It is well recognised that the inherent soil variability and the effect of vegetation, in particular the effect of tree root reinforcement, have a significant effect on the stability of a natural slope. However, in practice, these factors are not commonly considered in routine slope stability analysis. This is due mainly to the fact that the effects of soil variability and vegetation are complex and difficult to quantify. Furthermore, the available slope stability analysis computer programs used in practice, which adopt conventional limit equilibrium methods, are unable to consider these factors. To predict the stability of a natural slope more accurately, especially the marginally stable one, the effects of soil variability and vegetation needs to be taken into account. The research presented in this thesis focuses on investigating and quantifying the effects of soil variability and vegetation on the stability of natural slopes. The random finite element method (RFEM), developed by Griffiths and Fenton (2004), is adopted to model the effect of soil variability on slope stability. The soil variability is quantified by the parameters called the coefficient of variation (COV) and scale of fluctuation (SOF), while the safety of a slope is assessed using probability of failure. In this research, extensive parametric studies are conducted, using the RFEM, to investigate the influence of COV and SOF on the probability of failure of a cohesive slope (i.e. undrained clay slope) with different geometries. Probabilistic stability charts are then developed using the results obtained from the parametric studies. These charts can be used for a preliminary assessment of the probability of failure of a spatially random cohesive slope. In addition, the effect of soil variability on c'–ϕ' slopes is also studied. The available RFEM computer program (i.e. rslope2d) is limited to analysing slopes with single-layered soil profile. Therefore, in this research, this computer program is modified to analyse slopes with two-layered soil profiles. The modified program is then used to investigate the effect of soil variability on two-layered spatially random cohesive slopes. It has been demonstrated that the spatial variability of soil variability has a significant effect on the reliability of both single and two-layered soil slopes. Artificial neural networks (ANNs), which are a powerful data-mapping tool for determining the relationship between a set of input and output variables, are used in an attempt to predict the probability of failure of a spatially random cohesive slope. The aim is to provide an alternative tool to the RFEM and the developed probabilistic stability charts because the RFEM analyses are computationally intensive and time consuming. The results obtained from the parametric studies of a spatially random cohesive slope are used as the database for the ANN model development. It has been demonstrated that the ANN models developed in this research are capable of predicting the probability of failure of a spatially random cohesive slope with high accuracy. The developed ANN models are then transformed into relatively simple formulae for direct application in practice. The effect of root reinforcement caused by vegetation is modelled as additional cohesion to the soils, known as root cohesion, cr. The areas affected by tree roots (i.e. root zone) are incorporated in the finite element slope stability model. The extent of the root zone is defined by the depth of root zone, hr. Parametric studies are conducted and the results are used to develop a set of stability charts that can be used to assess the contribution of root reinforcement on slope stability. Furthermore, ANN models and formulae are also developed based on the results obtained from the parametric studies. It has been demonstrated that the factor of safety of a slope increase linearly with the values cr and hr, and the contribution of root reinforcement to a marginally stable slope is significant. In addition, probabilistic slope stability analysis considering both the variability of the soils and root cohesion are conducted using the modified RFEM computer program. It has been demonstrated that the spatial variability of root cohesion has a significant effect on the probability of slope failure. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1349971 / Thesis (Ph.D.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009

