bluuebunny/crossref_metadata_2025 huggingface dataset:
Pasture environments in Australia where reactive phosphate rock will be an effective phosphate fertiliser
Authors: Sale P. W. G. , Brown A. , Maclaren G. , Derbyshire P. K. , Veitch S. M.
Published: August 2004

Summary. Maps are constructed using Geographic
Information Systems (GIS) computer technology to identify privately held land
in the high rainfall zones of temperate and tropical Australia where highly
reactive phosphate rocks (RPRs) are likely to be effective phosphorus (P)
fertilisers for permanent pasture. Australia-wide RPR suitability maps were
based on annual rainfall, soil pH and the P sorption capacity of the soil. The
digitised soil map from the Atlas of Australian Soils and the soil profile
acidity map derived from the Atlas, were used to identify land areas with
suitable soil properties. The coarse scale of the Atlas, which has only the 1
dominant soil for each 100 ha minimum landscape unit, limits the precision in
identifying specific land types. Reactive phosphate rock suitability maps for
pasture land in Victoria were also developed using smaller land units and
state-wide digitised soil maps for surface pH and surface texture. The GIS
maps indicated that there are about 26.5 × 106 ha
of land in the high rainfall pastoral zone of Australia that have sufficient
annual rainfall and appropriate soil properties for RPR to become effective by
the 4th year after changing from annual water-soluble P fertiliser to RPR
fertiliser applications. Additional land with a lower rainfall might also be
suitable if the soil surface is not excessively sandy. The area of high
rainfall pasture land where RPR is likely to be as effective as water-soluble
P fertiliser in the first year of application is around 3 ×
106 ha. The major portion of this land is in North
Queensland, with smaller areas in southern Victoria, in far north-west
Tasmania and in the far south-west of Western Australia. More detailed GIS
maps for Victoria indicate that RPRs would become as effective as
water-soluble P fertiliser by the 4th year on more than 70% of private
land where annual rainfall exceeds 700 mm.
Effect of soil and foliar applications of zinc on cadmium concentration in wheat grain
Authors: Oliver D. P. , Wilhelm N. S. , Tiller K. G. , McFarlane J. D. , Cozens G. D.
Published: August 2004

Summary. The effectiveness of foliar applications of
zinc sulfate to decrease cadmium (Cd) concentration in wheat grain was
assessed at 3 field sites in South Australia—Tumby Bay, Cummins and
Keppoch. Foliar zinc (Zn) treatments were found to significantly
(P<0.001) decrease Cd concentrations in grain at only
1 site, Tumby Bay. At this site the highest foliar Zn treatment (0.67 kg
Zn/ha), which consisted of 2 applications of 0.33 kg Zn/ha applied
early and late, decreased the mean Cd concentration in grain from 0.025
mg/kg for the nil treatment to 0.017 mg/kg. Timing of application of
foliar Zn had no significant effect on Cd concentration in wheat grain.
The effect of soil applications of zinc sulfate on grain Cd concentration was
assessed at Tumby Bay only. There was no significant difference in grain Cd
concentration between the soil Zn treatments.
The results from this study suggested that the current recommended rates of
foliar applications of Zn to ameliorate Zn deficiency are not high enough to
decrease Cd concentration in wheat grain. This is most likely due to the
recommended foliar rate of 0.33 kg Zn/ha not providing excess Zn to the
plant such that there is enough Zn to be translocated to the root, which is
the site of Cd uptake by the plant. The results suggest that the benefits of
foliar Zn to minimise Cd concentration in grain are variable or that the rates
used to correct Zn deficiency under field conditions are too low to decrease
Cd uptake. Further work is required to distinguish between the 2
possibilities.
A long-term study of superphosphate and stocking rate on sheep production and plant and soil characteristics in central west New South Wales
Authors: Davies H. Lloyd , McFarlane J. D. , Oliveira O. L. P. de , King G. W. , James J. W.
Published: August 2004

Summary. The effect of 4 rates of superphosphate
application (250 kg/ha. year, 125 kg/ha. year, 125 kg/ha every 2
years or 125 kg/ha every 4 years) and a low and high stocking rate (3.6
and 5.4 ewes/ha, 1980–86; and 4.0 and 7.0 ewes/ha,
1986–89) on sheep liveweight, fleece weight, lamb weaning weight,
pasture production and botanical composition, soil pH, soil phosphorus,
manganese and aluminium concentrations were measured on a
Phalaris aquatica–subterranean clover pasture at
Stuart Town, New South Wales.
Only when 250 kg/ha of superphosphate had been applied annually was there
a higher level of soil phosphorus than with the other 3 systems. None of the
treatments affected soil pH, soil manganese or aluminium. There were large
year effects and individual plot effects on pasture and sheep production but
neither the superphosphate rates nor stocking rate significantly affected
pasture or animal production.
It was concluded that over a 9-year period the application of 125 kg/ha in
alternate years can maintain adequate soil phosphorus levels, and satisfactory
pasture and animal production on the central tablelands of New South Wales.
A modified split plug for oesophageal fistulated cattle
Authors: Robertson B. M. , Heuvel W. van den
Published: August 2004

Summary. A modified oesophageal fistula plug made from
polyethylene and polyvinylchloride pipe for use in cattle is described. The
incorporation of a locking collar with a curvature similar to the area around
the fistula combined with the use of a flexible joint filler results in almost
no fluid loss from the fistula. These modifications of a split plug design
ensure almost complete fluid retention within the oesophagus, a feature that
is essential for the accurate estimation of total saliva production in water
balance studies with cattle.
Trapping sheep blowflies with lures based on bacterial cultures
Authors: Morris M. C. , Morrison L. , Joyce M. A. , Rabel B.
Published: August 2004

