Graduation date: 1998

Graduation date: 1996

Graduation date: 1994

Errata inserted. / Bibliography: leaves 98-120. / x, 120, [4] leaves, [13] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study is concerned with the identification of genes related to the very early stages of meiosis when homologous pairing occurs. A cDNA library is prepared at the premeiotic interphase and prophase stages of meioses. Differential screening is used to identify and select clones showing preferential expression in anthers at early meiosis. Two selected clones are chosen for further analysis and to investigate a possible role in chromosome pairing. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

Photocopy of typescript / v, 177 leaves, 6 leaves of plates : ill. (part col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.) Dept. of Agronomy, University of Adelaide, 1981

Wheat improvement most often has been accompanied by a narrowing germplasm base, as newer cultivars have been derived from intercrosses between elite germplasm. However, there is a concern that narrow germplasm may restrict breeding improvement for important traits such as resistances to new biotic and abiotic stresses. In addition to germplasm base, the wheat kernel is a major component of wheat grain yield and an important factor for milling characteristics. Focusing on wheat kernel characteristics might be a key element to improve wheat genotypes for agronomic and quality traits. With the intention to broaden the wheat germplasm, and to explore the associations between kernel traits and agronomic as well as quality traits, a two-year study was initiated in 2009 to examine the influence of the kernel traits on the agronomic and quality attributes of a 160 Recombinant Inbred Lines (RIL) population developed from an adapted (ND 705) and a non-adapted genotype (PI 414566). The experiment was conducted at Prosper and Carrington, North Dakota, during 2009 and 2010. The RIL population had a better performance at Carrington than Prosper due to favorable climatic conditions at this location, in 2009 and 2010. The results in this study showed that kernel traits had a high correlation among them and they exhibited continuous variations suggesting a polygenic inheritance. Grain yield, kernel volume weight (KVW), and flour extraction were highly correlated with kernel width, length/width ratio, weight, and area. Eight RIL yielded better than the adapted parent ND 705 and two of the RIL along with three checks were significantly superior for gram yield compared with the other genotypes across all environments. Although the non-adapted parent has a facultative grown habit, several RIL required fewer days to flower compared to the adapted parent. Two RIL had better flour extraction compared to the other genotypes included in this study. These results indicated that kernel traits can play a significant role in improving agronomic and quality traits. Higher values for grain yield, KVW, and flour extraction were significantly associated with spheroid or round shape (short and plump), large, and heavy kernels. The high agronomic and quality attributes showed by some RIL demonstrated that the use of a non-adapted parent can broaden the genetic variability while increasing the genetic gain for certain traits. Also, breeders should pay attention to kernel size and shape during the parental selection for the development of populations with improved agronomic and quality traits.

Call number: LD2668 .T4 1979 M62 / Master of Science

Bibliography: leaves [129]-146

"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

This thesis describes studies into the genetic control of tolerance of wheat to high concentrations of boron ( B ). Initially, experiments were conducted to determine selection criteria for distinguishing between tolerant and sensitive genotypes for both glasshouse and field grown wheat. Responses of plants to high concentrations of B, under glasshouse conditions, included reduced vigour, delayed development, expression of symptoms of toxicity and reduced grain and total dry matter yields. Significant differences between tolerant and sensitive genotypes resulted for all parameters, however the greatest discrimination for tolerance to B, between genotypes, resulted during vegetative growth. Tolerant genotypes accumulated less B than the more sensitive genotypes for both glasshouse and field experiments. The concentration of boron in shoots was a highly heritable character and B concentrations in shoots were significantly correlated between high boron conditions in a glasshouse and the field. The concentration of B in grain was highly correlated with the concentration in shoots for field grown wheat, but this relationship did not occur for wheat grown in pots and the anomalous result was related to the artifical growth conditions. Grain is an appropriate tissue for analysis to determine the B accumulation, and therefore tolerance, for field grown wheat. The tolerance to B for wheat varieties of historical importance in Australia was investigated. Many of the historically dominant varieties are tolerant to B and all tolerant Australian varieties are interrelated. The initial tolerant varieties were Federation and Currawa and members of the derived family include Ghurka, Quadrat, Insignia, Heron, Olympic, Halberd, Spear and Dagger. The distribution of Insignia, Heron and Halberd followed a similar pattern in South Australia and the regions where these varieties were most widely cultivated corresponds to the regions where the highest concentrations of B have been measured in barley grain samples. Thus, there is correlative evidence that the high concentration of B occurring in the subsoils has been a major selective force in South Australian wheat production. Tolerance to high concentrations of boron is inherited as an additive character, however expression of tolerance varies from being a dominant to a partially dominant character depending upon the concentration of applied boron. Major gene control of tolerance to boron was identified from the segregation patterns of F2 and F3 generations derived from parents of contrasting tolerance to boron. The parents used represented five levels of tolerance to boron and the difference between successive levels of tolerance was under the control of single genes. Three independent single gene differences were identified. Transgressive segregation resulted between two tolerant lines, Halberd and G61450, and this suggests they have contrasting genes controlling the uptake of boron. A genetic model comprising four independent loci, designated Borl, Bor2, Bor3 and Bor4 was proposed for the five lines. The five lines and their proposed genotypes were : Kenya Farmer ( very sensitive ) borl bor2 bor3 bor4, ( W1 * MMC ) ( sensitive ) borl bor2 Bor3 bor4, Warigal ( moderately sensitive ) borl Bor2 Bor3 bor4, Halberd ( moderately tolerant ) Borl Bor2 Bor3 bor4 and G61450 ( very tolerant ) bor1 Bor2 Bor3 Bor4. As tolerance to high concentrations of B is under the control of major genes, incorporation of tolerance into sensitive but otherwise adapted local varieties should be readily achieved through backcrossing. The chromosomal location of genes controlling tolerance to B was undertaken by the use of intervarietal substitution lines, monosomic analysis and interspecific addition lines. Chromosome 4A of the Chinese Spring - Kenya Farmer substitution lines had a significant effect upon tolerance to boron and the 4A substitution line was more sensitive than Chinese Spring. Results for monosomic analysis were inconclusive, however chromosomes identified as the more probable locations of genes controlling tolerance to boron included 4A and 7D for analysis of the F3 ' s of ( Chinese Spring monosomics * G61450 ) and chromosomes 7B, 3A and 2B for reciprocal monosomic analysis between Chinese Spring and Federation. The Chinese Spring x Ag. elongatum amphiploid was more tolerant than Chinese Spring and the chromosome 7E addition line was also more tolerant than Chinese Spring. The results of three separate comparisons therefore implicate the chromosomes of homoeologous group seven in the control of tolerance to boron. Random F4 and F5 lines derived from the tolerant Halberd and sensitive I ( W1 * MMC ) were tested under naturally occurring high B conditions in the field. Chemical analysis of shoots and grain by inductively coupled plasma spectrometry found uptake of B to be independent of nine other elements. The correlation between tolerance to B, as measured by B uptake, and yield among lines of this population was tested at six sites to identify conditions where tolerance to B resulted in a yield advantage. A significant correlation between tolerance to B and yield resulted only at sites where high boron concentrations of grain resulted. Genetic variation for concentrations of several other elements in shoots and grain also occurred within this population and significant correlations between the efficiency of nutrient uptake and grain yield resulted for Mn at Two Wells and Minnipa while genotypes with low Na accumulation produced significantly higher yields than genotypes with high Na uptake at Rudall. Genetic variation in response to soil elements, other than B, may explain the variable performance of varieties, between environments, and this is an area which warrants further investigation. / Thesis (Ph.D.)--Department of Agronomy, 1990.