bluuebunny/crossref_metadata_2025 huggingface dataset:
Haploid production of Australian wheat (Triticum aestivum L.) cultivars through wheat × maize (Zea mays L.) crosses
Authors: Suenaga K. , Morshedi A. R. , Darvey N. L.
Published: August 2004

In order to reduce the labour for wheat haploid production through wheat maize
crosses, several emasculation methods were investigated in combination with
the ‘spike culture method’. Although the standard method whereby
wheat spikes were hand-emasculated and pollinated on the day of anthesis gave
a higher efficiency, the ‘non-emasculation method’ gave a
comparable response. The use of the non-emasculation method and spike culture
could eliminate much of the labour required for emasculation and treatment
with 2,4-D, which is normally applied by injection into wheat internodes or by
dropping onto florets after pollination with maize. Most of the selfed seeds
were easily identified by the presence of endosperm, and the probability of
contamination by the embryos originating from selfing among the presumptive
haploid embryos in the non-emasculation method was very low. Twenty-seven
Australian wheat cultivars were investigated for haploid production through
wheat × maize crosses using the non-emasculation and spike culture
methods. All of the 27 cultivars produced embryos after crossing with maize,
with a mean efficiency of 33·1% (embryos/florets). Except
for one cultivar, Tincurrin, plants were recovered from all of the cultivars
(average of 61·5% including Tinccurin). This innovation of
haploid production through wheat maize crosses is discussed.
Wool and liveweight responses to nutrition by Merino sheep genetically selected for high or low staple strength
Authors: Adams N. R. , Briegel J. R. , Ritchie A. J. M.
Published: August 2004

The biological mechanisms underlying differences in wool staple strength were
examined in 2 groups of Merino sheep that have been genetically selected for
high or low staple strength, while holding fibre diameter constant. The sheep
were fed below maintenance for 87 days, and then re-fed ad
libitum for 63 days with a diet containing either
9% or 23% crude protein, in a cross-over design, after which
they returned to the paddock until shearing. The fleeces of the 2 groups
differed in staple strength (25·2 v.17·5
N/ktex, P < 0·001) but were similar in
mean fibre diameter and clean fleece weight. However, the pattern of wool
growth was different. When fed below maintenance, sheep from the sound group
grew more wool than sheep from the tender group (P <
0·05), but lost more liveweight (P <
0·01). During re-feeding, the sound sheep grew less wool than the
tender sheep (P < 0·05), but gained more
liveweight. The mean fibre diameter at the point of break was similar in both
groups. Immediately after re-feeding, the fibre diameter increased more
rapidly in the tender group than in the sound (P <
0·001), but a similar difference was observed between the high and low
protein diets, with no effect on staple strength. The sound sheep had a lower
standard deviation of fibre diameter than the tender sheep
(P < 0·001), both in the whole fleece and in
3-weekly midside patches. The data indicated that the variability of fibre
diameter between fibres made a larger contribution than the variability along
fibres to the difference between the groups in overall variability of fibre
diameter.
The sheep were then grazed together at pasture for a second year and again
differed in staple strength. In addition, the sound sheep grew less wool on
green spring pastures and had a lower clean fleece weight
(P < 0·05). The differences in wool growth
rates between sheep from the sound and tender lines depended more on whether
pasture was green than on the amount of pasture available. We conclude that
the difference in staple strength between the sound and tender groups was most
closely associated with the variability between fibres in diameter, and was
also affected by a difference in variation in diameter along the fibres.
Staple strength was not affected by the amount of wool at the point of break,
or by the rate of change in fibre diameter after feeding. The sheep in the
sound group grew less wool than those in the tender group when on good
nutrition.
Measurement of fibre density and fibre bundles in the skin of sheep from different breeds
Authors: Nagorcka B. N. , Dollin A. E. , Ringrose-Voase A. J.
Published: August 2004

A procedure for analysing digitised scanning electron microscope (SEM) images
of impressions of sheep skin has been developed and tested. The new technique
for measuring fibre densities and fibre bundles was applied to a small number
of sheep from the Romney, Border Leicester, and Suffolk breeds, and in fine-
and strong-woolled Merinos. Skin impressions were taken from small shaved
areas of the skin, and fibres in digitised SEM images of the skin impressions
were counted and assigned to bundles. Estimates were made of the density of
epidermal follicles, the proportion of these which branch, the number of
fibres (follicles) per bundle, and the proportion of skin left bare of
follicles. An average distance between neighbouring epidermal follicles,
Λ E, was also measured. Λ E
was found to be correlated with fibre diameter. The total density of fibres
(follicles) in the animals sampled ranged from 10 to 100
follicles/mm2 , and fibre diameter ranged from ~35
to ~15µm. Despite this wide range, all animals examined were observed to
have derived (branched) follicles. The fraction of epidermal follicles which
branched varied from ~0·15 to ~0·45, and the average number of
fibres (follicles) per bundle ranged from 2·2 to 3·8.
Λ E was used to calculate an indicator of the
fraction of skin which is bare of follicles. This was found to be substantial,
varying between 0·4 and 0·7. Measurements were also made using
both serial transverse and serial longitudinal skin sections. The results
obtained with the different techniques were compared.
Fluxes of nitrogen derived from plant residues and fertiliser on a cracking clay in a semi-arid environment.
Authors: Armstrong R. D. , McCosker K. , Millar G. , Probert M. E.
Published: August 2004

