bluuebunny/crossref_metadata_2025 huggingface dataset:
Capillary electrophoresis of wheat gliadin proteins and its potential for wheat varietal identification using pattern matching software
Authors: Siriamornpun S. , Wootton M. , Cox J. M. , Bekes F. , Wrigley C. W.
Published: September 2002

Gliadins from 11 wheat flours were extracted with 30% ethanol and
fractionated by capillary electrophoresis on a 20-µm i.d. untreated
fused silica capillary using 0.1 M phosphate buffer (pH 2.5) containing
polymer modifier. Capillary electrophoresis conducted at a constant current
provided very good resolution and reproducibility (relative standard deviation

<0.5) in mp;lt;15 min. Pattern matching of the profiles was performed
with the PatMatch program to provide quantitative comparisons, using the
relative mobility and intensity data for each gliadin protein. Data processing
parameters, including the integration of the electrophoregram, were optimised
for separation of gliadins extracted from either whole-grain or flour samples.
The reproducibility and repeatability were compared using peak height
and/or area percentages. The optimal window width for identifying matching
gliadin peaks was 0.80–1.20% relative mobility units. Using these
conditions, it was concluded that unknown varieties could be identified with a
confidence level of 90–95%.
Novel germplasm providing resistance to barley yellow dwarf virus in wheat
Authors: Francki M. G. , Francki M. G. , Ohm H. W. , Ohm H. W. , Anderson J. M. , Anderson J. M.
Published: September 2002

The lack of suitable genes in existing wheat germplasm collections makes
breeding for specific traits a difficult task. Although tolerance to barley
yellow dwarf viruses (BYDV) has been reported in wheat accessions, there are
no suitable levels of resistance to BYDV, so genes are sought from wild
relatives. The ability for Thinopyrum species to inhibit
replication of BYDV makes them attractive sources of resistance for germplasm
development. Breeding programs are exploiting Thinopyrum
species to develop wheat germplasm resistant to BYDV. The transfer of genes
from Thinopyrum into wheat by wide crossing and
selecting progeny using molecular markers identified suitable material to some
strains of BYDV. The implementation of molecular marker technology has been
useful for rapid selection of wheat lines with resistance to some strains of
BYDV in a breeding program. However, it is now clear that
Thinopyrum species contain a number of resistance genes
on different genomes and homoeologous chromosomes. In order to achieve
broad-spectrum resistance to the various serotypes of the BYDV complex it will
be best to combine a number of these genes. Research efforts are now focussed
on introgressing other genes from Thinopyrum into wheat
that provide resistance to several additional strains of BYDV. Molecular
markers will play an important role during selection in pyramiding genes to
develop wheat germplasm with broadspectrum BYDV resistance.
Microsatellites as markers for Australian wheat improvement
Authors: Harker N. , Rampling L. R. , Shariflou M. R. , Hayden M. J. , Holton T. A. , Morell M. K. , Sharp P. J. , Henry R. J. , Edwards K. J.
Published: September 2002

Microsatellite markers have been shown to be highly polymorphic and simple to
use in hexaploid wheat. This study aimed to establish microsatellites as
informative markers for Australian wheat improvement. By screening
microsatellites developed as part of the Wheat Microsatellite Consortium and
other available microsatellite sources, 257 informative microsatellites for
Australian wheat varieties were identified and reported in the Australian
National Wheat Molecular Marker Program microsatellite database
(http://www.scu.edu.au/research/cpcg/). Of these, 151
microsatellites identifying 172 loci were scored on at least 1 of 4 double
haploid mapping populations and were then integrated, where possible, into
existing genetic maps. Polymorphism information content values were calculated
for most microsatellites to establish a reference for their value for future
investigations. The mapping of available microsatellites enhances the quality
of the genetic maps and may provide useful genetic markers for traits of
interest to the Australian wheat breeding programs.
Targetting AFLP-DNA markers to specific traits and chromosome regions
Authors: Campbell A. W. , Daggard G. , Békés F. , Pedler A. , Sutherland M. W. , Appels R.
Published: September 2002

The amplified fragment length polymorphism (AFLP) technique is widely used in
mapping of wheat as high polymorphism rates are obtained and the procedure is
relatively simple. In this study the AFLP markers were targetted to wheat
chromosome regions of interest, especially those in which random mapping
approaches located relatively few markers. Results showed that the combination
of bulk segregant analysis and AFLP markers could target new markers to
regions of interest in wheat, and as a result, additional markers were
identified for the dough mixing time and noodle colour traits. The new markers
for noodle colour were closer to this trait than the markers previously
identified by random procedures. As a result, their association with the trait
was more significant, an aspect that is important for selection efficiency. In
order to improve genome coverage, it was found that regions of chromosomes
containing telomere sequences could be targetted using AFLPs combined with a
telomere sequence anchor primer.
Septoria nodorum blotch resistance in Aegilops tauschii and its expression in synthetic amphiploids
Authors: Loughman R. , Lagudah E. S. , Trottet M. , Wilson R. E. , Mathews A.
Published: September 2002

