Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2004? / "March, 2004" Bibliography: leaves 204-229.

Thesis (Ph. D.)--Oregon State University, 1999. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Adelaide, 1994. / Includes bibliographical references (leaves 180-198).

"March, 2004" / Bibliography: leaves 204-229. / xv, 229 leaves : ill. (some col.), map (col.), photos (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The outcome of the yield evaluation trials conducted in this study was the identification of the high-yielding and widely adapted line, RH912025, which was consequently released as the variety Tamaroi. Development of B tolerant lines, with a grain yield advantage when grown under high B conditions in the field, means durum production will be able to expand into the marginal areas where B toxicity occurs. Furthermore, by pyramiding genes for B tolerance and dough strength (i.e. subunit 2*) into Tamaroi, the result should be widely grown germplasm, with premium quality for the international market. --p. x. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2005

Graduation date: 1994

Thesis (M. Ag. Sc.)--University of Adelaide, Dept. of Plant Science, 1997. / Includes bibliographical references (leaves 148-160).

Bibliography: leaves 180-198. / viii, 217 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1994

Bibliography: leaves 180-198.

Attempts to develop dual-purpose durum wheat cultivars for both pasta and bread-making have been unsuccessful. To better understand this limitation, thirty durum genotypes, selected based on their diverse geographical origin, and five bread wheat cultivars were compared as to their flour mixing properties, dough physical characteristics and baking performance. The polymeric composition of gluten protein was determined using SE-HPLC of unreduced flour protein extracts and the size-distribution of the gluten polymer was estimated by determining the SDS-unextractable polymer (macro-polymer) content. Durum genotypes were characterized by a lower bread-making quality compared to bread wheats, in spite of higher total flour protein and gluten polymer contents. This was due to a weaker gluten and lack of dough extensibility. The stronger gluten characteristics of bread wheats were associated with a greater ability to form macro-polymers. However, two durum cultivars had a higher macro-polymer content than many of the bread wheats, suggesting that an additional property, unrelated to size-distribution of the gluten, contributes to the greater loaf volumes observed for bread wheats. Considerable variability for most quality attributes was observed among durum genotypes. Gluten strength and dough extensibility were the most important factors associated with superior baking performance. These two parameters were not inter-related. Durum genotypes expressing LMWG-1 had the weakest gluten and the poorest baking performance. This allele contributed less protein to the glutenin fraction and the sub-units produced exhibited a reduced ability to form macro-polymers. Among the durum genotypes expressing LMWG-2, those carrying HMWG-(6+8) were characterized by a better baking quality than genotypes carrying HMWG-(7+8) or HMWG-20. Genotypes carrying HMWG-20 were characterized by a comparatively weaker gluten and a lower macro-polymer content. The better baking performance of genotypes expressing HMWG-(6+8) relative to that of genotypes carrying HMWG-(7+8) was attributed to the greater dough extensibility characterizing the former group, but not to differences in gluten strength-related parameters. There was no indication of differences in the gluten polymer's size-distribution between the two groups. / Graduation date: 1997

The success of a plant breeding program depends upon the availability of useable genetic diversity. Such diversity may be enhanced depending on the type of hybridization strategy employed. Segregating progenies resulting from F2 populations, a double cross, and a top cross were compared for the amount of useable genetic diversity associated with six traits in durum wheat. The parental lines were three winter selections, H7092-11, H7092-52, and WD5, and two spring cultivars, WPB 881 and Altar 84. Traits evaluated were (1) plant height, (2) days to maturity, (3) harvest index, (4) kernel weight, (5) grain yield, and (6) pigment content. Analysis of the population mean values suggested the superiority of the F1 top cross for plant height, kernel weight, and grain yield. The F1 top cross progeny also had the highest genetic variability for grain yield. F2 population of the cross Altar 84 I H7092-52 gave the highest mean values for days to maturity and harvest index, and showed the highest genetic diversity for traits other than grain yield. The only population showing detectable genetic variance for pigment content was the F2 progeny of the single cross WPB 881 / H7092-11. When genetic diversity was detected, the double cross was approximately intermediate between the two F2 populations from which it was derived. Transgressive segregation was more frequent in the top cross population for grain yield, kernel weight, and plant height. No associations between grain yield and the other traits were noted for the F2 population of the single cross Altar 84 I H7092-52 and the top cross population. For the second F2 population (WPB 881 / H7092-11) and the double cross population, grain yield was found to be associated with harvest index and plant height. The only consistent relationship across all segregating generations was a negative correlation between plant height and harvest index. Based on the genetic diversity and the transgressive segregation observed, top crossing appears to be the more promising in improving grain yield in the experimental material investigated. For specific traits other than grain yield, it would appear that single crosses would be a more productive approach, however progress would depend on the specific parental combination. The double cross was inferior to the other crossing strategies for the traits measured. / Graduation date: 1991