Microstructural evolution and mechanical characteristics in nanocrystalline nickel with a bimodal grain-size distribution

An attractive microstructural possibility for enhancing the ductility of high-strength nanocrystals is to develop a bimodal grain-size distribution, in which the fine grains provide strength, and the coarser grains enable strain hardening. Annealing of nanocrystalline Ni over a range of temperatures and times led to microstructures with varying volume fractions of coarse grains and a change in texture. Tensile tests revealed a drastic reduction in ductility with increasing volume fraction of coarse grains. The reduction in ductility may be related to the segregation of sulphur to grain boundaries.

Grain boundary strengthening in strongly textured magnesium produced by hot rolling

The grain size dependence of the yield stress in hot rolled 99.87 pct magnesium sheets and rods was measured in the temperature range 77 K to 420 K. Hot rolling produced strong basal textures and, for a given grain size, the hot rolled material has a higher strength than extruded material. The yield strength-grain size relation in the above temperature range follows the Hall-Petch equation, and the temperature dependencies of the Hall-Petch constants σ0 and k are in support of the theory of Armstrong for hcp metals that the intercept σ0 is related to the critical resolved shear stress (CRSS) for basal slip (easy slip) and the slope k is related to the CRSS for prismatic slip (difficult slip) occurring near the grain boundaries. In the hot rolled magnesium, σ0 is larger and k is smaller than in extruded material, observations which are shown to result from strong unfavorable basal and favorable 1010 textures, respectively. Texture affects the Hall-Petch constants through its effect on the orientation factors relating them to the CRSS for the individual slip systems controlling them.

Intake, growth and carcass characteristics of lambs consuming low digestible hay and cereal grain

The influence of barley and oat grain supplements on hay dry matter intake (DMI), carcass components gain and meat quality in lambs fed a low quality basal diet was examined. Thirty five crossbred wether lambs (9 months of age) were divided into four groups. After adaptation to a basal diet of 85% oat hay and 15% lucerne hay for one week, an initial group of 11 was slaughtered. The weights of carcass components and digesta-free empty body weight (EBW) of this group was used to estimate the weight of carcass components of the other three experimental groups at the start of the experiment. The remaining three groups were randomly assigned to pens and fed ad libitum the basal diet alone (basal), basal with 300 g air dry barley grain (barley), basal with 300 g air dry oat grain (oat). Supplements were fed twice weekly (i.e., 900 g on Tuesday and 1200 g on Friday). After 13 weeks of feeding, animals were slaughtered and, at 24 h post-mortem meat quality and subcutaneous fat colour were measured. Samples of longissimus muscle were collected for determination of sarcomere length and meat tenderness. Hay DMI was reduced (P<0.01) by both barley and oat supplements. Lambs fed barley or oat had a higher and moderate digestibility of DM, and a higher intake of CP (P<0.05) and ME (P<0.01) than basal lambs. Final live weight of barley and oat lambs was higher (P<0.05) than basal, but this was not reflected in EBW or hot carcass weight. Lambs fed barley or oat had increases in protein (P<0.01) and water (P<0.001) in the carcass, but fat gain was not changed (P>0.05). There were no differences in eye muscle area or fat depth (total muscle and adipose tissue depth at 12th rib, 110 mm from midline; GR) among groups. The increased levels of protein and water components in the carcass of barley and oat fed lambs, associated with improved muscle production, were small and did not alter (P>0.05) any of the carcass/meat quality attributes compared to lambs fed a low quality forage diet. Feeding barley or oat grain at 0.9–1% of live weight daily to lambs consuming poor quality hay may not substantially improve carcass quality, but may be useful in maintaining body condition of lambs through the dry season for slaughter out of season

The effect of row configuration on yield reliability in grain sorghum: II. Modelling the effects of row configuration