A collection of 433 Aegilops tauschii was screened for
response to infection with Stagonospora nodorum.
Resistance similar or marginally superior to the range observed in spring
wheat genotypes was readily identified. Three lines, RL5271, Aus18911, and
Aus21712, were resistant to a range of pathogen isolates and were similar in
resistance to a highly resistant French line, No.33. Accessions of
Ae. tauschii assessed as resistant or susceptible as
seedlings had corresponding reactions when tested as adult plants, with
resistance being commonly expressed as restricted lesion development.
Infection frequency differed between some Ae. tauschii
lines. Seedling resistance in synthetic bread wheats was expressed partially
or not at all depending on both the tetraploid and the
tetraploid/Ae. tauschii combination. Assessment of
adult responses among a range of synthetics showed occasional expression of
moderate resistance around the level observed among reference bread wheat
cultivars of similar maturity. Disease escape associated with late maturity
was common. One synthetic wheat, #231, derived from a resistant
Ae. tauschii, exhibited low adult disease expression
associated with late maturity. This line was resistant in seedling tests and
seedling resistance was dominant in F1 hybrids to bread
wheat.
A single gene controls resistance to septoria nodorum blotch in the Aegilops tauschii accession AUS21712
Authors: Murphy N. E. A. , Loughman R. , Wilson R. E. , Lagudah E. S. , Appels R. , Jones M. G. K.
Published: September 2002

A potential source of resistance to septoria nodorum blotch had been
identified in an accession of the wild wheat,
Aegilops tauschii. A cross was made between the
resistant Ae. tauschii accession, AUS21712, and a
susceptible accession, CPI110889, to study the genetics of resistance. The
parental accessions and the F1,
F3, and F4 progeny were screened
in the glasshouse as seedlings. The resistant parent took significantly longer
to develop symptoms, developed significantly fewer lesions, and expressed
significantly lower levels of disease than the susceptible parent. The
F1 mean response for disease severity indicated
resistance was dominant. The genotypic ratios generated from the screening of
the F3 and F4 generations were not
significantly different from the genotypic ratio expected for a single gene.
The efficacy of the resistance and its simple genetic control in the
Ae. tauschii accession AUS21712 means that the potential
exists to use this Ae. tauschii resistance gene in a
bread wheat breeding program.
Mapping components of flour and noodle colour in Australian wheat
Authors: Mares D. J. , Campbell A. W.
Published: September 2002

Flour and noodle colour influence the value of wheat
(Triticum aestivum L.) and are obvious targets for
breeders seeking to improve quality, end-product range, and marketability of
wheat. The objective of this investigation was to identify quantitative trait
loci (QTLs) associated with flour and noodle colour traits and with individual
components of colour. One hundred and sixty-three doubled haploid lines
derived from Sunco Tasman, white-grained, prime hard, and hard wheats adapted
to the north-eastern region of Australia were used for the bulk of this study
and were supplemented by doubled haploid populations derived from CD87 Katepwa
and Cranbrook Halberd for comparisons of flour colour. Samples of Sunco
Tasman, together with parental lines, were grown at Narrabri, NSW, in 1998 and
1999 and at Roma, Qld, in 1998 and used for visible light reflectance
measurements of flour brightness (CIE L*) and yellowness (CIE b*), and
white salted noodle (WSN) and yellow alkaline noodle (YAN) brightness,
yellowness, and colour stability. Xanthophyll content and polyphenol oxidase
(PPO) activity were measured spectrophotometrically.
No consistent QTLs were identified for flour L* or initial L* of WSN
and YAN. Xanthophyll content was very strongly associated with QTLs located on
chromosomes 3B and 7A and these QTLs also had a major influence on flour
b*, WSN b*, and YAN b*. Noodle brightness at 2, 24, and 48 h and
the magnitude of change in noodle L* and b* with time were affected by
QTLs on 2D, contributed by Tasman, and, to a lesser degree, 2A. The QTL on 2D
was clearly associated with control of grain PPO, an enzyme implicated in
darkening of Asian style noodles. QTLs located on 2B, 4B, and 5B and
associated with control of grain size or flour protein content also appeared
to influence a number of colour traits.
The hardness locus in Australian wheat lines
Authors: Osborne B. G. , Turnbull K. M. , Anderssen R. S. , Rahman S. , Sharp P. J. , Appels R.
Published: September 2002

