bluuebunny/crossref_metadata_2025 huggingface dataset:
The association between high molecular weight glutenin subunit compositions and the bread-making quality of Chinese and Japanese hexaploid wheats
Authors: Nakamura H.
Published: September 2002

Variation in the electrophoretic banding patterns of high molecular weight
(HMW) glutenin subunits of 274 hexaploid wheat
(Triticum aestivum) varieties from China was examined by
sodium dodecyl sulfate polyacrylamide gel electrophoresis. Twenty-seven
different major glutenin HMW subunits were identified. Each variety contained
3–5 subunits and 29 different glutenin subunit patterns were segregated.
Seventeen alleles were identified based on comparison of subunit mobilities
with those previously found for hexaploid wheat. Chinese hexaploid wheats
exhibited particular allelic variation in glutenin HMW subunit composition and
this variation differed from that found in wheats from Japanese and other
countries. Average Glu-1 quality scores of 274 Chinese
wheat varieties in the present study have been shown to be higher than that of
Japanese wheats. Considerable genetic variation in the HMW glutenin subunit
compositions of the Chinese wheats was observed in the present study and
previously. Alleles from Chinese hexaploid wheat varieties have not been
extensively introduced into Japan and other countries. The present data may
indicate possible applications of Chinese germplasm in wheat breeding
programs. To improve the wheat quality, genetic variation should be attempted
through the introduction of genes of Chinese varieties into varieties in Japan
and other countries.
Isolation of a virulent bacteriophage from a Propionibacterium species in the sheep rumen
Authors: Cheong J. P. E. , Cheong J. P. E. , Brooker J. D. , Brooker J. D.
Published: September 2002

Propionibacterium is a facultative anaerobe associated
with the rumen epithelium, the presence of which may influence the anaerobic
environment through oxygen scavenging, as well as providing a source of
propionate. Factors such as bacteriophages that influence
Propionibacterium populations may therefore be important
regulators of rumen function. This study describes the isolation and
identification of a ruminal Propionibacterium
bacteriophage.
Sheep rumen fluid was screened for Propionibacterium
species and 3 isolates were identified and characterised. One isolate, PA1,
was used as an indicator strain to screen for the presence of
Propionibacterium-specific virulent bacteriophages. A
virulent bacteriophage, PB2, was isolated from clear plaques on a lawn of PA1
cells and was shown by transmission electron microscopy to be a
siphovirus-like particle comprising an icosahedral head 50 nm in diameter and
a tail 140 nm in length. The bacteriophage was visibly attached to and within
PA1 cells, and was shown to infect all 3 ruminal isolates of
Propionibacterium and 4 of 6 clinical isolates of
P. acnes. Restriction mapping of bacteriophage PB2
demonstrated a 30.8 kb genome.
Role of soil pH, Ca supply, and banded P fertilisers in modulating ammonia toxicity to wheat
Authors: Zhang Xike , Rengel Zdenko
Published: September 2002

Di-ammonium phosphate (DAP) and mono-ammonium phosphate (MAP) banded
close to seed may cause ammonia (NH 3 ) toxicity by
inhibiting seed germination and early seedling growth. A pH increase around
the fertiliser band and/or limited Ca supply may exaggerate ammonia
toxicity. In the current study, wheat growth and gradients of pH, electrical
conductivity (EC), ammonium (NH 4
+ ), and P concentration in soil were studied by
comparing banded DAP + urea or MAP + urea fertilisers in control or
gypsum- or CaCO 3 -treated Lancelin soil. After 21 days
of wheat growth, visual symptoms of ammonia toxicity appeared in the
gypsum-treated and control plants, but not in the CaCO 3
-treated plants. The symptoms were more severe in the MAP treatments than in
DAP treatments. An addition of CaCO 3 increased soil pH
CaCl2 from 5.1 to 7.3, and the ammonium concentration was lower than that in
the gypsum-treated and control soils. In the gypsum-treated and control soils,
pH increased by nearly 1 unit in the vicinity of the DAP or MAP band. In
contrast, soil pH decreased in the location of the DAP or MAP band in the CaCO
3 -treated soil. Banding of MAP or DAP in the
gypsum-treated soil caused an increase in soil EC. The good plant growth on
the soil amended with CaCO 3 might have been related to
the low ammonium concentration in the soil and the high concentration of Ca.
Gypsum and CaCO3 decreased the availability of P
supplied in the MAP or DAP band. It was concluded that increased pH and higher
Ca content in sandy soil may alleviate ammonia toxicity to wheat.
On the relation between weather variables and sorghum ergot infection
Authors: Wang Enli , Meinke Holger , Ryley Malcolm , Herde Damian , Henzell Bob
Published: September 2002

