Bibliography: leaves 183-211. / xii, 211 leaves ; col. ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study evaluates the backcross breeding method for the introgression in barley of agronomically important traits into a malting quality background using molecular markers. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2000

No description available.

<p>Breeding dispersal can be a way for an individual to improve its fitness. Own reproductive success has been shown to be a cue to dispersal among many bird species. Natural selection should favor dispersal to higher-quality territories and a larger territory is predicted to improve fitness. Data from male rock pipits, <em>Anthus petrosus littoralis</em>, on the Swedish west coast indicated, as predicted, that dispersal follows an unsuccessful breeding year. However, no fitness improvement was detected after dispersal, leading to the conclusion that dispersing in itself does not lead to better fitness. Instead it was the acquisition of a larger territory that was the main cause of fitness improvement, unrelated to whether a male returned to an old territory or dispersed to a new one. However, remaining in one's old territory showed to be more beneficial than dispersing. There was a high variation within the rock pipit populations of Nidingen and Malön, due to year-to-year territory quality variation and individual quality among the birds, which could have had a big effect on the outcome of the analyses of the effects of dispersal.</p> / <p>Att byta revir kan vara ett sätt för en individ att förbättra sin fitness. Den egna reproduktiva framgången har påvisats påverka beslutet om revirbyte. Naturligt urval borde favorisera byte till ett revir av högre kvalitet och ett större revir förutsägs förbättra fitness. Data från skärpiplärkor, <em>Anthus petrosus littoralis</em>, tyder på att ett misslyckat häckningsår leder till spridning. Däremot påvisades ingen förbättring av fitness efter spridning, vilket leder till slutsatsen att spridningen i sig inte leder till bättre fitness. Istället var det anskaffandet av ett större revir som var den huvudsakliga orsaken till fitnessförbättring, orelaterat till om en hanne utökade sitt gamla revir eller flyttade till ett nytt. Däremot visade det sig vara bättre att stanna kvar i sitt gamla revir än att flytta. Det fanns en stor variation bland Nidingens och Malöns populationer av piplärka, på grund av årlig variation i revirkvalitet och individuell kvalitet bland fåglarna, vilket kan ha haft en stor effekt på resultatet av analyserna av spridningseffekterna.</p>

The hop (Humulus lupulus L.) is a dioecious, diploid (2n=2x=20) species. Triploid hops (2n=3x=30) are easily obtained from tetraploid by diploid crosses and are preferred because of their natural seedlessness and increased vigor. The female inflorescence is used for flavoring beer. Because brewers require product consistency, the brewing characteristics of a new aroma-type hop must closely match the variety it is intended to replace while showing improved adaptation and agronomic traits. Since triploid offspring should more closely resemble the tetraploid parent from which they receive two-thirds of their genetic material, breeders have traditionally selected known varieties to be the tetraploid parent with the expectation this will increase the likelihood of obtaining progeny with similar brewing chemistry. Tetraploid female parents are obtained through colchicine treatment of desirable diploid varieties. Naturally occurring tetraploid seedlings, sometimes found among the offspring of tetraploid by diploid crosses, if suitable for breeding, could eliminate the tedious colchicine treatment process now used to obtain tetraploids. Two such tetraploid males were obtained from an Oregon cross in 1983. Since these two tetraploid males had attractive quality traits similar to other males in the USDA germplasm collection with a proven history of producing aroma-type progeny, they were thought to be suitable for use in a polyploid breeding program for aroma hops. The objective of this study was to determine the feasibility of using males as tetraploid parents in diploid by tetraploid crosses to obtain triploid aroma hops. Tettnanger, a prized German aroma hop, was used as the diploid female parent for these crosses. Meiotic cells of the two tetraploid males showed some abnormalities at anaphase I and the quartet stage; however, fertility, as determined from seed production and germination, was adequate for breeding. Of 185 seedlings obtained, 57 were triploid females. The diploid by tetraploid seedling population had a higher percentage of males than previously reported for tetraploid by diploid crosses. One tetraploid male produced no triploid female offspring. Seed content of the female triploid seedlings when subjected to a heavy pollen load averaged 2.4% compared to 20.1% for diploid seedlings from Tettnanger crosses. Triploid progeny produced higher average yield than the Tettnanger parent. The two tetraploid males and Tettnanger were very similar in chemical quality traits comparable in male and female hops. Comparison among triploid and diploid progeny from diploid by tetraploid crosses and diploid open-pollinated Tettnanger seedlings demonstrated that the male parent influenced the a ratio, cohumulone content, and humulene to caryophyllene ratio of the offspring. Many of the female triploid offspring genotypes showed chemical quality traits similar to those of Tettnanger. / Graduation date: 1995

Thesis (M. S.)--Texas A&M University, 2005. / "Major Subject: Animal Breeding" Title from author supplied metadata (automated record created on Sep. 15, 2006.) Vita. Abstract. Includes bibliographical references.

Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Plant Breeding" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (M. S.)--Texas A&M University, 2005. / "Major Subject: Plant Breeding" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Plant Breeding" Title from author supplied metadata (record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (M. S.)--Texas A&M University, 2006. / "Major Subject: Plant Breeding" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Plant Breeding" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.