The genetic factors that determine grain hardness in Australian wheat
(Triticum aestivum L.) germplasm were investigated by
studying the grain from 4 crosses (160–180 lines per cross). Although
not all the crosses were between hard and soft wheats, the doubled haploid
lines derived from the crosses showed significant variation in hardness as
assessed either by the Single-Kernel Characterisation System (SKCS 4100) or
the scanning electron microscopy appearance of cut surfaces. The wheat
cultivars used in the study were Cranbrook, Halberd, CD87, Katepwa, Sunco,
Tasman, Egret, and Sunstar and of these only Egret is normally regarded as
soft. The quantitative information from the SKCS 4100 was integrated into the
genetic map information established for the Cranbrook Halberd, CD87 Katepwa,
and Sunco Tasman crosses. For the Egret Sunstar cross, the limited information
available from the positioning of genetic markers was used to specifically
examine the linkage between the hardness trait and the
Pina-D1 (puroindoline) genetic locus on 5DS, and very
close linkage was established. The Egret Sunstar cross was also used to
develop a more rigorous rheologically based analysis of the raw SKCS crush
response data. In addition, the cut surface of the lines was analysed and most
(98%) of the samples showed a genetic linkage between the appearance of
the cut surface (related to vitreousness) and the SKCS hardness index. Among
the other crosses only Cranbrook Halberd showed linkage of the hardness trait
to the previously identified hardness locus (ha) located on 5DS as defined by
DNA markers for the Pina-D1 locus, and the
microsatellite wmc233. The statistical association was shown to be highly
significant, with approximately 30% of the variation accounted for by
the 5DS region. Another region on chromosome 4D showed a significant
association in the Cranbrook Halberd cross. The CD87 Katepwa cross did not
show any consistent associations between the SKCS measures and chromosome
region, whereas in the Sunco Tasman cross a highly significant association
only on chromosome 4B (accounting for 20% of the variation) was
suggested. The Sunco Tasman cross showed an overlap of the chromosome region
that accounted for variation in both grain weight and hardness and this
influence of grain weight on hardness was independently confirmed by a
detailed qualitative rheological analysis of the crush response profiles for
the Egret Sunstar lines. It is evident from the study that, in Australian
wheat lines, there are some major effects on grain hardness that are not
associated with the classical ha locus located on 5DS.
Flour proteins linked to quality traits in an Australian doubled haploid wheat population
Authors: Cornish G. B. , Békés F. , Allen H. M. , Martin D. J.
Published: September 2002

The Cranbrook/Halberd doubled haploid population has provided a unique
opportunity to examine in detail the contributions made by a number of
different high molecular weight (HMW) and low molecular weight (LMW) glutenin
alleles to the dough properties in a set of homogeneous lines of wheat. A
range of different instruments was employed, including Farinograph,
Extensograph, Do-Corder, Resistograph, and GRL/EasyMix, to study the dough
rheology of the lines from 3 sites over 2 years. Correlation studies showed
that 2 basic parameters (dough strength and extensibility) were measured by
these different instruments. The results presented are mainly from the
Extensograph, which is a major Australian standard for determining release and
marketing classification of Australian wheats.
Approaches to investigate the data include bulk segregant analysis,
distribution of protein alleles in the population, and multiple linear
regression. As expected, the HMW glutenin alleles made a major contribution to
dough strength, with a minor, but not insignificant, contribution from the LMW
glutenin alleles. From a knowledge of their glutenin alleles, a glutenin
strength score (GSS) was devised to allow breeders to rank the dough strength
of various lines. The GSS scoring system is based on both HMW and LMW glutenin
alleles, adding to a total out of 10. Extensibility, on the other hand, was
predominantly influenced by protein levels in the flour and environmental
conditions such as site and season. However, the LMW glutenin alleles make a
significant genetic contribution to the extensibility, which can be assessed
by using a glutenin extensibility score. These two glutenin quality scores
currently include only the alleles present in the parents, Cranbrook and
Halberd, but this could be expanded to include a wider range of alleles by
analysis of the quality data from other doubled haploid populations. These
quality scores would then be an extremely useful tool for assessing the
potential quality of parental and early generation germplasm in wheat breeding
programs, by a knowledge of the allelic composition of their HMW and LMW
glutenins.
Screening cereals for genotypic variation in efficiency of phosphorus uptake and utilisation
Authors: Osborne L. D. , Rengel Z.
Published: September 2002

One hundred and six Australian cereal genotypes, including wheat, triticale,
and rye, were screened for their ability to take up and utilise soluble
phosphorus at different rates of P supply. Plants were screened in outdoor
tanks irrigated at regular intervals with nutrient solution amended with 3
rates of P. Genotypes were ranked according to the following 3 criteria: shoot
growth at deficient P supply, the relative shoot growth rate (dry weight at
deficient P/dry weight at sufficient P), and phosphorus utilisation
efficiency (amount of dry matter produced per unit of P accumulated in shoots
corrected for seed P content). Considerable genotypic variation in growth and
P utilisation efficiency was found in the cereal germplasm. Rye and triticale
were generally more efficient in taking up and utilising P than wheat at low
rates of P supply. Wheat genotypes Egret and Durati showed relatively high,
and genotype Cadoux relatively low, P efficiency.
A soil-based method to screen for zinc efficiency in seedlings and its ability to predict yield responses to zinc deficiency in mature plants
Authors: Genc Y. , McDonald G. K. , Graham R. D.
Published: September 2002