The feasibility of using legume leys to redress declining levels of soil
nitrogen (N) fertility on the heavy clay Vertisols of the northern Australian
grain belt depends partly on the ability of plant residues to supply N
directly to subsequent cereal crops. An alternative is the use of fertiliser N
in continuous cereal cropping. Two experiments were conducted (one in the
field, the other under polyhouse conditions) to compare the uptake of N from
either plant residues or ammonium sulfate fertiliser that had been labelled
with 15N.
In a field trial, 15N-labelled shoots of grain sorghum
and Desmanthus virgatus and ammonium sulfate were
applied to micro-plots and the flux of the added N between different soil
pools and a wheat crop was followed over 219 days. Only small amounts of
residue-derived N (<5%) were recovered in the mineral N of the soil
at a depth of 0-10 cm, whereas over 88% of the fertiliser N was present
as mineral N soon after adding the fertiliser. Soil microbial biomass-N was
increased following addition of residues. Recovery of added
15N in the wheat crop was much higher from the
fertiliser (35%) than from the 2 residue sources (<5%).
The pot trial compared a wider range of 15N-labelled
residues (shoot and root residues of
Desmanthus virgatus, Lablab
purpureus, and sorghum) with several rates of ammonium sulfate, applied in the
presence and absence of non-labelled grain sorghum residues, over 4 cropping
cycles. Dry matter production and N uptake were increased by application of
fertiliser N, although the response was reduced in the presence of
non-labelled sorghum residues; responses to residue N were much smaller than
those to fertiliser N. In the first crop following residue application
<7% of residue N was recovered, increasing to 12-23% over the
4 crops. Recovery of fertiliser N by the crops increased with the rate of
application, and also depended on whether it was applied together with
residues.
A feature of the results, in both the field and pot experiments, was the large
proportion of applied 15N that could not be accounted
for in either the soil or the crops, and these losses have been attributed to
denitrification.
Seasonal fluctuations in gross N mineralisation, ammonium consumption, and microbial biomass ina Western Australian soil under different land uses
Authors: Murphy D. V. , Sparling G. P. , Fillery I. R. P.
Published: August 2004

A field experiment was conducted to study the seasonal variation in gross N
mineralisation, NH4+ consumption
(immobilisation and nitriflcation), potentially available N, and microbial
biomass-N.Measurements were made during the wheat growing season in Western
Australia under continuouswheat, during the wheat phase of a 1 year lupin : 1
year wheat rotation, during the wheat phaseof a 2 year pasture : 1 year wheat
rotation, and under a subterranean clover pasture. The accuracyof gross N
mineralisation and NH4+
consumption within intact soil cores was reduced by the largespatial variation
in the size of the soil NH4+ pool.
Calculated daily rates of gross N mineralisation inthe 0-5 cm soil layer
ranged from 0·0 to 1·0 kg N/ha·day in the continuous
wheat, 0·1 to 0·8 kgN/ha·day in the lupin{wheat
rotation,- 0·1 to 1·3 kg N/ha·day in the
pasture-wheat rotation, and-0·1 to 2·5 kg N/ha·day in
the pasture treatment. Gross N mineralisation in the 5-10 cm soil layerunder
wheat followed the same range observed in the 0-5 cm layer; in continuous
pasture, lower rates were measured in the 5-10 cm layer compared with the 0-5
cm layer. The range in daily rates of
NH4+ consumption in a given
treatment was similar to the range in daily rates of gross N
mineralisation,precluding accumulation of
NH4+ in soil when considered over
a season. Gross N mineralised in the0-10 cm soil layer was equivalent to
10-19% of the total soil N in this layer. Net N mineralised,determined
from the difierence between gross N mineralisation and gross immobilisation,
was estimatedto be about half of the gross N mineralised during the wheat
growing season. Plant uptake wasestimated to be 13-37% of the total
gross N mineralised (0-10 cm) during the field season and wasgreater in the
wheat after legume compared with continuous wheat. Potentially available N,
measured by anaerobic incubation, declined by about one-third during the
season. At the beginning of the season, microbial biomass-N in the 0-5 cm soil
layer contained 61 kg N/ha in continuous wheat, 68 kgN/ha in the
lupin-wheat rotation, 73 kg N/ha in the pasture-wheat rotation, and 99 kg
N/ha underpasture. Only half of these quantities of microbial biomass were
detected by the end of the season. Microbial biomass-N was concentrated in the
surface soil layer with <25 kg N/ha in the 5-10 cmsoil layer under each
land use. A reasonable estimate of gross N mineralisation was obtained in
the continuous wheat and legume-wheat rotations by using a simple empirical
relationship based on thesize and activity of the microbial biomass, and
functions to describe the efiect of temperature andwater on microbial
activity. However, the pattern of gross N mineralisation in the pasture
treatment could not be explained using this approach.
Intermittent lighting and dietary sodium bicarbonate supplementation for laying hens at high temperatures
Authors: Balnave D. , Muheereza S. K.
Published: August 2004

