Influence of concentration, temperature and humidity on the toxicity of phosphine to the strongly phosphine-resistant psocid Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

BACKGROUND: The psocid Liposcelis bostrychophila Badonnel, is a widespread, significant pest of stored commodities, has developed strong resistance to phosphine, the major grain disinfestant. The aim was to develop effective fumigation protocols to control this resistant pest. RESULTS: Time to population extinction of all life stages (TPE) in days was evaluated at a series of phosphine concentrations and temperatures at two relative humidities. Regression analysis showed that temperature, concentration and relative humidity all contributed significantly to describing TPE (P < 0.001, R2 = 0.95), with temperature being the dominant variable, accounting for 74.4% of the variation. Irrespective of phosphine concentration, TPE was longer at lower temperatures and high humidity (70% RH) and shorter at higher temperatures and low humidity (55% RH). At any concentration of phosphine, a combination of higher temperature and lower humidity provides the shortest fumigation period to control resistant L. bostrychophila. For example, 19 and 11 days of fumigation are required at 15 °C and 70% RH at 0.1 and 1.0 mg L-1 of phosphine respectively, whereas only 4 and 2 days are required at 35 °C and 55% RH for the same respective concentrations. CONCLUSIONS: The developed fumigation protocols will provide industry with flexibility in application of phosphine.

Modelling environmental effects on phenology and canopy development of diverse sorghum genotypes

The ability to predict phenology and canopy development is critical in crop models used for simulating likely consequences of alternative crop management and cultivar choice strategies. Here we quantify and contrast the temperature and photoperiod responses for phenology and canopy development of a diverse range of elite Indian and Australian sorghum genotypes (hybrid and landrace). Detailed field experiments were undertaken in Australia and India using a range of genotypes, sowing dates, and photoperiod extension treatments. Measurements of timing of developmental stages and leaf appearance were taken. The generality of photo-thermal approaches to modelling phenological and canopy development was tested. Environmental and genotypic effects on rate of progression from emergence to floral initiation (E-FI) were explained well using a multiplicative model, which combined the intrinsic development rate (Ropt), with responses to temperature and photoperiod. Differences in Ropt and extent of the photoperiod response explained most genotypic effects. Average leaf initiation rate (LIR), leaf appearance rate and duration of the phase from anthesis to physiological maturity differed among genotypes. The association of total leaf number (TLN) with photoperiod found for all genotypes could not be fully explained by effects on development and LIRs. While a putative effect of photoperiod on LIR would explain the observations, other possible confounding factors, such as air-soil temperature differential and the nature of model structure were considered and discussed. This study found a generally robust predictive capacity of photo-thermal development models across diverse ranges of both genotypes and environments. Hence, they remain the most appropriate models for simulation analysis of genotype-by-management scenarios in environments varying broadly in temperature and photoperiod.

Effects of diet, temperature and photoperiod on development and survival of the bigeyed bug, Geocoris lubra

Bigeyed bugs (Geocoris spp., Hemiptera: Geocoridae) are common predators in Australian agricultural crops yet the development and reproductive biology of Australian geocorids has not been described before. Here we present the effects of diet, temperature and photoperiod on the development and survival of Geocoris lubra Kirkaldy from egg to adult. Nymphal survival of G. lubra reared on live aphids (Aphis gossypii Glover) was very low but improved slightly on a diet of Helicoverpa armigera (Hübner) eggs. Development was faster and nymphal survival improved significantly at 27°C compared with 25°C. Further investigation at 27°C showed photoperiod influenced development time, but not survival of immature G. lubra. Development time was significantly longer at 10L:14D. Fecundity of first generation G. lubra was not affected by photoperiod, although egg viability was greater at 12L:12D.

Annual forecasting of the Australian macadamia crop - integrating tree census data with statistical climate-adjustment models