Nutrient efficiency measures the ability of a plant to grow and produce grain
when the availability of a nutrient is low. Seedling tests for nutrient
efficiency will be most useful if the results correlate well with grain yield
responses. In two experiments, a diverse range of barley genotypes was
screened for zinc (Zn) efficiency at the seedling stage and the relationship
between vegetative and grain measures of Zn efficiency was examined.
In Expt 1, 54 barley and 4 wheat genotypes were grown at 2 levels of Zn (0.02
and 0.8 mg/kg soil) for 21 days. Zinc efficiency ranged from 18% to
52%. The visual symptoms of Zn deficiency varied considerably between
genotypes and was significantly correlated with Zn efficiency. Root:shoot
ratio was increased by Zn deficiency and varied between genotypes, but these
differences were not related to Zn efficiency. Zinc concentration and
especially Zn content at 0.02 mg Zn/kg were significantly related to Zn
efficiency. In Expt 2, 15 genotypes, selected on the basis of their response
in Expt 1, were grown to maturity at either 0.1 mg Zn/kg or 2.4 mg
Zn/kg. Zn efficiency, based on relative grain yield, ranged from 5%
to 54%. High efficiency was associated with a large number of grains
per plant and high kernel weight. Rankings of Zn efficiency in the experiment
were significantly correlated with the rankings for visual scores in Expt 1.
The 2 experiments suggested that deficiency symptoms at the seedling stage can
identify efficient genotypes and could be useful for routine screening for Zn
efficiency.
Independent data from multisite comparisons over 8 years were used to examine
the long-term performance of efficient and inefficient genotypes in the field.
Hierarchical cluster was used to define efficient and inefficient groupings
within the 56 genotypes examined in Expt 1, based on their responses to Zn.
The Zn-efficient genotypes tended to yield more than the Zn-inefficient
genotypes. The data provide prima facae evidence that
high Zn efficiency may contribute to improved adaptation of barley in South
Australia.
Nutritional strategies for the prevention of hypocalcaemia at calving for dairy cows in pasture-based systems
Authors: McNeill D. M. , Roche J. R. , Stockdale C. R. , McLachlan B. P.
Published: September 2002

This review considers the current literature on the macro-mineral nutrition of the soon-to-calve, or transition, dairy cow. Calcium is the main focus, since milk fever (clinical hypocalcaemia) appears to be the most common mineral-related problem faced by the transition cow Australia-wide. The importance of minimising calcium intake and optimising the balance of the key dietary electrolytes, sodium, potassium, sulfate, and chloride, in the weeks before calving is highlighted. Excess dietary potassium can, in some situations, induce milk fever, perhaps even more effectively than excess calcium. Excess sodium remains under suspicion. In contrast, excess dietary chlorine and, to a lesser extent, sulfur can improve the ability of the cow to maintain calcium homeostasis. Diets that promote either a hypomagnesaemia or hyperphosphataemia have also the potential to precipitate milk fever at calving. Current prevention strategies focus on the use of forages with moderate to low levels of calcium, potassium, and sodium, and also rely on or utilise addition of chloride and sulfate in the form of 'anionic' feeds. Anionic salts are one example of an anionic feed. However, legitimate questions remain as to the effectiveness of anionic salts in pasture-feeding systems. The causes and prevention of milk fever are considered from the perspective of the variety of Australian feedbases. Impediments to the use of anionic feeds in Australia feeding systems are outlined. The potential for improving maternal reserves of calcium around calving to reduce the risk of milk fever is also discussed.
Survival and growth of Aporrectodea longa (Lumbricidae) fed on sheep and cow dung with and without moxidectin residues
Authors: Svendsen Tina S. , Baker Geoff H.
Published: September 2002

Deep-burrowing (anecic) earthworm species that can enhance the incorporation
of surface organic matter such as dung are rare in pastures in southern,
mainland Australia. The anecic earthworm
Aporrectodea longa (Ude) (Lumbricidae), which is common
in northern Tasmania, has the potential to colonise pastures in the higher
rainfall areas of south-eastern Australia and is being considered for
introduction there to improve soil properties and pasture production. However,
in these areas, antiparasitic drugs are widely used in grazing ruminants and
residues of these drugs are excreted in the faeces. We studied the effects of
the broad-spectrum anthelmintic moxidectin in sheep and cow dung, on the
survival and growth of A. longa in the laboratory. Over
a 10-week period, there were no lethal or sublethal effects of the drug and
its metabolites in sheep and cow dung on A. longa. The
worms removed more sheep dung than cow dung from the soil surface and hence
had a higher growth rate on sheep dung.
Shearing ewes at mid-pregnancy is associated with changes in fetal growth and development
Authors: Revell D. K. , Morris S. T. , Cottam Y. H. , Hanna J. E. , Thomas D. G. , Brown S. , McCutcheon S. N.
Published: September 2002