Summary. Baits of
Proteus mirabilis cultured in a commercial medium or in
a gut mucus mixture were tested in New Zealand sheep pasture for their ability
to trap sheep strike flies. Liver–sodium sulfide baits were used for
comparison. At the start of the flystrike season, medium cultures were as
effective as liver–sodium sulfide baits in trapping flies. As the season
progressed, the liver–sodium sulfide mixture trapped a significantly
higher number of Lucilia cuprina and
Calliphora stygia than medium cultures, though they
trapped significantly fewer Chrysomya rufifacies.
In one case the medium culture trapped a significantly higher proportion of
gravid L. cuprina than the liver–sodium sulfide
mixture. Adding dimethyl sulfoxide to the medium culture significantly reduced
its efficacy.
The gut mucus culture was significantly less effective than the
liver–sodium sulfide bait in trapping gravid
L. cuprina, and significantly more effective in trapping
Chrysomya rufifacies. This is the first published record
of sheep strike flies being attracted by bacterial odours in the field.
Orientation stimulants from substances attractive to Lucilia cuprina (Diptera, Calliphoridae)
Authors: Morris M. C. , Woolhouse A. D. , Rabel B. , Joyce M. A.
Published: August 2004

Summary. Liver and liver–sodium sulfide mixtures,
sheep faeces, urine and gut mucus are known attractants for the sheep blowfly
Lucilia cuprina (Weid.). These substances were analysed
for volatile compounds using gas chromatography coupled with mass
spectroscopy. The most commonly detected compounds were tested in a bioassay
for their potential as attractants for gravid female
L. cuprina.
Flies orientated towards pulses of dimethyl sulfide at a concentration of 1
µg/g but not 0.1 or 10 µg/g. Ethane thiol elicited a
response at a concentration of 10 µg/g but not at 1 µg/g.
Dimethyl disulfide did not elicit orientation at 10 µg/g.
A survey of the cadmium concentration in kidney, liver and muscle of South Australian cattle
Authors: Koh T.-S. , Bansemer P. C. , Frensham A. B.
Published: August 2004

Summary. A survey to assess the extent of cadmium
accumulation in South Australian cattle was undertaken in 1989–91. Of
the 8635 cattle sampled, about 12% of the kidney samples and 1%
of the liver samples contained cadmium concentrations above the maximum
permitted concentration for human consumption of 2.5 mg/kg wet weight for
kidney and 1.25 mg/kg wet weight for liver. None of the 262 muscle samples
assayed contained cadmium concentrations above the maximum permitted
concentration of 0.2 mg/kg wet weight.
There was a significant effect of location, gender and season on the extent of
non-compliance. Of the regions examined, non-compliance rates for Kangaroo
Island, Lower Eyre, South East and Lower Central were significantly higher
than for the other regions. In general, non-compliance rates were higher in
female cattle than in male cattle, increased with age and were lowest in
spring. After adjustment for these factors, non-compliance rates were similar
across farm types, namely dairy, beef and feedlot.
Although there was a significant correlation between cadmium concentrations in
liver and in whole kidney, the confidence limit was considered excessive,
rendering liver cadmium values an unreliable predictor of cadmium values in
kidney.
Analysing correlated count data from field trials
Authors: Alston C. , Murison R.
Published: August 2004

Summary. Field experiments are often affected by both
spatial and temporal (i.e. repeated measures) correlation. In order to obtain
an analysis that is scientifically valid it is important to recognise the
underlying error structure and analyse the data accordingly.
We will discuss the analysis of count data which is spatially and temporally
correlated, and illustrate the difference between an independent error
structure model and a marginal Quasi-Likelihood model which attempts to
account for the correlation present in the data. We shall then show the
possible impact of inefficient analysis techniques on the subsequent economic
decisions.
Air temperature prediction model to control solar energy heating in a germination greenhouse at night
Authors: Elbatawi Ibrahim E. A.
Published: August 2004

Summary. The outdoor air temperature is not constant
especially in spring in Okayama city. The average night temperature ranges
from –2 to 20°C which is too low for the germination of most seeds.
A good knowledge of the future outdoor air temperature is necessary to decide
if greenhouse heating is needed for the next day. Using measured temperatures
from the preceding days and considering the minimum and maximum temperatures
given by the weather forecast, it was possible to accurately compute the
temperature for the next day.
Pumpkin, eggplant and tomato seeds were used in this study. A solar system was
used to heat the air inside a greenhouse at night using an
air–water–air heat exchanger and make a comparison with an
unheated greenhouse.
The performance of the solar collector and methods of heat exchange were
tested. It was shown that the solar energy collected was sufficient for
warming a nursery greenhouse overnight.
The system operated with a hot water flow rate of 0.647 L/min and an air
flow rate of 9.21 m3/min and could maintain the
greenhouse temperature between 16 and 20°C. The quantity of heat collected
and delivered by the solar system from incident solar radiation was about
50% in a day.
Heating the air inside the greenhouse at night produced 100%
germination for all seedlings. In comparison, in the unheated greenhouse the
germination ratio was 100, 93 and 27% for pumpkin, eggplant and tomato
respectively. The germination ratio outside the greenhouses was 100%
for pumpkin, 67% for eggplant and zero for tomato.
Developing indicators for monitoring catchment health: the challenges
Authors: Reuter D. J.
Published: August 2004

