School of Agriculture, Food and Ecosystem Sciences - Theses

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Innovation in response to environmental problems

Ewers, Craig. (University of Melbourne, 1990)

An important and long-standing field of agricultural extension research has involved the acceptance of new agricultural practices. Consistent with the applied, purposive nature of extension research and the emphasis on agricultural development, this field has centred around the question: How do we get farmers to adopt new technology? As such, the process has traditionally been viewed as one which is confined to the decisions of individual farmers. The role of those who develop and distribute the technology has generally been overlooked. It is argued in this thesis that when the development and promotion of agricultural technology are an integral part of government strategy, a great deal of decision-making happens before the technology even reaches the farm. Indeed, it will be shown that some innovations developed by government scientists may not become fully available to farmers. The complex interplay between science, technology and government policy forms a central theme throughout this thesis. Changes in agricultural practice are discussed with reference to the social and economic conditions that triggered them. In particular, the growing impact of the environmental movement on the development and diffusion of new cropping techniques throughout the 1980s is covered in depth. Two current Victorian government programs are critically reviewed along these lines. Finally, the views of farmers are analysed, through a survey of 146 wheat growers in North-East Victoria.
Tribes and territories : aspects of Aboriginal political geography in the Northern Territory of Australia

Davis, Stephen, 1951- (University of Melbourne, 1989)
Control of the black field cricket teleogryllus commodus (walker) (orthoptera: gryllidae) in Victoria

Murphy, Graeme, 1954- (University of Melbourne, 1985)

Techniques for improving control of the black field cricket Teleogryllus commodus were studied between 1981 and 1985 in series of laboratory and field trials in the western district of Victoria. In the laboratory, techniques were developed for assessing the palatability of substances to T. commodus. A number of plant extracts, especially water and acetone extracts from grasses, and other substances including sucrose and vegetable oils were shown to stimulate feeding in the cricket. Further laboratory trials showed that feeding stimulants could be used to encourage feeding on a commonly used substrate in cricket baits (wheat). Field trials to assess bait attractiveness revealed oats to be more attractive as a bait than wheat or barley. Efficacy trials conducted over consecutive years however, showed no differences in the level of control achieved with baits using wheat, oats or barley as the substrate. In addition, feeding stimulants added to the bait did not improve control, nor did the use of higher baiting rates. The level of control obtainable with the current recommended bait is between 80% and 95%.
Genotype environment studies in Pisum Sativum L. in relation to breeding objectives : ideotypes of pea

Berry, G. J. (University of Melbourne, 1981)

The overall objective of this thesis is to provide the information necessary to produce new varieties of pea which are more productive, easier to harvest and better suited to present day markets. This thesis defines ideal plant types (ideotypes) of pea and outlines how a breeding programme could produce and test them. Some effects of genotype and environment on morphology, development, growth, nodulation and yield component interactions are documented. Sets of near-isogenic lines, segregating populations and collection lines were grown in environments varying for photoperiod, temperature, daily radiant flux and soil nutrient levels. The results obtained, and reviews of the literature, provided the knowledge necessary to specify ideotypes. The ideotypes are defined at two levels: 1. Traits which confer benefits in terms of increased general adaptation to cropping systems, and 2. Traits which are specific to particular cropping systems and product uses. Increased general adaptation of pea should result from changes to plant form (e.g., leaflets replaced by tendrils, pods clustered at the top of the plant instead of being spread along the stems) and appropriate manipulation of yield components (e.g., high number of seeds/pod rather than many pods/node). Also, total yield of agricultural products from a crop rotation system will depend, in part, on the nitrogen fixing, ability of the pea crop. The time of flowering is an important trait conferring adaptation to specific cropping systems. The ideotypes have a condensed flowering period compared with current cultivars, so it becomes critical that flowering occurs at the optimum time. Models to predict the time of flowering from climatic data are presented for a range of genotypes. Other traits required in specific situations are determined by aspects such as market preferences and disease and insect problems. The genetic control of most of the ideotype traits is known and is relatively simple, so new plant types could be produced rapidly. A breeding programme based on the ideotype concept could use backcrossing to a recurrent parent to combine the desired traits into one plant type. It would be wise to do this on a range of genetic backgrounds and it would be necessary to test the new plant types for negative gene interactions and detrimental pleiotropy.
The soil-root interface of Lupinus Albus L. and its significance in the uptake of manganese, iron, and phosphorus

