School of Botany - Theses
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ItemNo Preview AvailableThe estimation of indole-3-acetic acid(University of Melbourne, 1979)This project evolved from a consideration of polarity in the embryo of the brown alga, Hormosira banksii. It was hypothesized that uneven distribution of auxin due to unilateral illumination led to the protrusion of the rhizoid on the dark side of the zygote. It was intended to test this hypothesis by supplying the zygotes with labelled indole-3-acetic acid and, after incubation in this medium, examine the zygotes using micro-autoradiography. The concentration of indole-3-acetic acid in the cell had to be determined in order that the radioactive compound could be supplied to the zygotes at physiological concentrations. This required the review and selection of extraction, purification and assay methods. The literature review encompasses examples of most of the types of methods in current use. Since the various methods of bioassay have many advantages, limitations and equipment requirements in common, only two methods are described. As the same can be said for other types of methods, these are not considered in detail. The literature review is directed at the researcher seeking a method for the assay of auxin, and, to this end, key references are cited to enable the worker to gain more information. On consideration of the equipment available, the method using the fluorescence of 2-methyl indole-?-pyrone appeared the most suitable. For purification, chromatography using a column of polystyrene resin seemed feasible. Finally, methanol, a widely-used solvent, was selected for extraction. The assay method was examined first, as the quality of extraction and purification could then be determined using the assay. Similarly, the purification was examined prior to the method of extraction. In assessing the capabilities of the methods, many problems were encountered - some peculiar to the equipment used, but several fundemental problems related to the techniques themselves. In fact, considering the findings of this work, it is apparent that the methods of auxin-assay warrant reappraisal with particular respect to losses.
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ItemPollen-wall proteins and breeding systems of plants(University of Melbourne, 1978)Quatitative cytochemical methods have been developed to estimate changes during development in the pollen-wall proteins. Acid phosphatase was used as a marker for intine proteins, and non specific esterase for the exine proteins. In marrow-stem kale, Brassica oleracea and ryegrass, Lolium perenne the intine enzyme showed two peaks of accumulation during development, the first corresponding to its synthesis and incorporation in the intine, and the second to accumulation in the pollen cytoplasm at maturity. In contrast, the exine enzyme showed a single peak at pollen maturation. This was correlated with dissolution of the tapetum and consequent loss of its very high esterase activity, coincident with the accumulation of esterase in the exine cavities. In sunflower, Helianthus annuus acid phosphatase and esterase were detected in both exine and intine sites during pollen development. Acid phosphatase was associated with the nexine at pre-vacuolate period with high levels in the tapetum. At mid-vacuolate period the tapetum became plasmodial and enzyme activity was detected around the exine surface and was transferred to the exine cavities by the end of the vacuolate period. Esterase activity was associated with the exine at pre-vacuolate period; subsequently during the vacuolate period, activity was present in the intine, and in the cytoplasm at maturity. Two peaks of accumulation were detected, closely resembling those for the intine marker enzyme in Brassica and Lolium. The developmental cytochemistry of the stigma of Helianthus, Lolium and Secale has been investigated with a view to understanding the nature of selfincompatibility, the site of tube arrest and the route of pollen tube penetration. The callose rejection response in pollen and stigma that has been established for Cosmos and various Crucifers have been found in Helianthus. The rejection reaction is found to occur in the pollen grain and pollen tubes of grasses. The callose produced in germinating self pollen of the grass, Secale cereale has been isolated by a degredative physicochemical procedure. Partial acid hydrolysis, enzyme hydrolysis, sugar analysis and methylation analysis have shown that the material is a 1,3-?-linked glucan; however some evidence points to the presence of 1,4-?-linkages in addition.
