bluuebunny/crossref_metadata_2025 huggingface dataset:
Alternative hosts and the epidemiology of potato leafroll virus in Queensland.
Authors: Thomas JE
Published: November 2004

Potato leafroll virus (PLRV) was the most frequently detected virus in potato crops grown at a trial site in the Lockyer Valley. Queensland. Levels of infection with PLRV were significantly higher in autumn crops grown from one-off certified (saved) seed (maximum 51%) than in crops grown directly from certified seed (maximum 6%). Potato viruses S and X were very uncommon (maximum incidence each of 1%) and potato virus Y was not detected in these crops. Tomato, Nicandra physalodes and Physalis sp. were identified as field hosts of PLRV in Queensland and, additionally, Stachys aruensis (Labiatae), Nicotiana benthamiana, Nicotiana tabacum and Solanum americanum (Solanaceae) were shown to be experimental hosts. In field trials in the Lockyer Valley and the Redlands district, PLRV was detected in 45-65% of symptomless tomato plants growing within 300 m of the nearest source of PLRV-infected potatoes. Virus levels were lower in the leaves of potato cv. Pontiac than in those of cvv. Bison and Sebago 5 weeks after primary (aphid-borne) infection, but these differences were no longer apparent after 11 weeks. Four weeks after emergence, virus levels in cv. Bison were markedly higher than in cvv. Pontiac and Sebago in plants with secondary (tuber-borne) infection. After 9 weeks, virus levels in all cultivars were similar and were greater in lower than in upper leaves.
Inoculation with root nodulating bacteria reduces the susceptibility of Medicago truncatula and Lupinus angustifolius to cucumber mosaic virus (CMV) and addition of nitrate partially reverses the effect
Authors: Wahyuni WS , Randles JW
Published: November 2004

The susceptibility of Medicago truncatula ssp. truncatula (barrel medic) cv. Jemalong and Lupinus angustifolius (lupin) cv. Illyarrie and Gungurru to cucumber mosaic virus (CMV) was reduced by prior inoculation of seedlings with commercial strains of root nodulating bacteria (Rhizobium or Bradyrhizobium, respectively). This effect was observed both with strains of CMV originating from legumes and with strains originating from non-legumes. The virus content of the nodulated plants which were successfully inoculated was not markedly affected by nodulation, indicating that nodulation affected susceptibility to inoculation, and not the ability of CMV to replicate. In lupins, the reduction in susceptibility followed mechanical and graft inoculation of plants with virus. The effect was first noted at about the time that acetylene reduction activity (ARA) was first detected and just before nodules appeared. Virus-infected lupins showed a delay in the development of nodules and a reduced ARA, compared with uninfected plants, indicating that there was a two-way interaction between the virus and Bradyrhizobium. Different growth conditions did not affect the ARA values, the severity of symptoms or the susceptibility of lupin to CMV. A minimum level of nitrate was required for medic growth both with and without the root nodulating bacteria. The addition of higher levels of nitrate to the nutrient solution partially reversed the effect of the nodulating bacteria, in that it increased the susceptibility of the plants. Medics not inoculated with Rhizobium and supplied with a high concentration of nitrate were the most susceptible to CMV. In a test to compare competent with incompetent bacteria, Rhizobium strain 1021 (which fixes N2) and its mutant, Rm 1491 (which does not fix N2), did not differ in their effect on susceptibility. Aggregates of virus particles and crystals of virus were found in nodule cells of medic plants, but virus particles and bacteroids were not found in the same cell. Individual and aggregated virus particles were commonly located along the cell wall of cells free of bacteroids. It is concluded that infection by root nodulating bacteria and external nitrogen supplementation have opposite effects on the susceptibility of barrel medic and lupin to CMV, and that CMV, in turn, reduces the effectiveness of the symbiosis between these bacteria and their host. Nodulation has little effect on virus replication, and both virus and bacteroids occur in the same nodule tissue.
Long term effects of rotation, tillage and stubble management on wheat production in southern NSW
Authors: Heenan DP , Taylor AC , Cullis BR , Lill WJ
Published: November 2004

A long term field experiment began in 1979 at Wagga Wagga, N.S.W., to compare the sustainability of a range of rotation, tillage and stubble management systems on a red earth. This paper reports yield, yield components and grain protein of wheat for 1979-90. Rotations considered were alternating lupin-wheat (LW), lupin-wheat-wheat (LWW), continuous wheat (WW) with and without N fertilizer (100 kg N/ha), and alternating sub-clover-wheat (CW). Soil N supply at the start of the experiment was high following many years of sub-clover based pasture. From 1979 to 1983, there was a negative grain yield response to N fertilizer and no response to a legume in rotation except in the drought of 1982 when low yields were recorded from LW. Thereafter, a positive grain yield response was usually produced to N fertilizer in WW rotations, until 1989 and 1990, when these crops displayed aluminium toxicity sym ptoms. Overall, average grain yields from legume rotations were higher than WW with added N fertilizer. Since 1983, LW rotations consistently produced higher mean grain yields than CW, but mean grain protein and total N uptake were lower. Yields and N uptake by the second wheat crop in a LWW rotation indicated little carryover of benefits from the lupins. Slightly higher mean grain yield and harvest index, but lower mean grain protein, were produced by direct drilling, compared with cultivation before sowing, following lupins or sub-clover. However, retaining stubble rather than burning in autumn consistently reduced grain yields. There was no evidence that early burial of wheat stubble following summer rain, rather than incorporation in autumn, improved grain yield or total N uptake. The build-up of giant brome grass and diseases, particularly where stubble was retained and crops direct-drilled, casts some doubt on the long term sustainability of these short term rotations in this environment.
Corrigendum - How much is a genetically superior ram worth?
Authors: Wade C , Goddard M
Published: November 2004

