Sorption/desorption equilibria control the concentrations of P in the soil solution and thereby both its chemical and bioavailability. Apart from the equilibrium phosphorus dynamic, which has been used to determine buffer power and the equilibrium concentration for the studied soils at Cruden Bay, Balmedie, Blairton Wood and Newburgh, the buffer power and equilibrium concentration were affected by the fertiliser incubation period. The differences in PBP and EPC were observed between the soils with high constituents of organic matter and clay in their texture and those which had sandy and sandy loam textures. The glasshouse study was conducted to evaluate the relationship between soil phosphorus availability and two contrasting spring barley genotypes. Both genotypes: Tocada and Natasha responded to added phosphate fertiliser in all treatments. The vegetative growth variations among the genotypes did not appear at different phosphorus levels for most of the studied soils. However, the study has revealed the differences in the root system of Tocada and Natasha in low phosphorus conditions. Tocada was prone to forming large root biomass when compared to Natasha in insufficient phosphorus conditions. Natasha behaved in the opposite way in sufficient phosphorus conditions. The findings of this study confirm that phosphorus use efficiency and root architecture of these genotypes are correlated with each other to exploit more available phosphorus in the rhizosphere. Both Agronomic and physiology Phosphorus use efficiency have been tested. Although the difference in agronomic phosphorus use efficiency among the genotypes was not recorded, some different observations in physiological phosphorus use efficiency among the genotypes were noticeable in some cases.

In Orkney, Bere (a landrace of barley) is traditionally cultivated in marginal areas with very low inputs. There was little information on the effects of different agricultural inputs on Bere. Therefore this research investigated the effects of nitrogen, fungicide and plant growth regulator on grain yield, quality and economic returns of Bere which were compared with Optic (a modern malting barley variety) during 2008 and 2009. The present study found that ears m-2 and 1000-grain weight were two important components responsible for yield variations between Bere and Optic and were consistently lower in the former than the latter. The results indicated that disease score, lodging index and grain nitrogen content were higher in Bere than Optic, and the former had more stable yield than the latter during the study period. Increasing nitrogen fertilizer rate enhanced ears m-2 and grain yield of both varieties. However, the highest N rate (90 kg ha-1) resulted in the highest disease score and lodging index which consequently reduced grain quality of Bere. Fungicide application at Zadoks growth stage 37 reduced disease score and enhanced grain yield of both varieties compared with control plots and this was attributed to higher ears m-2 and 1000-grain weight. The plant growth regulator Upgrade (mixture of ethephon and chlormequat chloride) applied at the recommended rate at Zadoks growth stage 31 resulted in the lowest lodging index in Bere. However, it had no significant effect on grain yield and grain nitrogen content of both varieties. Gross margin analysis indicated that Bere compared favourably with Optic due to its higher grain price. Although, plant growth regulator did not justify its expenditure for controlling lodging, its application is recommended to ease harvesting and to avoid pre-harvest yield and quality losses in Bere.

