School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemMeasurement of the degree of cell rupture in macerated lucerne( 1978)Cell rupture is a critical process in the fractionation of green crops. Despite the importance of this process there is no accepted method for quantitatively describing the degree of cell rupture in a sample of macerated forage. Several methods were investigated and developed as measures of the degree of cell rupture in samples of lucerne leaves macerated by extrusion:- (i) Separation of cells and enumeration of intact cells. (ii) Release of cellular substances:- (a) water soluble carbohydrates (b) potassium (c) sodium (d) electrolytes (e) water (iii) Standard juice expression technique as used by other workers. A total rupture standard was considered to be essential, and was achieved in samples of lucerne leaf tissue macerated initially using a mortar and pestle, followed by ten minutes exposure to ultrasound. The performance of these techniques was evaluated in terms of repeatability and of individual and comparative performance over a large range of degrees of maceration. The cell enumeration method was not developed because a suitable agent for separating the cells of lucerne leaf tissue could not be found. All substance release assays gave repeatable estimates of cell rupture and were highly correlated with each other. It was therefore concluded, that the release of cellular substances gave a reliable estimate of the degree of cell rupture. The standard juice expression technique was insensitive to changes in the degree of rupture and was inaccurate at high levels of rupture. It was concluded that the electrolyte release assay was the most appropriate estimate of cell rupture for use in the future.
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ItemAn evaluation of the role of extension in the Australian pig industry( 1978)Australian agriculture is adjusting to changes in technology, economic circumstances and markets. Extension services as much as the producers' need to change in response to changing industry needs, market trends and consumer demands. There has been much discussion on the problems that these changes present for extension, but none on the basis of empirical research or social science theories. A research program was developed to define the changes taking place in the structure and organisation of the Australian pig industry, and to identify the implications of these changes for pig producers and for extension agencies such as State Departments of Agriculture. The conclusion drawn from the review of the industry situation and from a Delphi survey of 10 experts in the pig industry was that the industry will become more technical and commercialised requiring continual adaptation by the producers to technical and economic changes in order to maintain and increase production efficiency. The survey results showed that a degree of assistance from research and extension was expected by producers to help them maintain and improve production efficiency. Based on the Theory of Personal Constructs, Kelly (1955) an interactive psychological testing procedure known as the Repertory grid was used to record producers' and extension officers' perceptions of each other and of extension services. Twenty pig industry officers, 16 non extension users, 20 extension users and 16 large commercial producers were interviewed. Separate analyses were carried out on the grids of individual subjects, providing profiles of constructs typically used by the subjects in relating to and evaluating people. The results clearly identified the constructs which farmers used in relating to extension advisers and advice. In general, all groups of subjects tended to stereotype people with whom they associated. Combination of both the results within subject groups revealed evidence of commonality within and between the groups in their perceptions. The extension officers saw themselves as progressive and useful while a large number of the producers saw them as theoretical and irrelevant. Extension users held favourable attitudes towards professional agricultural advisers, while large commercial producers and non extension users criticised them on the grounds that they were difficult to communicate with and lacking practical experience. As a group, extension officers were not aware of the questioned relevance of their advice nor of the difficulty experienced by producers in communicating with them. Owing to their practical background and shared experiences, all producers saw other producers as useful and as the most relevant source of advice. The roles they expect him to perform and the characteristics that producers expect from a professional extension adviser have been identified and their implications for the extension officer are discussed. The most obvious implications of the findings are that extension advisers fail to establish the relevance of information within the farmers' context of what is relevant. Based on the findings of the research the theory is proposed that extension programmes will be most successful when producers and extension workers share common perceptions of relevant problems. A philosophy and practice of extension is proposed to meet the farmers' own perception of needs. The interpretation of the results in terms of Personal Construct theory leads to the development of the model of human behaviour, that is, "man as an actor" instead of "man as something being acted upon". A philosophy of extension is developed based on the belief that extension can only be successful if it provides what farmers want. The philosophy states that extension should provide a helping role by facilitating, developing and supporting "man the actor" without dominating or controlling his actions. A practice of extension operating within the boundaries of the proposed new philosophy is developed from the helping relationship model of Carkhuff (1969). The goals of extension are defined as exploration, understanding and action which lead directly to the need for skills which are defined as the "interface skills" of attending, responding, personalising and initiating. The need for and the nature of extension training to provide extension officers with "interface skills" is discussed.