The economic value of a genetic difference between rams was estimated for stud and commercial tiers in the Australian Merino industry. Discounted returns were predicted using the method of Hill (1974). Results were generated for breeding schemes considering natural mating (Scheme A), artificial insemination (Scheme B), the use of home-bred sires at daughter stud level (Scheme C) and the use of culled stud ewes in lower tiers (Scheme D). The effects of discount rate and ram flock life were assessed. The value of one extra unit of genetic merit in three traits (Clean Fleece Weight, Fibre Diameter and WOOLPLAN index score) was found for commercial, daughter and parent tiers. One extra kilogram of clean fleece weight (CFW) was worth around $817 for a commercial level ram (all Schemes) and up to $390000 for a parent level ram in Scheme B. The same improvement was worth $4 per semen dose used at commercial level, and up to $3977 at parent stud level (Scheme B). Increasing the discount rate devalued later returns, reducing the number of discounted expressions. Increasing ram flock life increased ram value but reduced semen value. The results are discussed for current industry practice and values obtained previously for commercial rams. The economic value of multiple ovulation and embryo transfer is considered.
Reproductive performance and genetic parameters for Australian Dorset Sheep
Authors: Brash LD , Fogarty NM , Gilmour AR
Published: November 2004

Reproductive performance of ewes in a large Dorset stud flock is reported. The data included 2488 ewes with 10016 joining records over 25 years. Average performance for reproductive traits were: fertility 92%, litter size 1.31, neonatal lamb survival 91%, lamb survival to weaning 85%, with overall lambs born 1.20 and lambs weaned 1.02 per ewe joined. Differences between breeds (Poll Dorset and Dorset Horn), season of birth (spring and autumn) and season of joining (spring and autumn) were significant for most reproduction traits. Linear and quadratic regressions for age of ewe at joining were highly significant for all traits (P < 0.001) with maximum performance between three and six years of age. Estimates of heritability for ewe reproductive traits were: 0.062 � 0-02 for number of lambs born and 0.04 � 0.01 for number of lambs weaned per ewe joined, and component traits, 0.02 �0 -01 for fertility, 0 08 � 0 -02 for litter size and 0.00 � 0.01 for lamb survival. Estimates of repeatability were less than 0.14 for all the reproduction traits, which resulted in substantially higher predicted heritabilities when repeated records were used. Heritability estimates for average ewe lifetime performance, with approximately four records, were 0.08 � 0 06 for lambs born, 0.12 � 0.05 for lambs weaned, 0.08 � 0.04 for fertility, 0.l9 � 0 -04 for litter size and zero for lamb survival. The genetic correlations between litter size and lambs born and weaned were close to unity, whereas those for fertility were lower and declined from lambs born (0.6l � 0.22) to lambs weaned (0-45 � 0.30). The estimated heritability for ewe longevity, defined as the number of years the ewe remained in the breeding flock, was 0.00 � 0.03. The potential for genetic improvement in reproductive rate is discussed in relation to other reports in the literature and in the context of the roles of the Dorset breed in the Australian lamb industry. Increased reproductive rate in Dorset flocks impacts on stud profitability and the rate of genetic improvement from selection for other traits such as liveweight. The parameter estimates derived will be used in compiling breed-specific parameter sets for genetic evaluation in LAMBPLAN.
The influence of weather and climate on agriculturally important insects: an Australian perspective
Authors: Drake VA
Published: November 2004

Weather and climate affect insects and other arthropods of importance to agriculture in a wide variety of ways. Pest and beneficial insects, and insect vectors of plant and animal diseases, are all influenced both directly and indirectly by temperature, rainfall, wind, etc. These influences can be immediate or cumulative, and they can act either at the production site or, in the case of migrant species, at locations distant from it. Weather and climate influence, often very significantly, the development rate, survival, fitness, and level of activity of individual insects; the phenology, distribution, size, and continuity of insect populations; migration and the re-establishment of populations following local extinction; the initiation of outbreaks; the susceptibility of crops and stock to insect attack; and the capacity of producers to manage insect populations. In Australia, the high variability of rainfall is of particular significance in determining the size and quality of insect populations. Windborne migration can be important for transporting these populations into agricultural regions, and low winter temperatures in the south of the continent limit the distribution of tropical species. Current Australian research on these topics is directed mainly at the development of pest-forecasting systems, and at estimating the impact of global greenhouse warming.
Relationships among attributes of pure lines of bread wheat derived from heterotic F1 hybrids
Authors: Uddin MN , Ellison FW , O'Brien L , Latter BDH
Published: November 2004