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ItemNo Preview AvailableCollected papers submitted for the degree of Doctor of Science in the University of Melbourne(University of Melbourne, 1978)The two major themes of this thesis of published work reflect my interest in the function of the trace element boron in plant nutrition and also my later, and present, involvement with the whole-plant aspects of photosynthesis and carbon nutrition, including that of crop species. In the 1950's there was,in Australia, great interest in the plant physiology of the plant trace elements - Mn, Zn, Cu, Mo and B. This interest derived from the findings of the 1940's that the correction of trace element deficiencies (in plants, cattle and sheep) increased agricultural production in existing pastoral areas, and also allowed hitherto unproductive regions to be cultivated (see, Anderson, 1971 and Underwood, 1962). My interest in the function of boron in plant nutrition originated under these influences in 1956, when I arrived in Melbourne University on an appointment whose brief was to teach plant and crop physiology to Agricultural Science students. This research interest widened in the early 1960 ' s in include aspects of the photosythetic and gas-exchange behaviour of leaves and intact plants. This was prompted by several influences including an interest in the physiological aspects of crop production and plant adaptation, the horizons that were opened by Gaastra's (1959) pioneering paper, and the availability of infrared absorption instruments (IRGAs) that allowed the accurate and instantaneous measurement of carbon dioxide and water vapour in an air stream. These involvements were much stimulated by the, initially apparently disparate, work of the 1960's on the physiology and biochemistry of photosynthesis in which some intellectual coherence was achieved in 1969-1970. This was the realisation that there existed in plants at least three distinct 'modes' of photosynthesis - C^, C4 and CAM (see: Bj�rkmann, 1973). My continuing association with Agricultural Science, and with its students and problems, also lead to work in crop physiology, mainly using the ideas and techniques associated with the investigation of photosynthesis and growth.
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ItemThe ecology of amsinckia (amsinckia spp.) in wheat crops in Victoria(University of Melbourne, 1977)Amsinckia hispida, A. lycopsoides and A. intermedia are serious annual weeds of wheat crops in Victoria. Studies of cytology, seed germination, reproductive development, growth physiology, and competitive ability in relation to wheat were undertaken to elucidate the biological and ecological characteristics of Amsinckia that contribute to the success of these species as weeds. The most widespread species in Victoria is A. hispida, which was used in all the experimental studies. Observations in the field included all three species. Chromosome counts indicated the close relationship between A. hispida, a native of South America, and the other two North American species. All present similar problems as weeds. Germination was found to be regulated by a primary dormancy, which confined germination during after-ripening to low-temperatures (<10�C) and short photoperiods (darkness to 8 hr). In the field germination occurred as a flush, the magnitude of which depended on the timing and amount of rainfall, and the depth of burial. Seed produced in the previous spring, lying on or close to the soil surface, gave high germination percentages from the autumn to early winter. Ungerminated buried seed developed a light requirement for germination, which may be satisfied by cultivation. Seed held in the dark for 56 days at temperatures of 15� and 25�C developed a secondary dormancy, which greatly restricted germination under normally favourable conditions. These regulatory mechanisms would serve to confine germination to the normal growing season for Amsinckia, while providing several strategies for coping with adverse seasonal conditions as well as periodic cultivation. Reproductive development to flower initiation was retarded by increase in temperature from 10* to 20�C, whereas subsequent development was hastened by the same temperature increase. Increase in photoperiod from 8 to 16 hr greatly hastened development to flowering. Environmental regulation of development ensures that Amsinckia plants complete their life cycle before unfavourable conditions ensue in the late spring, irrespective of the time of germination, while balancing vegetative growth for maximum effectiveness in competition with reproductive growth for maximum seed production. Vegetative growth was characterized by a high relative growth rate (c. 0.18 mg mg-1 day-1) under moderate temperatures (15-20�C and high irradiance (no shade), associated with a high net assimilation rate (0.4-0.5 mg cm-2 day-1 ) and a high leaf area ratio (0.3-0.4 cm2 mg-1). A temperature optimum for growth in the range 15-20�C found in Amsinckia, is amongst the lowest reported for a temperate species. Potential seed production was extremely high - up to 2,000 seeds per plant in sward conditions. In competition with wheat, Amsinckia depended on its ability to respond rapidly to changes in the aerial and soil environments, in order that it maintain its share of light, nutrients and moisture. A reduction in irradiance elicited increases in leaf angle, leaf and stem lengths, specific leaf area, and shoot to root ratio. A reduction in the supply of soil nutrients resulted in a decrease in the shoot to root ratio. Where there was intense competition for both light and nutrients Amsinckia shoot dry weight was reduced by about 30%. Reductions in the yield of wheat resulting from competition from Amsinckia may be associated with a reduced supply of light,nutrients and/or moisture, but the results suggest that competition for soil moisture may have the greatest effect on wheat yields. The results have important implications on methods used to control Amsinckia. The possibility of reducing the effectiveness of Amsinckia by encouraging competition from wheat in the crop is stressed.