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ItemThe training needs of agribusiness in Australia : a commodity systems approach( 1978)Adopting the concept of agribusiness and the commodity systems approach, this study was conducted to assess the in-service training needs of the human resources in the wheat and the beef commodity systems of Victoria. Having defined the two selected commodity systems in their macro environment, the study concentrated at the level of the individual organization to determine the training needs for the managerial, the professional, and the sales staff. A mail questionnaire survey was conducted with a multi-cluster sampling technique amongst 708 agribusiness organizations in Victoria and a final response rate of 57% was achieved. The findings of this exploratory study indicated: (1) that there were no appreciable differences in the expressed training needs between the two commodities studied (wheat and beef), and amongst the three staff categories (managerial, professional, and sales staff) investigated; (2) that there was a higher level of need for management knowledge rather than for production knowledge; (3) that courses offered by Technical and Tertiary institutions in Victoria in the area of agribusiness were not recipient-oriented, and were seen as unsuitable for their needs; and (4) that the demand for communication training seen in terms of potential staff-numbers was considerable. Some suggestions regarding the implications of these findings have also been made to meet the training needs revealed by the study.
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ItemThe effect of applied N and P under mowing and grazing on the yield and botanical and chemical composition of irrigated pasture and on the nutrient status of a red-brown earth at Kyabram( 1978)A split plot experiment was conducted over 4 years to study the effect of method of harvesting (grazing and mowing) and applied N and P (5 rates of nitrogen ranged from 0 to 112 kg N ha -1 cut-1 and 6 rates of superphosphate ranged from 0 to 188 kg P ha 1 year year-1) on the yield, botanical and chemical composition of irrigated phalaris (Phalaris tuberosa x Phalaris arundinacea)/white clover (Trifolium repens L. cv. Irrigation) pasture and nutrient status of a red-brown earth at Kyabram. A second experiment was conducted over 2 years to find out the effect of rates (0 to 112 kg N ha. 1) and frequency of N application (2, 4 or 8 times year ) o n dry matter production, botanical composition and crude protein content of paspalum (Paspalum dilatatum)/white clover pasture. Results: Mowed plots significantly out-yielded grazed plots in the first two years. However, grazed plots significantly out-yielded mowed plots in the following two years. Nitrogen application significantly (P <0.01) increased dry matter production of grass/clover mixtures. The size of response was governed by the growth rate of pasture species, clover percentage in the sward, climatic conditions and the status of other nutrients in the soil. Splitting N rates in smaller but more frequent applications had no effect on total herbage yield or seasonal distribution. Response to N (kg D.M. kg N-1 ) declined as N rates increased. Phosphorus application up to 94 kg P ha -1 year -1 significantly (P,(0.01) increased pasture production and relative response was greater in winter. Occasionally, the P and N requirements for maximum production were higher for grazing than for mowing. Both methods of defoliation and fertilizer applications affected pasture composition and IT, P and K content in the herbage. Nitrogen application decreased N in the herbage before increasing it and P application up to 141 kg P ha- 1 year -1 increased it. The return by the grazing animal increased total soil N by 106 kg ha 1 year 1 and soil P (Colwell) by 1:0 p.p.m. in four years compared with the start of the experiment. The relationship between plant P and soil P and P rates were significant (P < 0.01). The available soil P decreased with P withdrawal or the application of 23.5 kg P ha-1 year -1 under grazing and 47 kg P ha -1 year-1 under mowing. Phosphorus and nitrogen application significantly affected available soil P. 60-80% of the available P accuminulated in the 0-5 cm and the downward movement increased by increasing P rates. The continuous mowing and P application significantly reduced available soil K. Defoliation method affected C/t:N ratio. Phosphorus application increased soil N whereas N application decreased it. P application at the rate of 23.5 kg ha-1 year-1 increased total soil N by 0.068% which is equivalent to 952 kg N ha-1 in five years. It was estimated that 4 to 4.7 p.p.m of P was required to be removed or added to the soil to change the available soil P by 1 p.p.m. The application of 196 kg N ha-1 year -1 as NH4 NO3 did not change the soil pH and 784 kg N ha 1 year 1 reduced soil pH by an average of ').4 unit.
