bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining satellite data with a simulation model to describe spatial variability in pasture growth at a farm scale
Authors: Moore A. D. , Vickery P. J. , Hill M. J. , Donnelly J. R. , Donald G. E.
Published: September 2002

Practical application of simulation modelling as a decision aid for grazing
system management usually involves an assumption of uniformity of model inputs
over a farm paddock or property. In reality, paddocks and farms display high
spatial variability in model inputs. There is considerable interest in
assessing the significance of this spatial variablity for anmal production and
enterprise profitability. This study seeks to demonstrate the use of spatial
data with the GRAZPLAN pasture model to provide estimates of annual net
primary production from pastures at a farm scale on the Northern Tablelands of
New South Wales, Australia. The GRAZPLAN pasture model was validated against
data from 2 separate field experiments for a typical improved pasture based on
Phalaris aquatica from 1968 to 1972. A spatial coverage,
classifying paddocks into 9 pasture types based on a botanical survey, was
used to define the pasture parameter sets used in simulations. A Landsat TM
satellite image classified to give 3 pasture growth status classes was used to
define within-paddock levels of a fertility index used in the simulation
model. Simulations over 1975–94 were conducted for all combinations of
pasture types and fertility scalar values using climate data for the CSIRO
Pastoral Research Laboratory near Armidale. Simulation output was written to a
lookup table and imported into a PC-based geographic information system. The
spatial data layers were combined to form a display template representing
spatial variation in pasture type, pasture condition and fertility. The
spatial template was reclassified using the lookup tables to create maps of
annual net primary production from pastures. Spatial variability in simulated
annual net primary production was greater for the paddocks with diverse
mixtures of sown and native species than for the more uniform highly improved
or pure native pastures. The difference in response to rainfall of simulated
net primary production was greater between different pastures types than
between different levels of the fertility index. The resulting maps provide a
demonstration of the way in which satellite imagery and other data can be
interfaced with a decision support system to provide information for use in
precision management of grazing systems. Implementation of such methods as a
management tool will depend on development of quantitative spatial data layers
which provide accurate and repeatable initial conditions and parameter values
for simulation models.
Similarities and differences in the genetic and physiological control of resistance to stemphylium leafspot in winter-active and semi-dormant lucernes
Authors: Irwin J. A. G. , Bray R. A.
Published: September 2002

Previously, it has proven difficult to improve resistance to some biotypes of
Stemphylium vesicarium in selections from lucerne cv.
Sequel (highly winter active) in contrast to selections from cv. Trifecta
(semi-winter dormant). Stemphylium leafspot is a disease of the cooler months,
and there are 2 possible explanations for the differing reactions: either the
winter-active genetic backgrounds do not contain the requisite resistance
genes, or the winter-active lines are physiologically disadvantaged through
their winter activity. A diallel cross was made between clones from Trifecta
and Sequel representing a range of disease reactions. Progeny were grown
either under summer or winter conditions before inoculation. For both
environments, variation was entirely additive. There was no interaction
between crosses (or parents) and the 2 environments, and there was a close
relationship (r = 0.93) between the breeding
values (gi) of parents in the 2 environments. The data
indicated that variation in both backgrounds was entirely additive, although
there were indications that phenotypic expression of resistance was stronger
in clones from the Trifecta background. To increase resistance in
winter-active material, it would be necessary to introgress the resistance
genes from non-winter-active material.
Genetic basis of crown rust resistance in perennial ryegrass, breeding strategies, and genetic variation among pathogen populations: a review
Authors: Kimbeng C. A.
Published: September 2002

Crown rust caused by the fungus Puccinia coronata f. sp.
lolii is probably the most serious disease of perennial
ryegrass (Lolium perenne L.). Breeding for resistance to
crown rust is a major component of most perennial ryegrass improvement
programs. This paper reviews the genetic basis of resistance to crown rust in
perennial ryegrass, existing breeding strategies and their progress, and
genetic variation in pathogen populations. Resistance to crown rust in
perennial ryegrass appears to be controlled by both major and minor genes.
Breeding for resistance to crown rust has traditionally been approached from a
quantitative perspective (polygenic system), and phenotypic recurrent
selection is by far the most commonly used method of selection. There appears
to be considerable variation in the pathogen population which may impact on
breeding progress. Owing to the present lack of information on the
host–pathogen interaction system of this economically important disease,
a basic model to study the
L. perenne–P. coronata f.
sp. lolii interaction system is presented. Its
application in a breeding program is discussed.
Sulfur supplementation of lupin grain diets fed to young sheep
Authors: Doyle P. T. , Ritchie A. J. M. , Ellis M. R.
Published: September 2002

