bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of low root-zone temperature on nodule initiation in narrow-leafed lupin (Lupinus angustifolius L.)
Authors: Peltzer Sally C. , Abbott Lynette K. , Atkins Craig A.
Published: September 2002

The effect of low root-zone temperature on nodulation of
Lupinus angustifolius [L.] cv. Yandee was
studied using glasshouse experiments in which the effects of temperature on
nodule initiation and subsequent nodule development could be assessed
separately. Low temperature (7 and 12˚C compared with 25˚C) reduced
the growth of both uninoculated plants supplied with adequate mineral N and
inoculated plants reliant on fixation alone for their N. However, even at
25˚C, growth of inoculated plants compared with plants supplied with
mineral N was limited, and at lower temperatures nodulation was severely
inhibited. The most sensitive stage to low root-zone temperature was nodule
initiation and there appeared to be a critical temperature between 7 and
12˚C at which initiation did not take place. Increasing the number of
bacteria in inocula (from 5 × 103 to 5 ×
107 viable cells/mL) did not overcome inhibition. A
number of diverse cultivars of L. angustifolius showed
the same response as cv. Yandee. Low temperature inhibition of nodule
initiation could be overcome by addition of culture solution collected from
around the roots of symbioses established at 25˚C. The culture solutions
were only effective if the roots at 25˚C were inoculated or, if collected
from around uninoculated roots of plants grown with mineral N, they were first
exposed to a Bradyrhizobium suspension and then
sterilised before addition to cultures at low temperature. The data indicate
that both plant and bradyrhizobial factors are required for nodule initiation
and that exudation of plant factors at low root-zone temperature is
insufficient to stimulate production of the nodulation factors from
Bradyrhizobium. At 25˚C, the nodulation zone of
lupin roots bore many fractures in the epidermis and showed a high frequency
of free root cap border cells, as well as a distinct matrix of extracellular
material. These features were significantly reduced at 12˚C and
essentially absent at 7˚C, indicating that at low temperature bacterial
entry may be restricted.
Genotypic differences in wheat for uptake and utilisation of P from iron phosphate
Authors: Osborne L. D. , Rengel Z.
Published: September 2002

Two glasshouse experiments were conducted to evaluate the genotypic variation amongst cereal genotypes in phosphorus uptake from relatively insoluble iron phosphate. Optimum rates of iron phosphate were established by growing 3 wheat and 1 triticale genotype on an infertile sand amended with iron phosphate. Shoot dry weight of all genotypes showed a classic Mitcherlich response with 95% maximum growth achieved with 174�mg P/kg soil. Two rates of FePO4 were selected representing a deficient and sufficient supply (26 and 339 mg P/kg soil, respectively).

These rates were used to screen 99 wheat, 8 triticale, and 4 cereal rye genotypes for phosphorus-use efficiency. Phosphorus efficiency was rated by 4 criteria: shoot dry weight at deficient P supply, shoot weight at deficient supply relative to shoot weight at sufficient P supply, P uptake efficiency (amount of P taken up per unit of P supplied), and P utilisation efficiency (shoot weight per unit P in plant).

No genotypes were rated as efficient under all 4 criteria. Only 2 genotypes were rated efficient (rye Bevy, rye PC00361) and one inefficient (Machete) under 3 criteria. Seven genotypes were rated as efficient on 2 indices (wheat Chinese 80-55, Westonia, and Wawht 2147; triticale Treat, AT48-94, and TX93-78-1; rye Bulgarian Pento), whereas 7 genotypes were rated as inefficient on 2 indices (Boricuta, Cadoux, Cunderdin, Insignia, Kalingri, Perenjori, and triticale Abacus). Significant genotypic variation was identified in cereals in the ability to take up and utilise P from poorly soluble Fe-P, although all genotypes were able to utilise this source of phosphorus to some degree.
Identification of research to improve the efficiency of breeding strategies for white clover in Australia - a review
Authors: Jahufer M. Z. Z. , Cooper M. , Ayres J. F. , Bray R. A.
Published: September 2002

A major challenge faced by today’s white clover breeder is how to manage
resources within a breeding program. It is essential to utilise these
resources with sufficient flexibility to build on past progress from
conventional breeding strategies, but also take advantage of emerging
opportunities from molecular breeding tools such as molecular markers and
transformation. It is timely to review white clover breeding strategies. This
background can then be used as a foundation for considering how to continue
conventional plant improvement activities and complement them with molecular
breeding opportunities.
In this review, conventional white clover breeding strategies relevant to the
Australian dryland target population environments are considered. Attention is
given to: (i) availability of genetic variation,
(ii) characterisation of germplasm collections,
(iii) quantitative models for estimation of
heritability, (iv) the role of multi-environment trials
to accommodate genotype-by-environment interactions, (v)
interdisciplinary research to understand adaptation to dryland environments,
(vi) breeding and selection strategies, and
(vii) cultivar structure. Current achievements in
biotechnology with specific reference to white clover breeding in Australia
are considered, and computer modelling of breeding programs is discussed as a
useful integrative tool for the joint evaluation of conventional and molecular
breeding strategies and optimisation of resource use in breeding programs.
Four areas are identified as future research priorities:
(i) capturing the potential genetic diversity among
introduced accessions and ecotypes that are adapted to key constraints such as
summer moisture stress and the use of molecular markers to assess the genetic
diversity, (ii) understanding the underlying
physiological/morphological root and shoot mechanisms involved in water
use efficiency of white clover, with the objective of identifying appropriate
selection criteria, (iii) estimation of quantitative
genetic parameters of important morphological/physiological attributes to
enable prediction of response to selection in target environments, and
(iv) modelling white clover breeding strategies to
evaluate the opportunities for integration of molecular breeding strategies
with conventional breeding programs.
Hardseededness in annual clovers: variation between populations from wet and dry environments
Authors: Norman Hayley C. , Cocks Philip S. , Galwey Nick W.
Published: September 2002