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ItemThe decline in productivity of second rotation pinus radiata (D. Don.) plantations in Southeast South Australia(University of Melbourne, 1972)
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ItemThe control of respiration in carrot-root tissue(University of Melbourne, 1970)1. The 'induced' respiration in carrot-root slices increases in two stages during washing in aerated, distilled water. Stimulation of respiration by DNP and pyruvate indicates that overall respiration rate in freshly cut tissue is regulated by the rate of the pentose phosphate or the glycolytic pathway. 2. Adenine nucleotides and glycolytic intermediates were extracted from phloem parenchyma during development and decline of the induced respiration, and were estimated by enzymatic analysis. The crossover theorem of Chance was used to identify regulatory reactions within pathways of respiration. Changes in respiration rate are correlated with a characteristic sequence of activation of the essentially irreversible reactions of the glycolytic pathway. The first stage of induced respiration corresponds to a period of active synthesis, when ADP produced in the cytoplasm from synthetic processes, stimulates pyruvate kinase. During the second stage, phosphofructokinase is stimulated by ATP. 3. The activity of pyruvate kinase, extracted from freshly cut phloem parenchyma is not affected by physiological concentrations of allosteric effectors of pyruvate kinase extracted from other sources. Hence, stimulation of pyruvate kinase in the first stage of induced respiration may be primarily due to a mass-action effect of increased ADP at the site of the ADP- dependent glycolytic reactions. 4. Exogenously applied adenine and uridine nucleotides, and nucleosides enter the metabolic phase of the carrot cell and markedly stimulate the respiration rate of freshly cut tissue. There is a crossover at pyruvate kinase within several minutes of adding either ADP or ATP, thus confirming the importance of this enzyme during the first phase of induced respiration. 5. The magnitude and direction of the respiration response to cyanide is positively correlated with the initial respiration rate. At rates below a 'critical value of initial respiration', low concentrations of cyanide may stimulate glycolysis by increasing the concentration of cytoplasmic ADP, and thereby stimulate glycolysis. 6. Variation in respiration rates of freshly cut tissue can be explained in terms of a range of endogenous ADP levels in different tissue batches. 7. The results of analyses of intermediates and nucleotides in tissue aging in water, and the effects of nucleotides, nucleosides, DNP, pyruvate and cyanide on respiration rate, glycolytic intermediates and adenine nucleotide levels all support the conclusion that development of induced respiration is controlled by the concentration of cytoplasmic ADP. 8. Although respiration of freshly cut slices is stimulated slightly by KC1 or NaCl, 'salt' respiration proper develops at the end of the second stage of induced respiration in xylem (70 hr) and phloem (30 hr) parenchyma slices. The capacity for salt respiration declines in tissue washed for more than 8 days. 9. A new, steady state of enhanced respiration is recorded within 1. 5 to 3 minutes of adding 50 mM KC1 to well-washed tissue in an O2 electrode system. 10. When the capacity for salt respiration is low, salt induces changes in glycolytic intermediates and adenine nucleotides, but, phosphoglycerokinase is the only enzyme greatly stimulated. 11. In well-washed slices capable of high salt respiration rates, salt alternately stimulates pyruvate kinase, phosphoglycerokinase and phosphofructokinase, and induces large oscillations in the level of total ADP. 12. It is concluded that the effect of salt on the concentration of cytoplasmic ADP at the site of glycolytic kinases is responsible for establishment of salt respiration.
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ItemNo Preview AvailableThe ecology of mixed-species forests of Eucalyptus in central Victoria, Australia(University of Melbourne, 1966)Mixed-species forests of Eucalyptus are common in Australia and within one area, the two or three species which may form these forests often appear to be equally successful. Two forests, one of E. obliqua and E. cypellocarpa and the other of E. obliqua and E. radiata, were studied in the Great Dividing Range of Central Victoria in order to discover the reasons for the successful cohabitation of the species. The barriers to successful interbreeding which occur between the species were investigated. E. obliqua and E. radiata belong to the same interbreeding group, but few or no hybrids are successful. Flowering times were found to be separated, but only by a short interval. It is suggested that weak interspecific hybrids may be formed, but are eliminated as the forest grows, E. cypellocarpa belongs to a different breeding group to the other species and is incompatible with them. Distributions of the species have been studied in order to discover the nature of interspecific differences. Australia-wide distributions show wide variation, but environmental data are too scarce to permit analysis of any interspecific differences in habitat. In Central Victoria E. cypellocarpa occurs in higher site quality areas than E. radiata, but the critical components of site difference were not established from field data. Experimental work in the glasshouse, using different levels of nutrition and soil water status, produced differences in total plant yield per pot, but showed interspecific differences too slight to assist in explaining the separation of species in the field. Frost may also be important, but no experiments were performed on relative species' frost resistance. Within each forest the relative frequency of tree species changes with tree height. E. cypellocarpa and E. radiata are more tolerant than E. obliqua. Tolerance to shade was tested by placing seedlings beneath shade screens, but the species were found to have similar responses. However, other factors, such as insect and fungal attack, grazing and drought, in combination with shade, may lead to the observed interspecific differences. Regeneration studies suggested that suppression may occur in both saplings and seedlings. Fires are an irregular but important environmental component, and studies of the fire resistance of the trees were initiated. Field studies of bark thickness and moisture content were combined with laboratory studies of fire effects. Seed production of the forests in the study area is cyclic, but E. obliqua and E. radiata have more reliable seed production than E. cypellocarpa. The seed on the tree is that used for forest reproduction: no soil storage of eucalypt seed occurs there. Cohabitation appears to be permitted by the presence of barriers to the success of interbreeding and through compensating interspecific differences.