In recent years many sorghum producers in the more marginal (<600 mm annual rainfall) cropping areas of Qld and northern NSW have utilised skip row configurations in an attempt to improve yield reliability and reduce sorghum production risk. But will this work in the long run? What are the trade-offs between productivity and risk of crop failure? This paper describes a modelling and simulation approach to study the long-term effects of skip row configurations. Detailed measurements of light interception and water extraction from sorghum crops grown in solid, single and double skip row configurations were collected from three on-farm participatory research trials established in southern Qld and northern NSW. These measurements resulted in changes to the model that accounted for the elliptical water uptake pattern below the crop row and reduced total light interception associated with the leaf area reduction of the skip configuration. Following validation of the model, long-term simulation runs using historical weather data were used to determine the value of skip row sorghum production as a means of maintaining yield reliability in the dryland cropping regions of southern Qld and northern NSW.

Response By Dairy Cows Grazing Tropical Grass Pasture To Barley or Sorghum Grain Based Concentrates and Lucerne Hay

This study investigated the responses by dairy cows grazing Callide Rhodes grass (Chloris gayana cv. Callide) pasture to supplementation with barley or sorghum based concentrates (5 grain:1 cotton seed meal) or barley concentrate plus lucerne (Medicago sativa) hay. It was conducted in summer - autumn 1999 with 20 spring calved cows in 4 treatments in 3 consecutive periods of 4 weeks. Rain grown pastures, heavily stocked at 4.4 cows/ha, provided 22 to 35 kg green DM and 14 to 16 kg green leaf DM/cow.day in periods 1 to 3. Supplements were fed individually twice daily after milking. Cows received 6 kg concentrate/day in period 1, increased by 1 kg/day as barley, sorghum or lucerne chaff in each of periods 2 and 3. The Control treatment received 6 kg barley concentrate in all 3 periods. Milk yields by cows fed sorghum were lower than for cows fed equivalent levels of barley-based concentrate (P<0.05). Faecal starch levels (14, 18 and 17%) for cows fed sorghum concentrate were much higher (P<0.01) than those of cows fed similar levels of barley (2.1, 1.2 and 1.7%) in each period respectively. Additional supplementation as lucerne chaff did not increase milk production (P>0.05). Increased concentrate supplementation did not alleviate the problem of low protein in milk produced by freshly calved Holstein-Friesian cows grazing tropical grass pasture in summer. Animal production for a consuming world : proceedings of 9th Congress of the Asian-Australasian Association of Animal Production Societies [AAAP] and 23rd Biennial Conference of the Australian Society of Animal Production [ASAP] and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, [DRF]. 2-7 July 2000, Sydney, Australia.

Unusual stress and grain size dependence for creep in nanocrystalline materials

Analyses of diffusion and dislocation creep in nanocrystals needs to take into account the generally utilized low temperatures, high stresses and very fine grain sizes. In nanocrystals, diffusion creep may be associated with a nonlinear stress dependence and dislocation creep may involve a grain size dependence.

Effective Use in Livestock Feeds of Mouldy and Weather-damaged Grain Containing Mycotoxins-Case Histories and Economic Assessments Pertaining to Pig and Poultry Industries of Queensland

Mould growth in field crops or stored grain reduces starch and lipid content, with consequent increases in fibre, and an overall reduction in digestible energy; palatability is often adversely affected. If these factors are allowed for, and mycotoxin concentrations are low, there are sound economic reasons for using this cheaper grain. Mycotoxins are common in stock feed but their effects on animal productivity are usually slight because either the concentration is too low or the animal is tolerant to the toxin. In Australia, aflatoxins occur in peanut by-products and in maize and sorghum if the grain is moist when stored. Zearalenone is found in maize and in sorghum and wheat in wetter regions. Nivalenol and deoxynivalenol are found in maize and wheat but at concentrations that rarely affect pigs, with chickens and cattle being even more tolerant. Other mycotoxins including cyclopiazonic acid, T-2 toxin, cytochalasins and tenuazonic acid are produced by Australian fungi in culture but are not found to be significant grain contaminants. Extremely mouldy sorghum containing Alternaria and Fusarium mycotoxins decreased feed conversion in pigs and chickens by up to 14%. However, E moniliforme- and Diplodia maydis-infected maize produced only slight reductions in feed intake by pigs and Ustilago- infected barley produced no ill effects. Use of these grains would substantially increase profits if the grain can be purchased cheaply.

