polypropylene mesh was developed. This method allowed embryogenic tissue to be easily transferred to fresh medium and produced a flat mat of mature embryos that were more accessible for harvesting. The tolerance of the embryos to desiccation, and the level of desiccation required to improve germinant quality, increased as the embryos matured. The largest improvement in germinant quality was achieved by slowly desiccating 39-d embryos at 5°C for 7 days over a 0.48 M NaCl solution with a water potential of -2 MPa and rehydrating them at 100% RH at a temperature of 5°C. This treatment produced approximately 84% normal germinants. More severe desiccation caused increasing damage. A temperature treatment of 5 and 10°C also improved germinant quality, producing 70- 80% normal germinants. The 5°C treatment can be used as a short-term storage method. Germinant quality from untreated embryos increased with maturity until the embryos became fully mature by 51 d, then quality quickly decreased. Mature 51-d embryos were stored for 8 weeks at 5°C with no loss of germinant quality. A 5°C temperature treatment for 4-8 weeks significantly improved the tolerance of 39-51 d embryos to flash desiccation (embryos were dried in a laminar flow hood and lost all free cytoplasmic water within 15 minutes). This has important applications in the development of synthetic seed. All of the 8-week cold stored 51-d embryos survived flash desiccation and 58% of them produced normal germinants. The roots developed desiccation tolerance faster than the cotyledons+hypocotyls. Rehydration experiments showed that slowly and rapidly desiccated embryos responded differently to the method of rehydration. Slowly desiccated embryos suffered less imbibitional damage if they were indirectly rehydrated at 100% RH. Flash desiccated embryos suffered less damage if they were rehydrated directly on germination medium. This suggests that there is no one simple explanation for damage as a result of desiccation and imbibition. Reduction of 2,3,5-triphenyltetrazolium chloride (TTC) was an effective test for delineating damaged areas in rehydrated embryos, but actual germination tests were the only way of accurately determining germinant quality. The above treatments have significantly improved germinant quality. / Graduate