Point-of-lay pullets were housed in 2 temperature-controlled rooms maintained
at a constant 32°C with either a conventional 16 h light : 8 h dark (16L :
8D) or an intermittent 3L : 1D lighting regimen. They were fed either a
conventional layer diet (12·0 MJ of ME and 199 g crude protein/kg)
or this diet supplemented with 1% sodium bicarbonate (NaHCO3).
Production and egg shell quality measurements were made at 8-week intervals
from 22 to 62 weeks of age. All measures were influenced by age. The 3L : 1D
regimen significantly increased feed intake (P <
0·001), weight gain (P < 0·01), egg
weight (P < 0·001), egg shell breaking
strength (P < 0·001), and shell thickness
(P < 0·01). Significant age×light
interactions were observed for feed intake, egg production, and egg mass. Hens
in the 3L : 1D regimen ate significantly (P <
0·001) more food and produced significantly (P
< 0·01) greater egg mass to 46 weeks of age. No significant
differences were observed after 46 weeks. Although not significant,
NaHCO3 consistently improved shell breaking strength.
The response was small in the 16L : 8D regimen (3%) compared with the
3L : 1D environment (7%), the latter being additional to the 14%
improvement resulting from the use of the 3L : 1D regimen. The results
indicate advantages from the use of intermittent lighting and dietary
NaHCO3 supplementation at high temperatures.
Seed production in cluster clover (Trifolium glomeratum L.). 2 Effect of sowing time and sowing rate on flowering time, abortion, seed size, and hardseededness
Authors: Smith F. P. , Cocks P. S. , Ewing M. A.
Published: August 2004

An ecotype of cluster clover (Trifolium glomeratum L.)
common to the wheatbelt of Western Australia was sown in pure undefoliated
swards at rates in the range 2-256 kg/ha, on 2 dates to give growing
seasons 13 and 18 weeks in length. Irrigation was phased out at the time of
flowering of late-sown plots. The treatments generated a scale of seed
production in cluster clover from 148 kg/ha (43 000
seeds/m2) to 1640 kg/ha (389 000
seeds/m2). Delayed sowing was more important in
reducing seed production than was increasing sowing rate. By comparison with
the early-sown plots, the late-sown plots had less above-ground biomass at
flowering (2053 v. 2728 kg/ha); 48-66% fewer
inflorescences per m2; a shorter vegetative phase (9
days); fewer seeds per inflorescence (26 v. 31); and
lesser seed mass (337 µg v. 436 µg). There
was little effect of the treatments on hardseededness except that
hardseededness after 1 season in the field was higher in seeds from late-sown
swards at high sowing rate (58%) than from late-sown swards at low
sowing rate or early-sown swards (40%). Neither sowing rate nor sowing
time influenced the within season pattern of hardseed breakdown.
The results indicate that cluster clover is capable of massive seed
production, and that even under highly stressed conditions seed production is
maximised by a high reproductive allocation and small seed size. Despite
conditions which reduced seed production by up to 90%, cluster clover
is able to maintain its seed quality. Relatively few inviable seeds are
produced and hardseededness is either unaffected or enhanced.
Effect of late nitrogen application on growth and nitrogen balance of two cultivars of water-stressed grain sorghum
Authors: Utzurrum Jr S. B. , Fukai S. , Foale M. A.
Published: August 2004

With development of water stress during grain filling, sorghum crops lose
green leaves, and nitrogen (N) is remobilised from the leaves to grain.
Supplementary N application just before anthesis may reduce leaf senescence,
contributing to dry matter production during grain filling and, hence, grain
yield. This hypothesis was tested using 2 sorghum hybrids which were known to
differ in capacity for osmotic adjustment and the ability to retain green
leaves under water stress, in a rainout shelter experiment in south-east
Queensland. When N was applied at depth (>70 cm) where water was available,
all N applied was apparently taken up by the plants, resulting in reduced leaf
senescence, particularly for leaves in the middle layer. Remobilisation of N
from leaf to grain during grain filling was reduced by the supplementary N
application.
Both stem and leaf were the source of remobilised N which contributed about
65% of the total grain N without supplementary N application, this
being reduced to about 30% with N application
The hybrid with known high osmotic adjustment had greater total above-ground
dry matter, particularly stem dry matter, at anthesis than the other,
providing more material for translocation to fill grains. It also maintained
greater leaf area during early stages of grain filling. This hybrid produced
significantly higher yield (465 v. 412
g/m2) only when supplementary N was applied. Without
supplementary N application, their yields were similar at about 350
g/m2.
It is concluded that provided N is taken up by the sorghum plants, late N
application is effective in increasing grain yield under water-limiting
conditions. Cultivars, however, differed in their responses to the
application.
Characters contributing to high yield in Currawong, an Australian winter wheat
Authors: Penrose L. D. J. , Walsh K. , Clark K.
Published: August 2004

This study investigated characters that contribute to high grain yield in the
recently released Australian winter wheat, cv. Currawong. Currawong was
released as a feed grade wheat for south-central New South Wales, with a
10% yield advantage over the highest yielding milling wheat with winter
habit, Rosella. When expressed as a percentage of the grain yield of Rosella,
Currawong was found to perform best at sites with low soil pH and high grain
yield. These sites corresponded to the wetter eastern margin of the wheatbelt
in south-central New South Wales. While part of the yield advantage of
Currawong is due to its tolerance of soil acidity, there remains an ability to
yield particularly well in environments conducive to high yield. In yield
component studies that were conducted over 2 seasons at Temora, the yield
advantage of Currawong appeared to be associated with its grainfilling
characters. Currawong had a more rapid rate of grainfill, and/or a longer
duration of grainfilling than other high-yielding winter wheats, leading to
significantly heavier grain.
From a plant breeding perspective, the high yield of Currawong is significant
for demonstrating rapid genetic gain for yield in Australian winter wheats.
The yield of Currawong also demonstrates the possibility of combining high
grain yield with the Sr26 stem rust resistance. Characters that confer high
yield in Currawong may be of limited benefit in environments where drought
stress limits the duration of grainfilling in wheat.
Genotypic variation for grain yield and grain nitrogen concentration among sorghum hybrids under different levels of nitrogen fertiliser and water supply
Authors: Kamoshita A. , Cooper M. , Muchow R. C. , Fukai S.
Published: August 2004