Rejection by pigs of mouldy grain containing deoxynivalenol

Weaner pigs on a farm near Beaudesert in south eastern Queensland refused to eat feed comprised largely of wheat and barley. Older pigs consumed small amounts and some prepubertal gilts subsequently displayed enlarged and reddened vulvas. Wheat, barley and triticale were grown on the farm during 1983, which was unusually and persistently wet. The wheat and triticale were harvested and stored for about 3 weeks with moisture contents above 14% before being fed. Samples of the wheat and triticale contained pale pink grains, which can indicate infection by the fungus Fusariurn grarninearurn Schw. On analysis 2 mycotoxins known to be produced by F. graminearurn were detected, deoxynivalenol (vomitoxin) which causes feed refusal and vomiting, and zearalenone which causes oestrogenic effects. Concentrations of deoxynivalenol in the wheat, triticale and barley were 34, 10, and <0.1 mg/kg respectively. Concentrations of zearalenone were 6.2, 2.8 and 0.1 mg/kg respectively. Subsequently, F. grarninearurn was isolated from grains and crop residues. Although the wet weather contributed to F. grarninearurn infection of the crops before harvest, most of the toxins probably developed during storage.

Utilisation of grain rations on sown pastures in central Queensland

A number of studies on Brigalow Research Station, Theodore, in Central Queensland, investigated the performance of different classes of cattle, with or without grain diets, on sown tropical pastures based on buffel and rhodes grasses. These studies were conducted for the Meat Research Corporation's DAQ 065 research project and monitored the growth, carcass attributes, meat quality and market suitability of weaner heifers and steers, 2% year-old steers and aged cull cows. The majority of grain feeding was on an ad lib basis during the winter-spring period when cattle growth rates on pastures are traditionally at or just above maintenance level. 21st Biennial Conference. 8-12 July 1996, University of Queensland. Brisbane.

Seasonal effects of foliar application of phosphonate on phosphonate translocation, in vitro pollen viability and pollen germination in `Hass' avocado (Persea americana Mill.)

Phosphonate fungicides are used widely in the control of diseases caused by Phytophthora cinnamomi Rands. For the most part phosphonate is seen as a safe to use on crops with phytotoxicity rare. However, recent research has shown that phosphonate has detrimental effects on the floral biology of some indigenous Australian plants. Since phosphonate fungicides are regularly used for the control of Phytophthora root rot in avocados, research was carried out to study the translocation of phosphonate fungicide in 'Hass' trees and any effects on their floral biology. Field-grown trees were sprayed with 0, 0.06 or 0.12 M mono-dipotassium phosphonate (pH 7.2) at summer flush maturity, floral bud break or anthesis. Following treatment, phosphonic acid concentrations were determined in leaves, roots, inflorescence rachi and flowers and in vitro pollen germination and pollen tube growth studied. Phosphonic acid concentration in the roots and floral parts was related to their sink strength at the respective times of application with concentration in roots highest (36.9.mg g±1) after treatment at summer flush maturity and in flowers (234.7 mg g±1) after treatment during early anthesis. Phosphonate at >0.03 M was found to be significantly phytotoxic to in vitro pollen germination and pollen tube growth. However, this rate gave a concentration far in excess of that measured in plant tissues following standard commercial applications of mono-dipotassium phosphonate fungicide. There was a small effect on pollen germination and pollen tube growth when 0.06 and 0.12 M mono-dipotassium phosphonate was applied during early anthesis. However, under favourable pollination and fruit set conditions it is not expected to have commercial impact on tree yield. However, there may be detrimental commercial implications from phosphonate sprays at early anthesis if unfavourable climatic conditions for pollination and fruit set subsequently occur. A commercial implication from this study is that phosphonic acid root concentrations can be elevated and maintained with strategic foliar applications of phosphonate fungicide timed to coincide with peaks in root sink strength. These occur at the end of the spring and summer flushes when shoot growth is relatively quiescent. Additional foliar applications may be advantageous in under high disease-pressure situations but where possible should be timed to minimize overlap with other significant growth events in the tree such as rapid inflorescence, and fruit development and major vegetative flushing.