To facilitate marketing and export, the Australian macadamia industry requires accurate crop forecasts. Each year, two levels of crop predictions are produced for this industry. The first is an overall longer-term forecast based on tree census data of growers in the Australian Macadamia Society (AMS). This data set currently accounts for around 70% of total production, and is supplemented by our best estimates of non-AMS orchards. Given these total tree numbers, average yields per tree are needed to complete the long-term forecasts. Yields from regional variety trials were initially used, but were found to be consistently higher than the average yields that growers were obtaining. Hence, a statistical model was developed using growers' historical yields, also taken from the AMS database. This model accounted for the effects of tree age, variety, year, region and tree spacing, and explained 65% of the total variation in the yield per tree data. The second level of crop prediction is an annual climate adjustment of these overall long-term estimates, taking into account the expected effects on production of the previous year's climate. This adjustment is based on relative historical yields, measured as the percentage deviance between expected and actual production. The dominant climatic variables are observed temperature, evaporation, solar radiation and modelled water stress. Initially, a number of alternate statistical models showed good agreement within the historical data, with jack-knife cross-validation R2 values of 96% or better. However, forecasts varied quite widely between these alternate models. Exploratory multivariate analyses and nearest-neighbour methods were used to investigate these differences. For 2001-2003, the overall forecasts were in the right direction (when compared with the long-term expected values), but were over-estimates. In 2004 the forecast was well under the observed production, and in 2005 the revised models produced a forecast within 5.1% of the actual production. Over the first five years of forecasting, the absolute deviance for the climate-adjustment models averaged 10.1%, just outside the targeted objective of 10%.

Low-temperature stabilization of pure Ni(IT)O

Ordinary nickel (II) oxide prepared by any of the usual methods is always contaminated with some higher valency states of nickel. Such nickel oxide however can be converted to pure nickel (II) oxide by soaking for some hours at 800–850°C in a closed system under a static inert atmosphere and in the presence of pure MnO as oxygen-getter. The resulting Ni(IT)O is highly resistant to oxidation.

Isolation, characterization and mapping of temperature-sensitive mutants of mycobacteriophage I3

Eighteen temperature-sensitive mutants of mycobacteriophage I3 have been isolated and partially characterized. All the mutants were defective in vegetative replication. Based on temperature shift experiments with the temperature sensitive mutants, the thermosensitive phase of the phage development period has been characterized for each mutant. The genes have been mapped by recombination analysis. The early, continuous and middle genes seem to cluster on the genetic map

CFD Analysis of conjugate natural convection in a vertical annulus

Conjugate natural convection in a vertical annulus with a centrally located vertical heat generating rod is studied numerically. The governing equations are discretized on a staggered mesh and are solved using a pressure-correction algorithm. A parametric study is performed by varying the Grashof number, aspect ratio, and the solid-to-fluid thermal conductivity ratio over wide ranges with the Prandtl number fixed at 0.7. Results are presented for the variation of several quantities of interest such as the local Nusselt numbers on the inner and outer boundaries, the axial variation of the centerline and interface temperatures, maximum solid, average solid and average interface temperature variations with Grashof number, and the average Nusselt number variation for the inner and outer boundaries with Grashof number. The average Nusselt number from the conjugate analysis is found to be between the Nusselt numbers of the isothermal and the isoflux cases. The average Nusselt numbers on the inner and outer boundaries show an increasing trend with the Grashof number. Correlations are presented for the Nusselt number and the dimensionless temperatures of interest in terms of the parameters of the problem.

The influence of temperature on the foaming of milk

The effect of temperature (5-85 °C) on the foaming properties of cows' milk was investigated. The foaming properties of milk as a function of temperature varied considerably depending on fat content and the processing conditions used in manufacture. Skim milk foams were most stable when formed at 45 °C. Milk fat had a detrimental effect on foam formation and stability of whole milk especially in the temperature range 15-45 °C. The detrimental effects of milk fat on foaming properties were reduced by homogenization and ultra-high-temperature (UHT) treatment. No correlation was observed between foam formation and surface tension of whole milk in the temperature range 15-45 °C. There was a pronounced difference in the bubble size distributions of whole milk and skim milk especially at half-life of the foams. Bubbles in whole milk foams were smaller and showed a higher degree of rupture as a result of coalescence than those in skim milk foams.

Using APSIM-soiltemp to simulate soil temperature in the podding zone of peanut

Measurement or accurate simulation of soil temperature is important for improved understanding and management of peanuts (Arachis hypogaea L.), due to their geocarpic habit. A module of the Agricultural Production Systems Simulator Model (APSIM), APSIM-soiltemp, which uses input of ambient temperature, rainfall and solar radiation in conjunction with other APSIM modules, was evaluated for its ability to simulate surface 5 cm soil temperature in 35 peanut on-farm trials conducted between 2001 and 2005 in the Burnett region (25°36'S to 26°41'S, 151°39'E to 151°53'E). Soil temperature simulated by the APSIM-soiltemp module, from 30 days after sowing until maturity, closely matched the measured values (R2 ≥ 0.80)in the first three seasons (2001-04). However, a slightly poorer relationship (R2 = 0.55) between the observed and the simulated temperatures was observed in 2004-05, when the crop was severely water stressed. Nevertheless, over all the four seasons, which were characterised by a range of ambient temperature, leaf area index, radiation and soil water, each of which was found to have significant effects on soil temperature, a close 1:1 relationship (R2 = 0.85) between measured and simulated soil temperatures was observed. Therefore, the pod zone soil temperature simulated by the module can be generally relied on in place of measured input of soil temperature in APSIM applications, such as quantifying climatic risk of aflatoxin accumulation.