Annual legumes rely on hardseededness, a form of seed dormancy, to spread the risk of mortality associated with germination and to encourage germination at the optimal time in a season. This paper examines seed softening strategies of a number of clover (Trifolium) species collected over a range of environments. Three hypotheses are tested. The first is that within species, long-term hardseededness increases with aridity due to the greater chance of failure to reproduce in dry environments. It is tested by comparing seed softening patterns of populations of a number of clover species collected from a range of environments. The second hypothesis, that annual legumes from dry environments have a smaller subset of seed softening strategies than legumes from wetter environments, is tested by comparing the range of seed softening patterns from all species found at collection sites. The third hypothesis is that within-year patterns of seed softening that prevent germination after summer rainfall may partially substitute for long-term hardseededness. It is tested by examining the relationship between within-year hardseededness and between-year hardseededness.

Accessions of the same species from different collection sites differed in both within-year pattern of seed softening and long-term hardseededness but there was little evidence that these differences were between ecotypes. Different species from the same collection site did not have similar seed softening strategies, and seed softening strategies of clovers from dry sites were as variable as those from wetter environments. Within-year pattern of seed softening does not appear to substitute for between-year hardseededness as a dormancy strategy.
Metabolic and production responses to different porcine somatotropin injection regimes in pigs
Authors: Dunshea F. R.
Published: September 2002

Thirty-two female crossbred pigs (initial weight 75 kg) were used in this experiment to investigate the effect of differing porcine somatotropin (pST) regimes on growth performance. Pigs were kept in individual pens and fed ad libitum a wheat-based diet formulated to contain 14.4 MJ DE/kg and 180 g ideal protein/kg. Treatments were daily injection with saline (Sal), daily injection with pST (5 mg) (D), bi-daily injection with pST (10 mg) (2D), and injection with pST (12 mg) every Monday, Wednesday, and Friday (MWF). On the days that pigs were not receiving pST they were injected with saline (0.5 mL). All pST regimes caused a reduction (P < 0.001) in feed intake and feed conversion ratio (FCR), although there was no significant effect on average daily gain. Feed intake decreased after the first injection and, for the D group, remained low and constant. Feed intake for the 2D group was also reduced but not to as great an extent as for the D group. Feed intake in the MWF group showed a clear temporal response, being low during the week but increasing over the latter part of the weekend. Thus, feed intake from Sunday until Monday mornings was 400 g greater (P < 0.001) than from Saturday until Sunday mornings. Therefore, it appears that the effects of pST on feed intake may be reduced when a 3-day interval is used between injections. Back fat was significantly reduced with all pST injection regimes, whereas estimated fat deposition was only significantly reduced in the D and 2D pigs. Plasma urea nitrogen was increased, whereas glucose was decreased during pST administration and the average concentrations of both metabolites during the first week of administration were strongly related (P < 0.001) to FCR over the full 3 weeks of the study (R = 0.733 and -0.683, respectively). Although daily injection with pST appears to give the greatest reduction in feed intake and fat deposition, an alternative pST injection regime involving less frequent pST injections can also improve growth performance similarly in finisher pigs.
Inheritance of partial resistance to the brown spot disease in Lupinus angustifolius L
Authors: Bradley F. H. , Oram R. N. , Malafant K. W.
Published: September 2002

Brown spot (BS) is a damaging disease of narrow-leafed lupins (Lupinus angustifolius L.), particularly in Western Australia. Breeding for resistance to the causal agent [Pleiochaeta setosa (Kirchn.) Hughes] has had some success. Here, earlier data on the extent and inheritance of resistance to BS are presented as a possible guide for future breeding programs. In 1980, 236 Mediterranean wild accessions from the Australian germplasm collection, and 17 cultivars and 20 breeding lines of L. angustifolius and L. albus L., were tested by natural infection in replicated short rows at 2 sites in southern New South Wales. The area of lower leaves covered by lesions was up to 70% lower on partially resistant lines than on commercial cultivars. Twelve wild accessions were consistently more resistant than 5 cultivars at Wagga Wagga in 1980 and in 2 subsequent years, in which 66 wild lines and 6 cultivars were tested. However, the rankings at Wagga Wagga differed from those in coastal Western Australia, suggesting that spatial differences occur in the pathotype composition of the fungus. The absence of sexual reproduction in the fungus suggests that its pathotype spectrum would change only slowly at each location. Unimodal distributions of BS scores for individual plants were found in the F2 of Illyarrie (susceptible) � CPI 67877 (resistant) and in the backcross to Illyarrie. The F2 mean was intermediate between the 2 parental means, and
only a few plants had a score as low as the resistant parent. The regression of the mean scores for 15 F2 families
from crosses among 7 wild lines, and between these and 2 susceptible cultivars, on the respective mid-parent values
gave a narrow-sense heritability estimate of 0.94 ± 0.17 on a family mean basis. Thus, resistance was controlled by
many loci with co-dominant alleles and should be robust. There was no linkage of resistance genes to the low
alkaloid or white flower/green plant loci. Assuming the absence of dominance, the upper limit of narrow-sense
heritability on a single plant basis was 0.50 ± 0.13. Several rounds of selection of partially resistant individuals in
F2 families and intercrossing among F3 plants from many different wild � domesticated crosses are likely to produce
cultivars with much more resistance than those now available. The applicability of the results at Wagga Wagga to
the eastern wheatbelt of Western Australia, where BS is acute, and optimum field selection procedures are
discussed.
Bone mineralisation and strength in range cattle
Authors: Holst P. J. , Murison R. D. , Wadsworth J. C.
Published: September 2002