Summary. This paper emphasises the critical importance
of achieving environmentally healthy and productive catchments in Australia.
This widely held societal goal requires an understanding of landscape
processes and predictions of how they might impact spatially on regional land,
water and vegetation resources. Such knowledge would assist the development of
more sustainable property and catchment plans.
Current developments in the application of indicators for assessing and
monitoring catchment health are briefly described, together with the emerging
challenges facing their wider adoption by land managers, the resource stewards
of rural Australia. These imposing challenges include: developing a core set
of nationally accepted catchment health indicators; meeting the requirement
for spatially dense data at reasonable cost; developing and testing new
environmental indicators related to on-farm nutrient management and the
potential for nutrients to leak off-site; and quantitative estimates of soil
biological health.
Comparative performance of spotted clover aphid and spotted alfalfa aphid on annual medic cultivars
Authors: Milne W. M.
Published: August 2004

Summary Twenty-three annual medic cultivars, hybrids and
accessions were tested for their suitability as hosts of 2 genetically
different biotypes of Therioaphis trifolii (Monell)
[spotted alfalfa aphid (SAA) and spotted clover aphid (SCA)] which
occur in Australia. Aphids were reared on excised trifoliate leaves on agar
containing a soluble fertiliser. Parameters measured were initial host
acceptance by adult aphids, mortality of 1st generation nymphs, developmental
time of apterous aphids, incidence of alate adults, and 4-day fecundity of
apterous adults. Host suitability indices were calculated for the 2 biotypes
on each of the accessions.
Spotted clover aphid clearly outperformed SAA on the majority of the medics
tested. It accepted most host plants more readily, and SCA nymphs nearly
always developed more rapidly, suffered lower mortality and produced fewer
alatae than those of SAA. A number of cultivars which had been bred for
resistance to SAA proved to be highly unsuitable hosts for SAA but relatively
suitable hosts for SCA. Spotted clover aphid has the potential to be a serious
pest on susceptible medics, and to be able to survive on resistant cultivars
until more favoured pasture legumes become available.
Australian Soil and Plant Analysis Council soil and plant quality assurance programs and the impact of variability of test results on clients
Authors: Rayment G. E. , Peverill K. I. , Shelley B. C.
Published: August 2004

Summary. In relatively few years, the Australian Soil
and Plant Analysis Council Inc. (ASPAC) has conducted 2 inter-laboratory
proficiency programs on plant material and 3 inter-laboratory proficiency
programs on soils. The purpose of these performance-based programs is to
enhance the quality of soil and plant analysis in Australasia, with guidance
where necessary from the soil and plant expertise of ASPAC members.
ASPAC’s inaugural ‘Accreditation Committee’ reviewed
published standards and existing laboratory accreditation/proficiency
programs in Australia and internationally before developing what is now in
full operation. This historical perspective and the 12 principles that guide
operations of ASPAC’s soil and plant proficiency programs are described,
as are the numeric procedures used to determine satisfactory performance.
Certificates are issued to successful laboratories on completion of each
program. Moreover, these remain current until signed certificates from the
next equivalent program are released. Wide variations in some data sets
suggest there is considerable scope to improve laboratory accuracy,
particularly for soil chemical tests. Some of these differences are sufficient
to markedly affect the assessment of fertiliser requirements. The present
‘Accreditation Committee’, in addition to State Representatives,
serve as ‘points-of-contact’ for laboratories that require
assistance to overcome problems with analytical accuracy and precision. ASPAC
encourages its member laboratories to seek and maintain NATA (National
Association of Testing Authorities, Australia) accreditation, in addition to
participating regularly in the performance-based proficiency programs run by
ASPAC.
Assessing irrigation requirements in the Ord Sugar Industry using a simulation modelling approach
Authors: Muchow R. C. , Keating B. A.
Published: August 2004

Summary. Sustainable irrigation guidelines that maximise
profitability and minimise water losses and accession to the watertable are
required for the new Ord Sugar Industry. In addition, knowledge on crop water
requirements is needed to guide water allocation and costing policies for the
expanding Ord Irrigation Area where sugarcane is likely to be a dominant crop.
Field data indicating water requirements for sugar in the Ord Irrigation Area
are few and this paper deploys a modelling approach to extrapolate from
knowledge of water requirements in other parts of the world. The approach
links long-term climatic data with soil water characteristics of the main soil
type, with a cropping systems model, to develop indicative estimates of
irrigation water requirement and yield consequences for different management
options for sugarcane production in the Ord.
Analyses of the growth of 12-month old ratoon crops were conducted using the
APSIM–Sugarcane model with historical climatic data from 1960 to 1985
and either a deep (188 mm available water to 160 cm depth) or shallow (144 mm
of water to 120 cm depth) Cununurra clay soil. Under maximum attainable growth
conditions where crops were irrigated after half the soil water supply was
depleted, average sucrose yield ranged from 26.7 to 29.0 t/ha, and the
irrigation requirement (assuming 100% application efficiency) ranged
from 22.7 to 23.8 ML/ha depending on ratooning date. Soil water holding
capacity had a major effect on the number of irrigations and the interval
between irrigation for a given irrigation schedule but little effect on yield
or irrigation requirement. Varying the irrigation schedule by changing the
level of soil water depletion before irrigation and thus the irrigation
frequency, showed the tradeoff between yield and irrigation requirement with
the most profitable irrigation schedule depending on the price of sucrose and
the cost of irrigation relative to other costs. Most of the year-to-year
variation in irrigation water requirement could be explained by the highly
variable effectiveness in soil storage of rainfall which ranged from 44 to
93%. This study has provided insight and indicative estimates of the
yield and irrigation requirements for different irrigation management options
for use in the establishment of an Ord River sugar industry. These estimates
will be further refined as field data become available.
The long-term impact of two pasture production systems on soil acidification in southern Queensland
Authors: Noble A. D. , Jones R. J. , Thompson C. H. , Jones R. M.
Published: August 2004