Sorghum [Sorghum bicolor (L.) Moench] is often
grown under nitrogen- or water-limited conditions, but there is little
information on genotypic variation for grain yield and grain nitrogen (N)
concentration under these conditions. This study examined the expression of
specific adaptation of hybrids to these stress conditions and, secondly, the
effect of N fertiliser application on yield and grain N concentration of the
hybrids. Two experiments, one irrigated and the other under rainfed
conditions, were conducted in 2 seasons to examine 14 hybrids grown under 3
levels of fertiliser N supply (0, 60, and 240 kg/ha).
Genotypic variation for yield and grain N concentration was generally larger
than the in˚uence of genotype environment (predominantly N and water)
interactions. Genotypic variation for phenology was important in determining
variation for yield and grain N concentration in high-input and rainfed
conditions when N was not the limiting factor, but not under N-limiting
conditions. Under high-input conditions (240 kg/ha of N fertiliser and
irrigated), maturity date accounted for about 50% of the genotypic
variation for grain yield (798-1049 g/m2), with
later maturing hybrids having a higher yield. Maturity date had little effect
on plant N content at maturity or N harvest index, and hence grain N
concentration (1·67-2·01%) was negatively correlated with
grain yield. Under N-limiting conditions, N fertiliser application had large
effects on yield and/or grain N concentration in both well-watered and
pre-anthesis water stress conditions. In the irrigated experiment, when N was
limiting (0 and 60 kg/ha of N fertiliser), genotypic variation for grain
yield (225-729 g/m2) was not related to that for
maturity date. It was, however, related to the variation in N uptake and dry
matter growth by anthesis in the non-fertilised treatment. There was
significant genotypic variation for grain N concentration
(0·94-1·26%), which was not explained by variation for
grain yield. Under rainfed conditions, where severe pre-anthesis water stress
occurred, phenology was important in determining about 40% of the
genotypic variation for yield (69-286 g/m2). The
late-flowering hybrids escaped the major impact of the pre-anthesis water
stress, had reduced damage to panicle development, and had higher N
utilisation, consequently producing higher grain yield.
Grain N concentration (1·09-2·85%) was again negatively
related with grain yield. Genetic improvement of N uptake is identified as a
possible breeding strategy for raising productivity and quality of grain
sorghum under N-limiting conditions.
Factors affecting soil acidification under legumes. II. Effect of phosphorus supply
Authors: Fang R. Y. , Tang C. , Raphael C.
Published: August 2004

Phosphorus deficiency is common in crop production. This pot experiment
examined whether the supply of
Ca(H2PO4)2
affected acid production by N2-fixing plants of 5 grain
and 4 pasture legume species grown in a P-deficient sandy soil for 60-64 days.
The legume species differed greatly in their response to P application.
Lupinus albus, L. luteus, and
Biserrula pelecinus were less responsive to P supply
than Cicer arietinum, Vicia faba,
Medicago polymorpha, Ornithopus sativus,
and Trifolium subterraneum, which in turn were less
reponsive than L. angustifolius.
Increasing P supply up to moderately deficient levels increased the amount of
acid production per unit shoot biomass (specific acid production), and further
increasing P decreased specific acid production. The effect of species on acid
production was greater than the effect of P supply. Among the species,
C. arietinum had the highest
specific acid production and B. pelecinus the lowest. Specific acid production was
correlated with concentrations of excess cations and ash alkalinity as well as
Ca and Mg but not P in shoot. There was a very good agreement between total
acid production and total content of excess cations in the whole plant,
irrespective of P supply and plant species. The results suggest that acid
production by legumes under various P supplies is related to the imbalance of
cation and anion uptake.
Ractopamine increases glucose turnover without affecting lipogenesis in the pig
Authors: Dunshea F. R. , Leur B. J. , Tilbrook A. J. , King R. H.
Published: August 2004

The β-agonist ractopamine (RAC) promotes protein deposition with little
effect on fat deposition in the pig. The present study was conducted to assess
whether the lack of effect on fat deposition was due to a lack of effect of
ractopamine on lipogenesis. Twenty crossbred pigs (initial liveweight 80 kg)
surgically prepared with cephalic vein catheters were used in a 2×2
factorial experiment with the respective factors being sex (boar or gilt) and
dietary RAC (0 or 20 mg/kg of ractopamine.HCl). Pigs were offered
3·0 kg/day of their respective diets for 24 days. On Day 4 and 23
of the experiment, pigs were injected with [U-
14C]-glucose and serial blood samples taken to
determine glucose turnover. Adipose tissue biopsies were taken 240 min after
injection of labelled glucose and lipogenesis was estimated from the
incorporation of 14C into adipose tissue lipid. Dietary
RAC increased average daily gain (P < 0·050),
and average growth rate was greater in boars than in gilts
(P < 0·050). Dietary RAC increased glucose
turnover by 24%, presumably to support the increased skeletal muscle
protein deposition that occurs during dietary RAC treatment. There was no
effect of dietary RAC on the rate of lipogenesis in adipose tissue, which is
consistent with the lack of effect of dietary RAC on the rate of fat
deposition.
β-agonist, adipose tissue.
PCR as an ecological tool to determine the establishment and persistence of Rhizobium strains introduced into the field as seed inoculant Diane
Authors: Hebb M. , Richardson Alan E. , Reid R. , Brockwell John
Published: August 2004