This study investigated the effect of mid-pregnancy shearing (at Day 70 of pregnancy, P70) on herbage intake of grazing single- and twin-bearing ewes, lamb birth weight, and cold resistance of new-born lambs. At pregnancy diagnosis on P50, 30 single-bearing and 30 twin-bearing ewes were allocated either to be shorn at P70 (n = 15 for each pregnancy rank) or to remain unshorn to serve as controls (n = 15 for each pregnancy rank). All ewes were mated over a 3-day period with synchronisation of their oestrus. Herbage intake was measured indirectly from in vitro pasture digestibility and faecal output of grazing ewes, with the use of intra-ruminal chromium slow-release capsules, over six 5-day periods from P64 to P105. The weights of placental and fetal tissues were assessed in a subgroup of 16 ewes at P140 and P141. In the remaining sheep, lamb liveweight at birth and during lactation until weaning at 103 days of age was measured, and cold-resistance of new-born lambs was assessed by measuring summit metabolic rate (SMR) by indirect calorimetry. Ewe liveweight (corrected for fleece weight), condition score, and herbage intake during pregnancy were not affected by shearing treatment. Mid-pregnancy shearing did not affect placental weight, but increased the relative weights (i.e. g/kg liveweight) of fetal thyroid gland and lungs and reduced the relative weight of adrenal glands and heart. The ratio of secondary to primary wool follicles in near-term fetal skin was about 10% higher in offspring of shorn than of unshorn ewes. The metabolic rate of fetal hepatic tissue was increased by mid-pregnancy shearing, particularly in twin fetuses, possibly indicative of an increase in placental transport of nutrients to the fetuses. This conclusion is supported by the greater birth weight (average response 0.5 kg) of lambs born to ewes shorn at mid-pregnancy. Mid-pregnancy shearing also increased the SMR of new-born twin lambs by 16%, but decreased the SMR of singleton lambs by 26%. These results indicate that mid-pregnancy shearing can increase lamb birth weight without increasing ewe herbage intake or placental weight. An increase in the efficiency of nutrient uptake by the placenta is implied, and possible effects on the activity of thermogenic tissues are discussed.
Temporal dynamics of gradients of phosphorus, ammonium, pH, and electrical conductivity between a di-ammonium phosphate band and wheat roots
Authors: Zhang X. K. , Rengel Z.
Published: September 2002

Our previous studies have demonstrated that di-ammonium phosphate (DAP) banded into soil led to a rise in pH and EC, and concentrations of NH4+ and bicarbonate-extractable phosphorus around the band. When these chemical gradients develop too close to plant roots, they may cause toxicity and stop root growth. However, the temporal dynamics of gradient development and effects on plants are not known. In this study, wheat was grown in specially constructed pots, with DAP banded 2.5 cm below the seed and either 1 or 2.5 cm horizontally from seed. Plants were harvested at different growth stages to establish the temporal variation in soil chemical gradients between the fertiliser band and the plant roots. Visual toxicity symptoms and decreased root and shoot dry weight and root length in the plants growing with
DAP banded 1 cm horizontally away from seed were obvious 14 days after sowing, but disappeared after 6 weeks.
Plants in that treatment had a significantly lower number of heads than control plants, implying that there was a
harmful effect on reproductive growth and yield with DAP banded too close to wheat seed.
The pH increased by one unit and EC increased 2-fold in the soil section containing a DAP band 14 days after
sowing. By Day 63, the pH peak disappeared and the EC peak in the 1-cm horizontal distance banding treatment
shifted toward soil sections containing the highest root density (4 cm away from the seed on the side opposite to
where fertiliser was banded). In the 2.5-cm banding treatment, the EC peak disappeared 42 days after sowing. The
ammonium peak was measured in the soil section containing the fertiliser band in the 1-cm banding treatment on
Day 14, but the peak shifted to the section with the highest root density by Day 42, and disappeared completely by
Day 63. The 2.5-cm banding treatment resulted in a lower ammonium peak compared with the 1-cm treatment after
14 and 42 days, and the highest concentration was found in the section with the highest root density by Day 63.
Phosphorus concentration gradients were similar to those of ammonium, except that less depletion and movement
of P occurred during the 63-day experiment.
In conclusion, the chemical gradients around the fertiliser band show strong temporal and spatial dynamics.
However, toxicity caused by close banding and hence high concentrations of ammonium in the initial growth stage
results in a decreased wheat yield potential.
Physiological causes for decreased productivity under high salinity in Boma, a tetraploid Chloris gayana cultivar. II. Oxidative stress
Authors: Luna C. M. , de Luca M. , Taleisnik E.
Published: September 2002

