The performance of irrigated mixtures of tall fescue, ryegrass and white clover in subtropical Australia. 2. The effects on yield and botanical composition of managing for quality.

The effects on yield, botanical composition and persistence, of using a variable defoliation schedule as a means of optimising the quality of the tall fescue component of simple and complex temperate pasture mixtures in a subtropical environment was studied in a small plot cutting experiment at Gatton Research Station in south-east Queensland. A management schedule of 2-, 3- and 4-weekly defoliations in summer, autumn and spring and winter, respectively, was imposed on 5 temperate pasture mixtures: 2 simple mixtures including tall fescue (Festuca arundinacea) and white clover (Trifolium repens); 2 mixtures including perennial ryegrass (Lolium perenne), tall fescue and white clover; and a complex mixture, which included perennial ryegrass, tall fescue, white, red (T. pratense) and Persian (T. resupinatum) clovers and chicory (Cichorium intybus). Yield from the variable cutting schedule was 9% less than with a standard 4-weekly defoliation. This loss resulted from reductions in both the clover component (13%) and cumulative grass yield (6%). There was no interaction between cutting schedule and sowing mixture, with simple and complex sowing mixtures reacting in a similar manner to both cutting schedules. The experiment also demonstrated that, in complex mixtures, the cutting schedules used failed to give balanced production from all sown components. This was especially true of the grass and white clover components of the complex mixture, as chicory and Persian clover components dominated the mixtures, particularly in the first year. Quality measurements (made only in the final summer) suggested that variable management had achieved a quality improvement with increases in yields of digestible crude protein (19%) and digestible dry matter (9%) of the total forage produced in early summer. The improvements in the yields of digestible crude protein and digestible dry matter of the tall fescue component in late summer were even greater (28 and 19%, respectively). While advantages at other times of the year were expected to be smaller, the data suggested that the small loss in total yield was likely to be offset by increases in digestibility of available forage for grazing stock, especially in the critical summer period.

Analysis and Modelling of the Effects of Water Stress on Maize Growth and Yield in Dryland Conditions.

It is essential to provide experimental evidence and reliable predictions of the effects of water stress on crop production in the drier, less predictable environments. A field experiment undertaken in southeast Queensland, Australia with three water regimes (fully irrigated, rainfed and irrigated until late canopy expansion followed by rainfed) was used to compare effects of water stress on crop production in two maize (Zea mays L.) cultivars (Pioneer 34N43 and Pioneer 31H50). Water stress affected growth and yield more in Pioneer 34N43 than in Pioneer 31H50. A crop model APSIM-Maize, after having been calibrated for the two cultivars, was used to simulate maize growth and development under water stress. The predictions on leaf area index (LAI) dynamics, biomass growth and grain yield under rain fed and irrigated followed by rain fed treatments was reasonable, indicating that stress indices used by APSIM-Maize produced appropriate adjustments to crop growth and development in response to water stress. This study shows that Pioneer 31H50 is less sensitive to water stress and thus a preferred cultivar in dryland conditions, and that it is feasible to provide sound predictions and risk assessment for crop production in drier, more variable conditions using the APSIM-Maize model.

Pre-cropping with canola decreased Pratylenchus thornei populations, arbuscular mycorrhizal fungi, and yield of wheat.

Root-lesion nematode (Pratylenchus thornei) significantly reduces wheat yields in the northern Australian grain region. Canola is thought to have a 'biofumigation' potential to control nematodes; therefore, a field experiment was designed to compare canola with other winter crops or clean-fallow for reducing P. thornei population densities and improving growth of P. thornei-intolerant wheat (cv. Batavia) in the following year. Immediately after harvest of the first-year crops, populations of P. thornei were lowest following various canola cultivars or clean-fallow (1957-5200 P. thornei/kg dry soil) and were highest following susceptible wheat cultivars (31 033-41 294/kg dry soil). Unexpectedly, at planting of the second-year wheat crop, nematode populations were at more uniform lower levels (<5000/kg dry soil), irrespective of the previous season's treatment, and remained that way during the growing season, which was quite dry. Growth and grain yield of the second-year wheat crop were poorest on plots previously planted with canola or left fallow due to poor colonisation with arbuscular mycorrhizal (AM) fungi, with the exception of canola cv. Karoo, which had high AM fungal colonisation and low wheat yields. There were significant regressions between growth and yield parameters of the second-year wheat and levels of AMF following the pre-crop treatments. Thus, canola appears to be a good crop for reducing P. thornei populations, but AM fungal-dependence of subsequent crops should be considered, particularly in the northern Australian grain region.

Cultivar-specific effects of pathogen testing on storage root yield of sweetpotato, Ipomoea batatas.

The accumulation and perpetuation of viral pathogens over generations of clonal propagation in crop species such as sweetpotato, Ipomoea batatas, inevitably result in a reduction in crop yield and quality. This study was conducted at Bundaberg, Australia to compare the productivity of field-derived and pathogen-tested (PT) clones of 14 sweetpotato cultivars and the yield benefits of using healthy planting materials. The field-derived clonal materials were exposed to the endemic viruses, while the PT clones were subjected to thermotherapy and meristem-tip culture to eliminate viral pathogens. The plants were indexed for viruses using nitrocellulose membrane-enzyme-linked immunosorbent assay and graft-inoculations onto Ipomoea setosa. A net benefit of 38% in storage root yield was realised from using PT materials in this study. Conversely, in a similar study previously conducted at Kerevat, Papua New Guinea (PNG), a net deficit of 36% was realised. This reinforced our finding that the response to pathogen testing was cultivar dependent and that the PNG cultivars in these studies generally exhibited increased tolerance to the endemic viruses present at the respective trial sites as manifested in their lack of response from the use of PT clones. They may be useful sources for future resistance breeding efforts. Nonetheless, the potential economic gain from using PT stocks necessitates the use of pathogen testing on virus-susceptible commercial cultivars. .