Appraisal of the establishment and persistence of inoculant strains, and the
diversity of the rhizobial populations in 2 field experiments, required the
precise characterisation of isolates from individual nodules. The polymerase
chain reaction (PCR) method of generating randomly amplified polymorphic DNA
(RAPD) from simple bacterial cell lysates was applied to nodule isolates
obtained from field plots of clover (Trifolium spp.) and
medic (Medicago spp.) plants inoculated with
Rhizobium leguminosarum bv.
Trifolium and Rhizobium meliloti.
Comparison of the PCR method with gel immune diffusion serology was applied to
selected nodule isolates obtained from the clover trial. Agreement between the
methods was high (97·6%). Further characterisation of nodule
isolates from the 2 field trials proceeded using PCR amplification profiles
only, which allowed a large number of isolates to be quickly and precisely
identified. Mean recovery of inoculant strains in the first season of the
clover trial was 76·5% across 10 hosts, and 45·3%
in the second season sampling. Recovery of inoculant strains in the medic
trial was assessed only during the second season of growth, which recorded a
mean recovery of 53% across 8 hosts. In addition to providing a rapid
and reliable means of identifying inoculant strains of
R. leguminosarum bv.
Trifolium and R. meliloti directly
in association with a range of different host plants, the PCR approach also
allowed inoculant strain types to be readily identified when recovered as
isolates from plots in which they had not been introduced. Analysis of the
non-inoculant strains by PCR also indicated that the naturalised populations
of rhizobia at both sites were highly diverse.
Follicle abnormalities and fibre shedding in Merino weaners fed different levels of nutrition
Authors: Peterson A. D. , Thompson A. N. , Schlink A. C. , Hynd P. I.
Published: August 2004

A study was conducted to examine the relationship between fibre shedding and
staple strength in Merino weaners genetically different in staple strength and
fed different levels of nutrition. Fibre shedding at the point of break along
the staple was estimated using 3 different techniques:
(i) a subjective scoring system of wool follicle
activity, based on their morphology in transverse skin sections;
(ii) the number of fibres with club-ends after
differential staining to identify remnants of the shed-follicle bulb; and
(iii) changes in the number of fibres in the
cross-section along individual staples. Irrespective of the technique used,
the estimated proportion of shed fibres did not differ significantly between
the sheep bred for sound and tender wool, but increased significantly
(P < 0·05) in response to adverse nutritional
conditions.
Across all treatments, there was a significant
(r2 = 0·63;
P < 0·001) correlation between the proportion
of shutdown follicles and the percentage decrease in the number of fibres in
the staple cross-section, although the average difference between the
techniques was 11·5%. Both techniques indicated that, on
average, about 30% of the total follicle population became inactive and
shed their fibre under the most adverse nutritional conditions, and that this
was as high as 50–60% for some individual sheep. Neither of these
techniques was closely correlated to the proportion of fibres with club-ends
(r2 = 0·15 and
0·20, respectively; P < 0·01).
The proportion of shutdown follicles and the percentage decrease in the number
of fibres in the staple cross-section explained 54% and 52% of
the variance in staple strength, respectively, compared with only 19%
explained by the percentage of fibres with club-ends at the point of break.
However, as fibre shedding failed to remove any variance in staple strength
additional to that already attributed to along- and between-fibre changes in
diameter, it is concluded that fibre shedding per se does not contribute
significantly to nutritional-induced differences in staple strength.
Components of staple strength in fine and broad wool Merino hoggets run together in a Mediterranean environment
Authors: Peterson A. D. , Doyle P. T. , Gherardi S. G.
Published: August 2004

Properties of fleeces and individual fibres were measured on 57 fine and 51
broad wool Merino hoggets, offered 1 of 3 supplementary feeding treatments, in
an attempt to relate properties of individual fibres to staple strength. The
fine wool hoggets (16·2 µm) grew wool of staple strength higher
(2·5–4·3 N/ktex depending on feeding treatment) than
that of the broad wool hoggets (20·1 µm). While there was no
difference in the intrinsic fibre strength between the genotypes, the
variation in diameter along fibres was 24% (P
< 0·05) greater in the broad wool sheep. The broad wool sheep also
grew fibres which were 50% stronger (P <
0·05) but 15% less extensible than the fine wool sheep. Staple
strength increased (P < 0·05) from 8·6
to 24·9 N/ktex as supplementary feeding during summer–autumn
was increased, for both genotypes. Increases in staple strength due to feeding
were associated with a 3·3-µm increase in the minimum diameter
along fibres (P < 0·05) and a 11·3-mN
increase in fibre strength (P < 0·05). A
multiple regression which included the coefficient of variation in diameter
along fibres, and the extensibility of fibres, accounted for 62% of the
variation in staple strength between sheep. The results enhance our
understanding of the mechanisms which affect staple strength.
Adverse responses in egg shell quality in late-lay resulting from short-term use of saline drinking water in early- or mid-lay
Authors: Balnave D. , Zhang D.
Published: August 2004