The risk of pollen-mediated gene flow from exotic Corymbia plantations into native Corymbia populations in Australia

Sectors of the forest plantation industry in Australia are set to expand in the near future using species or hybrids of the spotted gums (Corymbia, Section Politaria). Plantations of these taxa have already been introduced across temperate and subtropical Australia, representing locally exotic introductions from native stands in Queensland and New South Wales. A literature review was undertaken to provide insights into the potential for pollen-mediated gene flow from these plantations into native populations. Three factors suggest that such gene flow is likely; (1) interspecific hybridisation within the genus has frequently been recorded, including between distantly related species from different sections, (2) apparent high levels of vertebrate pollinator activity may result in plantation pollen being moved over hundreds of kilometres, (3) much of the plantation estate is being established among closely related taxa and therefore few barriers to gene flow are expected. Across Australia, 20 of the 100 native Corymbia taxa were found to have regional level co-occurrence with plantations. These were located most notably within regions of north-east New South Wales and south-east Queensland, however, co-occurrence was also found in south-west Western Australia and eastern Victoria. The native species found to have co-occurrence were then assessed for the presence of reproductive barriers at each step in the process of gene flow that may reduce the number of species at risk even further. The available data suggest three risk categories exist for Corymbia. The highest risk was for gene flow from plantations of spotted gums to native populations of spotted gums. This was based on the expected limited existence of pre- and post-zygotic barriers, substantial long-distance pollen dispersal and an apparent broad period of flowering in Corymbia citriodora subsp. variegata plantations. The following risk category focussed on gene flow from Corymbia torelliana × C. c. variegata hybrid plantations into native C. c. variegata, as the barriers associated with the production and establishment of F1 hybrids have been circumvented. For the lowest risk category, Corymbia plantations may present a risk to other non-spotted gum species, however, further investigation of the particular cross-combinations is required. A list of research directions is provided to better quantify these risks. Empirical data will need to be combined within a risk assessment framework that will not only estimate the likelihood of exotic gene flow, but also consider the conservation status/value of the native populations. In addition, the potential impacts of pollen flow from plantations will need to be weighed up against their various economic and environmental benefits.

Selecting for increased barley grain size

In this study, 120–144 commercial varieties and breeding lines were assessed for grain size attributes including plump grain (>2.8 mm) and retention (>2.5 mm+>2.8 mm). Grain samples were produced from replicated trials at 25 sites across four years. Climatic conditions varied between years as well as between sites. Several of the trial sites were irrigated while the remaining were produced under dryland conditions. A number of the dryland sites suffered severe drought stress. The grain size data was analysed for genetic (G), environmental (E) and genotype by environment (G×E) interactions. All analyses included maturity as a covariate. The genetic effect on grain size was greater than environmental or maturity effects despite some sites suffering terminal moisture stress. The model was used to calculate heritability values for each site used in the study. These values ranged from 89 to 98% for plump grain and 88 to 96% for retention. The results demonstrated that removing the sources of non-heritable variation, such as maturity and field effects, can improve genetic estimates of the retention and plump grain fractions. By partitioning all variance components, and thereby having more robust estimates of genetic differences, plant breeders can have greater confidence in selecting barley genotypes which maintain large, stable grain size across a range of environments.