The aims of the present study were to evaluate: i.) mixtures of spring barley (Hordeum vulgare L.) by combining cultivars differing in plant height or time of maturity, and ii) mixtures of cultivars of cocksfoot (Dactylis glomerata L.) and timothy (Phleum pratense L.) based on differences in maturity group. Experiments were conducted on mixtures of cultivars of spring barley and on mixtures of cocksfoot and timothy. The grain yields of all the mixtures tested in 1985 were similar. Of 4 mixtures tested, Midas/Triumph and Kym/Klaxon outyielded (though not significantly) their respective highest yielding pure stand component. Within mixtures, the taller or the earlier maturing component was more aggressive than the other component. All four mixtures produced relative yield totals (RYT) greater than 1.0. The highest RYT's came from mixing cultivars of different maturities. In the second experiment, in 1986, Triumph outproduced both Doublet and Klaxon, having more ears and grains per M2. The mixtures did not vary in grain yield from the mean of their pure stand components. In mixtures, the taller component was generally more dominant. In contrast to the previous year, all three mixtures tested in 1986 had yields approximately double those of the previous year, and RYT's less than 1.00. In the third experiment, application of fertiliser had a significant effect on the grain yield of pure stands and mixtures. At low fertilty, Triumph outproduced Doublet in both number of grains per area and grain yield, though at moderate fertility the opposite was true. In mixture, Triumph outcompeted Doublet at both low and moderate fertility levels. It produced more ears and grains per m2 and thus higher grain yields. The relative yields of Triumph were higher than those of Doublet. Similar results were found in glasshouse experiments. An experiment was set up in 1985, and ran over for 3 years, to investigate the performance of mixtures of early and late cultivars of cocksfoot and timothy. In the establishment year, there was no difference between total dry matter yield of full density pure stands of cocksfoot and timothy, though cocksfoot produced more tillers but less total harvestable leaf area than timothy. In the second year, full density pure stands of timothy produced higher total dry matter, mean number of tillers and total harvestable leaf area than full density pure stands of cocksfoot. In the third year (the only year when fertiliser was applied), full density pure stands of cocksfoot produced higher total dry matter, mean number of tillers and total harvestable leaf area than full density pure stands of timothy. Arguably, the best overall yield came from early cocksfoot/late timothy because it had one very high yielding year and in no year was RYT less than 1.0. The results from all the experiments suggest that mixtures can in some circumstances outyield the midmonoculture yields of their components. This occurs when (i) the components are of contrasting types ( e.g. in morphology and growth pattern) and (ii) when pure stand yields are inherently low. This reinforces the opinion that mixtures may be of greatest benefit in low input agricultural systems.

Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 2001. / This study investigated the effect of different homoeopathic potencies of abscisic acid (ABA) in the presence of gibberellic acid (GA3) on the production of a.-amylase in the de-embryonated endosperm half-seeds of barley (Hordeum vulgare) in order to investigate whether these potencies were able to produce a biological effect. The aleurone layer of the barley (Hordeum vulgare) grain secretes hydrolases that mobilise endosperm reserves during germination. The synthesis and secretion of these hydrolases (principally a.-amylase) is under hormonal regulation. Gibberellic acid (GA) stimulates the synthesis and secretion of a.-amylase and abscisic acid (ABA) reverses this effect. It is for this reason that barley aleurone has been used extensively as a model system for the study of signal transduction in response to GA and ABA (Ritchie, McCubbin, Ambrose, Kao and Gilroy, 1999). For this research five different homoeopathic potencies were used namely - the 4CH, 9CH, 15CH, 30CH and the 200CH. Two methods were used in this experiment namely - spectrophotometry and radial diffusion. For each method three replications were used. Each replication consisted of: five groups of 20 half-seeds treated with the various potencies (the 4CH, 9CH, 15CH, 30CH and the 200CH) of ABA, with a dilution at GA3 at 1x 10.g;five groups of 20 half-seeds treated with the of GA3 at 1X 10.9 (the control) and five groups of 20 half-seeds treated with only the incubation buffer (calcium nitrate). An a.-amylase curve was constructed for both methods using pure a.-amylase at 1350 enzyme units /mg / M

Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 2001. / The potentisation process during which homoeopathic preparations are produced, raises the concern that these remedies have a placebo effect, since they contain no active molecule of the substance used to prepare them (in ultra high dilutions) by the time they are administered to a patient. Plant models therefore offer a more direct method of examining the efficacy of homoeopathically prepared solutions. This study investigated the effects of homoeopathic preparations of gibberellic acid on the germination of barley seeds (Hordeum vulgare L.) as measured by a germination index. The effects of GA3 at potencies of 4cH, lScH, 30cH and 200cH on germination rate and seedling development were tested on barley seeds of high-, medium- and low- vigour. The index used comprised the rate at which seeds germinated, which was the time it took for 50 percent of those seeds that did germinate, to germinate (i.e. Tso); seedling development experiments as assessed by taking final germination counts 7 days after start of imbibition, shoot and root lengths, and seedling dry mass. Biological activity of homoeopathically prepared GA3 at lScH was evident in medium vigour seeds, since this treatment resulted in significantly long root development. Highvigour barley seeds imbibed in GA3 (0.5 g L\xB7l ) were found to germinate the fastest of all treatment groups, and high-vigour seeds imbibed in homoeopathically prepared GA3 at 4cH, 30cH and 200cH, germinated faster than those seeds not receiving GA3 in any form (the control). Amongst high-vigour seeds, prior imbibition with homoeopathically / M