Sorghum ergot (Claviceps africana) has had a significant
impact on seed production and breeders’ nurseries in Australia since it
was first found in 1996. In this paper, 3 distinct key development stages of
sorghum that are related to ergot infection were identified: flag leaf stage,
pollen starch accumulation stage, and flowering period. Relationships between
weather variables during these 3 stages and ergot severity as well as pollen
viability were analysed using observed data from 2 field trials, a serial
planting trial and a genotype trial, conducted at Gatton, Queensland. The
duration of the flag leaf stage and of the flowering period was estimated from
thermal time. An infection factor was introduced and calculated based on
hourly temperature during the flowering period. This infection factor and the
mean relative humidity at 0900 hours during the flowering period were the main
factors influencing ergot infection. Mean daily minimum temperature during
flag leaf stage also had a significant effect on ergot severity, although no
significant relation was found between this mean daily minimum temperature and
pollen viability. A linear regression model using the above 3 factors
accounted for 94% of the environmentally caused variation in ergot
severity observed in the genotype trial.
Susceptibility of mango (Mangifera indica L.) to cold-induced photoinhibition and recovery at different temperatures
Authors: Sukhvibul N. , Whiley A. W. , Smith M. K. , Hetherington Suzan E.
Published: September 2002

Cold-induced photoinhibition of photosynthesis and recovery from
photoinhibition in mono- and poly-embryonic mango cultivars were investigated
under field and controlled temperature and light conditions. Photoinhibition,
measured as a decrease in the ratio of variable to maximum chlorophyll
fluorescence emission (Fv/Fm), occurred in trees growing in the field in
winter and early spring. Fv/Fm ratios of all cultivars began to decrease
from about 0.49 in May, reaching minimum values of about 0.33 in mid July, and
then gradually increased to around 0.68 and exceeded pre-winter values by
early November. A seasonal change of leaf chlorophyll content in all cultivars
followed a similar pattern to the changes in Fv/Fm ratios during winter.
Susceptibility to cold-induced photoinhibition and a reduction in leaf
chlorophyll content were greater in poly-embryonic cultivars than in
mono-embryonic cultivars. There was a positive linear relationship between the
minimum air temperature the night before the measurement and the leaf
Fv/Fm ratio (r2 =
0.62–0.70). In controlled environmental experiments, poly-embryonic
cultivars were also more susceptible to photoinhibition than mono-embryonic
cultivars. When held at 10˚C and irradiated with a photosynthetic photon
flux (PPF) of 450 µmol/m2.s, photoinhibition
in detached leaves increased linearly with time. The extent of the reduction
in Fv/Fm ratios induced by 6 h irradiation was 43% and 56%,
respectively, in mono- and poly-embryonic cultivars. Recovery from
photoinhibition in detached leaves was promoted by exposure to a PPF of 20
µmol/m2.s for 24 h at 20˚C. Negligible
recovery occurred in photoinhibited leaves maintained at 10˚C.
Effects of clenbuterol on growth in underfed cattle
Authors: Sillence M. N. , Matthews M. L. , Badran T. W. , Pegg G. G.
Published: September 2002

This study examined the effects of clenbuterol on the growth of young cattle
(160 kg) that were fed a restricted quantity of a low-quality hay to simulate
dry-season pasture conditions in the tropics. Twenty Brahman steers were used.
Ten control animals lost an average of 0.24 kg/day in the first 17 days,
then maintained their liveweight for the remaining 21 days of the experiment.
By contrast, 10 clenbuterol-treated animals lost 0.3 kg/day for the first
17 days of the experiment, then continued to lose weight at a steady rate of
0.15 kg/day. In control steers, plasma concentrations of urea-nitrogen
decreased over the course of the experiment, and this effect was accelerated
by clenbuterol treatment (P < 0.05). There were no
marked changes in plasma concentrations of glucose, potassium, or
Nt-methylhistidine in response to clenbuterol
treatment. Clenbuterol had no effect on β2
-adrenoceptor density in the longissimus muscle, but there was a marked
increase in β2-adrenoceptors in both groups of
cattle over time. Despite their loss of liveweight, the carcasses of
clenbuterol-treated cattle were not lighter than controls (74.3
v. 72 kg, respectively) and contained 10% more
protein (P < 0.05). This was reflected by a trend towards increased weight
of the biceps femoris muscle (9%; P < 0.1).
These findings are consistent with clenbuterol causing a drive to deposit
muscle protein at the expense of other tissues, even when dietary protein and
energy are limited.
The potential of two rough-seeded lupin species (Lupinus pilosus and L. atlanticus) as supplementary feed for sheep
Authors: Miao Z. H. , Fortune J. A. , Gallagher J.
Published: September 2002

The rough-seeded lupins are better adapted to alkaline soils than the
domesticated lupins currently in use in commercial agriculture in southern
Australia. Lupinus pilosus and
L. atlanticus are two species of rough-seeded lupins
that are undergoing domestication, and could be very valuable for sheep as a
supplementary feed. However, there is little information on the nutritive
value of these lupins. Two experiments were conducted to evaluate the
nutritive value of L. pilosus and
L. atlanticus, compared with
L. angustifolius, which is widely used as an animal feed
in Australia. The results showed that the rough-seeded lupins examined had
larger seeds, a greater proportion of seed coat in the whole seed, and a
higher fibre content in the seed coat than domesticated lupins. Nitrogen (N)
content in the kernel of the various lupin species was similar. The high fibre
content in seed coat did not appear to limit the digestion of the seeds by
sheep as demonstrated by the high potential degradability of seed dry matter
(DM) for all lupin species. There were no significant differences
betweenL. pilosus,L. atlanticus,
andL. angustifolius as a supplementary feed provided at
low levels in DM digestibility (DMD), apparent energy digestibility (AED), and
N-balance, suggesting that L. pilosus and
L. atlanticus could be used in place of
L. angustifolius.
AlsoL. atlanticus could be substituted for
L. angustifolius at high levels of supplementation as
there were no differences in DMD, AED, apparent N digestibility, and N-balance
when these species were fed to sheep as a supplement to barley straw.
Supplementation with lupin seed at 150 g/day significantly improved DM
intake by 195 g/day, DMD by 8.7, and AED by 11.4 percentage units.
However, a high level of lupin supplementation in a diet based on barley straw
did not increase DMD and AED of the diet.
Breeding lucerne for Australia's southern dryland cropping environments
Authors: Humphries A. W. , Auricht G. C.
Published: September 2002

