Cryopreservation is the most promising method for the long-term conservation of germplasm of plants producing desiccation-sensitive seeds. While such seeds are generally termed recalcitrant in the context of conventional storage practices, the term ‘cryo-recalcitrant’ is used for germplasm which is not readily amenable to cryopreservation. Cryo procedures usually involve a sequential combination of steps which must be optimised to limit the stresses experienced by specimens, thus promoting their survival. The present contribution reports on the effects of some of the steps involved in cryopreservation on the survival of the embryos of the amaryllids, Ammocharis coranica, Brunsvigia grandiflora and Haemanthus albiflos, with the ultimate aim of developing a protocol(s) for the successful cryopreservation of the germplasm of these species. The main foci of the investigations were the effects of rapid (flash) drying, the use of the cryoprotectant additives, glycerol (5 & 10%) and DMSO (0.1 & 0.25%), and employment of different cooling rates on the zygotic embryos of the selected species, which are known to be recalcitrant as well as being cryo-recalcitrant. Furthermore, this study reports on attempts at improving the rapidity of dehydration during flash drying by applying a vacuum, and also of providing cathodic protection (via highly reducing cathodic water and/or direct exposure to a static {negatively-charged} cathodic field during flash drying) to the explants at various stages in the protocol. These techniques were employed in attempts to ameliorate the adverse effects of reactive oxygen species associated with stresses imposed by the procedures during the cryopreservation process. The embryos of Ammocharis coranica, Brunsvigia grandiflora and Haemanthus albiflos were initially at water contents (WCs, dry mass basis) of 3.28±0.52, 2.55±0.22, 4.48±0.92 g g-1, respectively, after harvest. These embryos proved to be tolerant to moderately rapid water loss in the short term, with >60% retaining germinability at water contents ≥0.5 g g-1. The results from this study confirmed that dehydration to water contents below 0.5 g g-1 (dry mass basis) compromised survival, and that this effect was exacerbated if the embryos were cryoprotected prior to drying. Interestingly, the rate of water loss in embryos of these species differed, with A. coranica and H. albiflos drying at a (comparably) much slower rate than those of B. grandiflora. Subsequent rapid cooling yielded promising results when compared with slow cooling, as 30% of glycerol cryoprotected, rapidly cooled A. coranica embryos that had been flash-dried to 0.36±0.10 g g-1 generated normal seedlings. It was clear, however, that the effects of these procedures were exacerbated when all the steps of the cryo procedure were applied sequentially. However, the work also showed that these adverse effects may be ameliorated if each step of the cryopreservation protocol is optimised on a species-specific basis, thus promoting the chances of survival after cryopreservation and facilitating subsequent seedling establishment. This was evident in the 30% germination obtained when embryos of A. coranica, which had been cryoprotected with glycerol prior to flash drying before exposure to rapid cooling, while those that had not been cryoprotected or were cryoprotected with DMSO before drying did not survive. The incorporation of cathodic protection during flash drying appeared promising as it promoted the survival of 10% of H. albiflos embryos dehydrated to WCs between 0.37 and 0.26 g g-1 (whereas no survival was achieved without the inclusion of this step), and 70% of A. coranica embryos that were dehydrated to 0.35±0.21. In addition, the reduction of the explant size, from a whole 6 mm embryo to a 3-4 mm excised axis, promoted survival by up to 30% for A. coranica and H. albiflos, even at higher WCs. However, survival in these cases was based on observations of abnormal development, i.e. the development of roots or shoots, or calli. No surviving embryos were obtained from B. grandiflora after cooling, regardless of the preconditioning treatment or rate of cooling, and this was accredited to the greater degree of sensitivity of these embryos to the cryo procedures than those of the other two species. The use of cathodic water to re-hydrate explants after dehydration and of applying a vacuum during flash drying did not result in any observable benefits, and require further investigation for optimisation. The very limited success towards establishing a cryopreservation protocol for the species investigated in this study reinforces the difficulties associated with the cryopreservation of recalcitrant germplasm, which informs the cryo-recalcitrance of some explants. However, the results obtained have helped to identify a number of intervention points that could be used to minimise the damage incurred during the various procedural steps involved in cryopreservation. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.

Three studies were conducted to determine the effects of nonstructural carbohydrate (NSC) sources on performance of dairy cows fed sunflower seeds. In the first study, the effects of NSC source on dry matter (DM) intake, milk yield and milk fatty acid composition were evaluated using fifteen lactating Holstein cows in a 3 x 3 Latin square design. In the second study, fifteen lactating Holstein cows were used in a completely randomized design to determine the effects of NSC on the total tract nutrient utilization. The third study was designed to determine in situ ruminal degradability of DM, CP, NDF and starch of dietary treatments of study one and two, where two ruminally fistulated cows used in a randomized complete block design. Results of the in situ ruminal degradability trial showed that BC and CBC had similar effective ruminal degradability of DM and CP which was higher (P < 0.05) than that of CC. However, starch ruminal degradability was highest for BC, intermediate for CBC and lowest for CC. Sources of NSC had no effect on the NDF in situ ruminal degradability. It was concluded that changing the source of NSC and feeding sunflower seeds can modify milk fatty acid composition without any adverse effect on milk yield or milk components, and with no detrimental effect on nutrients utilization. (Abstract shortened by UMI.)

The aim of this research is to assess various options for the management of topsoil stockpiles on disturbed lands and to evaluate the viability and germinability over time of the seedbanks in these stockpiles for use in rehabilitation. To predict their success, experimental trials were designed and conducted. / Thesis (MApSc(EnvironmentRecreationMg))--University of South Australia, 2002.

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "December, 2007." Includes bibliographical references . Online version available on the World Wide Web.

Thesis (M.Sc.) - Carleton University, 2005. / Includes bibliographical references. Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 119-125). Also available in electronic format on the Internet.

Thèse (M.Ress.Min.) -- Université du Québec à Chicoutimi, 2005. / Bibliogr.: f. [85]-95. Document électronique également accessible en format PDF. CaQCU

Thesis (Ph.D.)--Michigan State University. Dept. of Plant Biology, 2008. / Title from PDF t.p. (viewed on July 16, 2009) Includes bibliographical references (p. 273-293). Also issued in print.

Thesis (MScConEcol)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 433-445).