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"September, 1983". / Thesis (MSc)--Macquarie University, School of Biological Sciences, 1984. / Bibliography: leaves 128-142. / Introduction and background -- The time course of germination and its analysis -- Osmotic effects on germination -- High-humidity hydration of seeds -- Techniques of priming -- Field emergence of primed seeds -- Discussion. / Seed priming, which involves the hydration of seeds in an osmotic solution before sowing, produces seeds with improved germination performance. This study was aimed at optimizing the priming of tomato, carrot, onion and sorghum seeds by a method which could be readily scaled up for commercial use. -- Initially, to determine appropriate priming solutions, the germination responses of the four species to a range of osmotic potentials from 0 to -1.75 MPa in a range of osmotica - K₂HPO₄, K₃P0₄, KN0₃, K₂HPO₄ + KN0₃, K₃P0₄ + KN0₃ and Polyethylene glycol (PEG) - were investigated. -- The most effective priming treatment was shown to be one in which the osmoticum prevented germination without being toxi c, at a high osmotic potential. There were marked interactions between species, osmotic potential and the osmoticum used for priming. Tomato seeds were readily primed in any of the series of salt or PEG solutions . All of the solutions tried were adequate for carrot seeds. Onion seeds could be primed in either K₂HPO₄, K₃P0₄ or PEG solutions; however, all solutions were toxic to sorghum seeds or failed to prevent germination. -- The selected priming treatment was further optimized by experiments that investigated the influence of duration and temperature of priming. Priming at a lower temperature for a longer time was more beneficial than at higher temperatures. However, priming for too long a period was found to have adverse effects . Tomato seeds showed improved performance after priming for 16 t o 18 days at 15 C whereas for carrot seeds a duration of 8 to 10 days was adequate, but prolonged treatment led to reduced germination percentages. Columns of aerated solutions were found to be suitable for the priming of large quantities of tomato and carrot seeds. Air-drying of primed tomato and carrot seeds was possible without loss of germinability or priming effect. -- Limited field experiments at Yanco Agricultural Research Centre showed that primed tomato and carrot seeds emerged twice as fast as untreated seeds and had improved uniformity of emergence, particularly at low soil temperatures. These benefits from priming were maintained through to the first true leaf stage of development. -- It was concluded that it was possible to prime certain seeds in simple salt solutions by a method capable of expansion to commercial scales of operation and produce benefits to emergence which were maintained after drying to facilitate sowing using existing drilling equipment. / Mode of access: World Wide Web. / xi, 168 leaves

Thesis (Ph. D.)--University of Chicago, 1911. / "Reprinted from the Botanical gazette, vol. LV, no. 4." "Literature cited": p. 297-299.

Thesis (MSc)--Macquarie University, School of Biological Sciences, 1984. / "September, 1983". Bibliography: leaves 128-142.

Thesis (doctoral)--Kgl. Technischen Hochschule zu München, 1912. / Includes bibliographical references.

Thesis--Upsala. / Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, 1911. / "Reprinted from the Botanical gazette, vol. LV, no. 4." "Literature cited": p. 297-299. Also available on the Internet. Also issued online.

Thesis (Ph. D.)--University of Chicago, 1917. / "Private edition, distributed by the University of Chicago Libraries, Chicago, Illinois." "Reprinted from the Botanical gazette, vol. LXVII, no. 4, April, 1919." "Literature cited": p. 307-308.

In a study of the problems met in testing germination of coniferous tree seed, special attention is given to the variability between different seedlots of the same species. Known and suspected causes for this variability are discussed. These include seed source, genetic constitution of individual trees, seed maturity, treatments during the commercial extraction process and storage conditions. Loss in seed viability may occur during anyone of several phases of the extraction process, such as cone storage, kiln drying and dewinging. In the discussion of the germination test procedure the importance of a moist-cold pretreatment or "stratification" is indicated. It is shown, that many species of coniferous seed are subjected to such treatment in nature. The desirability of stratification of coniferous seed as a standard pretreatment prior to incubation is emphasized. The effect of stratification on temperature and light requirements is discussed for Douglas fir in particular. The usual methods for stratification and their disadvantages are described. In order to overcome some of the disadvantages of the older stratification methods, particularly the lack of control over seed moisture content, the "naked stratification" method was developed at the University of British Columbia. This method has been applied successfully to Douglas fir seed and seed from several other species. A detailed description is given of an experiment, designed to develop a standard germination test for western hemlock seed. This involved determination of an optimum incubation temperature, seed moisture content and stratification period. The "naked stratification" method was used. The effect of incubation temperature, seed moisture content and stratification on the final germination percentage and the rate of germination was evaluated, using analysis of Variance and the t-test. The results showed, that for germination of western hemlock seed the following treatments are most favourable. Stratification for 7 — 9 weeks with a seed moisture content of 50 - 75 percent,—which is obtained after approximately 33 hours of soaking,—followed by incubation at a constant temperature of 20°C. Under these conditions the germination test can be concluded in approximately 20 days. Different incubation temperatures influenced both final germination percentage and rate of germination. Different seed moisture contents and stratification periods generally did not affect the final germination percentage, but did have a pronounced effect on the rate of germination. Stratification did not seem to change the temperature requirements of western hemlock seed. Differences in the germination behaviour of the four seedlots tested were observed. / Arts, Faculty of / Social Work, School of / Graduate

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