Measurements were made of the number of spikes per unit area, the number of kernels per spike, kernel weight and plant weight in four heterotic hand-made hybrids and the commercial hybrid Comet, together with the parents of the hand-made hybrids, and 75 pure lines derived from each hybrid by single seed descent. Kernel weight exhibited the strongest heterosis, while the incidence of positive heterosis for the remaining yield components varied between crosses. Mid-parent heterosis for plant height was significant for all hand-made hybrids. In both hybrids and pure lines, high yield was associated with intermediate kernel weight and intermediate plant height, but for each trait higher values were observed in the hybrids and pure lines compared with their parents. In terms of both plant height and the major components of yield, viz. kernel number per unit area and kernel weight, the highest yielding pure lines and the hybrids were similar, demonstrating that it is possible to recover homozygous genotypes with the same basic characteristics as the heterotic hybrids from which they were derived. The absence of any consistent pattern on how the best lines obtained their yield suggests that selection for yield based on its components would be unrewarding, except for selection against extremes of kernel weight and plant height.
Phosphorus efficiency in pasture species. VIII. Ontogeny, growth, P acquisition and P utilization of Italian ryegrass and phalaris under P deficient and P sufficient conditions
Authors: Kemp PD , Blair GJ
Published: November 2004

The P efficiency of Italian ryegrass (Lolium multiflorum Lamk. cv Grasslands Tama) and phalaris (Phalaris aquatica L. cv Sirosa) was compared on both a temporal and ontogenetic basis. As ontogeny and growth are interrelated, such a comparison allowed the growth and physiological responses to P level of the two species to be separated from responses due to the species being at different ontogenetic stages at the time of comparison. Plants were grown from seed through to anthesis under P deficient and P sufficient conditions in soil in a glasshouse. The ontogenies of Italian ryegrass and phalaris were similar, but the rate of development of Italian ryegrass was greater at both P rates. P deficiency resulted in arrested reproductive development in phalaris. At both P levels shoot, root and total biomass and net P uptake per plant by Italian ryegrass were greater than by phalaris when the two species were compared on a temporal basis, but when compared on an ontogenetic basis the two species were similar. There were some differences in the allocation of P between the acid-soluble P, lipid P, and residue P fractions, but biomass production was not determined by the efficiency of P utilization. The superior biomass production of Italian ryegrass on a temporal basis was due to its greater seed size and rate of ontogeny rather than differences in photosynthetic rate, unit leaf rate, leaf area ratio or shoot: root ratio. Similarly, the greater P uptake per plant of Italian ryegrass on a temporal basis was driven by its greater plant size and faster root extension rate rather than by P uptake per unit root length. The level of vesicular arbuscular mycorrhizal (VAM) infection in the roots of the two species was similar under P deficiency but greater in phalaris under P sufficient conditions. Overall, the different temporal responses to P of Italian ryegrass and phalaris were largely related to their different rates of ontogeny and the interrelationships between ontogeny and growth rate rather than to differences in their physiology in relation to P acquisition and utilization.
Evaluation of Bos indicus and Bos taurus straightbreds and crosses. III. Direct and maternal genetic effects on growth traits
Authors: Arthur PF , Hearnshaw H , Kohun PJ , Barlow R
Published: November 2004

Data on Brahman and Hereford cattle and their crosses were used to estimate direct additive, direct heterosis, maternal additive and maternal heterosis effects for pre-weaning and post-weaning liveweights, average daily gain (ADG) and height at various ages. The cattle were born at Grafton, N.S.W., and raised on high, medium and low quality pastures until weaning. During the post-weaning period, the steers were grown in three environments in New South Wales, while the heifers remained at Grafton. Genetic effects were estimated by regression and the additive components expressed as deviations from Hereford effect. Weaning weight and pre-weaning ADG of Hereford calves (both sexes) were 237.8 kg and 827 g/day on high, 210.5 kg and 704 g/day on medium, and 128.3 kg and 425 g/day on low quality pastures respectively. Post-weaning ADG of Hereford steers (weaning to 36 months) and heifers (weaning to 30 months) was 296 and 240 g/day respectively. Direct heterosis was significant (P<0.05) for most traits. Estimates of direct heterosis for weaning weight were 24.9 and 20.2 kg, and for pre-weaning ADG were 79 and 68 g/day, on high and medium quality pastures respectively. Direct heterosis for ADG of steers (weaning to 36 months) and heifers (weaning to 30 months) was 91 and 76 g/day respectively. Estimates of maternal heterosis for weaning weights were 14.9, 30.9 and 37.8 kg and for pre-weaning ADG were 31 (not significant), 105 and 153 g/day, for high, medium and low quality pastures respectively. Maternal heterosis for ADG of steers (weaning to 36 months) was -47 g/day. There was a negative direct additive effect on post-weaning ADG in environments where pasture quality was good, but the effect was not significant on poor quality pasture. Maternal additive effect was negative for birth weight for high and medium quality pastures and positive for weaning weight and pre-weaning ADG on low quality pasture. The performance of untested crosses can be predicted from the estimates and models provided.
Scope for genetic evaluation and selection of beef cattle for growth to weaning when birth dates are not recorded
Authors: Meyer K , Graser HU
Published: November 2004