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ItemBody composition of swamp buffalo (Bubalus bubalis) : a study of developmental growth and of sex differences( 1978)A review has been made of developmental growth and of genetic effects on the body composition of some farm animals. Relationships between chest girth and body weight were studied using sets of data collected in Indonesia from 365 male and 404 female swamp buffalo, each classified to age as having 0, 2-6 and 8 permanent incisors. Linear regressions by which body weight may be predicted from chest girth are presented for each sex-age class. A body composition study, also carried out in Indonesia, was conducted using 12 buffalo bulls and 13 buffalo cows, comprising FBK (Fasted Body Weight; no feed or water for 14 h before slaughter) from 190 to 498 kg or EBW (Empty Body Weight; F minus weight of digests and bladder content) from 158 to 379 kg. Data on HCW (Hot Carcass Weight), HSW (Hot Side Weight), weights of offal components, SMW (Side Muscle Weight) , SBW (Side Bone Weight) , SFW (Side Fat Weight) , SCIW (Side Connective Tissue Weight), weights of SMG (Standard Muscle Groups) and weights of gut tissue components were recorded. The weights of head and tail muscles were also recorded to obtain BMW (Body Muscle Weight) , BBW (Body Bone Weight) , BFW (Body Fat Weight) and BCIW (Body Connective Tissue Weight). The body composition data were analysed by using the variables in the equation: y = axb in logarithmic form (log y = log a + b log x). Comparisons between sexes are being made by using one-sway analyses of co-variance. In the thesis, b values are referred to as growth coefficients or relative growth ratios, and a values as intercepts. (1) Body composition: The apparent and true dressing percentages were not affected by sex and did not change significantly throughout the ranges of FBW and EBW . Both apparent and true dressing percentages are much lower in buffalo than in cattle. At the same FBW or EBN, bulls had less FBW, heavier BBW and BCTW than cows. Bulls had a higher BMW than cows at the same EBW, but both had similar BMW at the same FBW. Sex affected the growth coefficient of head (bulls) cows) and omental fat (cows > bulls) relative to FBW, but it did not affect the growth coefficients of other offal components. Similar results were obtained when offal components were regressed on EBW, apart from the growth coefficient for hide(bulls > cows). At the same EBW, bulls had less blood, heavier head, hide and feet, lighter urogenital tract and alimentary tract than cows. At the same live-weight, the blood, head, feet, hide and alimentary tract appeared to be heavier in buffalo than in cattle. (2) Carcass composition: Sex affected the growth coefficient of SMW relative to HSW (bulls > caws), whereas those for other carcass components were similar between sexes. At the same HSW, bulls had higher SMW and SCIW and lighter SFW than cows (different intercepts), but both had similar SBW. Age (as distinct from erupted incisors) did not affect carcass composition of cows. Within sex comparisons at the same HSW shaved that the buffalo had more muscle than British beef cattle breeds and a similar amount to Bos indicus, Shorthorn cross and Friesian cattle, less fat than cattle, more bone than British beef cattle breeds but similar amount to Friesian cattle and less than Bos indicus cattle.