Climate change impacts on northern Australian rangeland livestock carrying capacity: a review of issues

Grazing is a major land use in Australia's rangelands. The 'safe' livestock carrying capacity (LCC) required to maintain resource condition is strongly dependent on climate. We reviewed: the approaches for quantifying LCC; current trends in climate and their effect on components of the grazing system; implications of the 'best estimates' of climate change projections for LCC; the agreement and disagreement between the current trends and projections; and the adequacy of current models of forage production in simulating the impact of climate change. We report the results of a sensitivity study of climate change impacts on forage production across the rangelands, and we discuss the more general issues facing grazing enterprises associated with climate change, such as 'known uncertainties' and adaptation responses (e.g. use of climate risk assessment). We found that the method of quantifying LCC from a combination of estimates (simulations) of long-term (>30 years) forage production and successful grazier experience has been well tested across northern Australian rangelands with different climatic regions. This methodology provides a sound base for the assessment of climate change impacts, even though there are many identified gaps in knowledge. The evaluation of current trends indicated substantial differences in the trends of annual rainfall (and simulated forage production) across Australian rangelands with general increases in most of western Australian rangelands ( including northern regions of the Northern Territory) and decreases in eastern Australian rangelands and south-western Western Australia. Some of the projected changes in rainfall and temperature appear small compared with year-to-year variability. Nevertheless, the impacts on rangeland production systems are expected to be important in terms of required managerial and enterprise adaptations. Some important aspects of climate systems science remain unresolved, and we suggest that a risk-averse approach to rangeland management, based on the 'best estimate' projections, in combination with appropriate responses to short-term (1-5 years) climate variability, would reduce the risk of resource degradation. Climate change projections - including changes in rainfall, temperature, carbon dioxide and other climatic variables - if realised, are likely to affect forage and animal production, and ecosystem functioning. The major known uncertainties in quantifying climate change impacts are: (i) carbon dioxide effects on forage production, quality, nutrient cycling and competition between life forms (e.g. grass, shrubs and trees); and (ii) the future role of woody plants including effects of. re, climatic extremes and management for carbon storage. In a simple example of simulating climate change impacts on forage production, we found that increased temperature (3 degrees C) was likely to result in a decrease in forage production for most rangeland locations (e. g. -21% calculated as an unweighted average across 90 locations). The increase in temperature exacerbated or reduced the effects of a 10% decrease/increase in rainfall respectively (-33% or -9%). Estimates of the beneficial effects of increased CO2 (from 350 to 650 ppm) on forage production and water use efficiency indicated enhanced forage production (+26%). The increase was approximately equivalent to the decline in forage production associated with a 3 degrees C temperature increase. The large magnitude of these opposing effects emphasised the importance of the uncertainties in quantifying the impacts of these components of climate change. We anticipate decreases in LCC given that the 'best estimate' of climate change across the rangelands is for a decline (or little change) in rainfall and an increase in temperature. As a consequence, we suggest that public policy have regard for: the implications for livestock enterprises, regional communities, potential resource damage, animal welfare and human distress. However, the capability to quantify these warnings is yet to be developed and this important task remains as a challenge for rangeland and climate systems science.

High-temperature superconductivity in the 100 K region in perovskite-related oxides of the Ln-Ba-Cu-O (Ln=Y or La) system

Oxides of the Y-Ba-Cu-O system are found to show onset of superconductivity in the 100–120 K region.