Estimates of (co)variance components and genetic parameters were obtained for a preweaning weight, recorded between 2 and 5 months after birth, and the subsequent gain till weaning for two herds in a selection experiment in Western Australia. Analyses were carried out both accounting for age at weighing and assuming birth dates and thus ages were unknown. On adjusting for the interval between weighings, preweaning gain appeared to be independent of age and equally heritable to weaning weight. Estimates of the direct genetic correlation between preweaning gain and weaning weight (adjusted for age) were 0.9 or higher, while both genetic and permanent environmental maternal correlations were close to unity. Implications for the use of preweaning weight as an alternative selection criterion to weaning weight when birth dates are not recorded are discussed.
Selenium fertilizers for pastures grazed by sheep. 2. Wool and liveweight responses to selenium
Authors: Whelan BR , Barrow NJ , Peter DW
Published: November 2004

Two forms of selenium fertilizer, Na2 Se04 (quick release) and BaSe04 (slow release), prepared by Mintech of New Zealand, were applied in 1987 to pasture at Bakers Hill in Western Australia at 10 g Se ha-1. Merino wethers grazing the pasture over the following 3 years had significant increases in liveweight and wool production even though the control sheep showed no clinical symptoms of selenium deficiency. Sheep treated with selenium intra-ruminal pellets that also grazed the selenium-fertilized pasture showed no signs of toxicity and also had significant increases in liveweight and wool production. There was no significant increase in wool fibre diameter from the selenium treatments. Responses to blood selenium indicated that whole blood selenium should be maintained at a minimum value of 60 8g Se L-1 or a minimum plasma concentration of 40 8g Se L-1 to avoid subclinical selenium deficiency.
Growth and yield response of barley and chickpea to water stress under three environments in southeast Queensland. II. Root growth and soil water extraction pattern
Authors: Thoma s , Fukai S , Hammer GL
Published: November 2004

Root growth and water extraction of two barley cultivars, Corvette (early maturing), Triumph (late maturing) and one cultivar of chickpea (Amethyst at Redland Bay and Borwen at Hermitage) were compared under three environments: April sowing and July sowing at Redland Bay and June sowing at Hermitage Research Station, south-east Queensland. This work was designed to explain differences in dry matter production in terms of root growth and water uptake during the crop growth, which relied only on stored soil moisture. In the April sowing where all crops grew well during the early stages of growth, decline in soil water with time for the whole profile was similar among all crops. In the winter sowings (June, July), total water use was less in chickpea than in barley, particularly during early stages when chickpea growth was poor. Water extraction patterns of two barley cultivars were similar in all experiments, though the late-maturing Triumph extracted slightly more water than early maturing Corvette towards maturity. Water extraction front velocities of the three crops were similar in each experiment. At Redland Bay, the water extraction front velocities varied from 1.4 to 1.6 cm day-1 in the April sowing and 2.3 to 2.4 cm day-1 in the July sowing, while they varied from 2.0 to 2.3 cm day-1 at Hermitage. However, descent of the water extraction front commenced later in chickpea than in barley when sown in winter months, and this resulted in lower total water use in chickpea, particularly at Hermitage. In both sowings at Redland Bay total root length increased rapidly to about 60 days after sowing in barley, whereas the increase was slower in chickpea. Root length density was high in the upper soil layers, and this was associated with high extractable soil water. In deeper layers both root length density and extractable soil water decreased. For a given root length density chickpea extracted more water than barley. These results indicate that the differences in root growth and water extraction by the two barley crops were rather small and were unlikely to be the reason for the differences in total dry matter production. Chickpea on the other hand appeared to be susceptible to low temperatures during early stages of growth, and this caused poor growth of both shoots and roots.
The reaction-diffusion (RD) theory of wool (hair) follicle initiation and development. I. Primary follicles
Authors: Nagorcka BN
Published: November 2004

A spatial prepattern mechanism based on a biochemical reaction referred to as a reaction-diffusion (RD) system is able to account for many aspects of the initiation and development of primary wool follicles. The RD system can spontaneously produce spatial patterns in the distribution of its chemical components within the epidermis and epithelium. The first pattern produced in the epidermis by the chosen RD system is a spotted pattern which gives rise to the first generation of primary central follicles. Follicles initiate at the location of the spots, i.e. the localized regions where maxima exist in the concentration of the chemical components of the RD system. As the primordial follicles begin to grow, changing their shape and size, the RD system is able to produce a time sequence of spatial prepatterns within the follicles. These spatial prepatterns have the capacity to regulate the development of the follicles, causing them to grow at an angle to the skin surface and providing a temporo-spatial cue for the initiation of a sweat gland. The same prepatterns which regulate the development of the primordial follicles also cause the early stage follicles to function as organizers. They do this by causing the spatial prepattern in the epidermis to change, resulting in the initiation of new generations of follicles. The prepatterns are able to cause the formation of trio groups of primary follicles, the alignment of these groups, and the rapidly increasing density of primary follicles observed during the early stages of wool follicle initiation. The prepattern mechanism also predicts the existence of an inverse genetic correlation between the density of spots and the size (diameter) of the spots produced by the RD system in the epidermis. As a result we expect a strong genetic correlation to exist between the density of primary follicles and the diameter of the fibres which those follicles produce. The same prepattern mechanism is able to account for many aspects of secondary follicle initiation and development, as described in an accompanying paper.
Productivity and cold resistance in ewes pre-lamb shorn by standard or cover comb
Authors: Dabiri N , Morris ST , Parker WJ , McCutcheon SN , Wickham GA
Published: November 2004