Gardner, W. K. (William K.) (University of Melbourne, 1981)

It has been demonstrated using an agar film technique that L.albus is able to dissolve colloids of iron/silicate, iron/ phosphate, aluminium/silicate and aluminium/phosphate and also suspensions of manganese dioxide, calcium mono-hydrogen phosphate and ferric hydroxide. Dissolution of these compounds was most marked in proteoid root regions of lateral roots (dense clusters of 20 laterals of limited growth) and certain regions of the tap root. Soil associated with these root regions was found to contain more protons, reductants and chelating agents than the bulk soil. The effect of iron and phosphorus nutrition was examined in acid washed sand. The effect of phosphorus nutrition was also examined in three soils (acid, neutral and alkaline) under glasshouse conditions. The response of wheat, L.angustifolius and L.albus to phosphorus was compared at three sites (acid, neutral and alkaline) in field trials. Proteoid root formation was found to be predominantly controlled by the phosphorus status of the plant. Manganese uptake in L.albus was related to proteoid root formation, and inversely related to phosphorus supply in both L.albus and L.anqustifolius. The ability of L.albus to utilise soil and added phosphorus decreased as the pH of the soil increased. The role of micro-organisms in proteoid root formation and function was investigated. Proteoid roots formed under sterile conditions, but more formed under non-sterile conditions. The effect of varying root morphology on exudation characteristics in the rhizosphere was examined by computer simulation. The main exudate from the roots of L.albus has been identified by gas-liquid chromatography and mass spectrometry as citric acid. It is hypothesised that citrate ions react with the soil colloid and form a diffusible polymeric ferric hydroxy phosphate which moves to the root surface where it is broken up by a combination of ferrous ion uptake, proton secretion and reduction. An attempt has been made to examine iron in the roots using electronmicroscopy and X-ray microprobe. The results suggest that iron is mobilised about the root system in large amounts, although this is not reflected in above ground parts. The effect of intercropping wheat and L.albus was examined in both glasshouse and field for effects on the mineral nutrition of both species. Wheat intercropped with lupins appears to have access to a larger pool of available phosphorus, manganese and nitrogen than has wheat grown on its own.
Aspects of the biology and salt tolerance of Phragmites australis (Cav.) Trin. ex Steud.

Clucas, Rowena D. (University of Melbourne, 1980)

Reeds thrive under a wide range of conditions, but in the Gippsland Lakes system, high salinity levels - both alone and in conjunction with other environmental factors - have greatly reduced Phragmites growth on the shoreline and removed the reed fringe entirely in some areas. The Gippsland Lakes system provides an unstable environment, where salinity levels and water levels fluctuate seasonally and also between drought and flood years. Distribution of reeds along the lake edges is correlated primarily with salinity levels, but also with exposure to wind, wave and current action. The amount of salt absorbed by reeds is directly related to site salinity. High salinities reduce many aspects of productivity, including shoot height, density and dry weight, and seed production. The actual salinity tolerance of Phragmites in the field is dependent upon the severity and duration of the salinity regime and other habitat factors operating. Conditions on the north shore of Lake Wellington are near the tolerance limit of Phragmites. Reeds accumulate large quantities of mineral elements and growth is greatly improved in areas of high nutrient status. Phragmites can readily be grown from rhizome or shoot cuttings if these are collected at the appropriate stage of development. Establishment from seed is a rare occurrence in the field and germination depends on the formation of viable fruits. In the three Victorian populations studied, less than two per cent of the florets contained viable seed.
Efficiency of nitrogen fertilization of dry-seeded rice in south-east Australia

Humphreys, Elizabeth ( 1986)