In tetraploid cultivars of Rhodes grass (Chloris gayana Kunth) productivity decreases significantly under saline conditions. Two closely related clones of cv. Boma (T and S), exhibiting different degrees of salt tolerance, were compared with determine the physiological causes for such decrease. In those clones, salt tolerance was associated with differences in the proportion of dry leaves, salt gland density, Na excretion rate, and oxidative stress damage. The purpose of this paper is to evaluate whether salt tolerance and oxidative stress development in these clones are related to the activity of two antioxidant enzymes. Experiments were conducted in a greenhouse, in winter and summer, in plants treated with 0, 100, or 200 mm NaCl. In the summer, increases in oxidative damage, as determined by malondialdehyde (MDA) concentration, mirrored decreases in CO2 fixation at high salinity, especially in clone S. In clone T, salinity induced higher increases in Fe-SOD (superoxide dismutase) activity in summer-grown plants, and in ascorbate peroxidase (APX) in winter-grown plants. Oxidative stress induced by low paraquat concentration also induced an increase in Fe-SOD in leaf segments of clone T, and APX was less affected in clone T than in clone S. These results suggest that the clones differ in the control of antioxidant enzymes. Nevertheless, leaf death in winter was not related to increases in MDA, indicating that the association between salinity, leaf senescence and oxidatives stress is also influenced by other factors.
Interactions between weaning age, weaning weight, sex, and enzyme supplementation on growth performance of pigs
Authors: Dunshea F. R. , Kerton D. K. , Cranwell P. D. , Campbell R. G. , Mullan B. P. , King R. H. , Pluske J. R.
Published: September 2002

Digestive capacity of early-weaned pigs may be insufficient to fully digest many ingredients currently used in weaner diets. The aim of this experiment was to determine whether an exogenous enzyme preparation with broad carbohydrase activity could benefit pigs that developmentally might be immature at weaning, especially with regard to gastrointestinal development. Eighty Large White × Landrace pigs were used in a 2 × 2 × 2 × 2 factorial experiment with the factors being: weaning age (14 or 24 days), weaning weight (heavy or light), sex (boar or gilt), and dietary Biofeed Plus CT (0 or 500 μg/g) which contained fungal xylanases, pentosanases and β-glucanases. Pigs were housed individually and given a wheat-based (550 g/kg) diet containing 15.0 MJ DE and 15.9 g lysine/kg on an ad libitum basis for 21 days. The diet also contained 50 g/kg of soybean meal and 50 g/kg of lupin (Lupinus�angustifolius) kernels. The liveweights of heavy (H) pigs weaned at 24 or 14 days and light pigs (L) weaned at 24 or 14 days were 7.9 and 5.3 and 5.2 and 3.9 kg, respectively. Pigs weaned at 14 days grew slower (157 v. 345 g/day) than those weaned at 24 days, although there was a suggestion of an interaction between age and weight at weaning (P = 0.081). Thus, H and L pigs weaned at 14 days grew at 148 and 166 g/day, whereas H and L pigs weaned at 24 days grew at 374 and 315 g/day, respectively. Although there was no main effect of enzymes on daily gain (248 v. 254 g/day, P = 0.80), feed intake (278 v. 284 g/day, P = 0.79), or feed conversion ratio (1.19 v. 1.25, P�=�0.35), there were interactions with weaning age on daily gain (P = 0.050) and feed intake (P = 0.060). Pigs weaned at 14 days grew slower (176 v. 138 g/day) and ate less (206 v. 174 g/day), whereas pigs weaned at 24 days grew faster (321 v. 369 g/day) and ate more (351 v. 394 g/day), when supplemented with enzymes. During the third week after weaning there were interactions between dietary enzymes and sex (P = 0.060) and dietary enzymes and age (P = 0.023) on daily gain. Thus, pigs weaned at 24 days and supplemented with Biofeed Plus CT grew more quickly during the third week (559 v. 460 g/day), whereas the converse was true for pigs weaned at 14 days (286 v. 334 g/day). Also, enzyme-supplemented boars grew better over this period (457 v. 371 g/day), whereas the converse was true for gilts (388 v. 423 g/day). In conclusion, these data clearly indicate that the greatest determinant of post-weaning performance under the present conditions was the age of the pigs at weaning. Dietary enzyme supplementation appeared most efficacious in boars weaned at an older age, although benefits did not become apparent until 2 weeks after weaning.
Current and emerging environmental challenges in Australian agriculture—the role of plant breeding
Authors: Richards R. A.
Published: September 2002