Three experiments were carried out to determine the long-term responses in egg
shell quality when hens were given saline drinking water for only a few weeks
either at the start of lay or in mid-lay. Shell quality of eggs from hens
given town water containing an additional 2 g sodium chloride (NaCl)/L as
drinking water for periods of 5 or 6 weeks prior to 30 weeks of age or between
48 and 53 weeks of age was significantly poorer at the end of lay than shell
quality of eggs from hens given town water throughout lay. Apart from these
short periods of saline water supply the NaCl-treated hens received town water
throughout lay. Shell defects were increased significantly after 55 weeks of
age even when no apparent detrimental effects of saline drinking water on
shell quality were observed during the period of saline water intake or when
the incidence of shell defects returned to normal after the replacement of
saline water with town water. The results indicate that the adverse effects of
saline drinking water on egg shell quality is of long-term significance, being
especially noticeable towards the end of lay.
Resistance to nematode parasites in Merino sheep: correlation with production traits
Authors: Eady S. J. , Woolaston R. R. , Ponzoni R. W. , Lewer R. P. , Raadsma H. W. , Swan A. A.
Published: August 2004

Merino sheep representing a range of bloodlines in resource flocks located
across Australia were tested for resistance to gastro-intestinal nematodes.
These flocks included the JB Pye Flock (Camden, NSW), Katanning Base Flock
(Katanning, WA), Turretfield Merino Resource Flock (Rosedale, SA), and the
CSIRO Finewool Flock (Armidale, NSW) and included a total of 328 sire groups.
Resistance to nematodes was measured by faecal egg count (FEC). Data were also
available for greasy and clean fleece weight (GFW and CFW, respectively),
fibre diameter (FD), and body weight (BW) at a range of ages from weaning to
21 months. Variance components were estimated by restricted maximum
likelihood, fitting an animal model and estimating covariances in a series of
bivariate analyses. Phenotypic correlations between
FEC0·33 and production traits were all close to
zero ( –0·09–0·02). Genetic correlations between
FEC0·33 and production traits were
–0·20, –0·18, and –0·26 for weaning
weight, 10-month BW, and 16-month BW, respectively; 0·21,
–0·06, and 0·21 for 10-month GFW, 16-month GFW, and
21-month GFW; 0·21, –0·05, and 0·07 for 10-month
CFW, 16-month CFW, and 21-month CFW; and –0·09,
–0·12, and 0·04 for 10-month FD, 16-month FD, and 21-month
FD. When estimates were pooled for all fleece traits and all BW traits, the
genetic correlations between FEC0·33 and GFW,
CFW, FD, and BW were 0·15, 0·10, –0·06, and
–0·21, respectively. Using pooled estimates for CFW, FD, and BW,
selection for a breeding objective based on production traits alone would lead
to an unfavourable correlated response in FEC0·33
of approximately 1% per year.
Multivariate Relationships between Floristic Composition and Stand Structure in Vegetation of Ku-ring-gai Chase National Park, New South Wales
Authors: Brocque Andrew F. Le , Buckney Rod T.
Published: August 2004

The relationships between stand structure and floristic composition were
examined from data collected from 100 quadrats on two soil types: Hawkesbury
sandstone and Narrabeen group soils, occurring within Ku-ring-gai Chase
National Park, New South Wales. Floristic composition was determined using the
frequency of species occurring within nine concentric sub-quadrats of total
area 500 m2. Stand structure was determined by a
multivariate classification scheme utilising the foliage projective cover of
eight strata within each quadrat. The patterns in floristic composition and
stand structure were examined through multivariate analyses. Procrustes
analysis of non-metric multidimensional scaling ordinations of both the stand
structure and composition data showed floristic composition gradients to be
well recovered by the structure data. Similar gradients were evident in both
vegetation attributes, between and within the two soil types, with the rank
order of community types across the ordinations being the same. However, some
important differences were evident between the ordinations of floristic
composition and stand structure between and within soil types. A number of
floristically dissimilar communities exhibited very similar multivariate
structural characteristics. In particular, two floristically distinct
communities on different soil types were indistinguishable in terms of their
structural characteristics. The multivariate analyses suggest a possible
convergence of some compositionally distinct communities towards a common
structural formation.
Aspects of the Floral Biology of Allocasuarina verticillata (Casuarinaceae)
Authors: Moncur M. W. , Boland D. J. , Harbard J. L.
Published: August 2004

Aspects of the floral biology of
Allocasuarina verticillata were recorded in a natural
stand in Canberra, Australia. The trees are dioecious, and flowering took
place during the autumn to spring months (May–October). The female
inflorescence consists of over 100 individual flowers, which remained
receptive for up to 12 weeks. The proportion of individual flowers pollinated
increased gradually over this time. The advantage of a long female receptive
phase is that each inflorescence can potentially receive pollen from a number
of male sources. Duration from pollination to fertilisation was 53–83
days. Male inflorescences dehisced over a 3–9 week period depending upon
air temperatures. Pollen germination was highest at 10˚C and 15˚C
and poor at 5˚C, 20˚C and 25˚C. Pollen grains remained turgid
at the lower temperatures for at least 3 days. Seed germinated well at
temperatures between 10˚C and 25˚C but there was a marked decline at
30˚C. Stratification of seed is suggested as a standard practice in
germination tests. Results are discussed in relation to developing tree
improvement strategies for domestication of the family Casuarinaceae.
A Trade-off between Fecundity and Drought Susceptibility in Adults and Seedlings of Hakea Species as Influenced by Leaf Morphology
Authors: Richards Michael B. , Groom Philip K. , Lamont Byron B.
Published: August 2004