Summary. Soil samples to a depth of 90 cm were collected
in 1996 from adjacent 1 ha paddocks which had either been established to a
leucaena-based or nitrogen-fertilised and irrigated pasture system in 1960 at
Samford, south-eastern Queensland, to assess the impact of these production
systems on soil chemical properties. The chemical properties were compared
with those of soil samples collected from the site in 1960. Soil pH under both
the nitrogen-fertilised and leucaena-based systems have declined significantly
to a depth of 40 cm against that of the soil samples collected in 1960.
However, the extent of acidification was higher under the more intensively
managed nitrogen-fertilised system compared with the leucaena-based system.
The acidification rates for the nitrogen-fertilised and leucaena-based pasture
systems over the 36-year period are 5.1 and 1.0 kmol
H+/ha.year, respectively, and are similar to values
observed under annual pasture systems of temperate southern Australia.
Associated with the decline in pH there was a decline in exchangeable
Ca2+ in the nitrogen-fertilised system and a
corresponding increase in exchangeable acidity.
The contribution of the nitrogen cycle to net acidification for the
leucaena-based pasture system was estimated to account for 20% of the
total net acid addition. This result is discussed in the light of a similar
study undertaken in the semi-arid tropics where the contribution of the
nitrogen cycle by a similar leucaena-based system was estimated to be
78% of the net acidification.
Application of non-selective herbicides during flowering of pasture legumes can reduce seed yield and alter seed characteristics
Authors: Wallace A. , Lancaster R. A. , Hill N. L.
Published: August 2004

Summary. Spraytopping, the application of a low rate of
non-selective herbicide (usually glyphosate or paraquat) to annual grass seed
heads in the spring or early summer for seed set control is widely practised
throughout Australia. While grasses are the targets of the spray treatment,
annual pasture legumes may also be damaged by spraytopping, particularly if
the legumes are flowering at the time of application.
The effect of applying glyphosate (90, 112 or 162 g a.i./ha), paraquat
(100 g a.i./ha) and glyphosate plus MCPA (90 + 150 g a.i./ha) to
subterranean clover (Trifolium subterraneum L. cv.
Dalkeith) and annual medic (Medicago polymorpha L. cvv.
Serena, Santiago and Circle Valley) pastures at various times during flowering
was investigated during the spring of 1993 and 1994. Experiments were located
at Tincurrin and Tenindewa, Western Australia.
Subterranean clover seed yield was most affected by applications of glyphosate
(90 and 162 g a.i./ha) and glyphosate plus MCPA (90 + 150 g
a.i./ha) during early–mid flowering. Seed yield was reduced by as
much as 88% following application of glyphosate plus MCPA when
20% of the subterranean clover plants were flowering. Treatment with
paraquat (100 g a.i./ha) during mid–late flowering reduced seed
yield of subterranean clover by 25–50% in experiment 1 only.
Medic seed yield was reduced up to 90% depending on cultivar when
glyphosate (112 g a.i./ha) was applied during early–mid flowering.
In addition to seed yield, the level of hard seed was assessed. Treatment of
subterranean clover during early–mid flowering with glyphosate (90 and
162 g a.i./ha) significantly reduced the quantity of hard seed produced.
Thirty–forty percent of subterranean clover seed was germinable soon
after seed set, compared with 7–17% germinable for the seed from
untreated plants. Treatment with glyphosate (112 g a.i./ha) reduced the
proportion of hard seed in the medics when applied during mid flowering.
Treatment with paraquat had little effect on the proportion of hard seed
formed.
This work demonstrates that using a spraytopping technique for control of seed
set in annual grasses may dramatically reduce seed yield in pasture legumes.
Spraytopping can further reduce the ability of legumes to persist in cropping
rotations by reducing the amount of hard seed formed. Implications for
practical farming systems are outlined.
Correlation between soil pH of collection site and the tolerance of wild genotypes of Lupinus angustifolius L. to neutral pH
Authors: Robson A. D. , Tang C.
Published: August 2004

Summary. Lupinus angustifolius L.
grows poorly on alkaline soils, and high pH appeared to be a major limiting
factor. In this study, 30 wild genotypes of this species collected from soils
with a wide range of pH (4.2–9.0) and texture (coarse sand–clay)
were grown in nutrient solution for 22 days to examine their tolerance of pH
7. Cultivars of L. angustifolius,
L. pilosus, L. luteus and
Pisum sativum were included for comparison. Root length,
nodule number, chlorophyll and iron concentrations in leaves were lower in
almost all wild genotypes grown at pH 7.0 compared with those at pH 5.2.
However, there was large variation in growth and nodulation in response to
high pH among genotypes. Compared with the value at pH 5.2, shoot weight at pH
7.0 ranged from 41 to 120%, chlorophyll concentration from 8 to
75%, iron concentration from 22 to 70%, root weight from 27 to
109%, root elongation rate from 61 to 96% and nodule number from
0 to 86%. However, the tolerance (as assessed by growth and nodulation)
of these wild genotypes to pH 7.0 was not correlated with soil pH or texture
at collection site, but iron chlorosis at pH 7.0 was weakly correlated with
collection site soil texture (r = –0.36,
n = 30) and seed size (r
= –0.45, n = 30), and early root
elongation correlated with seed size (r =
–0.55, n = 30). In addition, some wild
genotypes appeared to be more tolerant to pH 7.0 than existing cultivars of
L. angustifolius. The results confirm that soil pH at
collection site (as recorded in the Agriculture Western Australia
International Lupin Collection) is not a useful indicator for selecting high
pH-tolerant genotypes of L. angustifolius.
Population improvement in lucerne (Medicago sativa L.): components of inbreeding depression are different in original and improved populations
Authors: Kimbeng C. A. , Bingham E. T.
Published: August 2004