The efficiency and fate of fertiliser nitrogen applied to combine-sown rice were investigated in field experiments in which fertiliser timing, water regime and soil type were varied. The information gained was used to predict strategies for optimising fertiliser efficiency using current techniques, and to predict and test improved fertilisation technologies. The stage of crop growth, water regime and soil properties all had large and interacting effects on agronomic efficiency. On an infertile alkaline grey clay soil, agronomic efficiency of urea applied at sowing was very low (8 kg kg-1) compared with later applications associated with continuous flooding (up to 56 kg kg-1). The low efficiency was due to nitrification and subsequent de-nitrification during the flushing period. Nitrogen-15 balance studies indicated that 80% of the urea nitrogen was lost from the soil-plant system. The rapid nitrification rate and high loss of nitrogen on the grey soil contrasted with the very low levels of nitrate and low losses of nitrogen (10-25%) from urea applied to rice growing on an infertile acidic red soil under alternating conditions of saturation and aeration (sprinkler-irrigation). Furthermore, on a fertile acidic red soil in the same region, other authors have measured large yield responses to nitrogen applied at sowing. These differences highlight the need to consider soil properties and water management when attempting to predict optimum fertilisation strategies. Yields of sprinkler-irrigated rice (managed to replace water lost by evaporation) were reduced by more than 50% compared with rice grown under continuous flood. However, this was not due to decreased plant uptake or increased loss of fertiliser nitrogen in the sprinkler-irrigated treatments. The low yields appeared to be associated with plant water stress, decreased nitrogen mineralization (by approximately half) and location of the fertiliser nitrogen near the soil surface where root activity was probably restricted due to inadequate moisture. On the grey soil, maximum agronomic efficiencies occurred with application shortly before permanent flood or at early panicle elongation. Efficiency was doubled when urea was applied before permanent flood compared with shortly after permanent flood. The greater efficiency appeared to be associated with the deeper transport of the applied nitrogen into the soil, and consequently lower losses by ammonia volatilisation and/or nitrification/de-nitrification. However, even with the most efficient fertilisation strategies, plant 15N recoveries were less than 40%, while losses exceeded 20%. When the 15N balance data were considered in conjunction with the agronomic data,. it appeared that it would be possible to further increase agronomic efficiency if plant recovery of applied nitrogen could be increased. In particular, minimisation of losses of nitrogen (via nitrification/de-nitrification) from fertiliser applied before permanent flood was a most attractive option. Potential methods identified for increasing agronomic efficiency by minimising losses of nitrogen applied before permanent flood were deep placement and the use of nitrification inhibitors and slow release nitrogen sources. Several experiments were conducted in an attempt to improve fertiliser efficiency by banding urea and modified urea sources 5-7 cm below the soil surface before permanent flood. Plant recovery of 15N was increased by up to 20% with banding compared with surface broadcasting. The best recoveries were from urea super-granules (USG). An experimental fertiliser rig and a commercial seeder fitted with a triple disc assembly were used to band the fertilisers in the main plots. There was no significant yield advantage with banded urea over broadcast urea applied before permanent flood. The fertiliser rig caused considerable plant damage. Using the triple disc applicator, it was possible to band fertiliser below the soil surface with minimal soil disturbance, and plant damage, but only under i ideal conditions of soil moisture. Furthermore, where the soil surface was dry and cracked, penetration with the triple discs was no greater than the depth of the cracks into which surface applied urea prills would be washed upon flooding. The yield test of USG was unsatisfactory because of the excessive plant damage with this method. With current technology, there appears to be little scope for improving the efficiency of urea applied before permanent flood by mechanical placement below the soil surface.
Comparative study of induced mutation methods in potatoes (Solanum tuberosum L.)

Pongsupasamit, Siriporn ( 1990)