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ItemBiophysics and histochemistry of fruit growth and development( 1979)This thesis was prompted by the occurrence of frequent and substantial losses by rain damage of grapes grown for drying in the Murray River districts of Victoria. The problem is a long standing one and is by no means unique to grapes. Even a cursory survey of agronomic literature reveals the occurrence of similar problems in most fruit crops. Rain damage of fruit is usually manifested as fruit splitting, cracking or bursting. These processes are essentially the result of unregulated or uncontrolled growth. The approach taken in this thesis reflects my belief that a rational solution to the problem could emerge only through a better understanding of the fundamental processes governing fruit growth. (From Synopsis)
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ItemAlgal pollution and marine fouling in Port Phillip Bay( 1972)The growth of Ulva lactuca L. in conditions of organic pollution is discussed. Germlings and frond discs of Ulva were cultured in the laboratory to examine the relationship between growth and the chemical composition of a variety of growth media. Quantitative and qualitative aspects of marine fouling on test panels submerged in two areas of Port Phillip Bay, at depths between 3 and 15m, were studied in relation to environmental conditions. The factors controlling the deposition of weed on the beaches of Port Phillip Bay were investigated.
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ItemAn ecological study of the sub-tidal macrophytic vegetation of three selected areas of Port Phillip Bay: Werribee, Altona and Carrum; and a literature review: sewage and oil pollution in relation to macrophytic marine algae, with a short account of the "wasting disease" of the marine angiosperm Zostera( 1970)The problems of pollution, resulting from population explosion, increased technology, industry and commerce will undoubtedly be of foremost concern for present and future generations. Pollution arises primarily from the concentration of large human populations into small areas. Populations tend to condense in urban seaboard cities, and it is in such situations that the pollutionary side-effects of economic expansion are most evident. In the United States about half the population lives on the margins of the Oceans or of the Great Lakes and in Australia at least 65 percent of the populus lives in coastal cities. Early studies of aquatic pollution centred around the fresh water environment and it is only in the last two decades that the urgency of the need for more precise scientific knowledge of the biology of marine pollution has become apparent. Consequently, the literature concerned with the ecological effects of marine pollution has increased considerably in recent years, prompted in certain instances, by the lack of knowledge evident in the handling of emergency situations such as oil spillages. Such disasters have encouraged symposia, conferences and many texts dealing with facets of marine pollution ecology. More recent publications are by Fyn (1965), Olson and Burgess (1967), Smith (1968), and Carthy and Arthur (1968). These publications review the literature available on marine pollution, but although much research is now being done to ascertain the effects of pollution. on marine organisms, its effects upon macrophytic marine algae has not received as much attention as the zoobenthos, nekton and plankton which play a more important role in food chains terminating with man. Boney (1965) has written the only review to include consideration of the economic aspects of the effects of various contaminants on seaweeds. The word POLLUTION is derived from the past participle of the latin verb 'Polluere'. The Oxford English Dictionary defines 'Pollute' as follows: To make physically impure, foul or filthy; to dirty, stain, taint or foul. Definitions of marine pollution are diverse and often contentious. However, two fundamental precepts are frequently reiterated. Firstly, that marine pollution is a man-induced phenomenon - a notable exception to this being the "red tides" or blooms of poisonous phytoplankton familiar to phycologists; and secondly, that it produces a change in the biological balance of the environment that is detrimental to marine life or man.