Cattle (358) from western New South Wales were sampled at abattoirs as part of a survey of mineral status of range cattle. Each animal was described for breed, sex, age, and body condition, and their origin traced back to their range, which was described for forage offered and soil type. Rib bone samples were taken for chemical and mechanical analyses to provide data on percentage phosphorus (% P) and percentage calcium (% Ca) (fat-free bone), percentage ash, ash density, matrix density, ash : matrix, bending moment, and deformation. A tree-based classification model was used to form groups of animals with common background factors (e.g. soil, age, sex, weight). Several of these groups were suspected of being osteodystrophic based on the chemical and physical data. Young cows and cattle in poor body fat condition on poor quality forage were at risk and should have responded to phosphorus supplementation with rain and better pasture conditions.
Identification of osteodystrophy in these cattle was most readily diagnosed from ash density data and not from % P, % Ca, or Ca : P. Bone strength interpretation was limited to young cattle. Reference values, as an indication of normal range, are provided for each of the parameters.
Genotype by environment interactions affecting grain sorghum. II. Frequencies of different seasonal patterns of drought stress are related to location effects on hybrid yields
Authors: Chapman S. C. , Cooper M. , Hammer G. L. , Butler D. G.
Published: September 2002

Genotype × environment (G×E) interactions due to variation in soil
moisture and rainfall complicate the interpretation of sorghum hybrid
performance trials over locations (L) and years (Y). This paper aims to use
pattern analysis to explain measures of the G×L interaction for yield,
and whether these can, in turn, be explained using simulation models to
determine the occurrence of environment types (within-season patterns of
drought). The aim of this work is to simplify the analysis of G×E by
explaining it in terms of interactions of genotypes with environment types
(ET) that are not ‘fixed’ to locations and years.
In a sequential analysis of 17 seasons, 18 locations were separated into
groups that tended to represent either the northern (i.e. central Queensland,
CQ) or southern Queensland (SQ) regions. For a subset of 6 locations,
ordination partially explained differences among locations as being related to
latitude (r = 0.88) and rainfall
(r = −0.46), but they were better related
(r > 0.9) to the frequencies of 3 stress ETs as
determined by long-term crop simulations. These 3 environment types were: (1)
low stress (occurring in 33% of seasons); (2) severe terminal stress
with an early-season (9%) or midseason time (29%) of onset; and
(3) intermediate terminal stress with a midseason (9%) or late-season
(20%) time of onset. Low stress ETs were more common in two SQ
locations than in CQ. Stress ETs as defined by simulation models and pattern
analysis had more consistent relationships with simulated yields than did the
fixed descriptors of locations and years.
Sorghum hybrid trials for broad adaptation in Queensland should include
locations at least from each of the 2 regions and the results should be
interpreted in the context of the season in which they are conducted. To match
the long-term patterns in the 6 locations of the analysis, trial yields would
need to sample from at least 3 yield ranges: <1 t/ha, 1–3.5
t/ha, and >3.5 t/ha. Additional seasons of testing are likely to be
required when the locations used during a season do not adequately represent
the target population of environments over all locations and years.
Effect of seedling damage by redlegged earth mite, Halotydeus destructor, on subsequent growth and development of yellow lupin, Lupinus luteus, in the glasshouse
Authors: Liu A. , Ridsdill-Smith T. J. , Nicholas D. C.
Published: September 2002

