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Doctor of Philosophy / A rice grain is composed of 90% starch, and amylose contributes to up 30% of the starch with the remainder as amylopectin. The structure of starch largely defines the quality of rice, yet the methods to characterise starch have not been reviewed recently. This thesis begins by using the simplest form of starch, debranched amylopectin, to detail and apply the principles of molecular weight theory using Size Exclusion Chromatography (SEC) to illustrate that without correct calibration the molecular weight distribution of starch has been underestimated. In contrast to amylopectin, amylose is difficult to isolate from flour without causing irrevocable damage, is unstable in an aqueous system and is believed to be impossible to debranch with isoamylase. Here an amylose-rich fraction was extracted directly from flour using hot water to avoid the structural–damaging isolation techniques used previously. The ability of isoamylase to debranch the amylose was shown through traditional methods of controlled enzyme degradation of the starch, ensuring that association of chains did not hinder access to the enzyme activation site, and through the contrast of 1H NMR spectra before and after the debranching event. Further, it was shown that 20% of carbohydrate was not recoverable from the SEC, and the unrecoverable carbohydrate is likely to be of high molecular weight and with long chains. High temperatures during the grain filling period are known to impede on the rice quality of one classification of non-waxy varieties. That hypothesis was rigorously examined by growing rice from a wide genetic background in three temperature regimes, followed by analysis of amylose at a functional, structural and synthesis level. From that phenotypic data, the rice varieties could be divided into three distinct groups – two of poorer quality in an increasingly warmer climate. Candidate single nucleotide polymorphisms (SNPs) have been identified, and a mechanism proposed, to explain the phenotypes. Linking a phenotype to a SNP allows the opportunity for wide scale screening of varieties to predict the quality of rice in an increasing warmer environment. Rice quality has the potential to change with elevated carbon dioxide levels, both alone and with increased temperature. Here, the quality traits of varieties grown in four combinations of temperature and carbon dioxide levels were assessed. The negative impact of temperature on grain quality was unable to be overcome by an increase in carbon dioxide in all but one quality. Chalk is the undesirable opaque belly of a grain that defines the market price of the grain. In elevated carbon dioxide, the proportion of grains containing a high amount of chalk per grain which will increase the market value of the grain and may help to alleviate the burden of climate change on rice farmers.

The rise in atmospheric CO2 partial pressures that is predicted for the 21st Century is likely to increase productivity and alter nutrient of C3 crop plants. Consequently, physiological data on plant growth and nutrition at elevated CO2 are required, because these data underpin simulation models, which are needed for management of crops under the CO2 scenario for the mid to late 21st Century.In particular, information is required about management of nitrogen(N) fertilisation because this mineral nutrient plays a central role in the growh of many crops. Rice was chosen as a model plant because of its widespread consumption throughout the world and its responsiveness to CO2 and N fertilisation. There were three major hypotheses: first, that early exposure of rice plants to high CO2 is required to achieve the maximum growth and tillering response; secondly, that early increases in growth and tillering at high CO2 are associated with the phytohormone, ethylene; and thirdly, that growth at elevated CO2 decreases leaf N concentrations required to support maximum dry mass production and photosynthetic rates (critical concentrations).Several tests and experiments were conducted and results noted. It is likely that grain yield will be greater as the atmospheric CO2 partial pressure rises even when N supplies are low, providing that high CO2 does not cause accelerated tiller abortion at low N. / Doctor of Philosophy (PhD)

With the rapid increase of the world energy demand and consumption, the method and techniques to analyze, improve and optimize energy conversion systems have to deal not only with direct fuel exergy (energy) consumption, but also with other resources, which have associated exergy consumptions, and with environmental impacts, such as global warming. A general method for energy conversion system analysis is presented in this thesis. This method uses exergy as a measure to compare and analyze the natural resource consumption (both fuels and materials) and the global warming impact of different energy conversion systems for their life-time. The method, which adds the fuel production exergy and material exergy into consideration, allows more complete exergy analyses to be conducted. The global warming impact due to the chemical emissions and impact associated with direct exergy consumption (fuel consumption) as well as system equipment materials consumption of the energy conversion system are considered together in this thesis. Based on the concept of exergy, the Total Equivalent Resource Exergy (TERE), which includes both direct resource exergy consumption and resource exergy needed to recover the total equivalent global warming gases of the energy conversion system, is proposed in this thesis. TERE uses exergy as a criterion to compare the energy conversion systems and providing information of how effective a system is regarding the use of natural resources. The calculation of TERE values for the selected energy conversion systems indicates that the resource exergy and the environmental impact exergy are both substantial impacts and should be compared together. This concept of TERE can be used as the objective function for energy system design and optimization. / Graduation date: 1996

I examined habitat electivity and movement patterns of adult spring chinook salmon at microhabitat and channel unit spatial scales, and seasonal to annual temporal scales in seven streams in the Grande Ronde, John Day, and Imnaha basins. The objective was to compare habitat use and availability among streams, channel units, and microhabitats, and to assess chinook salmon fidelity to those habitats using radio-telemetry. The analyses showed that habitat quality and availability in the seven study streams varied. Each stream posed different physical constraints on adult chinook salmon habitat; this was reflected by the differential use of habitat by salmon among streams. Salmon elected pools almost exclusively in the John Day Basin, whereas pools and riffles were elected in near equal proportion in the Grande Ronde and Inmaha basins. Within streams, use was similar between years. Almost all salmon were observed in association with cover, but the type of cover largely reflected availablity. Chinook salmon elected the deepest depths within channel units (microhabitat scale), but not necessarily the deepest channel units among streams (channel unit scale). Chinook salmon did not elect cooler stream temperatures within channel units in any study stream, except the Middle Fork John Day River. Radio-tagged chinook showed a high fidelity to habitats, except when stream temperatures approached lethal limits. Due to stream specific differences in habitat availability and use, multiscale habitat assessments for individual streams are recommended to increase the success of watershed restoration activities. / Graduation date: 1999

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