Summary. We examined the effects of supplementation of
lupins with limestone or gypsum on liveweight change and wool production of
young Merino wethers [age 10 months; starting liveweight (mean s.e.m.)
34.8 0.33 kg]. Lupins with the added compounds were fed in amounts
estimated to provide metabolisable energy at 0.8, 1.0, 1.5 and 2.0 times
maintenance requirements. The remainder of the ration was cereal straw fed at
10% of the weight of lupins given. Lupins coated with limestone or
gypsum had a dry matter digestibility of 880 g/kg, and contained (g/kg
DM) nitrogen 56.1 v. 57.4, sulfur 2.3 v. 4.6 and calcium
7.9 v. 5.4 respectively.
As the amount of the ration fed was increased, there were linear increases
(P<0.001) in liveweight gain (–9 to 226
g/day), clean wool growth rate (5.3–10.2 g/day), and fibre
diameter of wool grown (18.0–21.6 m). There were no significant
differences between lupins coated with limestone or gypsum in liveweight
change (97 v. 105 g/day) or clean wool growth rate
(7.6 v. 7.5 g/day). While the addition of sulfur to
the diet reduced fibre diameter of wool grown (19.4 v.
20.0 m; P<0.01), this is not consistent with the
effects of increased sulfur amino acid supply which would be expected to
increase fibre diameter. It is concluded that the supply of inorganic sulfur
to ruminal organisms was not limiting production responses to lupins or that
there were other more limiting nutrients.
Field evaluation of seven grasses for use in the revegetation of lands disturbed by coal mining in Central Queensland
Authors: Harwood M. R. , Hacker J. B. , Mott J. J.
Published: September 2002

Pasture-based systems, dominated by the tussock forming
Cenchrus ciliaris cv. Biloela (buffel grass) and the
stoloniferous Chloris gayana cv. Pioneer (rhodes grass),
are commonly used in the revegetation of lands disturbed by coal mining in the
Bowen Basin of Central Queensland. Although able to establish quickly under
favourable conditions, neither species has proven entirely suitable for use in
this situation, particularly in providing effective ground cover for erosion
control on the re-contoured post-mining landscape. The aim of this study was
to evaluate a range of new pasture grasses, with the objective of identifying
accessions better adapted to the edaphic and climatic conditions of the areas
requiring revegetation.
Seven grasses were evaluated, on both bare spoil and replaced topsoil, at the
Saraji mine, about 25 km north of Dysart. Differences in establishment between
grasses were limited, although establishment was up to 5 times greater in the
replaced topsoil plots. Urochloa mosambicensis CPI 60128
exhibited better seedling survival (up to 8 times greater) and produced a more
extensive ground cover (up to 3 times greater) than the stoloniferous control
Chloris gayana cv. Pioneer under conditions of below
average rainfall (rainfall was below average in 70% of the months).
This work resulted in the commercial release of
U. mosambicensis CPI 60128 as cv. Saraji.
A survey of farmer practices and attitudes to nitrogen management in the northern New South Wales grains belt
Authors: Hayman P. T. , Alston C. L.
Published: September 2002

Summary. The use of nitrogen fertilisers to arrest the
decline in soil nitrogen fertility in the northern grains belt of New South
Wales has been the subject of many years of research, however, little is known
about how farmers make decisions about nitrogen fertiliser. A survey of 400
wheat farmers in northern New South Wales in April 1997 revealed that many
have recently changed their fertiliser practices. Although most respondents
had been growing wheat since the 1960s, regular applications of nitrogen only
commenced in the mid 1980s. Initially only low rates of nitrogen were applied,
but in the last 2–5 years, the nitrogen rates have substantially
increased. These changes are notable because until this decade, most were
content to rely mainly on mineralisation of soil organic nitrogen, whereas,
now, half the respondents in the survey plan to add as much nitrogen in
fertiliser in 1 year as was removed in the previous year’s wheat crop.
Farmers were asked to rate the importance of a number of factors that have
been promoted as means of tactically adjusting fertiliser rates. This study
found a disparity between the level of measurement and precision suggested by
the majority of research, development and extension programs compared with the
methods used by farmers. In general, the respondents to the survey have
rejected, or are yet to adopt, regular soil testing, the use of climate
forecasts and decision support programs. Rather, they rely on simple rules of
thumb based on readily accessible data such as past grain protein content and
cropping history.
Importance of low ethylene levels to delay senescence of non-climacteric fruit and vegetables
Authors: Ku V. V. V. , Shohet D. , Wills R. B. H. , Kim G. H.
Published: September 2002

The storage life of a range of non-climacteric fruit and vegetables was
assessed during storage at ambient temperature (20˚C) and low temperature
(0–5˚C) and ventilation with air containing ethylene over the range
<0.005–10 µL/L. The storage life of Chinese cabbage and
orange was found to be linearly extended with a logarithmic reduction in
ethylene concentration. Across 23 kinds of produce, there was about a
60% extension in postharvest life when stored in <0.005
µL/L compared with 0.1 µL/L, the commonly considered
threshold level for ethylene action. It is suggested that the threshold level
of ethylene action on non-climacteric produce is well below 0.005
µL/L and that the level of ethylene that accumulates around produce
in all commercial situations is always much greater than 0.005 µL/L.
Hence, any postharvest action that reduces the accumulation of ethylene around
non-climacteric produce during marketing will result in an increase in
postharvest life.
Physiological adaptations of Hymenachne amplexicaulis to flooding
Authors: Kibbler H. , Bahnisch L. M.
Published: September 2002