The fungal pathogen Bipolaris sorokiniana (teleomorph Cochliobolus sativus)causes the foliar disease spot blotch (SB) and the root disease common root rot (CRR). Spot blotch and CRR are serious disease constraints to barley production in warmer growing regions of the world, with estimated yield losses ranging from 30-70% from SB and 15-30% for CRR. Although chemical treatments may assist incontrolling spot blotch infections, the most effective and environmentally sound means of control for each disease is breeding for varieties with natural resistance. InAustralia, no commercially available varieties offer resistance to either SB or CRR. This study has sought to establish molecular markers that will be useful for selecting for resistance to each of these important fungal diseases.Barley cultivars derived from the breeding line NDB112 have provided durable SB resistance in the North Dakota region of the USA for over 40 years. The robustnessof this resistance had not been determined under Australian environmental conditions or with those B. sorokiniana pathotypes present within Australia. Toelucidate the genetics of resistance, two seedling and two field trials were conducted on an ND11231-12/VB9524 (ND/VB) doubled haploid (DH) population (180 lines).A molecular map of the ND/VB population was curated in order to provide a firm basis for mapping of resistance loci. Composite interval mapping revealed thatdifferent gene combinations are effective at different stages of plant development. Seedling resistance was found to be conditioned by a major locus on the short arm ofchromosome 7H and this region was validated in the related population ND11231-11/WI2875*17. A minor quantitative locus on chromosome 5HS was detected in one of the two seedling trials. However, this region requires further investigation to confirm its association to SB resistance in this population. Field resistance to SB in adult plants was found to be associated with two major quantitative trait loci (QTL)on chromosomes 7HS and 3HS; and a putative third minor QTL on chromosome 2HS. The 7H region is common between seedling and field resistance and is the most important locus for the expression of resistance at both stages of plant development. These findings largely concur with genetic studies of this trait in tworowed barley germplasm in North American environments.Common root rot is a difficult disease to phenotype for, and breeding programs will benefit from the identification of molecular markers linked to resistance. Data wasprovided from field trials of subsets of the population over four years. Using a novel approach combining the efficiency of bulked-segregant analysis with highthroughputDiversity Arrays Technology markers (BSA-DArT), CRR resistance was found to be conditioned by three putative QTL in an unmapped Delta/Lindwall population. QTL were identified on chromosomes 2HS, 4HS, and 7HS. To validatethe trait-linkage associations between the DArT markers and the CRR QTL,microsatellite (SSR) markers known to map to the regions identified by BSA-DArT were used. The 2H and 4H regions were validated using marker regression of the SSR markers in most seedling trials, whereas the 7H QTL, which is proximal to the location of the SB resistance QTL in the ND/VB population, was detected in only one seedling trial.The QTL identified in this study offer potential to combat the foliar and root diseases causes by this fungal pathogen. The chromosomal location of QTL for SB and CRR resistance have been found to differ in the ND/VB and D/L populations,which suggests that resistance to each disease is independently inherited. Further research is required to confirm the hypothesis that it is possible to combineresistance to both diseases into a single genotype. Such allelic combinations would provide elite germplasm that would benefit barley breeding programs world-wide.

Bibliography: leaves 149-173. / xiv, 173 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 184-209. / xx, 219 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis describes the occurence of natural, biologically based suppression of Rhizoctonia barepatch in a direct drilled system at Avon, South Australia. The supressive characteristics are transferable, removed by biocidal treatments, and active against increasing doses of R. solani AG-8, Gaeumannomyces graminis var. tritici and Fusarium graminearum. Disease severity and the viable population of Rhizoctonia are reduced in suppressive soil but the causal agent is still present. The microbial populations in suppressive and non-suppressive soil appear to differ both in their functioning and composition. The control strategy is developed through manipulation of the existing soil biota with farming practices. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996

xviii, 211 leaves : tables, photos, (1 col.), diags ; 25 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 Agronomy, 1976

It is well recognised that the inherent soil variability and the effect of vegetation, in particular the effect of tree root reinforcement, have a significant effect on the stability of a natural slope. However, in practice, these factors are not commonly considered in routine slope stability analysis. This is due mainly to the fact that the effects of soil variability and vegetation are complex and difficult to quantify. Furthermore, the available slope stability analysis computer programs used in practice, which adopt conventional limit equilibrium methods, are unable to consider these factors. To predict the stability of a natural slope more accurately, especially the marginally stable one, the effects of soil variability and vegetation needs to be taken into account. The research presented in this thesis focuses on investigating and quantifying the effects of soil variability and vegetation on the stability of natural slopes. The random finite element method (RFEM), developed by Griffiths and Fenton (2004), is adopted to model the effect of soil variability on slope stability. The soil variability is quantified by the parameters called the coefficient of variation (COV) and scale of fluctuation (SOF), while the safety of a slope is assessed using probability of failure. In this research, extensive parametric studies are conducted, using the RFEM, to investigate the influence of COV and SOF on the probability of failure of a cohesive slope (i.e. undrained clay slope) with different geometries. Probabilistic stability charts are then developed using the results obtained from the parametric studies. These charts can be used for a preliminary assessment of the probability of failure of a spatially random cohesive slope. In addition, the effect of soil variability on c'–ϕ' slopes is also studied. The available RFEM computer program (i.e. rslope2d) is limited to analysing slopes with single-layered soil profile. Therefore, in this research, this computer program is modified to analyse slopes with two-layered soil profiles. The modified program is then used to investigate the effect of soil variability on two-layered spatially random cohesive slopes. It has been demonstrated that the spatial variability of soil variability has a significant effect on the reliability of both single and two-layered soil slopes. Artificial neural networks (ANNs), which are a powerful data-mapping tool for determining the relationship between a set of input and output variables, are used in an attempt to predict the probability of failure of a spatially random cohesive slope. The aim is to provide an alternative tool to the RFEM and the developed probabilistic stability charts because the RFEM analyses are computationally intensive and time consuming. The results obtained from the parametric studies of a spatially random cohesive slope are used as the database for the ANN model development. It has been demonstrated that the ANN models developed in this research are capable of predicting the probability of failure of a spatially random cohesive slope with high accuracy. The developed ANN models are then transformed into relatively simple formulae for direct application in practice. The effect of root reinforcement caused by vegetation is modelled as additional cohesion to the soils, known as root cohesion, cr. The areas affected by tree roots (i.e. root zone) are incorporated in the finite element slope stability model. The extent of the root zone is defined by the depth of root zone, hr. Parametric studies are conducted and the results are used to develop a set of stability charts that can be used to assess the contribution of root reinforcement on slope stability. Furthermore, ANN models and formulae are also developed based on the results obtained from the parametric studies. It has been demonstrated that the factor of safety of a slope increase linearly with the values cr and hr, and the contribution of root reinforcement to a marginally stable slope is significant. In addition, probabilistic slope stability analysis considering both the variability of the soils and root cohesion are conducted using the modified RFEM computer program. It has been demonstrated that the spatial variability of root cohesion has a significant effect on the probability of slope failure. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1349971 / Thesis (Ph.D.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009