Summary. Inbreeding depression, the lowered fitness of
inbred individuals compared with their non-inbred counterparts, is an
important concept in lucerne improvement; but is poorly understood. Two-allele
autotetraploid populations are suitable for studying inbreeding depression,
especially when the population improvement strategy involves inbreeding,
because they are derived from chromosome-doubling of hybrid diploid plants.
They have a maximum of 2 alleles and a single allelic interaction per locus.
Inbreeding depression was compared in original 2-allele autotetraploid
populations and populations that had undergone inbreeding and selection. The
original and improved (selected) populations were produced by intercrossing 2
single-cross lines from the original and improved 2-allele autotetraploid
populations respectively. Herbage yield of the S1 and
intercrossed generations derived from these populations was evaluated in field
trials at Arlington, Wisconsin, USA, and used to estimate inbreeding
depression. Herbage yield of the S1 and intercrossed
generations derived from the improved population were significantly
(P<0.01) higher, by 13.3 and 24%,
respectively, than those derived from the original population. Selection
during inbreeding probably decreased the frequency of deleterious alleles and
accumulated favourable alleles. Inbreeding depression values were higher in
the improved compared with the original population. Genetic load of
deleterious alleles may account for much of the inbreeding depression observed
in the original population, whereas, in the improved population, loss of
heterozygosity or non-additive gene interactions between favourable alleles on
linked chromosome segments may account for the substantial inbreeding
depression. Therefore, in a population improvement program, the causes of
inbreeding depression seem to be more important than their estimated value.
Homeostatic interactions between the benthic microbial communities and the waters of a hypersaline lake, Lake Hayward, Western Australia
Authors: Burke Christopher M. , Knott Brenton
Published: August 2004

In hypersaline Lake Hayward, photosynthesis by benthic microbial communities
(BMCs) is normally sufficient to supersaturate the bottom water with dissolved
oxygen during periods of stratification. The BMCs are dominated by
cyanobacteria such as Cyanothece in the permanently
inundated centre of the lake and by Microcoleus in the
seasonally desiccated littoral. However, after an unusually dry year in 1987,
the salinity increased to 260 g L-1 and gypsum
precipitated throughout the lake. The turbidity generated was sufficient to
obscure the benthos completely despite the shallowness of the lake (<2 m).
As a result, the BMCs were greatly altered and the amount of oxygenic
photosynthesis was reduced. During the following winter (1988), during
stratification the bottom water became anoxic and sulfurous. However, during
the next few years the BMCs reestablished and were able to again supersaturate
the bottom water with oxygen. Limnological and microbiological changes that
occurred in this period are described and it is concluded that the BMCs
function as a strong homeostatic mechanism allowing long-term stability of the
present limnological characteristics of Lake Hayward. Therefore, the
development of the BMCs represented a significant step in the ontogeny of the
lake, which now differs distinctly from nearby lakes that do not contain such
BMCs.
Biology of modern Fragum erugatum (Mollusca, Bivalvia, Cardiidae) in relation to deposition of the Hamelin Coquina, Shark Bay, Western Australia
Authors: Berry P. F. , Playford P. E.
Published: August 2004

Fragum erugatum populations were sampled over two
consecutive years in Hamelin Pool, Lharidon Bight and Freycinet Harbour, which
are representative of the hypersaline and metahaline regimes of Shark Bay.
F. erugatum was widely distributed infratidally between
1.2 m and 6.5 m depth. Dense aggregations of zooxanthellae were present in
mantle and gill tissue. Shell shape of the population from Hamelin Pool
differs from that of the Lharidon Bight, Freycinet Harbour and Dampier
Archipelago populations. F. erugatum was found to be a
synchronous hermaphrodite. Settlements of juveniles, and modality of size
distributions, indicate a single annual spawning. Production estimates of dry
flesh and shell (CaCO3 inclusive) were much lower in
Hamelin Pool than in Lharidon Bight, largely because of the lower density of
F. erugatum recorded in Hamelin Pool. Although shells
are washed ashore continuously, large-scale deposition of the accumulated
infratidal coquinas, largely composed of F. erugatum
shells, probably occurs periodically in major storm events, thereby forming
the Hamelin Coquina.
Feeding and schooling behaviour of barracouta (Thyrsites atun) off Otago, New Zealand
Authors: O'Driscoll Richard L.
Published: August 2004