Redlegged earth mite (Halotydeus destructor) causes
feeding damage to some pulse species at the seedling stage. To quantify the
effect of this damage on subsequent plant growth and development, an
experiment was conducted in the glasshouse using yellow lupin,
Lupinus luteus cv. Motiv, which is highly susceptible to
the mites. After emergence, plants were infested with 0, 100, 150, and 250
mites/plant, collected from the field. Fourteen days after application,
mites were removed. Damage to plants was estimated at seedling stage,
flowering time, and maturity. At seedling stage (on Day 14), feeding damage
scores to cotyledons and true leaves were greater at higher mite densities.
Damaged plants produced fewer nodules, fewer lateral roots, and less dry
weight than the control. On Day 35, severely damaged plants failed to recover
and on the surviving plants, cotyledons and true leaves died earlier than on
the plants without damage. On Day 78, when plants were flowering, the
surviving plants produced fewer nodules and branches, and less dry weight per
plant than the control. The flowering time of plants with the mite treatments
was delayed by up to 6 days compared with the controls. The final shoot dry
weight, pod number, seed number, and seed yield per pot were significantly
reduced by the mite treatments. Feeding by H. destructor
on seedlings of yellow lupin caused a reduction in seed yield of 58% at
the highest mite density treatment. This significant economic loss needs to be
confirmed under field conditions, but it signifies the need to develop
appropriate control measures for this pest.
Distribution and temperature sensitivities of genes for stem rust resistance in Australian oat cultivars and selected germplasm
Authors: Adhikari K. N. , McIntosh R. A. , Oates J. D.
Published: September 2002

Seedlings of 40 Australian oat cultivars and 154 elite oat lines were tested
with various pathotypes of P. graminis avenae. Fourteen
cultivars carried Pg-2 and/or
Pg-4. One cultivar carried Pg-13
and 4 carried Pg-a. Several cultivars possessed
different combinations of Pg-1,
Pg-2, Pg-3, and/or
Pg-4, but none possessed Pg-8 or
Pg-9. Since most elite lines were resistant to all
cultures collected from the pathogenicity survey in 1993 and gave similar low
infection types, it was postulated that they all carried a common gene,
Pg-a. All isolates from the 1993 survey, except one from
northern New South Wales, were avirulent for Pg-a.
Studies of the effect of temperature on reaction to stem rust showed that
resistances in lines possessing Pg-8 and
Pg-16 became ineffective at 21.5°C, but were
effective at 17°C. Similarly, resistances in lines possessing
Pg-4, Pg-12, and
Pg-a were effective at 21.5°C, but became
ineffective at or above 26°C. Resistances conferred by
Pg-1, Pg-2,
Pg-13, and Pg-Sa were not affected
by temperature. Although resistance conferred by Pg-a
was temperature-sensitive, the retardation of fungal growth with decrease in
temperature suggested that increasing day temperatures would not cause the
breakdown of this resistance provided night temperatures remain cool.
Two genetic linkage maps of mungbean using RFLP and RAPD markers
Authors: Lambrides C. J. , Lawn R. J. , Godwin I. D. , Manners J. , Imrie B. C.
Published: September 2002

Two genetic linkage maps of mungbean derived from the cross Berken ACC 41 are
reported. The F2 map constructed from 67 individuals
consisted of 110 markers (52 RFLP and 56 RAPD) that grouped into 12 linkage
groups. The linked markers spanned a total map distance of 758.3 cM. A
recombinant inbred (RI) population derived from the 67
F2 individuals was used for the generation of an
additional linkage map. The RI map, composed entirely of RAPD markers,
consisted of 115 markers in 12 linkage groups. The linked markers spanned a
total map distance of 691.7 cM. Using a framework set of RFLP markers, the
F2 map was compared with another
F2 mungbean map constructed in Minnesota. In general,
the order of these markers was consistent between maps. Segregation distortion
was observed for some markers. 14.5% (16/110) of mapped
F2 markers and 24% (28/115) of mapped RI
markers segregated with distorted ratios. Segregation distortion occurred in
each successive generation after the F2 . The regions of
distortion identified in the Australian maps did not coincide with regions of
the Minnesota map.
Genetic variation for improving the salt tolerance of durum wheat
Authors: Munns R. , Hare R. A. , James R. A. , Rebetzke G. J.
Published: September 2002

Durum wheat (AB genomes) is more salt-sensitive than bread wheat (ABD
genomes), a feature that restricts its expansion into areas with sodic or
saline soils. Salt tolerance in bread wheat is linked with a locus on the D
genome that results in low Na+ uptake and enhanced
K+/Na+
discrimination. In order to introduce salt tolerance into current durum wheats
from sources other than the D genome, a search for genetic variation in salt
tolerance was made across a wide range of tetraploids representing 5
Triticum turgidum sub-species
(durum, carthlicum,
turgidum, turanicum,
polonicum). Selections were screened for low
Na+ uptake and enhanced
K+/Na+
discrimination. This was assessed in seedlings grown in 150 mМ NaCl with
supplemental Ca2+, by measuring the
Na+ and K+ accumulated
in the blade of a given leaf over 10 days. Large and repeatable genetic
variation was found. Low Na+ accumulation and high
K+/Na+
discrimination of similar magnitude to that of bread wheat was found in the
sub-species durum. These selections have the potential
for improving salt tolerance in durum wheat breeding programs.
Effects of temperature and leaf wetness duration on infection of pear leaves by Venturia pirina
Authors: Villalta O. N. , Washington W. S. , Rimmington G. M. , Taylor P. A.
Published: September 2002