Lucerne is a deep-rooted perennial forage legume with an important role in
preventing dryland salinity in southern Australian cropping regions. Annual
cereal production has created a water-use imbalance, which is placing the
industry under threat through rising saline watertables and resultant dryland
salinity. Lucerne is being incorporated into cropping systems to reduce
groundwater recharge and improve the sustainability of grain production.
Existing lucerne varieties have been developed for the animal industries,
primarily for the areas with high rainfall or irrigation. The new challenge is
to develop lucernes specifically for southern Australian cropping systems.
This paper provides a background literature review of the breeding challenges
that are anticipated in the development of these new types of lucerne. Lucerne
is intolerant of acidic soils, waterlogging, saline soils, and intensive
grazing. Other important attributes covered include the ability of the plant
to fix nitrogen with existing rhizobia and be resistant to diseases that
affect lucerne and other crops in the rotation. Finally, this paper addresses
some of the breeding strategies that will be used to screen lucerne germplasm
for tolerances to these soil conditions and diseases.
An adaptation analysis of Australian and CIMMYT/ICARDA wheat germplasm in Australian production environments
Authors: Sivapalan S. , O'Brien L. , Ortiz-Ferrara G. , Hollamby G. J. , Barclay I. , Martin P. J.
Published: September 2002

An adaptation analysis was conducted in an attempt to identify adapted
germplasm and potential indicator or probe varieties that could be used for
more efficient germplasm introduction and evaluation. A set of 39 advanced
wheat breeding lines and named varieties from Australian breeding programs and
10 from the CIMMYT/ICARDA programs were tested using 20 environments
across the Australian wheatbelt during a period of 3 years. AMMI analysis and
classification analysis were performed on grain yield data. Five groups of
genotypes with similar patterns in performance within each group were
identified, mostly reflecting their origin and pedigree. Most of the genotypes
from the CIMMYT/ICARDA programs clustered together as did most of those
from the University of Adelaide and Agriculture Western Australia breeding
programs. Four groups of environments with similar trends in discriminating
genotypes within each group were identified. There was a clear discrimination
between subtropical and Mediterranean environments. Subtropical environments
with supplementary irrigation showed similar patterns to Mediterranean
environments. Basic differences in adaptation and phenotypic stability among
genotypes from the CIMMYT/ICARDA programs in relation to genotypes from
several breeding programs in Australia were identified. CIMMYT/ICARDA
genotypes such as Attila, Nesser, Pfau/Seri//Bow, Genaro 81, and
Maya/Nac performed well, especially in subtropical environments. The
Australian varieties Hartog and Vulcan showed similar performance and could be
used as indicator varieties for assessing introduced germplasm for subtropical
regions. University of Adelaide developed genotypes Trident, Spear, Excalibur,
and RAC 655, along with the Agriculture Western Australia genotypes Tammin and
82Y:1186, showed wide adaptation to all environments and could be used as
indicator varieties for wide adaptation. Similarly, genotypes such as BT
Schomburgk, Pelsart, and Sunvale could be used as indicator varieties for the
other genotype groups. The results of this study can serve as a basis for
identification and introduction of germplasm from the CIMMYT/ICARDA
programs for various Australian production environments. It has also provided
an understanding of the pattern of discrimination of genotypes across each
region of the Australian wheatbelt.
Science with NIFS, Australia's First Gemini Instrument
Authors: McGregor Peter J. , Dopita Michael , Wood Peter , Burton Michael G.
Published: September 2002

The Near-infrared Integral Field Spectrograph (NIFS) will beAustralia’s first Gemini instrument. NIFS is a near-infrared, imaging spectrograph that will be used with the ALTAIR facility adaptive optics system on Gemini North to perform near-diffraction-limited imaging spectroscopy over a 3·0″ × 3·0″ field of view with 0·1″ wide slitlets and a spectral resolving power of ˜5300. NIFS will operate in the wavelength range from 0·94–2·50 µm where ALTAIR delivers its greatest gains. Its primary purpose is to study moderate-surface-brightness structures around discrete objects that are revealed at high spatial resolution by ALTAIR. NIFS will address a wide range of science from studies of Galactic star formation and the Galactic centre to the nature of disk galaxies at z ˜ 1. Studies of the demographics of massive black holes in galactic nuclei and studies of the excitation conditions in the inner narrow-line regions of Seyfert galaxies have been identified as two core NIFS programs. These and other science drivers for NIFS are discussed.
Atmospheric Modelling of the Companion Star in GRO J1655-40
Authors: Buxton Michelle , Vennes Stephane
Published: September 2002