Quantum supersymmetric generalisation of Bogomolnyi bounds

We review here classical Bogomolnyi bounds, and their generalisation to supersymmetric quantum field theories by Witten and Olive. We also summarise some recent work by several people on whether such bounds are saturated in the quantised theory.

Impact of control strategies on bellyache bush (Jatropha gossypiifolia L.) mortality, seedling recruitment, population dynamics, pasture yield and cost analysis

Bellyache bush (Jatropha gossypiifolia L.) is an invasive weed that has the potential to greatly reduce biodiversity and pasture productivity in northern Australia’s rangelands. This paper reports an approach to develop best practice options for controlling medium to dense infestations of bellyache bush using combinations of control methods. The efficacy of five single treatments including foliar spraying, slashing, stick raking, burning and do nothing (control) were compared against 15 combinations of these treatments over 4 successive years. Treatments were evaluated using several attributes, including plant mortality, changes in population demographics, seedling recruitment, pasture yield and cost of treatment. Foliar spraying once each year for 4 years proved the most cost-effective control strategy, with no bellyache bush plants recorded at the end of the study. Single applications of slashing, stick raking and to a lesser extent burning, when followed up with foliar spraying also led to significantly reduced densities of bellyache bush and changed the population from a growing one to a declining one. Total experimental cost estimates over 4 successive years for treatments where burning, stick raking, foliar spraying, and slashing were followed with foliar spraying were AU$408, AU$584, AU$802 and AU$789 ha–1, respectively. Maximum pasture yield of 5.4 t ha–1 occurred with repeated foliar spraying. This study recommends that treatment combinations using either foliar spraying alone or as a follow up with slashing, stick raking or burning are best practice options following consideration of the level of control, changes in pasture yield and cost effectiveness.

Genetic studies of body mass index yield new insights for obesity biology

Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10−8), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ~2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.

ACIAR Reduce pest disease related yield decrease in sweet potato Papua New Guinea

Develops and extends DEEDI and partner technologies, improves yields and quality by removing virus diseases and some pests. Objectives: 1.Develop and test sweet potato pest and disease control strategies 2.Increase dissemination and adoption of pathogen tested and Integrated Pest Management strategy for pest and disease control.

Agronomic Packages for Improved Yield and Quality in the Australian Peanut Industry

Monitoring aflatoxin and developing improved peanut drying practices, cadmium management and web based irrigation decision support systems.

Developing agronomic solutions to improve barley yield and grain quality

The main aim of this project is to develop variety management packages to help tailor commercial malt and feed barley production in the Northern GRDC Region to commercial malt and feed barley specifications. Field trials are designed to give information.

DAN00106 Developing agronomic solutions to improve barley yield and grain quality

Producing management packages for new northern barley varieties. Evaluating silage barley varieties.

Stay-green wheat for increased yield and yield stability

This project will provide information, germplasm, selection techniques and strategies for breeders to develop high-yielding stay-green wheat cultivars for Australian growers via a "three pronged" research strategy.

Proton NMR studies of dihalogenated phenyl benzamides: two-dimensional higher quantum methodologies

The scalar coupled proton NMR spectra of many organic molecules possessing more than one phenyl ring are generally complex due to degeneracy of transitions arising from the closely resonating protons, in addition to several short- and long- range couplings experienced by each proton. Analogous situations are generally encountered in derivatives of halogenated benzanilides. Extraction of information from such spectra is challenging and demands the differentiation of spectrum pertaining to each phenyl ring and the simplification of their spectral complexity. The present study employs the blend of independent spin system filtering and the spin-state selective detection of single quantum (SO) transitions by the two-dimensional multiple quantum (MQ) methodology in achieving this goal. The precise values of the scalar couplings of very small magnitudes have been derived by double quantum resolved experiments. The experiments also provide the relative signs of heteronuclear couplings. Studies on four isomers of dilhalogenated benzanilides are reported in this work.

Visualization of enantiomers using natural abundant 13C-filtered single and double quantum selective refocusing experiments: Application to small chiral molecules

The routine use of proton NMR for the visualization of enantiomers, aligned in the chiral liquid crystal solvent poly-γ-benzyl-l-glutamate (PBLG), is restricted due to severe loss of resolution arising from large number of pair wise interaction of nuclear spins. In the present study, we have designed two experimental techniques for their visualization utilizing the natural abundance 13C edited selective refocusing of single quantum (CH-SERF) and double quantum (CH-DQSERF) coherences. The methods achieve chiral discrimination and aid in the simultaneous determination of homonuclear couplings between active and passive spins and heteronuclear couplings between the excited protons and the participating 13C spin. The CH-SERF also overcomes the problem of overlap of central transitions of the methyl selective refocusing (SERF) experiment resulting in better chiral discrimination. Theoretical description of the evolution of magnetization in both the sequences has been discussed using polarization operator formalism.