Three different agents , gamma irradiation , ethylmethanesulphonate (EMS) and somacloning, were used to induce mutation in potatoes (Solanum Tuberosum L.) (cv. Tasman). Tuber eyes and plantlets were subjected to gamma irradiation and EMS treatment. Each set of 300 from both tuber eyes and plantlets was treated with the LD50 dose of gamma irradiation and EMS calculated from the LD50 determination. For tuber eyes, one set of 300 single-eye pieces was gamma irradiated with 3 Krad (LD50) and the second set was treated with 0.5%, 4 h EMS (LD50). Likewise for plantlets, one set of 300 plantlets was gamma irradiated with 4 Krad (LD50) and the second set was treated with 0.8%, 4 h EMS (LD 50). The two-step procedure was used to regenerate 200 somaclones from internode pieces of the cultivar Tasman. Somacloning was the most effective method in inducing variation for plant and tuber morphological characters with total frequencies of 47.9%(SC1), 133.3%(SC2), 27.0%(VM2, gamma irradiation of eyes), 14.1% (VM2, EMS of eyes), 7.7% (VM2, gamma irradiation of plantlets) and 12.4% (VM2, EMS of plantlets. Frequencies of solid mutation as a proportion of all mutation i.e. solid+chimeric were 55.6% (SC2), 69.2% (VM2, gamma irradiation of plantlets), 30.0% (VM2, gamma irradiation of eyes), 22.2% (VM2, EMS of plantlets) and 15.0% (VM2, EMS of eyes). The ratio of solid : chimeric mutations was substantially higher from somacloning (SC1 and SC2) than gamma irradiation which, in turn, was higher than that from EMS treatment. Chimeric mutation occurred as two forms i.e. uniformly or sporadiacally expressed throughout the plant. Sporadic chimerism was substantially higher in frequency than the uniform type for the three mutagenic agents. Mean values for the four quantitative characters, plant height, stem number, tuber weight and tuber number per plant in the SC2 population were significant lower than the respective control value. Gamma irradiation of tuber eyes gave significant (P=0.01) increases in mean plant height, tuber weight and tuber number per plant in the VM2 population but significant (P=0.05) reduction in stem number per plant while stem number per plant was the only charcter in the VM2 from gamma irraditation of plantlets and EMS treatment of eyes which was significantly (P=0.01) different (lower) from the respective control value. While EMS treatment did not significantly alter these four charcters in the VM2 from treatment of plantlet. In the SC2 population approximately 50% of the plants were aneuploid while there were no such occurences in the VM2 populations from EMS or gamma irradiation treatment. The three agents also caused low levels of polyploidy which appeared to be lower in the SC2 , compared with VM2 populations from EMS and gamma irradiation treatment. In vitro tuberization was used to speed up the procedures for detecting a possible reversible change of the white tuber skin mutant to pink from somacloning. Approximately twenty eight percent of the somaclone plants from normal Tasman exhibited tuber skin colour mutation from pink to white. Of the 100 regenerated somaclones of the white tuber skin mutant , one exhibited pink tuber skin colour but paler than the normal colour of cv. Tasman. It was speculated that the mutation from pink to white tuber skin colour of the cv. Tasman in the present study involved two loci, E and D , while the reverse mutation from white to pale pink involved only one locus, E. Isozyme analysis of ten enzyme systems namely, 6-PGD, MDH, Eb, Me, GDH, PDX, G6PD, PGI , PGM and GOT, of a control, somaclone (SC2), and VM2 populations from gamma irradiation and EMS treatment of plantlets revealed that the three agents were each all effective in inducing isozyme variation in potatoes (cv.Tasman). EMS (60.0%) and somacloning (58.9%) appeared to be of approximately equal effect in inducing variation across the 15 isozyme loci from the ten exzyme system examined. While gamma irradiation induced substantial levels of isozyme variation above that of the control population its effect (46.7%) was considerably lower than somacloning and EMS. The means values of unbiased gene diversity for 12 isozyme loci for the SC2 and VM2 population from gamma irradiation and EMS treatment were all significantlly (P=0.4) different from the control value. EMS appeared to induce a somewhat higher level of variation than somacloning while gamma irradiation appeared to be less effective than somacloning in inducing variation. Mean values for unbiased gene diversity for 12 polymorphic isozyme loci for the four populations were 0.8077 (VM2, EMS), 0.8011 (SC2), 0.8008 (VM2, gamma irradiation) and 0.7821 (control). Isozyme variation across the 12 loci , in the SC2 and VM2 populations from both gamma irradiation and EMS treatment , differed from the control population with Prevosti distance values of .120 , .086 and .148 respectively. Similar results were observed for Nei mininmum distance and Rogers genetic distance values which the VM2 from EMS was more divergent from the control population than was the SC2 which in turn was more divergent from the control population than was the VM2 from gamma irradiation. Amongst the treated populations the SC2 was more divergent from the VM2 from EMS than the VM2 from gamma irradiation revealing the differences in specificity and types of variations induced between somacloning and EMS than somacloning and gamma irradiation.
Lactation in mice as a model to study genetic improvement of dairy cattle in the tropics

Westra, Paridjata ( 1989)