We have measured the rotational velocity of the companion star to be Ʊrot sin i= 80 ± 10 km s ˗1 (1σ) by fitting Kurucz model spectra to our observed spectrum of the black-hole candidate GRO J1655–40. From this we have calculated q = 0·31 ± 0·08, the mass of the compact object to be M1 = 7·91 ± 3·79 Mô (1σ) and for the companion starM2 = 2·76 ± 1·79 Mô (1σ), which is consistent with previous studies. We have also determined Teff = 6500 ± 50 K and [Fe/H] = −0·15 +0·15-0·10.
What do Quasars Look Like?
Authors: Francis Paul J.
Published: September 2002

Microlensing observations may give us the first nano-arcsecond scale information about the structure of quasars. I review what is currently known about quasars on these scales, highlighting the principal uncertainties. I cover both the continuum emission and the broad line region. I conclude that little is firmly known about the structure of quasars.
Cosmological Parameter Survey Using the Gravitational Lensing Method
Authors: Premadi Premana W. , Martel Hugo , Matzner Richard , Futamase Toshifumi
Published: September 2002

Using a multiple-lens plane algorithm, we study light propagation in inhomogeneous universes for 43 different COBE-normalized Cold Dark Matter models, with various values of the density parameter Ω0, cosmological constant λ0, Hubble constant H0, and rms density fluctuation σ8.We performed a total of 3798 experiments, each experiment consisting of propagating a square beam of angular size 21.9″ 21.9″ composed of 116 281 light rays from the observer up to redshift z = 3. These experiments provide statistics of the magnification, shear, and multiple imaging of distant sources. The results of these experiments might be compared with observations, and eventually help constrain the possible values of the cosmological parameters. Additionally, they provide insight into the gravitational lensing process and its complex relationship with the various cosmological parameters.
Radio Images of the Globular Cluster 47 Tucanae
Authors: McConnell D. , Deacon R. , Ables J. G.
Published: September 2002

We present deep ATCA radio images of the globular cluster 47 Tucanae made at 1.4 and 1.7 GHz and identify 9 compact sources in the cluster core with 11 pulsars. At present there are several pulsars for which pulse timing analyses have not yet yielded precise positions. We examine other sources in the image, and on the basis of their spectral index find two that would possibly correspond to the pulsars with undetermined positions.
Fifty Years of Research on Stellar Atmospheres
Authors: Mihalas Dimitri
Published: September 2002

I would like to begin by saying what a pleasure it is for me to be here. For my entire adult life I have wanted to come to Australia. Actually, I have been invited to visit here twice before, but each time I was thwarted by circumstances beyond my control. But this time I was determined to (a) prove that the third time is indeed the charm, and (b) pay homage to Walter Stibbs, who in my mind is the epitome of a scholar and a gentleman. I have known Walter as colleague, teacher, and friend, not to mention as an inspiration, both professional and personal. So I am here today to try to give some sense of progress in the study of stellar atmospheres, a field that Walter has graced with his virtuosic touch. I will follow an unabashedly personal path, describing the development as I experienced it. I will focus almost entirely on early-type stars, where we may reasonably expect the atmospheric layers to be homogeneous, and in radiative equilibrium. Only at the end will I mention our nearest stellar neighbor, the Sun, which, because we can study it in so much detail, offers counterexamples to almost all of the the theory that works so well for early-type stars. I offer apologies in advance to anyone this approach may offend.
The Mechanisms for the Generation of Pulsar Radio and High-energy Emission
Authors: Machabeli George Z.
Published: September 2002

The recent theory of propagation and generation of waves in a pulsar’s magnetosphere is discussed. In particular we consider models of pulsar radio emission due to plasma instabilities. Wave–particle interactions can lead to quasilinear diffusion increasing a particle’s pitch-angle. The recent model of γ-ray emission from synchrotron radiation as a result of quasilinear diffusion is discussed.
Intraday Variability in Northern Hemisphere Radio Sources
Authors: Krichbaum T. P. , Kraus A. , Fuhrmann L. , Cimò G. , Witzel A.
Published: September 2002

We summarise results from flux density monitoring campaigns performed with the 100 m radio telescope at Effelsberg and the VLA during the past 15 yrs. We briefly discuss some of the statistical properties from now more than 40 high declination sources (δ ≥ 30°), which show intraday variability (IDV). In general, IDV is more pronounced for sources with flat radio spectra and compact VLBI structures. For 0917+62, we present new VLBI images which suggest that the variability pattern is modified by the occurrence of new jet components. For 0716+71, we show the first detection of IDV at millimetre wavelengths (32 GHz). For the physical interpretation of the IDV phenomenon, a complex source and frequency dependent superposition of interstellar scintillation and source intrinsic variability should be considered.
Quasar Astrophysics with the Space Interferometry Mission
Authors: Unwin S. C. , Wehrle A. E. , Jones D. L. , Meier D. L. , Piner B. G.
Published: September 2002