The introduced grass Hymenachne amplexicaulis has been
established for use in ponded pastures in Central Queensland. However, its
ability to out compete native species and invade wetlands makes it a potential
weed. To determine the characteristics that make it a successful ponded
pasture species, the adaptation of H. amplexicaulis to
flooding has been investigated.
The growth and development of H. amplexicaulis under
flooded and non-flooded conditions was compared in a series of experiments
carried out in three 2 m high galvanised steel tanks. Leaf, stem and root
sections were taken to determine the timing and extent of aerenchyma
formation. The effect of flooding on the pattern and distribution of growth
was also determined.
Hymenachne amplexicaulis is adapted to flooding because
it has the capacity for rapid elongation of the stem and the formation of
adventitious roots. Aerenchyma was present in stem, leaf and root tissues in
both flooded and non-flooded plants. The aerenchyma would provide buoyancy as
well as aiding the circulation of gases. When the plants were flooded,
submerged leaves senesced rapidly and the previously exposed, but now
submerged nodes produced adventitious roots. Under flooding, the growth of
leaves increased at the expense of the roots, presumably maintaining the
effective photosynthetic leaf area. The implications and limitations of these
adaptations are discussed.
Distribution of Hymenachne acutigluma (Steudel) Guilliland in ponded pasture is limited by photosynthetic response to temperature
Authors: Kibbler H. , Bahnisch L. M.
Published: September 2002

Hymenachne amplexicaulis, an exotic grass established in
ponded pasture in Central Queensland has the potential to become a weed. A
suggested alternative, the native grass H. acutigluma
produced little biomass when flooded. This investigation attempted to identify
limitations to the growth of H. acutigluma under flooded
conditions.
A series of experiments compared the characteristics conferring adaptation to
flooding of H. acutigluma with those of
H. amplexicaulis. Photosynthetic activity of the 2
Hymenachne spp. was compared in response to light and
temperature. The distribution of resources in response to reduced
photosynthesis and flooding was also determined.
When flooded, H. acutigluma had similar structural
adaptations to H. amplexicaulis. However,
H. acutigluma had a lower photosynthetic rate at reduced
temperatures and the photosynthetic leaf area decreased when flooded. The
implications of these findings are discussed in terms of limitations to the
distribution and productivity of H. acutigluma in ponded
pasture.
Dietary supplements of methionine increase breast meat yield and decrease abdominal fat in growing broiler chickens
Authors: Wallis I. R.
Published: September 2002

The response of male broiler chickens to graded amounts of an essential amino
acid (methionine) or an amino acid analogue (methionine hydroxy analogue free
acid, MHA-FA) was examined in this experiment. The effects of each supplement
on food intake, food conversion and the masses of a demand tissue (breast
meat) and an indicator of body fat (abdominal fat pad) were measured. Birds
grew significantly faster, ate more and had a lower food conversion ratio when
there was more DL-methionine or MHA-FA in the diet. After standardising the
differences in food intake between treatments, there were still highly
significant differences in liveweight between diets. After removing the
variation due to treatment differences in body mass, the data showed that
adding either DL-methionine or MHA-FA to the diet increased the mass of breast
meat and reduced the size of the abdominal fat pad. Exponential equations
fitted to the body mass and feed conversion ratio data indicate that, in an
equimolar comparison, MHA-FA is 78 and 70% as potent as DL-methionine
for growth and feed conversion ratio respectively. Similar equations fitted to
the carcass data show that MHA-FA is only 71% as potent as
DL-methionine in depositing breast tissue. Increasing amounts of DL-methionine
reduced the variability in liveweight and carcass, breast and abdominal fat
pad weights. Adding 0.05% MHA-FA reduced variability in these traits
compared with the basal ration but higher amounts of MHA-FA had no additional
effect.
Seasonal variation in fibre diameter and length in wool of grazing Merino sheep with low or high staple strength
Authors: Schlink A. C. , Mata G. , Lea J. M. , Ritchie A. J. M.
Published: September 2002

The associations between fibre growth characteristics and wool staple strength
were investigated in groups (n = 10) of Merino
wethers with either low or high staple strength. Sheep grazed together on
pastures based on subterranean clover and annual rye grass for about 13
months. The sheep were weighed and injected intradermally with
[35 S]-cysteine at about 14-day intervals.
Mid-side patches were harvested and dye bands placed in the wool at about
28-day intervals.
Patch clean wool growth, pasture digestible dry matter/ha and pasture
crude protein/ha had similar seasonal amplitudes of production (287, 286
and 267% of respective minimum). These were significantly higher than
the seasonal amplitude in liveweight (24.5%). The seasonal amplitude in
fibre diameter was significantly greater than that for rate of fibre
elongation (71.4 and 41.4% respectively). This seasonality in fibre
length and diameter resulted in statistically significant seasonal
fluctuations in the ratio of fibre length growth to fibre diameter.
Fortnightly variability in fibre diameter was not significantly related to
variability in fibre length growth rate between sheep for individual time
periods. However, for the pooled data over the experimental period a
statistically significant relationship
(R2 = 0.13,
P<0.01) was improved with the addition of parameters
for sampling time and staple strength group.
Staple strengths for the low and high staple strength groups were 25.6 and
32.8 N/ktex respectively (P = 0.057). There
were no significant differences between the staple strength groups in seasonal
change in liveweight, wool production or fibre parameters measured in this
study but the low staple strength group had longer fibres. Staple strength was
most highly correlated with mid-side fibre diameter coefficient of variation
(R2 = 0.50) followed by
seasonal amplitude in liveweight.
The influence of alkalinity and water stress on the stomatal conductance, photosynthetic rate and growth of Lupinus angustifolius L. and Lupinus pilosus Murr.
Authors: Tang C. , Turner N. C.
Published: September 2002