In chapter one of this thesis aspects of reproduction and production, mainly milk production were reviewed. Components of reproductive efficiency such as the fertility components: age at calving, service periods, days open, calving interval and non return rate; were also investigated. The physiological relationship between those traits and milk production and persistency, in both temperate and tropical environments, was also considered, as well as longevity or stayability as other alternatives for evaluating reproduction. Attention was put on first and second lactation performance. With a view towards understanding physiological aspects of reproduction and production in dairy cows, the nature of lactation in mice was reviewed from the relatively few works that have been done. The papers reviewed included the role of pre-natal and post-natal maternal effects and the relationship between littersize and milk-yield. Daily yield and lactation from a number of studies were compared. Theories of genotype-environment interaction (GM) and adaptation, as well as their implications, were reviewed in the subsequent part of. chapter 1. Evidence of GEE in dairy cattle (Friesian, Holstein or Friesian-Holstein, crossbred with Friesian, and native) in both reproductive characters and milk production throughout the tropic regions were examined particularly closely. Mating systems and selection responses in genetic improvement programmes also were reviewed. Constraints and shortcomings for the achievement of genetic progress through natural mating, AI and progeny-testing in the tropics were examined in conjunction with attainment of high milk production in the temperate countries. The use of new technology (MOET) for manipulating reproductive efficiency was also introduced in the hope that it can be used to increase breeding efficiency in the tropics. The milk-yield and reproductive . characters, of two genotypes of mice (one genotype had been selected for high early reproductive and milking performance and the other was a random bred control) were measured in the normal and a hot environment to check if GEI were present. Both genotypes had been developed in the normal temperature. Evidence of interaction was found in the second parity and only in reproductive traits, e.g. fecundity, interval between mating and birth of second parity. These results are supported by many studies of GEI for both milk-yield and reproductive characters in dairy cattle in the tropics. Milk production does not show GEI, if the environment is defined merely as temperature. The previous selection of the improved genotype had resulted in positive correlated responses in: litter size and litter weight at birth in the first parity, production characters (growth characters and preweaning weight of the litters) in both parities, and on milk production but not on persistency. The selected line did maintain its superiority across environments. However females from the improved genotype performed worse in almost all characters in the hot environment compared to the normal environment. In an analogy with dairy cattle, the high production capacity of the selected line was not exhibited in the adverse environment. Problems of genetic improvement in the tropics were discussed. They included the use of appropriate selection criteria based on . more knowledge of both physiological and genetical relationships between milk-yield and other-characters, with the aim of increasing adaptability and productivity in the target environment. Other possibilities for genetic improvement of dairy cattle in the tropics and the use of synthetic breeds for overcoming the problems in the long term were also discussed.
Supplementation during late pregnancy and early lactation in dairy goats

Djoharjani, Trianti ( 1990)

An experiment was conducted at Mt. Derrimut Field Station from February 1988 to October 1988, to study the effect of feed supplementation at different times during late pregnancy and early lactation on milk production and litterweight of dairy goats. The experiment compared milk production and composition, litterweight and nutrient intakes of two groups of goats. Group A were supplemented with urea molasses mainly during late pregnancy (6 weeks before parturition continued for 3 weeks in early lactation). Group B were supplemented with urea molasses, mainly in early lactation (2 weeks before parturition continued for 7 weeks in early lactation). The feed supplement comprised 3.5% (w/w) urea in molasses given at a rate of 20% (w/w) of intake of basal diet dry matter. Basal diet comprised of a 50:50 mixture of chopped lucerne hay and oaten chaff. The basal diet and feed supplement were offered at a level of 25% above the }intake and given three times a day. A Mineral vitamin supplement at rate of 2% of feed offered was included. The results showed that there were no significant differences (P > 0.05) in litterweight , milk production or nutrient intakes throughout the experiment. Litterweights were 6.7�8.1 kg (group A) and 8.2�1.4 kg (group B). Litter size was not significantly differed (P > 0.05) between group A and group B (1.8�0.8) vs (2.3�0.5), therefore, birthweight was also not significantly differed i.e. 3.6�0.7 kg vs 3.5�0.4 kg for group A and group B, respectively. Milk production was 2.5 kg/d for both groups. Intakes of dry matter were 1731�395 g/d (group A) and 1831�525 g/d (group B). Between physiological stages, however, there was a significant difference (P < 0.01) in intake of nutrients. In early lactation intake of nutrients was higher than during late pregnancy. It was concluded that different timings of provision of supplementation during late pregnancy and early lactation did not make any difference in milk production, since greater number of foetuses hampered intake of nutrients during late pregnancy resulted in poorer body condition at birth. A positive energy balance in early lactation was utilized to recover body losses during pregnancy, but not for milk production.

School of Agriculture, Food and Ecosystem Sciences - Theses

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