Chlormequat can be applied to winter barley for growth manipulation with a view to increasing ear number per m<SUP>2</SUP> and hence grain yield, but, reviewing the literature on field trials showed the effects were not consistent. Previous work showed that the grain yield per m<SUP>2</SUP> of winter barley was strongly correlated with the number of grains per m<SUP>2</SUP> which itself was shown to be mostly influenced by the number of ears per m<SUP>2</SUP>. Three agronomic factors, cultivar, sowing date and nitrogen fertiliser, were identified from the literature as important influences on ear production in winter barley. These were therefore considered to have the potential to modify plant response to chlormequat, in terms of ear production, and might thus account for some of the inconsistency of the effect of chlormequat on grain yield in field trials. The intention of these studies was to move towards a description of winter barley production systems into which chlormequat may be integrated to consistently increase grain yield. Because little information was available on the growth, development and grain yield components of field grown modern winter barley cultivars, these attributes were monitored and analysed in detail for a range of modern cultivars grown at two sites in north-east Scotland in the harvest years 1984 and 1985. Tipper and Maris Otter were identified as strongly contrasting cultivars, being good examples of the extremes of the range of growth parameters found. In addition, the analyses identified the extreme importance of high cultivar biomass per plant for the attainment of high cultivar grain yield per plant. Evidence that increases in biomass have already contributed to the higher grain yields of modern cultivars of both spring barley and winter wheat was also found within the literature. The effect of chlormequat at a range of application times in the spring on early and late sowings of Igri, Tipper (low ear production) and Maris Otter (high ear production) was tested. When averaged over all cultivars and sowing dates chlormequat applied prior to stem extension significantly increased the number of ears per m<SUP>2</SUP> in 1983--4 which led to increases in grain yield. In 1984--5 chlormequat applied at the start of stem extension significantly increased the number of grains per ear and significantly increased grain yield; within-plant uniformity, in terms of shoot contribution to grain yield, was also increased. Chlormequat had no consistent effect on the grain yield of the cultivars Igri and Tipper, but did increase the grain yield of both early and late sown Maris Otter by increasing the number of grains per m<SUP>2</SUP>. These higher grain numbers were achieved through consistent increases in the number of ears per m<SUP>2</SUP> which were nearly always associated with increases in the number of grains per ear on the main stem and early primary tillers. These larger sink sizes of Maris Otter followed temporary reductions in shoot height which were offset by compensatory increases in shoot growth. The growth, development and grain yield components of Maris Otter were described in detail with a view to enabling cultivars with similar growth characteristics to be identified. Application of nitrogen fertiliser did not modify the effect of chlormequat on shoot height or shoot dry weight. In these experiments chlormequat increased neither ear number per m<SUP>2</SUP> nor grain number per ear; therefore, the effect of nitrogen application strategy on the ability of chlormequat to increase in sink size could not be evaluated. It was suggested that application of chlormequat to Igri winter barley receiving more than 100 kg N/ha is unlikely to reduce grain yield. These investigations confirmed the extreme importance of high crop biomass for the attainment of high grain yield. The findings of these investigations together with the findings of a re-analysis of advisory service field trial data on the effect of chlormequat on winter barley are discussed in relation to commercial winter barley production. Finally, it is suggested that more consistent increases in grain yield may be achieved by restricting the use of chlormequat for tiller manipulation to cultivars of the Maris Otter type such as Halcyon and Pipkin which are slow developing, produce relatively large numbers of tillers and eventually many ears per plant.