The effects of temperature and wetness duration on the infection of pear
leaves (Pyrus communis L.) by
Venturia pirina were studied by inoculating plants with
ascospores and conidia under controlled conditions and in the field. Under
controlled inoculations, minimum wetness durations that lead to leaf
infections by ascospores were 27, 15, 13, 11, 10, 9, and 9 h at 4, 8, 10, 12,
15, 20, and 25°C, respectively. In parallel inoculations with conidia, the
minimum wetness durations that lead to leaf infections were similar to
ascospores at temperatures between 12°C and 25°C, but at lower
temperatures (4, 8, 10°C), conidia infected leaves only after an
additional 2 h of leaf wetness. The relationship between minimum wetness times
and temperature was best described using an exponential regression. In field
experiments, leaf infection on plants inoculated with ascospores and conidia
under various naturally occurring wetness and temperature conditions was in
close agreement with those under controlled conditions. Disease severity
(percent of leaf area infected) increased with increasing leaf wetness
duration at all temperatures. The optimum temperature for infection was
20°C. Analysis of variance with orthogonal polynomial contrasts was used
to define the relationship of the angular transformation of disease severity
to temperature and leaf wetness duration.
Yellow lupin (Lupinus luteus) tolerates waterlogging better than narrow-leafed lupin (L. angustifolius) III. Comparison under field conditions
Authors: Davies C. L. , Turner D. W. , Dracup M.
Published: September 2002

This study determined whether the tolerance of yellow lupin to waterlogging,
observed in experiments in controlled environments, occurs under field
conditions. Of particular interest is the impact of waterlogging on the
distribution of roots because lupin is exposed to terminal drought in the
south of Western Australia, which in itself can have a profound effect on
yield. A field experiment was undertaken in the central grain-growing region
of Western Australia near Beverley using hydraulically isolated plots to
impose and remove waterlogging in a duplex soil. The responses of root and
shoot growth of narrow-leafed and yellow lupin to waterlogging in the field
were similar to those observed in the controlled environment experiments. In
the field experiment, waterlogging had no effect on seed yield of yellow lupin
but reduced it by 61% in narrow-leafed lupin. Waterlogging more than
halved the dry weight of narrow-leafed lupin but reduced it by only 19%
in yellow lupin. In yellow lupin, yield was 3.4 t/ha with waterlogging and
3.8 t/ha without waterlogging, compared with 1.4 t/ha with
waterlogging and 3.5 t/ha without waterlogging in narrow-leafed lupin.
Waterlogging had no effect on the harvest index of yellow lupin (0.26) but
reduced it from 0.36 to 0.31 in narrow-leafed lupin. The larger effect of
waterlogging on the yield of narrow-leafed lupin was mainly attributable to
fewer pods.
Net root growth ceased during waterlogging in both species. After
waterlogging, roots of yellow lupin grew at a similar rate to the controls,
whereas roots of narrow-leafed lupin grew at a much slower rate than the
controls. Waterlogging halved the root density of yellow lupin at 25 cm depth
and almost eliminated the roots of narrow-leafed lupin at this depth. After
waterlogging, root production in the surface 10 cm increased to about 0.5
cm/cm 3 in yellow lupin but to 0.2 cm/cm
3 in narrow-leafed lupin. At depth (>20 cm), roots of
waterlogged yellow lupin continued to grow while those of waterlogged
narrow-leafed lupin grew little, if at all. Yellow lupin tolerated
waterlogging in the field better than narrow-leafed lupin because it
re-established its root system at depth after waterlogging was removed and it
produced more fertile pods.
The grazing value of tall fescue (Festuca arundinacea) and phalaris (Phalaris aquatica) for sheep production in the northern tablelands of New South Wales
Authors: Ayres J. F. , McPhee M. J. , Turner A. D. , Curll M. L.
Published: September 2002

The grazing value of phalaris–white clover and tall fescue–white
clover pastures was compared in a temperate summer-rainfall environment in the
high rainfall zone of eastern Australia. Data were derived from an experiment
which evaluated pasture cultivars when grown in binary mixtures and grazed by
sheep. The data were also simulated with the decision support system SheepO
(Version 4.0) and validated by visual techniques, deviance measures, and
statistical tests. The model generally simulated green biomass, liveweight
gain, and clean fleece weight with acceptable accuracy. Pasture based on tall
fescue–white clover produced more green pasture biomass in all seasons,
in all years, and at both low (10 sheep/ha) and high (15 sheep/ha)
stocking rates when compared with phalaris–white clover. Sheep grazing
tall fescue–white clover pasture were turned off about 5 kg heavier each
year and produced about 0.6 kg/head more clean fleece weight; the wool
production per head of sheep grazing tall fescue–white clover at 15
sheep/ha was similar to that for sheep grazing phalaris–white clover
pasture at 10 sheep/ha. These differences in wool production were
accompanied by consistent effects on wool quality; the fleeces of sheep
grazing tall fescue–white clover pasture were markedly sounder in
tensile strength but broader in fibre diameter. These data and the SheepO
simulations highlight the potential for pasture cultivars with enhanced
seasonal growth and nutritive value to alleviate feed-gaps and improve the
feed-base for grazing animals.
Association of the Leu127 variant of the bovine growth hormone (bGH) gene with increased yield of milk, fat, and protein in Australian Holstein-Friesians
Authors: Shariflou M. R. , Moran C. , Nicholas F. W.
Published: September 2002