To test the hypothesis that fish in schools forage more successfully than
individual fish, an analysis was made of the stomach contents of barracouta
(Thyrsites atun), a facultatively schooling species of
fish, in a wild fish population. Schooling (n =
29) and non-schooling (n = 86) barracouta were
captured during a side-scan sonar survey of pelagic fish off the coast of
Otago, New Zealand. The proportion of fish with empty stomachs was lower and
the mean wet mass of gut contents was higher in barracouta from schools. The
increased feeding success of fish in schools was due to increased consumption
of krill, Nyctiphanes australis. In regions where the
density of krill in net tows was high (>1000 individuals
km-1 tow length) or moderate (100–1000 individuals
km-1), the mean wet mass of krill in the stomachs of
schooling barracouta was 2–4 times higher than in the stomachs of
non-schooling barracouta. Few schools of barracouta were observed in areas
with low densities of krill (<100 individuals km-1).
Schooling by barracouta seems to be a feeding strategy to exploit surface
swarms of krill.
Effect of limb damage on the survival and burial time of discarded spanner crabs Ranina ranina (Linnaeus)
Authors: Kirkwood John M. , Brown Ian W.
Published: August 2004

Spanner crabs (Ranina ranina) often lose legs or
segments of legs when being disentangled from fishing nets. Two field
experiments investigated the effect of this on survival of discarded undersize
crabs. To examine mortality directly attributable to limb damage, 100 crabs
were each subjected to one of five treatments: no damage, or removal of one
dactylus, three dactyli, one leg or one cheliped. Limb damage had a
significant effect on survival, mean mortalities being, respectively,
5%, 20%, 25%, 55% and 90%. Thus, present
fishing methods may lead to high mortality among discarded crabs.
To examine whether limb damage leads to increased exposure to predation, 40
crabs were released after each was subjected to one of the above treatments.
There was no significant effect of limb damage on the time it took crabs to
bury themselves. Crabs sank at a mean rate of 0.26 m
s-1, and on reaching the sea floor most crabs were
motionless for up to 20 min before becoming active and immediately burying
themselves; time to burial ranged from 6 s to 20 min, with 65% burying
themselves within 68 s of reaching the sea floor.
Elasmobranch exploitation in Africa
Authors: Kroese M. , Sauer W. H. H.
Published: August 2004

The impact of fisheries on elasmobranchs in Africa is not well documented.
Available data suggest that there are no large shark fishing nations (>
10000 t year-1), reported landings for 1994 being around
39 000 t. This value is believed to be a underestimate, because of a lack of
data on catches and landings from the various different fishing methods and
the large number of nations fishing in African waters. Existing data are
mostly linked to industrial fisheries, although the artisanal sector could be
responsible for substantial catches. Landed by-catch and discard rates of
elasmobranchs are unknown for most commercial fisheries targeting teleosts.
Limited data sources allowed only crude estimates of catch. The artisanal
fishery is calculated to land a minimum of 20 000 t of sharks, whereas the
industrial trawl sector is likely to catch 23 000 t. A conservative estimate
for the African continent and the surrounding islands is ~95 000 t. The
quality of catch-and-effort data for both commercial and subsistence fisheries
on the African continent needs to be improved, and the by-catch issue should
be investigated through trained onboard observers.
Oceanographic implications of recent planktonic foraminifera along the southern Australian margin
Authors: Li Qianyu , McGowran Brian
Published: August 2004

The distribution of planktonic foraminifera along the southern Australian
margin is strongly gradational from warmer assemblages in the west to more
temperate assemblages in the east. This pattern follows a decreasing
temperature gradient generated by the warm Leeuwin Current which flows
southward and then eastward on the southern margin. The abundances of tropical
and subtropical species including Globorotalia menardii and Globigerinoides
trilobus s.l. decrease rapidly after rounding the south-western corner, while
the temperate index species Globorotalia inflata increases and subsequently
dominates the fauna towards the east, especially on the Lincoln and Lacepede
shelves of South Australia. This W–E gradation is also observed in the
relict Pleistocene assemblages, indicating that the Leeuwin Current has been
influential since at least the last interglacial time. The interaction between
the warm and saline water from the Great Australian Bight and cold water from
the south produced an assemblage in deeper parts of the Bight with abundant
small species such as Globigerina falconensis, Globotur-borotalita rubescens,
Neogloboquadrina pachyderma and
Turborotalita quinqueloba.
Oils rich in docosahexaenoic acid in livers of sharks from temperate Australian waters
Authors: Nichols Peter D. , Bakes Michael J. , Elliott Nicholas G.
Published: August 2004

The livers from the two main commercially-targeted shark species in southern
Australia (Mustelus antarcticus, gummy shark;
Galeorhinus galeus, school shark), together with
Squalus acanthias (white-spotted spurdog), were analysed
for oil content and composition, and fatty acid composition. The yield of oil
from the liver was 30-64% (wet weight) for
M. antarcticus and 50-53% (wet weight) for
G. galeus. Lipid classes were determined by thin-layer
chromatography with flame ionization detection, with the major lipid being
triacylglycerol (≥95%); other minor lipids were polar lipid, wax
ester, sterol (mainly cholesterol) and free fatty acid. Long-chain ω-3
polyunsaturated fatty acids accounted for between 33% and 39% of
the total fatty acids in all three species, and docosahexaenoic acid (DHA)
concentrations were between 13% and 18%. The liver oils of
M. antarcticus and G. galeus and
other shark species may be an attractive source of w-3 fatty acids,
specifically DHA, for direct use and/or for adding further value.
Sampling juvenile Penaeus latisulcatus Kishinouye with a water-jet net compared with a beam-trawl: spatial and temporal variation and nursery areas in Gulf St Vincent, South Australia
Authors: Kangas M. I. , Jackson W. B.
Published: August 2004