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ItemShallow flow through vegetation( 1978)A review of the literature indicated that existing equations most frequently used to predict hydraulic resistance for shallow flow through both simulated and real vegetation were developed empirically under conditions dissimilar to those which exist in overland flow or in border-check irrigation. Published relationships for shallow flows expressing hydraulic retardance as a function of parameters describing the physical characteristics of the channel, the fluid, and the flow, pertain to flows in channels with much smaller relative roughness than that provided by real vegetation. When water flows through vegetation, there is a drag force exerted by the channel bed (earth), together with the much larger force exerted by the vegetative parts. In order to study these separate effects, a detailed program was carried out under conditions closely relating to uniform flow. Relationships between a resistance parameter and a number of other dimensionless ratios characterising shallow flow through real vegetation were stated in an initial form, as determined by dimensional analysis. The studies were carried out in a concrete channel and a tilting flume for empirical verification of the analysis. In the experiments with both sets of equipment, an irrigation-variety wheat was grown on smooth surface sandy soil. It was concluded that under these conditions it is possible to develop equations for hydraulic resistance in terms of parameters which are measures of the physical characteristics of shallow flow through vegetation. The contribution of the soil to total retardance will decrease with depth of flow. The simple discharge-depth relationship equation was also shown to be applicable to shallow flow through real vegetation. It is recommended that in particular, a further study be made comparing the drag caused by hairy stems as distinct from that offered by varieties of the same type of vegetation that do not have such stems.
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ItemStudies on the biology and taxonomy of Colletotrichum species( 1978)Studies on the biology and taxonomy of over 350 isolates of Colletotrichum from the temperate and tropical regions of Australia and from southern Florida are presented in this thesis. Many aspects of these fungi, including growth on hosts and in culture, the germination process, sexual reproduction, morphology and soluble protein patterns, have been critically investigated with the aim of finding as many characters as possible with taxonomic value. The reliability of previously used and new criteria for delimiting taxa is evaluated and whether variation in the genus Colletotrichum, as it occurs in Australia, can be satisfactorily fitted into the systematic scheme proposed by von Arx (1957a), 1970) is discussed. The unreliability of host range in delimiting species of Colletotrichum, except its use in cross-inoculation studies, is shown. The finding that host species and organ infected have a greater influence on symptom expression than the identity of the invading fungus led to the rejection of disease symptoms as a taxonomic criterion. The superiority of oatmeal agar in in vitro growth studies of Colletotrichums, especially in cultural comparisons, is demonstrated. For the first time, seta production is established as a valuable taxonomic criterion. The value of growth reaction to temperature as a criterion for delimiting species is reduced by the possible existence of temperature ecotypes which restricts useful comparisons to one climatic region. Studies on germination and appressorium formation have demonstrated that this process is a character of the genus as a whole. Sexual state investigations have helped to explain. the variability in cultural characters of sexual isolates and have shown that sexual characters are generally of little use in delimiting several species. Morphological studies confirmed the value of conidium morphology, providing it is used critically, and established the value of seta characters in delimiting taxa of Colletotrichum. The morphology of appressoria and stromatic structures are also shown to be of taxonomic value. By confirming and extending the results of morphological studies, disc polyacrylamide gel electrophoresis of soluble proteins is strongly recommended as a valuable supplementary aid to such studies. Conidium shape, cultural characters and seta morphoIogy are recommended as the most valuable criteria for delimiting taxa of Colletotrichum. Although variation in the genus Colletotrichum, as it occurs in Australia, can be generally fitted into the systematic scheme of von Arx (1957a, 1970), some modification of this scheme is recommended. The agriculturally important forms of C. gloeosporioides (sensu von Arx), C. lindemuthianum, C. musae, C. orbiculare and C. trifolii, are regarded as separate species, readily distinguishable from each other and from C. gloeosporioides by many criteria. Within C. gloeosporioides (sensu von Arx), several groups of isolates, including Group B, Group C (C. fragariae) and Group E were readily distinguished from other isolates by many criteria and Groups D and F were distinguished by a few criteria. Further work is planned to determine the true status of Groups B, D, E and F. Similarly, within C. graminicola (sensu von Arx) , two groups of isolates were clearly distinguished from each other. The taxonomv of C. graminicola is currently being investigated in a joint project with Dr. B.C. Sutton. In addition, further work is recommended to evaluate the true status of C. coccodes and C. destructivum.
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