The occurrence of the
Leu127/Val127
variants of the bovine growth hormone (bGH) gene and their effect on milk
production traits was investigated in Australian Holstein-Friesian cattle.
Animals were genotyped for the
Leu127/Val127
variants, with RFLP methodology, using PCR and AluI
digestion of PCR products (AluI-RFLP). Alleles
Leu127 and
Val127 occurred with frequencies
of 82% and 18%, respectively. The quantitative effect of this
polymorphic site on milk-production traits was estimated from lactation data
and test-day data. Results from the 2 data sets consistently showed that the
Leu127 allele is associated with
higher production of milk, fat, and protein and is dominant to
Val127. The average effects of
the gene substitution are 95 L for milk yield, 7 kg for fat yield, and 3 kg
for protein yield per lactation. This locus may be directly responsible for
quantitative variation or it may be a marker for a closely linked quantitative
trait locus (QTL) for milk-production traits in Australian dairy cattle. In
either case, it will be useful as an aid to selection for improvement of milk
production traits. As the Leu127
allele is dominant, selection of AI sires homozygous for the
Leu127 allele
(Leu127/Leu127) will result in maximum benefit without the need for genotyping cows.
Genetic variability in a collection of Stagonospora nodorum isolates from Western Australia
Authors: Murphy N. E. , Loughman R. , Appels R. , Lagudah E. S. , Jones M. G. K.
Published: September 2002

Stagonospora nodorum isolates were collected from the
Western Australian grain-belt during 1993. These isolates and a subset of
isolates taken from a single location were used to assay the level of
variation within the pathogen population. The isolates were compared using
anonymous nuclear DNA markers. Three low copy-number and a single high
copy-number RFLP probe were used to generate polymorphisms. The collection
exhibited a high genotypic diversity for the high copy-number probe, a result
consistent with the high level of sexual reproduction previously found in the
fungal population. The high level of genotypic diversity was consistent with
previous international studies. There was no evidence of differentiation
between the total collection of isolates and the subset of isolates taken from
the single location. Further work needs to be undertaken to determine if the
aggressiveness of the pathogen is influenced by the host genotype.
Pea yield decline syndrome in South Australia: the role of diseases and the impact of agronomic practices
Authors: Davidson J. A. , Ramsey M. D.
Published: September 2002

Sixty commercial pea crops were surveyed in 1995 to determine the causes of
declining yields. Blackspot (Mycosphaerella pinodes and
Phoma medicaginis var. pinodella)
and downy mildew (Peronospora viciae) were prevalent in
most crops and were identified as probable major contributors to the syndrome.
Short rotation intervals (<5 years) between pea crops in paddocks were
correlated with increased levels of blackspot and lower grain yields. Early
sowing dates were correlated with increased levels of blackspot. A detailed
survey of blackspot development was conducted in 5 commercial paddocks in
1996. The relative importance of sowing time and rotation varied between
regions and seasons. The impact of a range of herbicides and the
micronutrients manganese and zinc on blackspot, caused by the
M. pinodes component of the blackspot complex, was
investigated in a field trial during 1996. The herbicides diuron, metribuzin,
and fluazifop significantly increased blackspot crown lesions compared with
the nil treatment. There was a significant interaction between blackspot
severity, herbicides, and the micronutrients manganese and zinc. Manganese
concentration in pea plants was negatively correlated with the severity of
blackspot crown lesions and positively correlated with severity of downy
mildew.
Event frequency and severity of sorghum ergot in Australia
Authors: Wang Enli , Meinke Holger , Ryley Malcolm
Published: September 2002

The temporal and regional distribution of the severity and potential number of
events of sorghum ergot on grain sorghum in Australia were analysed using
daily climatic data from 1957 to 1998. This analysis was conducted using both
a rule-based method and a regression model. Between December and March, the
main flowering period for most commercial grain sorghum crops, we found a
likely increase of ergot events in eastern Australia from south to north as
well as from west to east. When crops flowered in April or May the number of
potential monthly events increased, particularly in the southern areas. The
smallest number of events occurred when flowering occurred between September
and December. The temporal and geographic distribution of the number of events
and severity of sorghum ergot is closely related to relative humidity during
the flowering period. The analysis indicates that grain sorghum crops
flowering between early December and February are unlikely to be severely
infected with sorghum ergot. Late flowering sorghum has increased risk to
severe infection, especially in the coastal regions.
Evaluation of Western Australian canola meal for growing pigs
Authors: Mullan B. P. , Pluske J. R. , Allen J. , Harris D. J.
Published: September 2002