[Truncated abstract] Some plants, such as legumes, are able to use atmospheric nitrogen as a nitrogen source due to the nitrogen-fixing bacteria residing in specialised root structures called nodules. The exchange of carbon and nitrogen between the host plant (legume) and the nitrogen- fixing micro-symbiont is vital for biological nitrogen fixation. In particular, transport of C4-dicarboxylates, mainly malate, from the plant to the micro-symbiont, and the reverse transport of fixed nitrogen in the form of ammonium are essential for symbiotic nitrogen fixation. In the legume nodule, the symbiosome membrane (SM) surrounds the bacteroid and all exchanges of metabolites and nutrients that occur between the plant and the micro-symbiont must cross this membrane. Recently it has been established that cycling of amino acids across the SM is also critical for optimal symbiotic nitrogen fixation. Therefore to fully understand this agriculturally significant phenomenon, the mechanisms facilitating these exchanges need to be investigated. The major aim of this study was to increase the understanding of nutrient exchange within the nodule at the molecular level by isolating and characterising genes encoding transporters responsible for malate and amino acids transport in soybean (Glycine max, L.), with particular interest in genes significantly or highly expressed in nodules. A combination of molecular and biochemical techniques was used to achieve this. ... Southern blot analysis showed that a small gene family of up to five members encodes these proteins in soybean. A full-length cDNA, designated GmAAP5, was isolated that encodes a novel, putative amino acid transporter. Molecular characterisation of this cDNA and that of GmAAP1 (GenBank Accession no: AY029352), a previously identified putative amino acid transporter gene, was done. Expression analyses showed relatively high expression of GmAAP5 in soybean nodules compared to that in leaf and root tissues, while GmAAP1 showed uniformly high expression in root, leaf and nodule tissues. Phylogenetic analysis of the deduced amino acid sequences of known functional AAPs from dicotyledonous plants revealed that GmAAP1 is most closely related to AAP2 from V. faba, while GmAAP5 is more closely related to AAPs from non-leguminous plants than from leguminous plants. Based on the functional characterisation of the AAPs with which GmAAP1 and GmAAP5 cluster, it is likely that both transporters are neutral and acidic amino acid transporters within the AAP subfamily.