A glasshouse experiment examined the effect of water stress on the growth of
Lupinus angustifolius L. and
Lupinus pilosus Murr. grown on an acid sandy soil, a
limed sandy soil and an alkaline clay soil. Decreasing soil water content
decreased the stomatal conductance and photosynthetic rate, and reduced plant
growth. The responses of both species to water stress were generally similar
in the sand and limed soils, but in the alkaline soil,
L. angustifolius grown with limited water had markedly
lower conductances and photosynthetic rates than the plants in the other soils
at equivalent soil water contents. In adequately watered plants, the lupin
species differed substantially in their growth response to soil types. Whereas
the growth of L. pilosus was unaffected, the shoot dry
weight of L. angustifolius grown on the limed and
alkaline soils for 25–44 days was reduced by 32–54 and
44–86%, respectively, compared with the growth in the acid soil.
The poor growth of L. angustifolius appeared to be
primarily due to its poor root growth. In the alkaline soil, water stress
reduced rather than stimulated root growth. The results suggest that, in the
field, the limited root growth of L. angustifolius on
alkaline soils will exacerbate water deficits when the topsoil dries out in
the latter part of the season.
Phosphorus availability and the growth, mineral composition and nutritive value of ephemeral forbs and associated perennials from the Pilbara, Western Australia
Authors: Islam M. , Turner D. W. , Adams M. A.
Published: September 2002

The effect of phosphorus fertiliser on plant growth and the quality of leaf
tissues for herbivores were investigated in field and glasshouse experiments.
In the field, the relative abundance of ephemeral forb species was strongly
affected by the seasonal variation in rainfall. In winter,
C3 ephemeral forbs were abundant, whilst in summer,
C4 ephemeral grasses dominated. During the dry months,
growth of all species was poor. After rain, grasses to which phosphorus had
been added increased growth significantly.
Nutrient concentrations in ephemeral forbs were significantly greater than
those in perennial or ephemeral grasses. Phosphorus concentrations were low in
perennial and ephemeral grasses and declined during the dry months. The
nitrogen : phosphorus ratio of ephemeral forbs and perennial shrubs suggested
a deficiency of phosphorus, whilst that of ephemeral grasses suggested a
deficiency of nitrogen.
A glasshouse experiment investigated the response to phosphorus of 2 common
and abundant ephemeral forbs –
Ptilotus macrocephalus which responded to all treatments
up to a maximum rate of 200 kg P/ha, and
Ptilotus exaltatus which increased in growth up to a
maximum rate of 100 kg P/ha. In both species, the concentration of
phosphorus increased significantly with phosphorus supply, while that of
nitrogen did not vary significantly among phosphorus treatments.
Generalisations about growth and nitrogen and phosphorus nutrition of native
species based on more mesic plant communities are not readily applied in the
arid and chronically phosphorus-poor Pilbara environment. Instead, plant
life-cycle and life form play major roles in determining nitrogen or
phosphorus limitations and plant responses to added nutrients.
Seed growth of desi and kabuli chickpea (Cicer arietinum L.) in a short-season Mediterranean-type environment
Authors: Davies S. L. , Turner N. C. , Siddique K. H. M. , Leport L. , Plummer J. A.
Published: September 2002

The influence of terminal drought on the seed growth of 3 chickpea
(Cicer arietinum L.) genotypes was examined in a field
experiment at Merredin, Western Australia. Tyson, a small-seeded desi
cultivar, ICCV88201, a desi breeding line (sister line to the recently
released Sona cultivar) with medium-sized seed, and Kaniva, a kabuli cultivar
with large seed, were grown under rainfed and irrigated conditions. In the
rainfed plots, leaf water potential had decreased from above –1.2 MPa to
about –2.5 MPa and net photosynthesis from 21 to 29 µmol
CO2/m2. s to below 10
µmol CO2/m2.s, by the
time seed filling commenced. Rainfed plants had significantly fewer pods than
irrigated plants, regardless of genotype. In rainfed plants average seed
weight was reduced by 19, 23 and 34% and yield by 74, 52 and 72%
in Tyson, ICCV88201, and Kaniva respectively. Individual pods were tagged at
pod set on previously-selected representative plants and were weighed
separately from the rest of the plant over 6 subsequent harvests so that the
rate and duration of seed fill could be measured. Genotypic differences in the
maximum rate of seed fill were found to exist in chickpea. In both irrigated
and rainfed conditions, Kaniva had the highest maximum rate of seed fill
followed by ICCV88201 and Tyson. Both the rate and duration of seed growth
were reduced in the rainfed plants, regardless of genotype. Reductions in the
dry weight of the pod shell suggest that the remobilisation of dry matter from
the pod may contribute 9–15% of the seed weight in rainfed
chickpea.
Evaluation of a non-chemical disinfestation treatment on quality of pome fruit and mortality of lepidopterous pests
Authors: Chervin C. , Kreidl S. L. , Franz P. R. , Hamilton A. J. , Whitmore S. R. , Thomann T. , Vitou J. , Merriman P. R. , Walker R.
Published: September 2002