Precision optical astrometry of quasars and active galaxies can provide important insight into the spatial distribution and variability of emission in compact nuclei. SIM — the Space Interferometry Mission — will be the first optical interferometer capable of precision astrometry on quasars. Although it is not expected to resolve the emission, it will be very sensitive to astrometric shifts, for objects as faint as R magnitude 20. In its wide-angle mode, SIM will yield 4 microarcsecond absolute positions, and proper motions to about 2 microarcsecond/yr. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. SIM should be able to answer the following questions. Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? Do the relative positions of the radio core and optical photocentre of quasars used for the reference frame tie change on the timescales of their photometric variability? Do the cores of galaxies harbour binary supermassive black holes remaining from galaxy mergers? In this paper we briefly describe the operation of SIM and the quasar measurements it will make. We estimate the size of the astrometric signatures which may be expected, and we discuss prospects for using astrometry as a fundamental tool for understanding quasar nuclei.
The Chemical Yields Produced by Zero Metal Massive Stars
Authors: Limongi Marco , Chieffi Alessandro
Published: September 2002

In this review we compare the three existing sets of theoretical yields of zero metal massive stars available in the literature. We also show how each of these three different sets of yields fits the element abundance ratios observed in the extremely metal poor star CD 38°245. We find that, at present, no theoretical set of yields of zero metal massive stars is able to satisfactorily reproduce the elemental ratios [X/Fe] of this star.
Polarisation Characteristics and Variability of the Compact Radio Structures of AGN
Authors: Gabuzda Denise C.
Published: September 2002

Very long baseline interferometry (VLBI) polarisation measurements provide information about the parsec-scale magnetic field structures in compact active galactic nuclei (AGN), as well as the densities of relativistic and thermal electrons in the radio emitting regions. This paper reviews the role of polarisation VLBI in studies of AGN variability on both relatively long and short (intraday) timescales.
Variability Constraints on Blazar Magnetic Fields
Authors: Baring Matthew G.
Published: September 2002

Synchrotron self-Compton (SSC), external Compton, and hadronic models of blazar emission all invoke particle acceleration at relativistic shocks as the dissipation mechanism seeding their non-thermal X-ray and gamma-ray emission. Studies of diffusive acceleration at such relativistic shocks are more sparse than those pertaining to their non-relativistic counterparts. This paper presents acceleration time results from the theory of relativistic shock acceleration that are pertinent to AGN observations. This temporal information interfaces critically with the observed rapid variability of blazars. Very recent theoretical results are presented, where it is determined that acceleration times can never become arbitrarily short in relativistic shocks, but are dominated by diffusion in the downstream region and couple to the particle's gyroperiod. This fundamental bound links to the variability timescale to generate a firm lower bound to the environmental magnetic field of blazars such as Mrk 421. Consistency of such a bound with SSC spectral models and flare decay times is discussed.
The Role of Interstellar Scintillation in Intraday Variations at Centimetre Wavelengths
Authors: Rickett Barney
Published: September 2002

The evidence in support of interstellar scintillation as the predominant cause of intraday variations at centimetre wavelengths is reviewed. A new evaluation of the highest brightness temperature implied for AGN is found to be consistent with the Doppler factors in typical jet models, but requires the scattering to occur within about 30 pc of the Earth.
Biogeography, evolution and palaeoecology of Nothofagus (Nothofagaceae): the contribution of the fossil record
Authors: Hill Robert S.
Published: September 2002

Nothofagus is an ancient genus with a distribution that
has attracted considerable interest from biogeographers. The lack of consensus
among biogeographical reconstructions is probably due to emphasis being placed
solely or largely on the living species. Nothofagus had
a much greater distribution and diversity in the past than it has now; this
makes it difficult to reconstruct its history from living species’
interrelationships and distribution. Unfortunately, the fossil record is
difficult to interpret, and contains many records that convey no useful
information or possibly even misinformation. However, the best fossil records
of Nothofagus provide past distributions that must be
explained by biogeographical hypotheses and place minimum times on
evolutionary events within the genus. They also provide information on past
ecological associations that are best explained by invoking extinct climates.
An in situ, Late Pleistocene Melaleuca fossil forest at Coal Head, western Tasmania, Australia
Authors: Rowell Marcus V. , Jordan Gregory J. , Barnes Richard W.
Published: September 2002

Stumps of more than 365 tree and shrubs are preserved in growth position on
the shores of Macquarie Harbour, western Tasmania. The most likely age is Last
Interglacial or early Last Glacial. The in situ forest
was almost monospecific Melaleuca (probably
M. ericifolia) swamp forest, with one very large
Nothofagus cunninghamii, occasional
Acacia, interspersed with tussocks of
Gahnia grandis. The Melaleuca
stumps showed a more or less continuous size distribution, and tree rings
suggested an age range from a few years to approximately 100 years or more.
Similar vegetation occurs now in parts of lowland western and northern
Tasmania, particularly in poorly drained, undisturbed, coastal sites. The
composition of the in situ fossil forest differed
markedly from previously recorded macrofossil and fossil palynomorph floras,
suggesting that both of the latter included significant allochthonous
components.
Dispersal and monoecy in Atriplex cinerea (Chenopodiaceae)
Authors: Heyligers Petrus C.
Published: September 2002