This study demonstrates that the water-jet net is more effective than a beam
trawl in capturing juvenile Penaeus latisulcatus. In
contrast with the beam trawl, which is maximally effective only at night when
prawns are active, the jet net captures high numbers of prawns in daylight.
This, combined with its ability to minimize catchability effects, makes the
jet net very suitable for sampling juvenile
P. latisulcatus. For sampling prawns of widely varying
size, perpendicular trawls were more effective than parallel trawls because
larger individuals are distributed in deeper waters. Nursery areas for
P. latisulcatus are intertidal sand/mudflats and
there is little daily variation of prawn abundance and distribution within one
site. Large differences in abundance of juvenile prawns were observed
throughout Gulf St Vincent with highest concentrations in the northern part of
the gulf.
Agrobacterium tumefaciens-mediated Transformation of Double Haploid Canola (Brassica napus) Lines
Authors: Kazan K. , Curtis M. D. , Goulter K. C. , Manners J. M.
Published: August 2004

Double haploid (DH) genotypes of canola (Brassica napus
L.) have a high level of genetic uniformity but have not been previously
tested for genetic transformation. Transgenic plants from three of four DH
genotypes derived from cv. Westar were obtained by inoculation of either
hypocotyl segments or root explants with
Agrobacterium tumefaciens. For hypocotyl transformation,
A. tumefaciens strain LBA4404 containing a binary
plasmid with the neomycin phosphotransferase gene
(nptII) and a CaMV 35S-peroxidase gene cassette was
co-cultivated with hypocotyl segments taken from the 5–6-day-old
seedlings. Transformation frequencies for hypocotyl explants of two DH
genotypes were 0.3–3%. Direct evidence for genetic transformation
of hypocotyl explants was obtained through molecular hybridisation analysis.
Using this protocol, mature transformed plants were obtained within 4–6
months of co-cultivation. A method of root transformation was successfully
modified for one DH genotype of canola and transgenic plants were obtained at
a frequency of 2%. Using this protocol, a peroxidase gene
promoter–GUS fusion construct was introduced into a DH genotype. Tissue
specific GUS expression driven by the peroxidase gene promoter in transgenic
plants was analysed by GUS staining. Transformation systems for double haploid
canola lines will permit the assessment of introduced genes for their effect
on agronomic and physiological traits.
Photoperiod Alters Diurnal Carbon Partitioning into Sorbitol and Other Carbohydrates in Apple
Authors: Wang Z. , Yuan Z. , Quebedeaux B.
Published: August 2004

The current experiments were designed to determine the diurnal carbon
partitioning among sorbitol, sucrose, and starch in mature apple
(Malus domestica Borhk. cv. Gala) leaves and to
determine whether photoperiod altered photosynthate partitioning among
carbohydrates. Sorbitol accounted for > 80% of newly fixed
14C-labelled carbohydrate during the light period.
Forty-seven percent of sorbitol that had accumulated at the end of the light
period disappeared during the dark period. As photoperiod increased from 1 to
10 h, sorbitol, glucose, fructose, and starch concentrations in mature apple
leaves increased, but were stable from 10 to 14 h. Sucrose concentration, on
the other hand, decreased slightly as photoperiod increased. As a result,
sorbitol to sucrose ratios increased from 2 in the 1-h photoperiod to 5 in the
10-h photoperiod. The relative partitioning of 14C into
sorbitol increased, whereas the partitioning into sucrose, glucose, and
fructose decreased as photoperiod increased from 1 to 10 h. Our results
suggest that longer photoperiods favoured sorbitol over sucrose accumulation
while shorter photoperiods favoured sucrose over sorbitol synthesis. The
observed changes in sorbitol and sucrose concentrations with changes in
photoperiod may result from different rates of synthesis and export.
CO2 and Temperature-dependent Induction in C4 Photosynthesis: an Approach to the Hierarchy of Rate-limiting Processes
Authors: Laisk Agu , Edwards Gerald E.
Published: August 2004

Rate-limiting processes for C4 photosynthesis were
examined in Sorghum bicolor, an NADP-ME type species,
and Amaranthus cruentus, an NAD-ME type
C4 species, by studying the kinetics of transient
changes in photosynthetic rates following rapid changes in
CO2 or temperature. Primary responses (faster than 15
s) to increasing CO2 or temperature are considered
direct effects on the turnover rate of the C4 cycle,
whereas medium transient changes (2–3 min) are considered due to
build-up of C4 cycle intermediates, and the slowest
transient changes (20–30 min) are thought to be related to end product
synthesis. Reciprocal plot of carboxylation rates versus cell wall (dissolved)
CO2 concentration (Cw) gives an
apparent Km (CO2) of 8 µM
and a Vm of 200 µmol
m-2 s-1 for PEP carboxylase, which
is about 4 times higher than the maximum rate of photosynthesis. Under
strictly limiting CO2, the rate of PEP carboxylation in
C4 photosynthesis is independent of temperature
(20–35°C), suggesting a physical rather than a biochemical
limitation. It is suggested that the rates of C3 and
C4 cycles are coordinated through the pool sizes of the
C4 cycle, which are in equilibrium with the pool of
3-phosphoglyceric acid. At low CO2, the
C4 pools decrease and are slowly regenerated at elevated
CO2, restricting the CO2 response
of C4 photosynthesis.
The CO2 Concentrating Mechanism of C4 Photosynthesis: Bundle Sheath Cell CO2 Concentration and Leakage
Authors: Jenkins Colin L. D.
Published: August 2004