Australian pome fruit exports to northern America and Japan are rejected if
they contain lightbrown apple moth (Epiphyas postvittana
Walker) or codling moth (Cydia pomonella Linnaeus)
respectively. A warm controlled atmosphere (CA) disinfestation treatment (72 h
at 28˚C at 0, 1 or 2 kPa O2 ), followed by varying
lengths of cold storage (5 weeks, 10 weeks or 6 months), is described. Four
cultivars were studied: Packham’s Triumph pears
(Pyrus communis Linnaeus); Royal Gala; Fuji and Pink
Lady apples (Malus domestica Borkh.). Consumer panels
found that fruit subjected to the 2 kPa O2 warm CA
treatment and cold storage were as acceptable as control fruit. This is an
important finding as previously published results for a harsher treatment
described treated fruit (especially Pink Lady) as being less acceptable than
controls. Some advanced ripening was observed for treated Packham’s
Triumph pears. After 5 and 10 weeks cold storage, treated Royal Gala apples
were generally firmer than the controls. Insects were also subjected to the 2
kPa O2 warm CA treatment. The most tolerant life stage
(MTS) of lightbrown apple moth was the sixth instar with an
LT95 of 37 days cold storage (0.5˚C) after the 2
kPa O2 warm CA treatment. Comparison with previous
research suggests that the 2 kPa O2 warm CA treatment
approximately halves the time required in cold storage for effective control
of late instar lightbrown apple moth. A LT95 of 81 days
was achieved for fifth instar codling moths (considered to be the MTS) and
this may need to be reduced for export to Japan. Preliminary observations
suggested that there may not be substantial difference between the resistance
of non-diapausing and pre-diapausing codling moth larvae to the warm CA
followed by cold treatment.
Seed dormancy release in three common pasture grasses from a Mediterranean-type environment under contrasting conditions
Authors: Bolger T. P. , Chapman R. , Le Coultre I. F.
Published: September 2002

Pastures in the Mediterranean region of Australia are typically comprised of a
mixture of winter annuals, including grasses and legumes, which utilise a seed
bank to survive the long, dry summer. The risk of out-of-season summer rain
requires species from such environments to adopt appropriate strategies to
protect their seed banks. The seed bank strategies of the grasses from these
environments have, so far, received little attention. We conducted an
experiment to observe the dormancy release characteristics of 3 grasses common
to these environments when stored under contrasting thermal regimes. The
grasses studied were great brome grass (Bromus diandrus
Roth), annual ryegrass (Lolium rigidum Gaud.), and
barley grass (Hordeum leporinum Link).
The different species displayed contrasting dormancy release characteristics
over the summer. Two of the species examined (great brome grass and annual
ryegrass) displayed relatively late release from dormancy which gave high
levels of protection from false breaks. The other (barley grass) displayed
earlier release from dormancy which would enable it to better exploit earlier
true breaks but make it more sensitive to false breaks. Unlike pasture
legumes, high and fluctuating temperatures were not necessary for the seeds of
these grasses to become germinable. In fact, exposure to high temperatures
appeared more likely to suppress release from dormancy.
Evaluation of pyrimethanil (Scala) for the control of Botrytis cinerea on harvested Geraldton waxflower
Authors: Taylor M. N. , Wearing A. H. , Joyce D. C. , Simons D. H.
Published: September 2002

Pyrimethanil (Scala) is a fungicide that might be used for control of
Botrytis cinerea infecting Geraldton waxflower. New
treatments are sought to reduce the risk of developing strains of
B. cinerea that are resistant to fungicides commonly
used against it, such as benomyl (Benlate) or iprodione (Rovral). Scala was
applied to waxflower as a postharvest dip at 1.5 or 2 mL product/L.
Disease severity on and flower and leaf drop from waxflower bunches
pre-inoculated with B. cinerea were significantly
(P = 0.05) reduced by treatment with Scala.
Further, flower and foliage vase lives were significantly
(P = 0.05) longer as a result of postharvest
treatment with Scala as compared with water-treated (control) stems. Similar
degrees of disease control where achieved with either Scala or Rovral. The
results demonstrate that Scala has real potential as an alternative fungicide
for control of B. cinerea on waxflower.
Strip grazing to control wool growth rate of sheep grazing green annual pastures
Authors: Young J. , Doyle P. T. , Booth P.
Published: September 2002