The cover comb has been developed in New Zealand as a means of increasing residual fleece depth after shearing and so increasing the resistance of shorn sheep to cold-stress. The effects of pre-lamb shearing ewes with cover or standard comb, and of leaving ewes unshorn until after weaning, on their feed intake, productivity, and cold resistance were studied. Border Leicester x Romney ewes were divided into three groups balanced for pregnancy status, ewe age and liveweight. Two groups of ewes were shorn, by either cover comb or standard comb, on day 114 of pregnancy (P114) and one group left unshorn until weaning on day 84 of lactation (L84). Ewes were managed under the same conditions during pregnancy and lactation. Ewes shorn pre-lamb by cover comb had lower mortality from shearing to lambing, and lower organic matter intakes and biting rates at P123-126 than ewes shorn by standard comb. These parameters did not differ between ewes shorn pre-lamb by cover comb and unshorn ewes except biting rate which was greater in the cover comb-shorn group. Twenty days after shearing (P134), the liveweights of ewes were greater in the unshorn group than in the cover comb-shorn group (P < 0.05), which was in turn heavier (P < 0.05) than ewes shorn by standard comb. Midside clean wool growth rates were greater in standard comb- and cover comb-shorn ewes during the post-shearing period (to day 40 of lactation) than in unshorn ewes ( P < 0.05). Similarly, the yield and brightness of wool were superior (P < 0.05) in pre-lamb shorn groups. Lamb liveweights at birth, docking and weaning, and lamb survival, were similar between shearing policies. Rectal temperature (RT) was significantly (P < 0.05) lower in both pre-lamb shorn groups than in the unshorn group on day 3 post-shearing (S3), but by S5 only the ewes shorn by standard comb had lower RT. These results suggest that the greater amount of residual wool in cover comb- vs standard comb-shorn ewes provides a low cost practical method for reducing the two important disadvantages of pre-lamb shearing, namely increased cold-stress and feed intakes post-shearing.
Leaf area development in barley—model construction and response to soil moisture status
Authors: Milroy SP , Goyne PJ
Published: November 2004

A model to simulate leaf area development for barley at the whole plant level was constructed. Data for leaf area development in the absence of soil water stress were collected from irrigated field trials grown at Hermitage Research Station, near Warwick, Queensland, in 1990. The response of leaf area expansion to soil water status was measured in a glasshouse trial. In the model, green leaf area per plant (GPLA) is derived as the difference between total leaf area produced per plant (TPLA) and senesced leaf area (SPLA). TPLA and SPLA are described by logistic functions of thermal time. Two types of senescence are included: that due to ageing of the whole plant (ontogenetic senescence) and senescence associated with the development of large canopies (light-induced senescence). The onset of ontogenetic senescence is linked to anthesis, whereas light-induced senescence occurs if the leaf area index of the crop exceeds 5.5. Leaf expansion of plants in pots varying in the fraction of transpirable soil water available (FTSW) was compared with leaf expansion of those in well-watered pots three times per week. The relationship between relative leaf expansion (RLE) and FTSW was described by a logistic function (r2 = 0.96). A 50% reduction in RLE occurred when FTSW = 0.34. Similarly, a logistic function described the relationship between relative transpiration (RT) and FTSW (r2 = 0.96). A 50% reduction in RT occurred when FTSW = 0.17. Potential leaf expansion as predicted by the non-stressed model was reduced in response to moisture stress via a ramp function relating RLE to RT. The model gave an unbiased prediction of the leaf area dynamics for 21 rainfed and irrigated crops of barley grown in southern Queensland between 1986 and 1993 (RMSD = 1.09 m2 m-2, r2 = 0.75, n = 76). Precision may have been reduced by the lack of information available on parameters for soil water balance when barley is grown on a range of soil types.
Starch pasting properties and genetic relationships of wheat cultivars important to Victorian wheat breeding
Authors: McCormick KM , Panozzo JF , Eagles HA
Published: November 2004

Starch quality, particularly high paste viscosity, is important in producing marketable wheat for several end uses. Peak starch paste viscosity was measured for 65 wheat cultivars significant to Victorian wheat breeding. Coefficients of kinship were calculated between these cultivars to assess their genetic relationships. In terms of paste viscosity, 15 of the 20 highest ranking cultivars were related. Currawa, a cultivar released in 1912, was the common ancestor and proposed source of high paste viscosity in this family of cultivars, which included the currently grown cultivar, Rosella. Most cultivars in the lower rank were closely related to WW15, which is a semi-dwarf parent from CIMMYT that was used extensively in Australian breeding programs in the past two decades. This survey provides information for choosing parental material for starch quality improvement and offers an explanation for the decrease in peak viscosity of modern Australian cultivars.
Time to flowering in narrow-leafed lupin
Authors: Reader MA , Dracup M , Kirby EJM
Published: November 2004