Dryland farming systems are evolving due to sustainability issues and market pressures that impact on growers; levels of atmospheric CO2 and temperatures, both of which can dramatically impact on crop growth, are increasing at unprecedented levels; subsoil constraints and water stress remain. In this paper I assess the emerging and current environmental challenges to farmers and identify challenges and opportunities for plant breeders. Questions are raised which require debate. For example, crops will soon be growing at atmospheric CO2 levels more than triple those in which they evolved. Should plant breeders be responding to the anticipated effects of elevated CO2 and temperature? In other instances, issues are discussed which require immediate research by the plant breeding community. Examples of the latter are breeding crops that maximise water and nutrient use, either by increasing the rooting zone and/or improving the ability to grow roots into inhospitable subsoils; also, breeding crops specifically to overcome constraints imposed by farming systems. Immediate attention to these issues is required to sustain our landscape and agricultural systems as well as enhancing our ability to grow crops for an internationally competitive market place.
Evaluation of fungicides for the management of sclerotinia blight of peanut
Authors: Ryley M. J. , Kyei N. A. , Tatnell J. R.
Published: September 2002

Three trials were conducted in the Burnett region of southern Queensland,
Australia, in the 1993–94 and 1994–95 seasons to determine the
efficacy of fluazinam, procymidone, and iprodione for managing sclerotinia
blight of peanut. Different combinations of rates, nozzle types, and spraying
times were used in each trial. Two or 3 sprays of fluazinam at 0.75 and 1.0 kg
a.i./ha, and of procymidone at 0.688 and 0.75 kg a.i./ha, were the
most effective combinations that reduced disease incidence and increased
yield. Iprodione at rates up to 0.5 kg a.i./ha did not significantly
improve the yield compared with unsprayed treatments in any trial. In one
trial at Tingoora in 1994–95, pre-infection treatments in which the
first spray of fluazinam or procymidone was applied before symptoms appeared
were more effective than post-infection treatments in which the first spray
was applied soon after symptoms were seen. At J. Bjelke-Petersen Research
Station (JBPRS) in 1994–95, a banded spray of procymidone at 0.688 kg
a.i./ha using a single flat-fan 8004VB nozzle centred over the row
significantly increased yield and reduced disease incidence compared with a
spray using 3 hollow-cone nozzles (HB4-70) per row, with 1 nozzle over the row
and 1 drop nozzle on each side of the row directed at the bases of the plants.
At JBPRS in 1993–94, a band spray of fluazinam at 0.333 kg a.i./120
L.ha, applied with a single flat-fan 80015EVB nozzle immediately after the
appearance of symptoms, was as effective in reducing the rate of disease
development for 3 weeks, as was a directed application using three 80015EVB
nozzles at the same time and concentration, but at 3 times the rate per area
(1.0 kg a.i./360 L.ha).
Analysis of line x environment interactions for yield in navy beans. 2. Pattern analysis of lines and environment within years
Authors: Redden R. J. , DeLacy I. H. , Butler D. G. , Usher T.
Published: September 2002

Seven years of multi-environment yield trials of navy bean
(Phaseolus vulgaris L.) grown in Queensland were
examined. As is common with plant breeding evaluation trials, test entries and
locations varied between years. Grain yield data were analysed for each year
using cluster and ordination analyses (pattern analyses). These methods
facilitate descriptions of genotype performance across environments and the
discrimination among genotypes provided by the environments. The observed
trends for genotypic yield performance across environments were partly
consistent with agronomic and disease reactions at specific environments and
also partly explainable by breeding and selection history. In some cases,
similarities in discrimination among environments were related to geographic
proximity, in others management practices, and in others similarities occurred
between geographically widely separated environments which differed in
management practices. One location was identified as having atypical line
discrimination. The analysis indicated that the number of test locations was
below requirements for adequate representation of line × environment
interaction. The pattern analyses methods used were an effective aid in
describing the patterns in data for each year and illustrated the variations
in adaptive patterns from year to year. The study has implications for
assessing the number and location of test sites for plant breeding
multi-environment trials, and for the understanding of genetic traits
contributing to line × environment interactions.
Quantitative genetic studies on wool yellowing in Corriedale sheep. II. Clean wool colour and wool production traits: genetic parameter estimates and economic returns
Authors: Benavides M. V. , Maher A. P.
Published: September 2002