Twenty samples of canola seed collected throughout south-western Australia
after the 1995 harvest were analysed for oil and total glucosinolate levels.
Average oil and total glucosinolate levels were 378 g/kg and 14.0
mmol/kg (oil-free dry matter, DM), respectively. The subsequent
single-press canola meal [containing an average of 96 g/kg oil and
10.5 mmol/kg total glucosinolates (oil-free DM)] extracted from 8
batches of the original canola seed was then used in 2 growth experiments. In
Expt 1, canola meal was included in diets for growing–finishing pigs at
levels of 0, 50, 100, 150, and 200 g/kg in the diet, and replaced
Australian sweet lupins. In this study, feed was offered on an
ad libitum basis between 23 and 110 kg liveweight (LW).
In Expt 2, the same inclusion levels of canola meal were used; however, feed
intake was standardised across treatments (approximately 3 times maintenance)
to assess the impact of glucosinolate intake on performance and thyroid weight
in pigs between 19 and 94 kg LW. In Expt 1, performance was similar
(P > 0.05) in pigs offered up to 200 g/kg of
canola meal. In Expt 2, average daily gain was similar between treatments
(P > 0.05), although a linear decline in both daily
gain (P = 0.244) and feed : gain
(P < 0.05) with increasing canola meal levels was
detected. Increasing amounts of canola meal in the diet were associated with
heavier (P < 0.001) thyroid weights, suggesting a
negative influence of the products of glucosinolate hydrolysis on thyroid
function. Single-press canola meal is a suitable alternative to other protein
sources; however, at levels >150 g/kg for growing–finishing pigs,
higher intakes of glucosinolates were associated with a tendency for decreased
pig performance and thyroid hypertrophy despite the canola varieties used
being ‘low glucosinolate’.
Water deficit effects on sweet corn. II. Canopy development
Authors: Stone P. J. , Wilson D. R. , Jamieson P. D. , Gillespie R. N.
Published: September 2002

The response of sweet corn canopy development to timing and severity of water
deficit was determined in an experiment using a mobile rainshelter. Six
irrigation treatments were applied such that plots experienced: (1) no water
deficit; (2) full water deficit; (3) moderate pre-silking deficit; (4) severe
pre-silking deficit; (5) moderate post-silking deficit; or (6) severe
post-silking deficit. Soil moisture content profiles were measured using
neutron moisture probes and water deficit was quantified using the concept of
‘potential soil moisture deficit’ (Dp), which was calculated from
climatic data. Water deficit reduced leaf area, and the effect varied
depending on its timing and severity. Early water deficit reduced the rate of
leaf expansion (but not duration of expansion) and, consequently, the maximum
area of individual leaves; it therefore reduced the maximum leaf area index
(LAI). Moderate post-silking water deficit did not significantly reduce
maximum LAI, but it hastened leaf senescence. Severe water deficit late in
crop growth reduced canopy development by decreasing maximum LAI and advancing
leaf senescence. A model was developed which accounted for these effects. Two
measures of Dp were defined which related to both short-term transient
responses and those integrated over longer times. The model made it possible
to simply and mechanistically describe the effects of water deficit on canopy
development.
Characterisation of Australian isolates of Fusarium oxysporum f. sp. cubense by DNA fingerprinting analysis
Authors: Gerlach K. S. , Bentley S. , Moore N. Y. , Pegg K. G. , Aitken E. A. B.
Published: September 2002

Genetic variation among Australian isolates of the fungus
Fusarium oxysporum f. sp. cubense
(Foc), which causes Fusarium wilt in banana, was
examined using DNA amplification fingerprinting (DAF). Ninety-four isolates
which represented Races 1, 2, 3, and 4, and vegetative compatibility groups
(VCGs) 0120, 0124, 0125, 0128, 0129, 01211, 01213/16, and 01220 were
analysed. The genetic relatedness among isolates within each VCG, and between
the 8 different VCGs of Foc present in Australia was
determined. The DNA fingerprint patterns were VCG-specific, with each VCG
representing a unique genotype. The genetic similarity among isolates within
each VCG ranged from 97% to 100%. Among the different VCGs of
Foc, 3 major clusters were distinguished which
corresponded with race. All Race 1 and 2 isolates (VCGs 0124, 0125, 0128, and
01220) were closely related and clustered together, the Race 3 isolates from
Heliconia clustered separately, and all Race 4 isolates
(VCGs 0120, 0129, 01211, and 01213/16) clustered together.
Fifteen isolates from Alstonville, NSW, were characterised because although
they were classified as Race 2 based on their recovery from cooking banana
cultivars, they belonged in VCG 0124, which had previously contained only Race
1 isolates. The occurrence of more than one race within a VCG means that
vegetative compatibility grouping cannot be used to assign pathotype to
pathogenic race as previously thought. It was possible to distinguish the Race
1 and Race 2 isolates within VCG 0124 using DNA fingerprinting, as each race
produced a unique DNA fingerprint pattern. Among the Australian isolates, DNA
fingerprinting analysis identified 9 different VCGs and genotypes of
Foc.
Cysteine may play a role in the immune response to internal parasites in sheep
Authors: Miller F. M. , Blair H. T. , Birtles M. J. , Reynolds G. W. , Gill H. S. , Revell D. K.
Published: September 2002