The relationship between flowering time and daylength and temperature is described for L. angustifolius using multiple linear regression. The main cultivar was Gungurru but cvv. Danja, Yorrel and the L. albus cv. Kiev Mutant were also studied. Regression analyses were performed on time to flowering observations for lupins grown with serial sowings at up to 12 sites over up to 5 years in Western Australia (there were 102 separate observations of time to flowering for Gungurru). Time to flowering in the L. angustifolius cultivars was best explained by a model incorporating terms for average temperature and daylength between sowing and flowering. Models of this form were not satisfactory for L. albus, probably because of vernalization requirements which the L. angustifolius cultivars do not have. Using data from the experiment with the widest range of sowings, 94.6% of the variation in time to flowering was explained by the above model and an additional 3.5% was explained by including an interaction term. The rate of progress through all stages of development to flowering, except for the period between appearance of the last leaf and flowering, was sensitive to temperature. The rate of leaf appearance responded to both temperature and daylength and the rate of progress through the period between appearance of the last leaf and flowering was sensitive only to daylength.
Responses in wool growth, liveweight, glutathione and amino acids, in Merino wethers fed increasing amounts of methionine protected from degradation in the rumen
Authors: Mata G , Masters DG , Buscall D , Street K , Schlink AC
Published: November 2004

The aim of the experiments reported was to evaluate the protection from microbial breakdown of two methionine formulations (Lactet and Mepron) and to measure responses in wool production, liveweight, amino acids and glutathione in blood and tissues when one of these forms of methionine (Lactet) was supplied to merino wethers fed at maintenance. Lactet was well protected against microbial breakdown in the rumen. Peak values for concentrations of methionine in plasma, following administration of the different forms of methionine into the rumen, were 574, 148 and 143pmol L-1 for Lactet, DL-methionine and Mepron. Production responses to dosed levels of Lactet (0, 1, 2, 3, 5, 8 g methionine dayw1) were measured over 63 days in the animal house. Significant linear responses were obtained for wool growth (4-38%), fibre diameter (0.5-2 8m) and liveweight gain (30-1 15%). Concentrations of reduced glutathione in blood, liver and skin were increased, at some times during the experiment, by provision of Lactet. However, responses were inconsistent and highly variable among sheep, Glutathione was of limited use as an indicator of sulfur amino acid intake or status. Sulfate in plasma increased markedly at all levels of Lactet intake, and there was a linear relationship between Lactet intake and the concentration of sulfur in wool. Plasma free methionine and the ratio of methionine to total essential amino acids showed significant linear responses to the supplements. It was concluded that Lactet was an effective method of supplying rumen-protected methionine to ruminants.
Evaluation of Angus, Charolais and Hereford as terminal sire breeds on Hereford and first-cross cows. I. Growth of progeny
Authors: Hearnshaw H , Arthur PF , Johnston D , Stephenson PD
Published: November 2004

Pre-weaning growth of 482 Angus, Charolais and Hereford sired progeny out of straightbred Hereford (H x H) , and first-cross Brahman x Hereford (B x H) , Simmental x Hereford (S x H) and Friesian x Hereford (F x H) dams was evaluated. The dams grazed either high, medium or low quality pasture (pre-weaning pasture system) at Grafton, NSW. Progeny of dams from high quality pre-weaning pasture were slaughtered at 281 days of age for the vealer market. The progeny of dams from medium and low quality pre-weaning pastures were evaluated for post-weaning growth on pasture, on commercial properties in temperate NSW. They were slaughtered for either the yearling domestic (both sexes) or heavy export steer markets. Average daily gain (ADG) for the entire pre-weaning period was greater (P < 0.05) for Charolais (845 g/day) than Angus (790 g/day) and Hereford (783 g/day) sired progeny. This resulted in a higher ( P < 0.05) weaning weight of Charolais sired progeny of dams on high or medium quality pre-weaning pasture. On low quality pasture, however, sire breed differences in weaning weight were not significant (P > 0.05). This indicates that adequate nutrition should be provided for Charolais sired progeny to express their higher growth potential. Post-weaning ADG of Charolais sired progeny was higher (P < 0.05) than that of Angus or Hereford sired progeny, resulting in 14 months liveweight (for yearling domestic cattle) of 370, 345 and 345 kg and 27 months liveweight (for heavy export steers) of 635, 585 and 569 kg for Charolais, Angus and Hereford sired progeny respectively. Progeny of B x H dams on medium or low quality pre-weaning pastures had the highest pre-weaning ADG and weaning weight, but the lowest post-weaning ADG. This resulted in 27 months liveweight of 558, 582, 628 and 616 kg for steer progeny from H x H, B x H, S x H and F x H dams respectively.
Pasture production under a series of Pinus radiata-pasture agroforestry systems in South-West Victoria, Australia
Authors: Kellas JD , Bird PR , Cumming KN , Kearney GA , Ashton AK
Published: November 2004

Net pasture production has been monitored over time on an on-going Pinus radiata-pasture agroforestry experiment located at Carngham, Victoria. Established in 1983 by thinning a 2-year-old plantation, the study contains five treatments (systems): open pasture (no trees), 60 trees/ha, 200 trees/ha wide-spaced, 200 trees/ha 5-row belt and 1360 trees/ha. Net pasture production was only weakly affected by the proximity of trees in the 60 trees/ha and 200 trees/ha wide-spaced systems. However, in the 200 trees/ha 5-row belt system, pasture production was often significantly less within the tree zone and at 1.5 m from the tree edge compared with production at 10.5 m from the tree edge. While there was a trend for greater pasture production at 10.5 m and 18 m from the tree line than occurred in the open pasture system, the width of pasture adjacent to the 5-row belts was too narrow (36 m) to demonstrate any shelter benefit on pasture production. From 1990 to 1992, pasture production (kg ha-1) for each system was similar, although production tended to decrease with increasing tree stocking. Following the cessation of pruning (1992), pasture production was significantly reduced by increased tree stocking, such that pasture production in the 200 trees/ha wide-spaced and 200 trees/ha 5-row belt systems was 60% and 69% and 23% and 67% of open pasture in 1993 and 1994 respectively.
Comparison of controls on development in breeding lines from Australian and CIMMYT/ICARDA winter and facultative wheat breeding programs
Authors: Penrose LDJ , Mosaad M , Payne TS , Ortiz-Ferrara G , Braun HJ
Published: November 2004