Germination of Hymenachne amplexicaulis and H. acutigluma under contrasting light, temperature and nitrate regimes

A laboratory experiment compared germination of the invasive exotic grass Hymenachne amplexicaulis (Rudge) Nees and the native H. acutigluma (Steud.) Gilliland. Seeds of both species were exposed to combinations of light (constant dark, alternating dark/light or constant light), temperature (constant or alternating) and nitrate regimes (with or without the addition of KNO3). Three seed lots of H. amplexicaulis (fresh, two adn four months old) and one of H. acutigluma (fresh seed) were tested. A significant temperature x light x nitrate x seed lot interaction occured. At a constant temperature very few seeds of either H. amplexicaulis or H. acutigluma germinated, regardless of the light regime or addition of KNO3. Generally, maximum germination occurred under a combination of alternating temperature, the presence of light (either constant or alternating) and the addition of KNO3. The exception was four month stored H. amplexicaulis seed, which reached maximum germinaction without the need for KNO3. Fresh seed of both H. amplexicaulis and H. acutigluma exhibited similar germination requirements. These findings suggest that conditions that buffer seeds from light and/or temperature fluctuations could reduce germination and possibly extend the life of seed banks of both H. amplexicaulis and H. acutigluma. Conversely, for land managers trying to control the exotic H. amplexicaulis, activities that create more favourable conditions for germination may help deplete seed banks faster.

Soil type does not affect seed ageing when soil water potential and temperature are controlled

To investigate the effects of soil type on seed persistence in a manner that controlled for location and climate variables, three weed species—Gomphocarpus physocarpus (swan plant), Avena sterilis ssp. ludoviciana (wild oat) and Ligustrum lucidum (broadleaf privet)—were buried for 21 months in three contrasting soils at a single location. Soil type had a significant effect on seed persistence and seedling vigour, but soil water content and temperature varied between soils due to differences in physical and chemical properties. Warmer, wetter conditions favoured shorter persistence. A laboratory-based test was developed to accelerate the rate of seed ageing within soils, using controlled superoptimal temperature and moisture conditions (the soil-specific accelerated ageing test, SSAAT). The SSAAT demonstrated that soil type per se did not influence seed longevity. Moreover, the order in which seeds aged was the same whether aged in the field or SSAAT, with L. lucidum being shortest-lived and A. sterilis being longest-lived of the three species.

Growth and carcass characteristics of cast-for-age Merino ewes fed sorghum-based feedlot diets

Grain feeding low bodyweight, cast-for-age (CFA) sheep from pastoral areas of eastern Australia at the end of the growing season can enable critical carcass weight grades to be achieved and thus yield better economic returns. The aim of this work was to compare growth and carcass characteristics for CFA Merino ewes consuming either simple diets based on whole sorghum grain or commercial feed pellets. The experiment also compared various sources of additional nitrogen (N) for inclusion in sorghum diets and evaluated several introductory regimes. Seventeen ewes were killed initially to provide baseline carcass data and the remaining 301 ewes were gradually introduced to the concentrate diets over 14 days before being fed concentrates and wheaten hay ad libitum for 33 or 68 days. Concentrate treatments were: (i) commercial feed pellets, (ii) sorghum mix (SM; whole sorghum grain, limestone, salt and molasses) + urea and ammonium sulfate (SMU), (iii) SMU + whole cottonseed at 286 g/kg of concentrate dry matter (DM), (iv) SM + cottonseed meal at 139 g/kg of concentrate DM, (v) SMU + virginiamycin (20 mg/kg of concentrate) for the first 21 days of feeding, and (vi) whole cottonseed gradually replaced by SMU over the first 14 days of feeding. The target carcass weight of 18 kg was achieved after only 33 days on feed for the pellets and the SM + cottonseed meal diet. All other whole grain sorghum diets required between 33 and 68 days on feed to achieve the target carcass weight. Concentrates based on whole sorghum grain generally produced significantly (P < 0.05) lower carcass weight and fat score than pellets and this may have been linked to the significantly (P < 0.05) higher faecal starch concentrations for ewes consuming sorghum-based diets (270 v. 72 g/kg DM on day 51 of feeding for sorghum-based diets and pellets, respectively). Source of N in whole grain sorghum rations and special introductory regimes had no significant (P > 0.05) effects on carcass weight or fat score of ewes with the exception of carcass weight for SMU + whole cottonseed being significantly lower than SM + cottonseed meal at day 33. Ewes finished on all diets produced acceptable carcasses although muscle pH was high in all ewe carcasses (average 5.8 and 5.7 at 33 and 68 days, respectively). There were no significant (P > 0.05) differences between diets in concentrate DM intake, rumen fluid pH, meat colour score, fat colour score, eye muscle area, meat pH or meat temperature.