Successful seedling recruitment is vital for the persistence of fire-killed
species in a community. Maximising seed and seedling production (fecundity)
and the ability of adults and seedlings to survive summer drought are crucial
in taking advantage of post-fire recruitment opportunities. In this study, the
fecundity (seed and seedling production), mortality and water relations of
fire-killed Hakea species with contrasting leaf
morphologies (broad and terete) were examined over 2 consecutive years of
exceptionally low rainfall at two sites, to investigate possible trade-offs
between drought susceptibility (as influenced by leaf morphology) and
fecundity of a species. Adult mortality was high in the broad-leaved species
(H. smilacifolia Meissn. and
H. undulata R.Br.) and low in terete-leaved species
(H. erinacea Meissn.,
H. circumalata Meissn. and
H. polyanthema Diels) with high transpiration rates
(broad-leaved species) associated with greater plant death. Only
H. smilacifolia had proportionally greater fecundity to
compensate for high adult mortality. Seedling mortality increased
proportionally with higher initial seedling : parent ratios (adult fecundity).
Lowest mortality was for the terete-leaved species, apparently achieved by
means of a combination of drought avoidance and tolerance mechanisms.
Hakea undulata seedlings had the highest mean leaf area,
but mortality was highest in H. smilacifolia. Thus, for
seedlings, leaf morphology was not as strongly related to drought
susceptibility as it was for adults.
Reproductive Potential of Obligate Seeder and Resprouter Herbaceous Perennial Monocots (Restionaceae, Anarthriaceae, Ecdeiocoleaceae) from South-western Western Australia
Authors: Meney K. A. , Dixon K. W. , Pate J. S.
Published: August 2004

Pre- and post-dispersal reproductive success was studied in 22 species from
three related Southern Hemisphere families, Restionaceae, Ecdeiocoleaceae and
Anarthriaceae. Pre-dispersal success was compared for resprouter and obligate
seeder species using seed: ovule ratios and carpel: flower ratios. The data
indicated a high level of variability between taxa but pre-dispersal
reproductive success of obligate seeders was significantly higher (67%
conversion of ovules to seeds) than that of resprouters (35%). Two
seeders, an extremely rare species
(‘Chordifex’
abortivus) and a strongly clonal species
(Alexgeorgea subterranea), showed pre-dispersal
reproductive success values lower than or equal to the mean value for
resprouters. Post-dispersal reproductive success was predicted in terms of
proportions of germinable seeds produced per ovule (as determined by
in vitro germination of isolated embryos). Data again
varied widely between taxa, averaging 23% conversion of ovules to seeds
with no clear relationship to regeneration mode. The mean number of germinable
seeds per culm ranged from 0.03 to 21 between species, with cases of
particularly low ovule output and/or low germinability in critically low
germinable seed numbers for a species. The regeneration potential of a subset
of species was assessed as mean annual production of germinable seed per
reproducing plant of a population. The data indicated low values (less than
eight seeds per adult) for all but three highly fecund species, suggesting
that germinable seed output in some species might be scarcely able to
compensate for natural senescence or catastrophic loss of parent populations
(e.g. after fire, disease, increased competition following eutrophication).
Uncertainty in Palaeoclimatic Reconstructions Based on Leaf Physiognomy
Authors: Jordan Gregory J.
Published: August 2004

There are several methods of predicting terrestrial palaeoclimates from the
size and shape of fossil leaves (foliar physiognomy). The assumptions and
sources of uncertainty of these methods are considered and used to determine
the true uncertainty. Their ability to predict mean annual temperature (MAT)
is poor. The approximate standard errors for samples of living vegetation in
North America are in the range of 1.7˚C to 2.5˚C, but the true
uncertainty for fossil samples is higher. Specimens with very different
physiognomy to typical specimens in the model have higher uncertainties.
Besides these uncertainties, the processes of fossilisation, the allocation of
specimens to taxa, and the effects of other factors on foliar physiognomy all
increase the uncertainty of the predictions. Overall uncertainties in the
predictions of MAT are equivalent to standard errors of about 3–5˚C
depending on the nature of the fossil site and flora. Other factors affect
foliar physiognomic predictions significantly because predicted MAT does not
change as rapidly with altitude as true MAT, and floras from different parts
of the world with similar temperatures give different temperature predictions.
Mean annual temperature and one precipitation parameter (probably mean annual
precipitation or the growing season precipitation) can be predicted more or
less independently, although the predictions of precipitation are weak.
Physiognomic signals for other climatic parameters are weak or apparently
non-existent, and previously published predictions of past equability are
primarily based on correlations with modern MAT, rather than physiognomy.
Isozyme Variation in Eucalyptus nitens and E. denticulata
Authors: Cook Ian O. , Ladiges Pauline Y.
Published: August 2004

Seed samples from 22 populations across the geographic range ofE. nitens (Deane & Maiden) Maiden s. str. andE. denticulata I.O. Cook & P.Y. Ladiges wereanalysed for isozyme variation and estimation of the genetic distance betweenthe two taxa. Analysis of 12 enzyme systems in 3 buffer systems revealed 12polymorphic and 5 monomorphic loci. The results confirm the distinctiveness ofE. nitens and E. denticulatapreviously reported for morphological characteristics. A single population ofthe related species E. quadrangulata Deane & Maidenwas distinct from, and more heterogeneous than, populations of the other two taxa. The results also show regional genetic variation withinE. nitens that correlates with observed differences inmorphology. Three races were identified: northern and central NSW; southern NSW and Mt Kay in eastern Victoria; Baw Baw Ranges and Central Highlands inVictoria. Geographically isolated populations, particularly from central andnorthern NSW, showed the least genetic variation. Variation was highest in anequivocal population from Mt Gregory, central Victoria, where the distributionof E. nitens overlaps with that ofE. denticulata.
A Multivariate Growth-form Analysis of Grassland and Forest Forbs in South-eastern Australia
Authors: Lunt Ian D.
Published: August 2004