Genetic Impacts of the Hull on Barley Grain Quality

Barley hull plays an important role in malt and feed quality and processing. In this study we measured the variation in hull con-tent along with other grain quality traits namely, kernel discolouration and degree of pre-harvest sprouting, in a single map-ping population. There were significant (p < 0.05) genetic as well as environment effects. In addition, heritability was calculated for hull content to be 29% and 47% for two years’ data. From the analysis, major QTL markers were identified in con-trolling the expression of hull content on chromosomes 2 (2H), and 6 (6H) with significant (P < 0.05) LOD scores of 5.4 and 3.46 respectively. Minor QTLs were identified on 1 (7H), 4 (4H), 5 (1H) and 7 (5H). The region at marker Bmac310 on 4(4H) could be associated with dormancy gene SD4. A number of the QTLs also coincided with regions for either kernel discolouration or preharvest sprouting resistance (dormancy). The results indicate that variation exists for hull content, which is influenced by both growing environment as well as genetically, although the genetic variance explained less than half of the total variance. Further, hull content also impacts on other grain quality attributes including dormancy, sprouting resistance and kernel appearance.

Measurement of genetic and environmental variation in barley (Hordeum vulgare) grain hardness

In this study, we assessed a broad range of barley breeding lines and commercial varieties by three hardness methods (two particle size methods and one crush resistance method (SKCS—Single-Kernel Characterization System), grown at multiple sites to see if there was variation in barley hardness and if that variation was genetic or environmentally controlled. We also developed near-infrared reflectance (NIR) calibrations for these three hardness methods to ascertain if NIR technology was suitable for rapid screening of breeding lines or specific populations. In addition, we used this data to identify genetic regions that may be associated with hardness. There were significant (p<0.05) genetic effects for the three hardness methods. There were also environmental effects, possibly linked to the effect of protein on hardness, i.e. increasing protein resulted in harder grain. Heritability values were calculated at >85% for all methods. The NIR calibrations, with R2 values of >90%, had Standard Error of Prediction values of 0.90, 72 and 4.0, respectively, for the three hardness methods. These equations were used to predict hardness values of a mapping population which resulted in genetic markers being identified on all chromosomes but chromosomes 2H, 3H, 5H, 6H and 7H had markers with significant LOD scores. The two regions on 5H were on the distal end of both the long and short arms. The region that showed significant LOD score was on the long arm. However, the region on the short arm associated with the hardness (hordoindoline) genes did not have significant LOD scores. The results indicate that barley hardness is influenced by both genotype and environment and that the trait is heritable, which would allow breeders to develop very hard or soft varieties if required. In addition, NIR was shown to be a reliable tool for screening for hardness. While the data set used in this study has a relatively low variation in hardness, the tools developed could be applied to breeding populations that have large variation in barley grain hardness.

Impact of resistance on the efficacy of binary combinations of spinosad, chlorpyrifos-methyl and s-methoprene against five stored-grain beetles

Laboratory experiments were conducted to determine the efficacy of spinosad (a biopesticide), chlorpyrifos-methyl (an organophosphorus compound (OP)) and s-methoprene (a juvenile hormone analogue) applied alone and in binary combinations against five stored-grain beetles in wheat. There were three strains of Rhyzopertha dominica, and one strain each of Sitophilus oryzae, Tribolium castaneum, Oryzaephilus surinamensis and Cryptolestes ferrugineus. These strains were chosen to represent a range of possible resistant genotypes, exhibiting resistance to organophosphates, pyrethroids or methoprene. Treatments were applied at rates that are registered or likely to be registered in Australia. Adults were exposed to freshly treated wheat for 2 weeks, and the effects of treatments on mortality and reproduction were determined. No single protectant or protectant combination controlled all insect strains, based on the criterion of >99% reduction in the number of live F1 adults relative to the control. The most effective combinations were spinosad at 1 mg kg-1+chlorpyrifos-methyl at 10 mg kg-1 which controlled all strains except for OP-resistant O. surinamensis, and chlorpyrifos-methyl at 10 mg kg-1+s-methoprene at 0.6 mg kg-1 which controlled all strains except for methoprene-resistant R. dominica. The results of this study demonstrate the difficulty in Australia, and potentially other countries which use protectants, of finding protectant treatments to control a broad range of pest species in the face of resistance development.