In recent years, a new threat to barley crops has emerged and gained substantial attention due to its rising economic importance. Relatively little is known about the infection strategy and development of Ramularia leaf spot (RLS) disease on barley. Therefore the overall aim of this project was to increase the understanding of fundamental biology and life cycle of the causal agent, R. collo-cygni. Chapter 2 describes the horizontal transmission of the fungus on barley. Both field and transgenic R. collo-cygni isolates expressing GFP and dsRed fluorescent reporter markers were utilised to visualise the infection progression in living host tissues by various light and confocal microscopy. The existence of a previously unknown structure called stomatopodium (infection peg), involved in the penetration of stomata, was demonstrated. The fungus initially exhibited symptomless epiphytic growth, extending above epidermis and connecting the hyphal aggregates inside substomatal cavities and subsequent initial sporulation. However, during the transition into symptomatic phase, the organised intercellular growth of hyphae into the mesophyll was observed. This hyphal network was involved in the production of asexual spores demonstrating that the raprture of epidermal layer was responsible for local necrosis observed for RLS. In addition to barley, several other speculated R. collo-cygni hosts have been used to verify their compatibility to the pathogen. In chapter 3, a whole plant inoculation assay was developed to investigate the mode of the fungal seed-borne transmission by using GFP expressing strain of the fungus. It is shown here for the first time that the vertical transmission is systemic, involving symptomless colonisation of embryo and closely resembled the mode of dissemination observed for Neotyphodium species, mutualistic fungal endosymbionts on grasses. The impact of fungal infection on seed germination ability was also examined that revealed no significant difference between clean, moderate and high levels of R. collo-cygni DNA. Chapter 4 represents an attempt to discover and analyse the sexual development in R. collo-cygni. As a first step to understand the sexual reproduction cycle in this apparently asexual species, the genetic structure of the mating system was characterised by using PCR-based techniques which demonstrated the heterothallic nature of the fungus. The defined population of R. collo-cygni field isolates was then screened for the presence of the discovered mating type idiomorphs (mat) to determine the frequencies of the mating types in the defined R. collo-cygni populations. The segregation ratio of mat1 and mat2 close to 1:1 indicated a frequent sexual reproduction. In order to verify the existence of functional sexual stage in R. collo-cygni, potential sexual development was induced using the potentially compatible isolates and a comprehensive analysis was undertaken by correlative use of light-, confocal- and low temperature scanning electron microscopy. Two types of multicellular bodies were observed and described. First was the speculated Asteromella stage (male donor) that carries spore-like spermatia. The second structure initially resembled sclerotia that in only a few instances developed into perythecium/ pseudothecium that appeared to carry the sexual spores, ascospores enveloped in asci. Chapter 5 demonstrates the role of rubellin toxin in symptom development by using autofluorescence phenomenon. The structure of putative molecular machinery involved in rubellin biosynthesis was addressed by using bioinformatics approaches and the complete R. collo-cygni genome sequence. A gene cluster encompassing several components of other known secondary metabolite biosynthesis pathways, such as that of dothistromin and aflatoxin, was found and putative protein function of the genes is hypothesised.

No description available.

Bibliography: leaves 132-155. / viii, 155 leaves : ill., plates, charts (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A putative callose synthase gene, designated HvGSL1 cDNA is siolated from barley and its involvement in callose biosynthesis is investigated. A near-full length HvGSL1 cDNA encoded a protein showing approximately 30% identitly with that of yeast FKS genes at the amino acid level. The function of this geen was investigated by heterologous expression, protein purification, immunochemistry and mass spectrometric analysis. Results provide strong evidence that the gene encodes a protein which is associated with callose synthase activity, and is likely to encode the catalytic subunit of the synthase complex. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2003

Bibliography: leaves 133-157. / xiii, 157, [22] leaves, [31] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The principle aim of the work described in this thesis was to use protein engineering to increase the thermostability of barley (1->3,1->4)-B-glucanases / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2000