Biserrula pelecinus L. has been introduced to Australia from the Mediterranean region, in the last decade due to many attractive agronomic features. This deep rooted, hard seeded, acid tolerant and insect resistant legume species provides high quality food for cattle and sheep, and grows well under the harsh edaphic and environmental conditions of Australia. In 1994, B. pelecinus was introduced to a site in Northam, Western Australia where there were no native rhizobia capable of nodulating this legume. The introduced plants were inoculated with a single inoculant strain of Mesorhizobium sp., WSM1271. This study investigated whether a diversity of rhizobia emerged over time. A second objective was to investigate the possible mechanisms involved in the diversification of rhizobia able to nodulate B. pelecinus. Eighty eight isolates of rhizobia were obtained from nodules on B. pelecinus growing at the Northam site in August 2000, six years after introduction. These plants were self-regenerating offspring from the original seeds sown. Molecular fingerprinting PCR with RPO1 and ERIC primers revealed that seven strains (novel isolates) had banding patterns distinct from WSM1271 while 81 strains had similar banding patterns to WSM1271. A 1400 bp internal fragment of the 16S rRNA gene was amplified and sequenced for four of the novel isolates (N17, N18, N45 and N87) and WSM1271. The phylogenetic tree developed using these sequences clustered the novel isolates in Mesorhizobium. There were >6 nucleotide mismatches between three of the novel isolates (N17, N18, N87) and WSM1271 while there were 23 nucleotide mismatches between N45 and WSM1271. When B. pelecinus cv. Casbah was inoculated with the novel isolates, five (N17, N18, N39, N46 and N87) yielded <40% of the shoot dry weight of the plants inoculated with the original inoculant (WSM1271). Novel isolates N15 and N45 were completely ineffective on B. pelecinus cv. Casbah. Physiological experiments to test the ability of the novel isolates and WSM1271 to grow on 14 different carbon sources (N acetyl glucosamine, arabinose, arbutine, dulcitol, β-gentiobiose, lactose, maltose, melibiose, D-raffinose, saccharose, L-sorbose, D-tagatose, trehalose and D-turanose) as the sole source of carbon, intrinsic resistance to eight different antibiotics (ampicillin, chloramphenicol, gentamicin, kanamycin, nalidixic acid, spectinomycin, streptomycin and tetracycline) and pH tolerance (pH 4.5, 5.0, 7.0, 9.0) revealed that the novel isolates had significantly different carbon source utilization patterns to WSM1271. However, pH tolerance and intrinsic resistance to antibiotics were similar between the novel isolates and WSM1271 except for streptomycin (100 μg/ml). Novel isolates N17, N18, N46 and N87 were susceptible for this antibiotic while the other novel isolates and WSM1271 were resistant. Host range experiments were performed for the novel isolates N17, N18, N45, N87, WSM1271 and two other root nodule bacteria (RNB) previously isolated from B. pelecinus growing in the Mediterranean region (WSM1284 and WSM1497) for twenty one legumes (Amorpha fruticosa, Astragalus adsurgens, Astragalus membranaceus, Astragalus sinicus, Biserrula pelecinus cv Casbah, Dorycnium hirsutum, Dorycnium rectum, Glycyrrhiza uralensis, Hedysarum spinosissimum, Leucaena leucocephala, Lotus corniculatus, Lotus edulis, Lotus glaber, Lotus maroccanus, Lotus ornithopodioides, Lotus parviflorus, Lotus pedunculatus, Lotus peregrinus, Lotus subbiflorus, Macroptilium atropurpureum, and Ornithopus sativus). Only isolate N17 have the same host range as WSM1271 in that they both nodulated B. pelecinus and A. membranaceus, while the other three novel isolates, WSM1284 and WSM1497 had a broader host range than WSM1271. Three isolates N18, N45 and N87 formed small white nodules on M. atropurpureum, in addition to nodulating the above hosts. Isolates N18 and N45 also nodulated A. adsurgens while N45 was the only isolate to nodulate L. edulis. Isolate N87 was the only isolate to nodulate A. fruticosa. WSM1497 nodulated A. adsurgens, A. membranaceus, B. pelecinus and L. corniculatus while WSM1284 was a promiscuous strain that nodulated 16 host species out of the 21 tested. A 710 bp internal region of nifH, a 567 bp internal region of nodA and a 1044 bp internal region of intS were sequenced for N17, N18, N45, N87 and WSM1271. The sequence comparison showed that the sequences of the above three genes of the four novel isolates were identical to that of WSM1271. Eckhardt gel electrophoresis revealed that WSM1271, three other RNB isolates from B. pelecinus from the Mediterranean region and isolate N18 each have a plasmid of approximately 500 kb while N17, N45 and N87 are plasmid free. Probing of the plasmid DNA from the Eckhardt gel with nifH and nodA probes indicated that these two genes were not located on the plasmid. Furthermore, the results of this study demonstrated that 92% of the nodules on B. pelecinus growing in the Northam site six years after the introduction of this plant were occupied by the inoculant strain and the N2 fixation efficiency of the progeny strains of WSM1271 remain similar to the mother culture. This study also showed that the carbon source utilization pattern, intrinsic antibiotic resistance and pH range of the progeny strains of WSM1271 remain relatively similar, except for few variations in carbon source utilization patterns. This thesis clearly demonstrated that phenotypicaly, genetically and phylogenetically diverse strains capable nodulating B. pelecinus evolved through symbiotic gene transfer from the inoculant strain to other soil bacteria within six years. The presence of intS, and the evidence of gene transfer between these Mesorhizobium strains indicates that transfer of symbiotic genes may have occurred via a symbiosis island present in WSM1271.

Thesis (doctoral)--Helsinki University of Technology, 2007. / Includes bibliographical references. Also available on the World Wide Web.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 5 uppsatser.