To investigate the potential role of cysteine in the increased parasite
susceptibility of sheep selected for increased wool production, ten 2-year-old
rams from both fleece-weight-selected (FW) and randomly selected (C) Romney
lines received either 2 g of supplemental cysteine per day (+CYS) or
saline (+SAL), via abomasal infusion. Following drenching to remove any
pre-existing parasites, all sheep were dosed with
Haemonchus contortus and
Trichostrongylus colubriformis infective larvae. Sheep
were also subjected to non-parasitic immune challenges: inoculation with
ovalbumin and a commercial clostridial vaccine containing the tetanus toxin.
Cysteine infusion elevated plasma cysteine concentrations by an average of
65% (P < 0.0001), but no difference in
cysteine levels was observed between selection lines. Off-pasture faecal egg
counts (FEC) were higher in FW sheep (645 v. 200
eggs/g, P < 0.01). FEC were unaffected by
selection line or infusion treatment following experimental infection,
although FEC of +SAL sheep were at least double those of +CYS sheep.
Total parasite numbers in the abomasum and small intestine at slaughter were
unaffected by selection line or infusion treatment. Cysteine infusion tended
to result in greater peripheral eosinophilia over the experimental period
(P < 0.10), and higher counts of globular leukocytes
in the abomasum at slaughter (P < 0.05).
Anti-parasite antibody responses showed no response to experimental infection,
tending to drop over time; previous parasitic infection may have confounded
results. There were no effects of selection line or infusion treatment on IgG
responses to tetanus toxin, although data suggested that a swifter response
occurred in +CYS sheep. Anti-ovalbumin IgG responses tended to be greater
in +CYS sheep (Day 52, P < 0.10). This study
supports the greater susceptibility of FW sheep in natural parasitic
challenge, as indicated by off-pasture FEC. Cysteine appears to influence
certain aspects of immunocompetency in sheep, although the exact role of
cysteine in the relationship between wool production and parasite
susceptibility requires further elucidation.
Finding Pulsars at Parkes
Authors: Manchester R. N.
Published: September 2002

There are many reasons why it is important to increase the number of known pulsars. Not only do pulsar searches continue to improve statistical estimates of, for example, pulsar birthrates, lifetimes and the Galactic distribution, but they continue to turn up interesting and, in some cases, unique individual pulsars. In the early days of pulsar astronomy, the Molonglo radio telescope led the world as a pulsar detection instrument. However, the Parkes radio telescope, with its frequency versatility and greater tracking ablility, combined with sensitive receivers and powerful computer detection algorithms, is now the world’s most successful telescope at finding pulsars. The Parkes multibeam survey, begun in 1997, by itself will come close to doubling the number of known pulsars. Parkes has also been very successful at finding millisecond pulsars (MSPs), especially in globular clusters. One third of the known MSPs have been found in just one cluster, 47 Tucanae.
Mid-Infrared Imaging of the Einstein Cross QSO
Authors: Agol Eric , Wyithe Stuart , Jones Barbara , Fluke Chris
Published: September 2002

Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out synchrotron models, but consistent with dust emission models. Other constraints rule out starburst models. The flux ratios greatly constrain the lens model.
Gravitational Microlensing of Giant Luminous Arcs: a Test for Compact Dark Matter in Clusters of Galaxies
Authors: Lewis Geraint F.
Published: September 2002

The true nature of dark matter in the universe still eludes us. This paper discusses a new test for the detection of stellar mass compact dark matter in galaxy clusters by observing its gravitational lensing influence on the surface brightness of giant luminous arcs. If dark matter is in the form of stellar mass compact objects, then the extremes of such variability are accessible to a monitoring campaign with the Hubble Space Telescope. With the advent of the Next Generation Space Telescope, cluster dark matter in the form of compact objects will induce a ubiquitous ‘shimmering’ of the giant arcs.
The Spectra of Red Quasars
Authors: Francis Paul J. , Drake Catherine L. , Whiting Matthew T. , Drinkwater Michael J. , Webster Rachel L.
Published: September 2002

We measure the spectral properties of a representative sub-sample of 187 quasars, drawn from the Parkes Half-Jansky, Flat-radio-spectrum Sample (PHFS). Quasars with a wide range of rest-frame optical/UV continuum slopes are included in the analysis: their colours range over 2 < B–K < 7. We present composite spectra of red and blue sub-samples of the PHFS quasars, and tabulate their emission line properties.

The median Hβ and [O III] emission line equivalent widths of the red quasar sub-sample are a factor of ten weaker than those of the blue quasar sub-sample. No significant differences are seen between the equivalent width distributions of the C IV, C III] and Mg II lines. Both the colours and the emission line equivalent widths of the red quasars can be explained by the addition of a featureless red synchrotron continuum component to an otherwise normal blue quasar spectrum. The red synchrotron component must have a spectrum at least as red as a power-law of the form Fυ α υ−2.8. The relative strengths of the blue and red components span two orders of magnitude at rest-frame 500 nm. The blue component is weaker relative to the red component in low optical luminosity sources. This suggests that the fraction of accretion energy going into optical emission from the jet is greater in lowluminosity quasars. This correlation between colour and luminosity may be of use in cosmological distance scale work.

This synchrotron model does not, however, fit ˜10% of the quasars, which have both red colours and high equivalent width emission lines.We hypothesise that these red, strong-lined quasars have intrinsically weak Big Blue Bumps.

There is no discontinuity in spectral properties between the BL Lac objects in our sample and the other quasars. BL Lac objects appear to be the red, low equivalent width tail of a continuous distribution. The synchrotron emission component only dominates the spectrum at longer wavelengths, so existing BL Lac surveys will be biased against high redshift objects. This will affect measurements of BL Lac evolution.

The blue PHFS quasars have significantly higher equivalent width C IV, Hβ and [O III] emission than a matched sample of optically selected QSOs.