The C4 acid cycle functions in C4
photosynthesis to concentrate CO2 in bundle sheath (BS)
cells, thereby minimising oxygenase activity of Rubisco and associated
photorespiration. Some key features of this process are reviewed here. During
steady-state photosynthesis, the CO2 concentration
maintained in BS cells must be a compromise since, at the higher levels
required to prevent photorespiration, the potential for
CO2 leakage from BS cells would be increased. Despite
its central importance in C4 photosynthesis, it has not
been possible to precisely determine the BS CO2
concentration. Leakage requires that the C4 cycle rate
exceeds the net photosynthesis rate and lowers the efficiency of the overall
process. Leakage of CO2 from the BS has been estimated
by a number of indirect and, recently, by more direct methods. In a
simulation, simple relationships between Rubisco activity, photorespiration,
and leakage were calculated at increasing BS CO2
concentrations. From this, and determined values for leakage, the likely
concentration of CO2 in BS cells may be 10–20-fold
greater than in mesophyll cells. Higher concentrations would have little
further effect on oxygenase activity.
Genetic Manipulation of Key Photosynthetic Enzymes in the C4 Plant Flaveria bidentis
Authors: Furbank Robert T. , Chitty Julie A. , Jenkins Colin L.D. , Taylor William C. , Trevanion Stephen J. , Caemmerer Susanne von , Ashton Anthony R.
Published: August 2004

The NADP-malic enzyme type C4 dicot
Flaveria bidentis (L.) Kuntze was transformed with
antisense and cosense gene constructs that resulted in specific decreases in
single photosynthetic enzymes. The enzymes targeted were
ribulose-1,5-bisphosphate carboxylase/oxygenase [EC 4.1.1.39]
(Rubisco), pyruvate, Pi dikinase [EC 2.7.9.1] (PPDK) and NADP malate
dehydrogenase [EC 1.1.1.82] (NADP-MDH). These enzymes were chosen as
targets because they have low activity compared to photosynthetic rates
(Rubisco), are subject to complex covalent regulation (NADP-MDH), or both
(PPDK). T1 progeny of a number of lines of these transformants were examined
for the effects of these gene constructs on enzyme levels and photosynthetic
performance. Rubisco antisense transformants expressing between 15 and
100% of wild-type enzyme activity were obtained. Pyruvate, Pi dikinase
antisense lines were obtained with 40–100% wild-type levels. NADP
malate dehydrogenase sense constructs caused a co-suppression of enzyme
activity with some lines containing less than 2% of wild- type
activity. Under saturating illumination, the control coefficients for these
enzymes were determined to be up to 0.7 for Rubisco, 0.2–0.3 for PPDK
and effectively zero for NADP-MDH. The implications of these observations for
the regulation of photosynthetic flux and metabolism in
C4 plants and the role of regulation by covalent
modification are discussed.
Effects of growth temperatures of 5 and 25°C on long-term responses of photosystem II to heat stress in atrazine-resistant and susceptible biotypes of Erigeron canadensis
Authors: Dulai Sándor , Molnár István , Lehoczki Endre
Published: August 2004

When leaves of atrazine-resistant (AR) and atrazine-sensitive (S) plants of
Erigeron canadensis (L.) Cronq. grown at 25°C were
exposed to continuously rising temperatures, the heat-induced changes in the
initial level (F0) of modulated
fluorescence indicated an enhanced heat sensitivity of the chloroplasts in the
leaves of the AR biotype. The critical
(Tc) and peak temperatures
(Tp) of the
F0 v. T curves for the leaves of the S biotype grown at
5Q°C were considerably lower, in contrast with the leaves of the AR
biotype, for which these values were very similar to those at 25°C. For
the warm and cold-acclimated AR biotype, the temperature dependences of the
fluorescence quenching parameters were not greatly different, in contrast with
the S plants. The different growth temperatures resulted in a shift in the
optimal thermal interval of CO2 fixation between the
cold and warm-acclimated S biotype, whereas this interval was nearly the same
for the AR biotype grown at the two temperatures. The results suggest that,
besides the D1 protein mutation, the growth temperature
independence of the thylakoid fluidity, over and above a higher susceptibility
to heat stress, may cause the limited capacity of acclimation to temperature
in AR plants.
Semidian rhythmicity in the flowering response of Pharbitis nil to changes in temperature
Authors: Heide O.M. , King R.W. , Evans L.T
Published: August 2004

Our earlier experiments on flowering in the short day plant
Pharbitis nil involved far- red/dark (FR/D)
interruptions of 90 min duration at various times during a continuous light,
constant temperature period before a single inductive dark period. They
revealed a rhythm with a period of 12 h, hence semidian. We concluded that the
phasing of this semidian rhythm determined the length of darkness required for
floral induction. This conclusion has since been challenged so we sought other
pretreatments which reveal the semidian rhythm. Interruptions at
12°C–17°C for 45–90 min at various times prior to the
inductive dark period were as effective as FR/D in eliciting the semidian
rhythm, with significant effects on flowering persisting for at least three
cycles in constant conditions in continuous light. The rhythmic response to
12°C pretreatments was 3 h out of phase with that to FR/D
pretreatments.
Flowering responses to the semidian rhythm exposed by 12°C pretreatments
were additive to and independent of those to a circadian rhythm. Some evidence
was obtained of reversal of the inhibition or promotion of flowering by
FR/D or 12°C by exposure immediately afterwards to the other
pretreatment at times of their opposite effect. Pretreatments at 12°C,
like those with FR/D, either reduced (if promotive) or extended (if
inhibitory) the length of the dark period required for floral induction in
this short day plant.