Atriplex cinerea Poir., indigenous to southern coasts of
Australia, has occasionally been found along the shores of Cook Strait, New
Zealand. Buoyancy tests have shown that most fruits stay afloat less than 5
weeks. Published data from drift bottle and drift card experiments indicate
that it takes at least 300 days for a floating object to cross the Tasman Sea.
It is therefore unlikely that A. cinerea fruits have
arrived in New Zealand unaided. Transport on rafts of flotsam or by migrating
birds are mooted possibilities. Atriplex cinerea is
dioecious or monoecious. Monoecious plants are self-compatible and thus one
individual could start a new population. Inspection of herbarium specimens and
plants in the field showed that there is at least a one in five and possibly a
better than a one in three chance that a plant is monoecious.
Atriplex cinerea is hexaploid. Some plants of
A. canescens (Pursh) Nutt., a polyploid species from
North America, change their gender from year to year owing to the sexually
labile nature of tetraploid and hexaploid genotypes. Inherent genetic factors
as well as seasonal weather conditions have an influence on these changes. It
would be interesting to find out whether this also happens in
A. cinerea. As A. cinerea is used
for saltland rehabilitation, a study of its variability could benefit the
selection of better-adapted strains.
Patterns of morphological variation and allelic distribution across a zone of overlap between two subspecies of Geleznowia verrucosa (Rutaceae)
Authors: Broadhurst Linda M. , Coates David J. , Tan Beng H.
Published: September 2002

Patterns of morphological and allelic variation were examined between the two
subspecies of Geleznowia verrucosa Turcz. (Rutaceae) and
putative hybrids across a rare zone of overlap between the two taxa.
Morphometric analyses with 17 quantitative or derived characters
differentiated the two subspecies. Individuals within the overlap zone, which
were morphologically difficult to characterise, were variously placed
indicating their probable mixed parentage. Allelic patterns in 16 allozyme
loci were also examined for polymorphism and patterns of distribution. Eight
loci were either monomorphic or exhibited low levels of polymorphism. The
remaining eight loci and in particular the five aspartate aminotransferase
(Aat) loci, strongly indicate asymmetric gene flow and
introgression from subsp. formosa ms to subsp.
verrucosa ms. In addition, subsp.
verrucosa ms exhibited alleles that were unique to this
population.
Conservation genetics and ecology of the endangered rainforest shrub, Triunia robusta, from the Sunshine Coast, Australia
Authors: Shapcott Alison
Published: September 2002

Triunia robusta, which until recently was thought to be
extinct, is now classified nationally as endangered. It is an understorey
species restricted to the subcoastal rainforests in a small region of the
Sunshine Coast, Queensland. The project involved sampling the genetic
variation and measuring the population size and size distribution of
T. robusta and its geographically closest congener
T. youngiana, which occurs further south and has a wider
geographic distribution. A total of 877 T. robusta
plants were recorded across the 11 populations, approximately half
(56.8%) of these were juveniles less than 1 m tall, whereas in
T. youngiana only about 36.4% of a population was
composed of juveniles. Genetic diversity was similar but significantly higher
for T. robusta than T. youngiana
if the very small T. robusta populations (2 or 3 plants)
were excluded from analysis (P < 0.05). The mean
percentage of polymorphic loci among populations was high for both species.
Triunia robusta is not, on average, more inbred than the more common
T. youngiana. There was more differentiation between the
T. robusta populations, which were in close proximity,
than between the more geographically separated
T. youngiana populations. Thus, there is evidence of
more gene flow between populations of T. youngiana than
between those of T. robusta. However, there was no
geographic relationship between genetic similarity and geographic proximity in
T. robusta
Grazed, burnt and cleared: how ecologists have studied century-scale vegetation changes in Australia
Authors: Lunt Ian D.
Published: September 2002

Ecological studies of century-scale vegetation changes in Australia were quantitatively reviewed by assessing relevant papers according to a range of methodological and environmental attributes. In general, century-scale vegetation dynamics are rarely studied by Australian ecologists. Most studies of century-scale changes are short-term studies with one sampling period, and few long-term experimental studies exist. Century-scale changes are well documented in open forests, grassy woodlands, tussock grasslands and rainforests, but little information is available from lowland heathlands, herblands or hummock grasslands. Tall open forests and rainforests have received the most comprehensive attention. Five major genres of research were recognised from a multivariate analysis of methodological attributes: (1) single-species tree-ring and fire-scar studies; (2) forest dynamics and age-structure studies; (3) floristic degradation studies (usually caused by stock grazing); (4) archival benchmarking studies; and (5) palynological research. These genres tend to focus on different ecosystems and ecosystem attributes, giving incomplete pictures of vegetation changes even in some well-studied ecosystems. In all genres other than forest dynamics studies, century-scale changes are commonly described by comparing present conditions with a pre-European reference point, and few studies have documented successive vegetation changes within the period of European occupation. Considerable opportunity exists to document long-term ecosystem responses to successive disturbances resulting from European disturbance regimes.
Root biomass and root fractal analyses of an open Eucalyptus forest in a savanna of north Australia
Authors: Eamus D. , Chen X. , Kelley G. , Hutley L. B.
Published: September 2002