This study sought to compare developmental controls in breeding a within two winter wheat improvement programs, one Australian and a CIMMYT/ICARDA program based in West Asia. Developmental controls considered were intrinsic earliness, and responses to photoperiod and to vernalization. The reliability with which each control on development had been measured was tested in separate experiments using the wheats utilized in the Australian program. Measures of intrinsic earliness showed significant agreement between experiments, better agreement being found for response to photoperiod and between integrated response to vernalization and time to double ridge after late summer sowings. The wheats utilized in the CIMMYTI/CARDA programs were found to be quick in intrinsic earliness, and to possess little response to photoperiod. While these controls varied more for the wheats utilized in the Australian program, commercial Australian winter wheats were similar to the CIMMYTI/CARDA lines. Lines utilized by both programs were represented by types with spring, facultative and winter habit. The clearest differences between programs were that CIMMYTI/CARDA winter wheats appeared to have much stronger response to vernalization than the Australian winter wheats. These findings suggest breeders would find a good proportion of segregates, from crosses between the Australian and the CIMMYTI/CARDA winter wheats, to be developmentally adapted to south-central New South Wales. This suggests CIMMYTI/CARDA winter wheats provide a matching pool from which to access germplasm to introduce new characters into Australian winter wheats.
Australian papaya dieback: evidence against the calcium deficiency hypothesis and observations on the significance of laticifer autofluorescence
Authors: Aleemullah M , Walsh KB
Published: November 2004

The cause of the dieback disorder of Carica papaya (papaya, papaw, or pawpaw) is unknown, although it is a severe problem for the Queensland industry. In this study, tlle progression of morphological and anatomical symptoms during a growing season in Yarwun is documented. Most plants which displayed a brown discoloration of the vascular tissue developed external symptoms. The discoloration initiated in the stem zone which supported leaves, and developed acropetally into the stem apex, and basipetally into the trunk and in part of the root system. The discoloration was autofluorescent under blue or ultraviolet light, and was associated with laticifers in xylem and phloem tissue and in ray parenchyma. Laticifer autofluoresence was not observed in calcium-deficient plants, nor in the browning associated with nematode damage, but this symptom was present in association with tissue damage caused by Amblypelta lutescens (Distant) and in plants suffering root rot. Laticifer discoloration may represent a general stress reaction by the plant. Tyloses developed in xylem elements, associated with the wilting of the crown, following development of leaf chlorosis and the bending of the stem tip. Dieback-affected apical tissues were lower in total calcium content than healthy tissues, but were not below an experimentally determined critical concentration. It is suggested that the low calcium content represents a secondary symptom of the disorder. caused by a tylosis-induced decrease in hydraulic conductivity and consequently in calcium transport.
The effect of nutrition and exercise in carcass parameters and the level of glycogen in skeletal muscle of Merino sheep
Authors: Pethick DW , Rowe JB
Published: November 2004

This study investigated the effects in sheep of feed intake and exercise training on (i) the level of glycogen in muscle, and (ii) carcass quality traits including growth rate, carcass weight, fat score, and the ultimate pH of muscle. Merino wethers, 12-months-old and starting body weight 38 kg, were individually penned and housed indoors. The effects of nutrition and exercise were tested for 2 levels of activity (sedentary v. exercised) and 4 levels of feed intake (1, 1.3, 1.5, 2.2 x maintenance) with 8 sheep per group housed individually. Exercise training was for 1 h at 8-9 km/h (approx. 55-65 VO2max), 3 times per week from week 4 to 9 of the experiment. The diet was 20% cereal straw, 26% lupin grain, 53% barley grain, mineral and vitamin premix, and virginiamycin. Animals were slaughtered at an abattoir in week 10. Regular exercise reduced growth rate, carcass weight, and fat score, but did not affect intake. At the highest level of intake, carcass weight was reduced by 0.53 kg and fat depth over the 12th rib (GR fat depth) by 6.3 mm, suggesting that muscle yield was increased. At all sampling times, the level of glycogen in the m. semimembranosis (SM) and m. semitendinosis (ST) increased linearly with increasing feed intake. Regular exercise caused increased glycogen level in SM samples immediately post-slaughter and in the SM, ST, and m. longissimus dorsi (LD) 48 h post-slaughter. The ultimate pH of muscle was reduced as the level of feed intake increased for all muscle groups. Exercise caused a reduction in the ultimate pH of the ST with no change for the SM and LD. The results indicate that glycogen levels in muscle are highly responsive to nutrition and regular exercise. In addition, exercise caused a reduction in subcutaneous fat with no change in feed intake.
Measurement of the shear and tensile fracture properties of leaves of pasture grasses
Authors: Henry DA , Macmillan RH , Simpson RJ
Published: November 2004