We compared strip grazing (SG) as a means of controlling wool growth rate,
reducing variation in fibre diameter along the staple, and of carrying more
Merino sheep through winter on green annual pastures, with set stocking (SS)
in 3 experiments. In experiments 1 and 2, SG involved grazing to a residual
feed on offer (FOO) of 400 kg DM/ha with an estimated intake of about 0.8
kg DM/day for each sheep. Treatments commenced after pasture establishment
in autumn–winter, with both treatments stocked at 20 wethers/ha
until late spring. During spring, average liveweight changes were lower
(P<0.01) under SG than SS (55
v. 153 g/day experiment 1; –16
v. 217 g/day experiment 2). Strip grazing, compared
with SS, reduced (P<0.01) the variation in wool
growth rate and fibre diameter along the staple leading to lower
(P<0.01) clean wool weights (3.54
v. 3.94 and 2.97 v. 4.12 kg), but
finer (P<0.01) (20.9 v. 22.0
and 19.5 v. 21.5 mm), stronger
(P<0.01) (28.6 v. 25.3 and 39.9
v. 35.5 N/ktex) wool. However, there was also an
increase in vegetable matter content of the wool. The effects on annual
pastures were to increase grass (79 v. 48 and 59
v. 25%) and reduce legume (12
v. 36 and 22 v. 54%)
content at the end of spring.
In experiment 3, two strip grazing treatments were used: SGl with a residual
FOO of about 400 kg DM/ha and a stocking rate of 28 wethers/ha; and
SGh with a residual FOO of about 800 kg DM/ha and stocking rate of 14
wethers/ha. The stocking rate for SS was 12 wethers/ha. SGl, following
an autumn deferment, enabled a stocking rate of 28 wethers/ha to be
sustained through winter without supplementary feeding. This is substantially
higher than the district average stocking rate of about 7 sheep/ha. Strip
grazing reduced (P<0.01) liveweights at the
completion of treatments (SGl 41.9 v. SGh 47.9
v. SS 60.3 kg), reduced
(P<0.01) clean wool weights (3.40
v. 3.72 v. 4.54 kg) and mean fibre
diameter (19.1 v. 19.0 v. 20.9 m),
but increased staple strength (21.3 v. 19.0
v. 16.9 N/ktex).
These results are discussed in relation to opportunities to utilise strip
grazing in sheep production systems on annual pastures in south-western
Australia.
Response of onions (Allium cepa L.) to phosphate fertiliser placement and residual phosphorus on a Karrakatta sand
Authors: Robertson W. J. , McPharlin I. R.
Published: September 2002

The phosphorus (P) requirement of irrigated onions
(Allium cepa L. cv. Creamgold) was measured over 2
consecutive spring plantings using superphosphate that was freshly-applied and
applied 9 months before planting, at 0–800 kg P/ha on a newly
cleared Karrakatta sand of low natural P fertility. The response of onions to
placement of phosphate fertiliser (banded or broadcast) was also investigated.
There was a significant (P<0.001) bulb yield response
to level of applied P in all experiments. There was no significant effect of
placement on yield although the concentrations of P in the youngest mature
leaves and bulbs were on average 18% higher (i.e. 0.40
v. 0.34%) than in the broadcast treatment. A
rectangular hyperbola described the relationship of P uptake by shoots or
bulbs to level of applied P. Recovery efficiency (RE) of fertiliser P (P
uptake by bulbs at rate i of applied P – uptake in
absence of applied P/rate i of applied P) by bulbs
after curing decreased from 0.43 at 50 kg P/ha to 0.06 at 600 kg P/ha.
Recovery efficiency by bulbs at applied P required for 95 and 99% of
maximum yield was 0.20 and 0.14 respectively.
The level of freshly-applied P required for 95 and 99% of maximum
relative yield over the 2 years (maximum yield, 80–100 t/ha) was 122
and 203 kg P/ha (Mitscherlich relationship,
R2 = 0.82), respectively,
at <10 g/g Colwell P soil test (newly cleared sites). The marketable
(total – reject) yield was 94% and 92% of total yield at
122 and 203 kg P/ha respectively.
Bicarbonate-soluble P extracted from the top 15 cm of soil was determined on
residual P sites over 2 years where P was applied at 0–800 kg/ha.
These soil test levels were related to bulb yield in a Mitscherlich
relationship (R2 = 0.90).
The critical soil test P values required for 95 and 99% of maximum
relative yield, over the 2 years, were 50 and 80 g/g respectively.
Phosphorus in the youngest mature leaves required for 95 and 99% of
maximum yield ranged from 0.22–0.28 to 0.26–0.32%,
respectively, from the Mitscherlich regressions, depending on plant stage
(i.e. leaf number or days after sowing) although there was no consistent trend
with age. Soil testing can be used to reduce current applications of
fertiliser P without reducing yield. Plant testing can be used to monitor the
P status and associated fertiliser needs of onions on sands. Both these
testing procedures need to be verified in commercial crops with a wide
variation in soil test P levels and management practices. Soil and plant
testing could therefore be used to reduce fertiliser application and cost,
improve fertiliser RE by onions and reduce fertiliser P losses to water
systems on the Swan Coastal Plain. Changing placement from broadcasting to
banding does not appear to improve the efficiency of phosphate fertiliser use
by irrigated onions on Karrakatta sands.
Foliar application of rare earth elements to maize and mungbean
Authors: Diatloff E. , Asher C. J. , Smith F. W.
Published: September 2002