Below-ground biomass of a Eucalyptus savanna forest was
estimated following trenching to depths of 2 m around 16 mature trees in a
tropical savanna of north Australia. Correlations among below-ground and
various components of above-ground biomass were also investigated. In
addition, root morphology was investigated by fractal analyses and a
determination of an index of shallow-rootedness was undertaken. Total root
biomass was 38.4 t ha–1, including 1 t
ha–1 of fine roots. About 77–90% of
total root biomass was found in the upper 0.5 m of soil. While fine-root
biomass density was approximately constant (0.1 kg
m–3) in the top soil, irrespective of distance
from a tree stem, coarse-root biomass showed large variation with distance
from the tree stem. Significant positive correlations among total root
biomass, total above-ground biomass, diameter at breast height, leaf biomass
and leaf area were obtained. It is likely that total root biomass can be
reasonably accurately estimated from aboveground biomass and fine-root biomass
from tree leaf area. We present equations that allow the prediction of
belowground biomass from above-ground measures of tree size.
Root morphology of two evergreen and two deciduous species was compared by the
use of three parameters. These were the fractal dimension
(d), which describes root system complexity; a
proportionality factor (α), which is the ratio of the cross-sectional
area before and after branching; and two indices of shallow-rootedness (ISR).
Roots were found to be amenable to fractal analyses. The proportionality
factor was independent of root diameter (Dr) at any
branching level in all tree species examined, indicating that branching
patterns were similar across all root sizes. The fractal dimension
(d) ranged from 1.15 to 1.36, indicating a relatively
simple root structure. Mean d was significantly
different between E. tetrodonta (evergreen) and
T. ferdinandiana (deciduous); however, no significant
differences were found among other pairs of species.
Terminalia ferdinandiana had the highest ISR, while
Planchonia careya (deciduous) had the lowest. In
addition, differences in ISR between P. careya and the
other three species were significant, but not significant among
E. miniata, E. tetrodonta and
T. ferdinandiana. There were clear relationships among
above-ground tree stem diameter at breast height, stem base diameter, and
horizontal and vertical proximal root diameter. By the use of mean values of
and stem diameter, we estimated the total crosssectional area of root and root
diameter-class distribution for each species studied.
Post-fire response of shrubs in the tablelands of eastern Australia: do existing models explain habitat differences?
Authors: Clarke Peter J. , Knox Kirsten J. E.
Published: September 2002

Fire is an important ecological factor that influences the distribution and
abundance of plant populations of shrub species in fire-prone habitats.
Comprehensive information about the fire-response syndromes and post-fire
recruitment of seedlings in tableland habitats of eastern Australia is poorly
known. In particular, data on shrubs occurring in grassy habitats are lacking
for temperate regions of Australia. The post-fire response and recruitment
patterns of shrub taxa were recorded from research burns and wildfires on the
New England Tablelands over 4 years in the following four habitats: grassy
woodlands and open forests, shrubby open forests, wet heaths and rocky
outcrops. The ratio of obligate seeder to resprouter species differed among
habitats, with the highest ratio occurring on rocky outcrops (90 : 10) and the
lowest in grassy forests (19 : 81). Post-fire recruitment of seedlings was
also highest on rocky outcrops whereas seedlings were rarely observed in the
wet heaths and grassy forests. The following six models that explain these
patterns were reviewed: fire and grazing frequency, soil nutrients and
texture, habitat openness and environmental variability. No one model could
uniformly explain differences in fire response across all habitats but a
combination of disturbance-frequency and regeneration-niche models may provide
a mechanism for the patterns observed. Field and laboratory experiments are
needed to examine allocation to persistence (resprouting) and reproduction in
species with different fire-response syndromes. These experiments also need to
examine both disturbance-frequency and regeneration-niche factors in
manipulative experiments.
Symptom development on two wild, perennial grasses infected by Peronosclerospora species (Family Peronosporaceae: the downy-mildew fungi)
Authors: Ryley Malcolm J.
Published: September 2002

The reproductive structures of the downy-mildew fungi,
Peronosclerospora nobleiand
Peronosclerospora eriochloae, develop only on chlorotic
leaves of tall, vegetative tillers of the perennial grasses
Sorghum leiocladum (wild sorghum) and
Eriochloa pseudoacrotricha (early spring grass),
respectively. They are never found on the leaves of flowering tillers, even
when tillers of both types grow from the same tussock. The development of
symptoms on infected tillers of both hosts and the morphological and
anatomical changes to host tissues on infected tillers are detailed.
Geographic variation in seedling morphology of Chukrasia species
Authors: Kalinganire A. , Pinyopusarerk K. , Williams E. R.
Published: September 2002

Seed collected from 23 native provenances of Chukrasia A.Juss. and one Australian land race was used to study geographic variation in seedling morphology under temperature-controlled glasshouse conditions. Twenty-four variates were measured for each seedling and the resultant data subjected to univariate and multivariate analyses. The multivariate analyses effectively separated the Chukrasia genus into three different groups or eco-geographical clusters. The most important characteristics that separated the groups were bark structure, leaf type and midrib colour. The first group, provenances from China, Laos, Malaysia, Vietnam and the Australian land race, is characterised by smooth bark, pinnate or intermediate leaves and reddish-green to greenish-red midrib. The second group, provenances from Myanmar and Thailand, is characterised by rough bark, mainly bipinnate leaves and green midrib. The third group, provenances from Sri Lanka, is characterised by rough bark, bipinnate leaves and red midrib. The study clearly shows Chukrasia to be a polymorphic species comprising at least three ecotypes or possibly three ecospecies. A study of allozyme variation may better reveal the systematics within the genus.
Breeding system, reproductive efficiency and weed potential of A. baileyana
Authors: Morgan Anne , Carthew Susan M. , Sedgley Margaret
Published: September 2002