The shear fracture properties of leaves of pasture grasses were measured using a shearing device consisting of 2 blades at fixed angles. The mechanics of the shearing process were examined with both paper and leaves of Festuca arundinacea. The investigations indicated that the intrinsic strength of the material being cut is best represented as force exerted during the cut divided by the length of the cutting blade in contact with the material. Tensile fracture properties of leaves of 5 pasture grasses were also measured, and the relationship between tensile and shear properties was examined. Intrinsic shear strength was weakly negatively correlated with tensile strength.
Microcosm assessment of potential molluscicides for control of the rice snail Isidorella newcombi sens. lat. (Gastropoda: Basommatophora: Planorbidae)
Authors: Stevens MM , Faulder RJ , Coombes NE
Published: November 2004

Twenty-seven pesticides were evaluated for their toxicity to mature Isidorella newcombi (Adams & Angas), a serious pest of irrigated rice in NSW, Australia. Evaluations were conducted using microcosms in which typical field conditions were simulated. Only 3 compounds, niclosamide, n-tritylmorpholine, and nicotinanilide, provided >95% mortality at an initial screening rate of 3 mg/L. These compounds were assessed at a range of rates using both immediate and delayed-exposure bioassays to determine LC values and comparative persistence. Niclosamide (as Bayer Bayluscide� 250 g/L EC) and n-tritylmorpholine (as Shell FresconB 165 g/L EC) were the most toxic (LC90, immediate exposure, 0.19 mg/L for both compounds), whilst the corresponding LC90 value for nicotinanilide (laboratory grade in DMSO) was 0.53 mg/L. Persistence (reflected by a slower increase in LC90 values over time in delayed exposure bioassays) was strongest in nicotinanilide and weakest in n-tritylmorpholine. Although niclosamide is the most promising compound for the control of I. newcombi, further development of nicotinanilide is also recommended, as it represents a potentially valuable tool for use in situations where low fish toxicity is required.
Reducing post-partum anoestrous interval in first-calf Bos indicus crossbred beef heifers. III. Effect of nutrition on responses to weaning and associated variation in metabolic hormone levels
Authors: Jolly PD , McSweeney CS , Schlink AC , Houston EM , Entwistle KW
Published: November 2004

Interactions between effects of undernutrition and weaning on the duration of post-partum anoestrus and associated variation in milk yield, suckling behaviour, and metabolic hormone levels in Droughtmaster [Bos indicus x Bos taurus (518, 3/8)] first-calf cows were studied in 2 successive years. Low body condition score at calving (3.5f 0.1, scale 1-9) was associated with prolonged post-partum anoestrous intervals in suckled cows, but provided cows were maintaining liveweight, ovarian cyclicity resumed within 50 days if calves were weaned 70 days post-partum. This response to weaning was totally inhibited in cows that calved in low body condition that lost liveweight post-partum (Year 1). In contrast, marked levels of post-partum liveweight loss (23%) did not affect resumption of ovarian cyclicity in response to weaning (at 50 days post-parturn), or time to conception, among cows that calved with high body condition scores (5.8 � 0.2, Year 2). Reduced milk yields and calf weight gains among underfed cows were associated with higher suckling frequencies and durations ( P < 0.05). Acyclic interval after weaning was negatively related to body condition score at weaning (P < 0.01), and positively related to preweaning suckling intensity (P < 0.01). The time taken to resume ovarian cyclicity after weaning increased by a factor of 1.2 for every half unit decrease in body condition score at weaning, and by a factor of 1.3 for every 30-min increase in time suckled per day prior to weaning. Within level of nutrition, higher frequencies and durations of suckling were associated with higher plasma prolactin levels. Plasma IGF-1 levels were consistently depressed in underfed cows, whereas plasma insulin and GH levels were less affected by nutritional treatments. Effects of undernutrition in suckled cows appear to operate at least partly through interactions with milk yield and suckling intensity. Management of post-partum anoestrus in Bos indicus cows should focus on the conservation of cow body condition and on the strategic use of early weaning.
Resistance to alfalfa mosaic virus in button medic (Medicago orbicularis)
Authors: Pathipanawat W , Jones RAC , Sivasithamparam K
Published: November 2004

Seventy-five accessions of M. orbicularis were screened for resistance to alfalfa mosaic virus (AMV) by application of viruliferous aphids to plants. Thirty of these accessions were then exposed to infection in the field and 22 were graft-inoculated. Three types of resistance to AMV were found among the different accessions. These were 'extreme resistance' in SA 15222, 'systemic hypersensitivity' in SA 2570, SA 9310, SA 10282, SA 12337, and SA 15052, and 'partial resistance', a type that was intermediate between the two, in SA 5073, SA 13905, and SA 17711. M. orbicularis accession SA 10282 (hypersensitive) was crossed reciprocally with SA 4268 (susceptible), and the resulting F1 plants were allowed to self naturally or were backcrossed with SA 4268. F2 progeny and backcross progeny plants were graft-inoculated with AMV to determine segregation ratios (hypersensitive : non hypersensitive). The ratios from both the crosses and reciprocal crosses and from the backcross populations indicated that the hypersensitive response to AMV may be controlled by a single dominant gene for hypersensitivity for which we tentatively propose the name Nam-1. M. orbicularis accessions provide a valuable source of AMV resistance for use in breeding virus-resistant cultivars of a range of useful annual medic species.