The foliar application of rare earth elements to plants has been reported to
increase yields of a range of crops particularly when soils contain low levels
of rare earth elements. A rare earth element fertiliser obtained from China
was chemically analysed and found to contain 45.3% nitrate plus
8.7% lanthanum and 12.4% cerium; lanthanum and cerium were the
most abundant rare earth elements measured. This fertiliser was applied once,
as 0, 0.025, 0.05, 0.1, 0.5 and 1.0% (w/v) aqueous solutions to the
foliage of 10-day-old maize (Zea mays L. cv. Hycorn 82)
and 14-day-old mungbean [Vigna radiata (L.) Wilczek
cv. Berken] plants grown in a nutrient-rich potting mix of low total rare
earth element status. For comparison, a duplicate set of plants was sprayed
with solutions containing analytical grade lanthanum and cerium nitrate at
concentrations equivalent to those measured in the rare earth element
fertiliser. No beneficial effects of the rare earth element treatments were
observed. The shoots of maize and mungbean sprayed with ≤0.1% rare
earth element fertiliser or equivalent appeared completely healthy throughout
the experiment, but plants in the 0.5 and 1.0% treatments showed
symptoms of leaf burn in maize, and small necrotic spots on mungbean leaves
within 1–3 days of treatment. These symptoms became more severe over the
next 5–9 days. The shoot dry weight of mungbean sprayed with 0.5 and
1.0% solutions was significantly (P<0.05)
reduced by 27%. Symptoms observed on plants sprayed with lanthanum and
cerium nitrate solutions were similar to those observed on plants sprayed with
the rare earth element fertiliser, and similar growth reductions occurred
also.
Persistence of introduced strains of Rhizobium leguminosarum bv trifolii in acidic soils of north-eastern Victoria
Authors: Slattery J. F. , Coventry D. R.
Published: September 2002

Summary. A 5-year study was undertaken to establish if
introduced rhizobia with higher tolerance to Al than the current inoculant
Rhizobium can persist and continue nodulating
subterranean clover (Trifolium subterraneum L.) in
acidic soils. Two Rhizobium leguminosarum bv
trifolii strains were introduced as seed inoculants with
subterranean clover at 2 acidic sites (pHCa 4.1 and
pHCa 4.3), where lime and gypsum had been applied as
soil amendments. Strain NA3001 was selected for its tolerance to high Al
concentrations when grown on an agar medium and WU95, which is a widely used
commercial inoculant strain, for its relatively poor tolerance to Al when
grown on agar. Liming the soil increased its pH and reduced the concentration
of extractable Al at both sites. In the year the subterranean clover was sown,
strain WU95 had nodule occupancy of 20–49%, decreasing with time
to 4–7% after 5 seasons (1991–95). The nodule occupancy of
strain NA3001 was initially lower than strain WU95 (14–16%), but
its occupancy did not vary with time (significant strain x time interactions,
P<0.05). These data indicate that the acid-tolerant
strain NA3001 has the potential to persist in these strongly acidic soils and,
despite the presence of high background populations of naturalised rhizobia,
to continue initiating nodulation. The use of soil amendments (lime and
gypsum) to increase pH and reduce soluble Al concentrations did not affect the
nodule occupancy of either NA3001 or WU95 with time, nor did it slow the rate
of decline in nodule occupancy of WU95.
Population improvement in lucerne (Medicago sativa L.): genetic analyses in original and improved populations
Authors: Kimbeng C. A. , Bingham E. T.
Published: September 2002

Most quantitative genetics analyses are limited to the first (mean) and second
(variance) degree statistics and their derivatives. Analyses based on third
(skewness) and fourth (kurtosis) degree statistics can be useful especially
for detecting and characterising the nature of gene interactions. Third and
fourth degree statistics were analysed and used to interpret differences in
forage yield among S1 families of lucerne derived from
double-cross populations that were synthesised before (OGDC) and after (AGDC)
improvement via inbreeding and selection. Higher levels of genetic load
(deleterious alleles) were revealed in the OGDC population compared with the
improved population. The analyses also revealed the importance of gene
interaction for forage yield in lucerne. In the unselected OGDC population,
interaction between alleles in repulsion phase linkages was more important,
whereas, in the selected AGDC population, interaction between alleles linked
in coupling phase assumed greater importance. The above results suggest that
inbreeding and selection in lucerne can accumulate favourable alleles over
generations of selection and result in population improvement. Skewness and
kurtosis are relatively easy to compute and interpret and should serve as
valuable tools in tetraploid quantitative genetics analyses.
Enhanced accumulation of mineral-N following canola
Authors: Kirkegaard J. A. , Mele P. M. , Howe G. N.
Published: September 2002

The accumulation of mineral-nitrogen (N) in the top 10 cm of soil during the
summer fallow was measured in 2 replicated field experiments following a range
of crops including wheat, oats, canola, peas and lupins. At the first site,
mineral-N was measured following harvest and in autumn before sowing
subsequent crops across 3 seasons (1994–96). Crop residues were retained
on the surface with intermittent grazing by sheep throughout the summer fallow
and burnt before the autumn measurements. The smallest increase in mineral-N
accumulation occurred following the cereals in all 3 seasons (mean increase 31
kg/ha). The highest accumulation of mineral-N in all seasons occurred
following canola (mean 94 kg/ha), 3 times as much as that following
cereals, and significantly higher than that after the legumes in 2 of the 3
seasons (mean 50 kg/ha). Differences in the amount, N content, or C : N
ratio of the surface-retained crop residues are unlikely explanations for the
observed differences in mineral-N accumulation. At a second site, measurements
of the accumulation of mineral-N following canola and wheat were accompanied
by measurements of populations of selected microorganisms involved with N
cycling in soil. More mineral-N accumulated after canola than after wheat,
however, populations of free-living, N-fixing bacteria, potential
Azospirillim species and
NH4+ oxidising bacteria were
significantly lower following canola than following wheat, and populations of
total bacteria and NO2−
oxidising bacteria did not differ. These results suggest that greater
mineral-N accumulation following canola does not result from a shift in those
microbial populations which favour mineral-N accumulation, however, more
detailed studies are required to resolve the exact cause of the differences. A
possible explanation is that biocidal compounds released by canola roots
during decay may cause a general ‘biofumigation’ and thereby
result in a flush of mineral-N similar to that which accompanies chemical
fumigation.
Effect of fungicides, seaweed extracts, tea tree oil, and fungal agents on fruit rot and yield in strawberry
Authors: Washington W. S. , Engleitner S. , Boontjes G. , Shanmuganathan N.
Published: September 2002