Acacia baileyana F.Muell. is a native environmental weed which has invaded bush areas of south-eastern Australia from ornamental plantings. There are two main colour forms, the typical green-leaf form and the variety `purpurea', which has purple new growth. Only the green form appears to have invaded natural bush. The weed potential of A. baileyana was investigated in terms of its breeding system and seed production. It was found that the purple form is as reproductively efficient as the green form. Both forms were outcrossing, highly self-incompatible, grew very rapidly and flowered by two years of age. For open, natural pollination, final pod set was low-less than 0.41%. However, seed production was high due to the high number of flowers present. Maximum flower production for a 2-year-old plant was over 300 000, resulting in more than 8000 seeds. Precocity and high flower numbers appear to be the reasons for the weed status of A. baileyana. Given the similarity in reproductive efficiency between both forms, it is postulated that the absence of the purple form as a weed could be due to it being a relatively new horticultural variety, or to the purple colour being a recessive trait.
Geographic distribution of C3 and C4 grasses recorded from stable carbon isotope values of bone collagen of South Australian herbivores
Authors: Pate F. Donald , Noble Andrew H.
Published: September 2002

Cortical bone samples were collected from marsupial and eutherian herbivores
at five field sites along a 1275-km south–north transect from temperate
coastal to arid interior South Australia in order to address variability in
stable carbon isotope composition. Collection sites were located along the
eastern border of the state. Mean annual rainfall along the transect ranges
from 700–800 mm at coastal Mount Gambier to 150–175 mm at Cordillo
Downs in the north-east corner of the state. Bone collagen carbon isotope
values become more positive towards the arid north in relation to increasing
quantities of C4 grasses. Thus, stable carbon isotope
analysis of bone specimens provides a method to address dietary selection and
dietary variability in Australian herbivores. In addition, isotopic analyses
of archaeological and palaeontological bones and teeth can be used to address
changes in Quaternary climate and vegetation distributions in Australia.
Pollinator behaviour, mate choice and the realised mating systems of Grevillea mucronulata and Grevillea sphacelata
Authors: Richardson Matthew B. G. , Ayre David J. , Whelan Robert J.
Published: September 2002

Successful long-term conservation and management of populations of plants
requires successful management of the suite of factors that determine their
‘realised’ mating systems. Within the genus
Grevillea, mating systems are potentially complex. They
may vary among species and among populations within a species, reflecting
variation in pollinator behaviour and diversity (‘potential’
mating systems) and in breeding system (the ‘preferred’ mating
system). We used a combination of pollinator observations, pollination
experiments and electrophoretic analysis of seed from open pollinations, to
examine variation in potential and preferred mating systems in two populations
of each of two ‘spider-flowered’ Grevillea
species: G. mucronulata (visited by honeyeaters and
honeybees, although only birds effected pollen removal and transfer) and
G. sphacelata (visited only by honeybees, which made
frequent contact with pollen and stigmas). Almost all observed bird and insect
foraging bouts on either species involved movements among inflorescences
within plants or among inflorescences on closely neighbouring plants. On the
basis of these data, the mating system was predicted to involve a high level
of selfing or inbreeding. However, the pollination experiment revealed that
both species were highly self-incompatible and showed a clear preference for
outcross pollen in mate-choice experiments. For both species, fruit set
through autogamy was lower than 0.7% and fruit set from
self-pollinations was always significantly lower than for outcross
pollinations (0–11% cf. 25–33% for
G. mucronulata and 0% cf. 4.2–8.8%
for G. sphacelata). Allozyme studies revealed that
genotypes in open-pollinated seeds on 20 G. mucronulata
and 20 G. sphacelata plants were surprisingly uniform,
best explained by outcrossed matings between close neighbours. We found little
between-population variation in any aspect of the mating system for either
species. These studies reveal that the preferred mating system of the plant
and the pattern of pollinator behaviour interact to determine the mating
system in a population, emphasising the need for a multifaceted investigation
of mating systems, especially in predicting the fates of populations that have
pollination systems altered by disturbance, small size, isolation and
introduced species such as the honeybee.
Genetics and the conservation and use of Australian wild relatives of crops
Authors: Brown A. H. D. , Brubaker C. L.
Published: September 2002

Genetical research stands to make crucial contributions to the
in situ conservation of wild Australian relatives of
crop plants, management of their ex situ germplasm
collections, and their use in crop improvement. For instance, population
genetic theory is basic in formulating collecting strategies. Results from the
neutral allele model indicate that allelic richness in samples from
equilibrium populations is, although directly proportional to the population
size, proportional to the logarithm of the sample size. Such trends underline
the importance of dividing the sampling effort among many populations. Our
empirical genetical studies have been in the Australian wild relatives of
soybean and cotton. These species not only contain significant genetic
resources for improving their related crops, but also may be at risk from
unwanted hybridisation. In perennial Glycine species,
previous cytological and genetic research detected major races within the
G. tabacina polyploid complex. A maternal phylogeny on
the basis of chloroplast restriction-site variation defined plastome lineages
and clarified the evolution of the polyploid complexes. Ongoing research with
nuclear sequences focuses on the relationship between chloroplast and nuclear
phylogenies and morphology. In Gossypium, estimates of
interspecific hybrid fertility and outcrossing rates in natural populations
near current cotton crops point to negligible risk of transgene escape from
genetically engineered commercial cotton cultivars.