The growth-form composition of grazed and unburnt, grassy forest remnants and
ungrazed, frequently burnt, anthropogenic native grasslands in Gippsland,
Victoria were compared, using a multivariate, clustering analysis of the
growth-form and life-form attributes of 53 forb species. Groups comprising (1)
annual forbs, (2) clambering, repent and decumbent perennials, and (3) rosette
perennials and rhizomic ground-cover forbs occurred in significantly more
forest than grassland quadrats. One group, mostly containing tall erect
geophytes with linear basal leaves, occurred in significantly more grassland
than forest quadrats. Grassland quadrats contained significantly more tall
forbs (> 20 cm) than forest quadrats, whilst forest quadrats contained
significantly more forbs of short to medium height (< 20 cm). There was a
significant, positive correlation between plant height and frequency of
occurrence in grassland quadrats (rs = 0.58,
P < 0.001), and a significant, although weak,
negative correlation in forest quadrats (rs =
-0.29, P < 0.05). Short forbs are likely to have been
depleted from grassland sites owing to competition from the dominant tussock
grass, Themeda triandra Forsskal. By contrast, ground
cover in forest sites is of relatively low stature, biomass and cover,
allowing short forbs to persist. The relative paucity of tall forbs from
forest remnants is suspected to be at least partly due to intensive stock
grazing in the past.
Preliminary Investigation of Genetic Variation within and between Cultivated and Natural Populations of Banksia coccinea and Banksia menziesii
Authors: Rieger M. A. , Sedgley M.
Published: August 2004

The randomly amplified polymorphic DNA (RAPD) technique followed by analysis
of molecular variance (AMOVA) was used to determine the level of variation
within and between commercial plantations of
Banksia coccinea R.Br. and
B. menziesii R.Br. in South Australia and natural
populations in Western Australia. For B. coccinea, the
majority of variation was within populations (66.1%), while between all
populations accounted for 20.8%. The variation between cultivated and
natural populations was 13.2%. There was close clustering between the
cultivated populations, which appeared to be most closely related to the
inland natural populations. In contrast, the variation between cultivated and
natural populations for B. menziesii was 0.4%
with the majority of the variation within populations (93.2%) and
6.4% between all populations. The cultivated and natural populations
formed a single cohesive cluster. These data indicate that the full range of
natural genetic diversity of B. menziesii appears to
occur in the cultivated plantations, but this was not the case for
B. coccinea.
Seed Production, Pollinator Attractants and Breeding System in Relation to Fire Response — Are There Reproductive Syndromes among Co-occurring Proteaceous Shrubs?
Authors: Lamont Byron B. , Olesen Jens M. , Briffa Peter J.
Published: August 2004

The reproductive biology of two species pairs was compared, one member of
which (Dryandra sessilis (Knight) Domin,
Hakea erinacea Meissner) is susceptible to severe stress
and disturbance by fire (nonsprouter) and stores few seeds in its crown, while
the other (D. lindleyana Meissner,
H. cristata R.Br.) is resilient (resprouter) and also
stores most of its seeds for some years. It was hypothesised that the
nonsprouter would have a high annual seed production associated with a suite
of attributes directed towards that end (forming a reproductive syndrome), and
that the resprouter would have the reverse properties. Over 30 attributes were
assessed, covering putative pollinators, pollinator attractants and rewards,
flower phenology, breeding system, and flower, fruit and seed production.
Dryandra sessilis produced far more seeds than
D. lindleyana, due to prolific flower production and a
high fruit : flower ratio (associated with an effective outcrossing breeding
system). Hakea erinacea produced significantly more
seeds than H. cristata, which was attributable to its
smaller fruits and exceptionally high fruit : flower ratio (associated with
highly effective selfing). The correlation of seed production and fruit :
flower ratio with susceptibility to fire was not supported by any consistent
pattern among the other reproductive attributes.
The Role of Callistemon Fruits and Infructescences in Protecting Seeds from Heat in Fires
Authors: Brown Claire L. , Whelan Robert J.
Published: August 2004

A number of Australian plant species tolerate fires because seeds are
protected in woody fruits and are released after fire, but there is little
information about the role of the fruit, or a collection of fruits, in
protecting seed from the heat of a fire. This study examined the effects of
various temperatures applied to infructescences of
Callistemon citrinus (Curtis) Skeels on seed
germination. The protective role of the dense collection of fruits in
maintaining seed viability was tested by experimentally ‘thinning’
infructescences before heating. Heating of infructescences significantly
increased the percentage of seeds germinating from less than 20% at
room temperature to over 35% at 200˚C, but caused a decline, with
further temperature increase to 800˚C. There was a slight but
statistically significant increase in the percentage germination of seeds from
thinned infructescences. Increased germination following exposure to high
temperature may be a way for a plant to synchronise germination after
high-intensity fire, while spreading it out if seeds are released in the
absence of fire or after a low-intensity fire.