Seven fungicides, 2 seaweed extracts (Maxicrop and Seasol), tea tree oil
(Multicrop), and fungal agents including yeasts and an isolate of a
Trichoderma sp., were compared for the control of fruit
rots in strawberries in 5 field trials in Victoria, Australia. The fungicides
tested were thiram, iprodione, dichlofluanid, chlorothalonil, fluazinam,
phosphorous acid and fosetyl-aluminium. All treatments were applied as foliar
sprays (at recommended rates) at weekly intervals, except for one of the
Trichoderma treatments in which
Trichoderma was cultured on rice and applied around
plants at 1 and 5 weeks after the start of the trial. Rots were assessed after
harvest by incubating fruit for 3 days at room temperature
(15–25˚C). Between 55 and 71% of fruit developed rot in the
unsprayed plots and consisted mainly of grey mould
(Botrytis cinerea), leak (Rhizopus
and Mucor spp.), anthracnose
(Colletotrichum acutatum), leather rot
(Phytophthora cactorum), and stem end rot
(Gnomonia comari).
All fungicides except fosetyl-aluminium and phosphorous acid significantly
(P<0.05) reduced the total incidence of fruit rots by
27–72%. Thiram, dichlofluanid and chlorothalonil reduced grey
mould by 61–94%, anthracnose by 63–100% and leather
rot by 65–100%; iprodione reduced grey mould by
60–94% and leak by 74–96%. In one experiment each,
fluazinam reduced grey mould by 85% and leather rot by 100%, and
phosphorous acid reduced leather rot by 100%. Thiram, iprodione and
phosphorous acid also reduced stem end rot by 55–100%. Of the
biocontrols, seaweed extracts and oil, only tea tree oil in 1 trial of 3
reduced the total incidence of fruit rots significantly (by 31%), and
in 2 trials significantly reduced anthracnose, and leather rot by
60–88% and 71–72% respectively. In 2 out of 3
trials, Trichoderma sp. reduced
(P<0.05) grey mould by 29–63%. In one
trial each, seaweed extract 1, and a yeast treatment amended with malt
extract, both reduced grey mould by 40 or 54% respectively. The
addition of sucrose to the yeast treatments significantly increased the
incidence of anthracnose infection. Chlorothalonil, dichlofluanid, thiram and
iprodione sprays increased the yield (weight) of healthy fruit significantly
(P<0.05) compared with that from untreated plants by
43–114%. By contrast, none of the biocontrol treatments, the
seaweed extracts or tea tree oil increased fruit yields.
Bacterial blotch of melons caused by strains of Acidovorax avenae subsp. citrulli
Authors: O'Brien R. G. , Martin H. L.
Published: September 2002

The watermelon fruit blotch organism (Acidovorax avenae
subsp. citrulli) was confirmed as the cause of a
bacterial disease of rockmelon seedlings in January 1996. Further outbreaks
occurred in commercial nurseries during 1996–98. An associated field
disease was not observed in rockmelon and honeydew crops until May 1998 when
wet conditions led to severe leaf spotting and fruit infection in many crops
in the Burdekin district of North Queensland. Isolates of
A. avenae subsp. citrulli
originating from these outbreaks were considerably more pathogenic to
rockmelon plants than isolates originating from watermelon crops in South
Queensland. They were also less pathogenic to the weed host
Cucumis myriocarpus and could constitute new strains of
the fruit blotch organism. Tests showed the disease was readily seed
transmissible from naturally infected rockmelon and honeydew fruit for at
least 3 months after seed extraction.
Modelling pesticide residues on greasy wool: surveys of the insect growth regulators triflumuron and diflubenzuron
Authors: Morcombe P. W. , Gillibrand M. , Horton B. J. , Armstrong R. T. F. , Campbell N. J. , Best D. J. , Barr W. , Karlsson J.
Published: September 2002

Surveys have examined the relationship between louse and flystrike treatments
on farms and the resulting residues of insect growth regulators on greasy
wool. These results have been summarised using a model of the on-farm survey
data. The model estimated the amount of chemical taken up by the wool at
application. This was based on experimental breakdown rates of these
insecticides on wool determined in controlled trials.
The data indicated that the backliner, triflumuron, when used off-shears
within 24 h of shearing, was normally applied at slightly higher than the
recommended rate on-farm and left an average residue of 30 mg/kg greasy
wool at the following shearing 12 months later. Diflubenzuron, applied by
dipping or jetting, was usually applied at lower than the recommended rates,
and left an average residue of 40 mg/kg on the wool at shearing 12 months
later. When treatment was applied to very short wool (<3 weeks after
shearing) the residue was only about 20 mg/kg, but when applied at later
times after shearing the residue at the following shearing was not closely
related to the time of treatment.
The model can be used to estimate the expected residue level and likely range
of results from most standard insect growth regulator treatments. This will
improve advice to producers so most can meet specified industry standards.