The potential for improvement of clean wool colour (CWC) in Corriedale sheep
via selection was examined. The heritability, and phenotypic and genetic
correlations, of CWC, brightness (Y), greasy (GFW) and clean (CFW) fleece
weights , yield percentage (Yield), mean fibre diameter (MFD), and visual
colour score were estimated from 440 progeny of 19 sires of a Corriedale flock
using restricted maximum likelihood (REML) procedures with average information
algorithm (AIREML).
The heritability of CWC was estimated at 0.27±0.13. Clean wool colour
showed strong positive genetic correlations with CFW and MFD. Visual colour
score and CWC were also positively genetically correlated. As expected, direct
selection criteria against MFD, CWC, or visual colour score would reduce CWC;
however, direct selection against MFD would improve clean wool colour with
negligible reductions on CFW, thus resulting in small economic gains.
Several selection indices were calculated having either CFW, MFD, and CWC or
CFW and MFD as selection criteria. The b-values of an unrestricted index were
estimated at I1 = + 1.15 CFW + 0.13 MFD
+ 0.43 CWC, with positive correlated responses for all 3 breeding
objective traits (CFW, MFD, and CWC). A second index, where CFW was restricted
to nil genetic change, was estimated at: I2 =
+ 0.14 CFW − 0.02 MFD + 0.01 CWC. This index was expected to
cause a negligible genetic gain for CWC (−0.04 Y–Z
units/head.year). To avoid economic losses with the reduction on CFW, a
third selection index was calculated where CWC was restricted to nil change.
The index was estimated at I3 = +0.61 CFW
− 0.07 MFD + 0.02 CWC with expected increases in CFW and decreases
in MFD. Selection indices with (a) CFW and MFD
(I4) and (b) CFW, MFD, and visual
colour score (I5) as selection criteria would increase
CFW, MFD, and CWC at the same rates observed in I1.
Peppermint rust in Victoria: the incidence - severity relationship and its implication for the development of an action threshold
Authors: Edwards J. , Taylor P. A. , Parbery D. G. , Halloran G. M.
Published: September 2002

Todd's Mitcham peppermint is grown in north-eastern Victoria for
essential oil production. Peppermint rust, caused by
Puccinia menthae, reduces oil yields by up to
50%. Disease progress was monitored over 4 seasons (1994–98) on
untreated peppermint and peppermint treated each season with propiconazole.
The untreated peppermint died out within 4 years. A relationship between
disease incidence and disease severity was found that could be described by
the equation Y = 0.26 x 10
0.02X where Y is disease severity
(%) and X is disease incidence (%), with a
linear phase at levels of disease incidence <60%. The relationship
was consistent for data from different seasons, two separate geographic
regions of Victoria, and for pot- and field-grown peppermint. The use of the
incidence–severity relationship to develop an action threshold for the
initiation of fungicide treatments is discussed.
Response of sweet potato cultivars to acid soil infertility factors. I. Effects of solution pH on early growth
Authors: Ila'ava V. P. , Asher C. J. , Blamey F. P. C.
Published: September 2002

Sweet potato [Ipomoea batatas (L.) Lam.] is
cultivated on soils varying widely in chemical properties, but relatively
little is known about the effects of pH on the growth of this crop. In
commercial and subsistence agriculture, sweet potato is propagated mostly from
stem cuttings. This paper reports effects of a range of pH treatments
(3.5–8.0) in flowing solution culture on early growth from cuttings of
15 sweet potato cultivars. Root growth was either greatly reduced or inhibited
at pH 3.5. Increasing the pH to 4.0 markedly increased root development.
Further increases in solution pH from 4.0 to 8.0 did not appear to affect root
growth in most cultivars. Top growth in most cultivars showed a tendency to
increase when pH was increased from 3.5 to 5.5 before declining with further
increases in solution pH. The sweet potato cultivars studied differed widely
in their tolerance to low pH, producing 16–48% of maximum top dry
mass at pH 3.5. Tissue analysis from selected cultivars showed that K and Ca
appeared to be limiting at pH 3.5, while P may have been deficient at pH 8.0.
Results of this study indicate that low pH per se does
not appear to be a major factor responsible for poor sweet potato yields in
acid soils.
Genetic and environmental factors affecting temperament of zebu and zebu-derived beef cattle grazed at pasture in the tropics
Authors: Burrow H. M. , Corbet N. J.
Published: September 2002

Separate experiments were conducted in 2 zebu-derived herds grazed at pasture
in the dry tropics of Central Queensland, to determine genetic and
environmental effects on At Duckponds, temperament of
crossbreed steers and heifers from 2 calf crops was assessed using an
objective flight speed score and 2 subjective scores (a visual flight speed
score and a crush score) to determine whether the subjective tests were useful
as selection criteria for on-farm selection programs. At Belmont, temperament
of bull and heifer calves from 7 calf crops was measured by recording
objective flight speed scores of individual animals at weaning (6 months), 12
months, and 18 months.
At Duckponds, heritabilities of average objective flight speed, visual flight
speed, and crush scores were 0.35, 0.08, and 0.30, respectively. Phenotypic
and genetic correlations between the different measures of temperament were
moderate to low. Based on low correlations and re-ranking of fixed effect
classes that occurred between subjective tests, it was concluded the
subjective tests were not sufficiently correlated with the objective measure
to justify their use. The objective flight speed score is recommended as the
test of choice for use in breeding programs using
Bos indicus or Bos indicus derived
animals. At Belmont, even a single flight speed score was moderately
heritable, but use of the average of 2 or 3 repeated flight speed scores
substantially increased heritability. The realised heritability of average
flight speed score was 0.48, almost identical to the estimated heritability of
average flight speed score of 0.50. Direct responses to a single generation of
divergent selection for single flight speed scores at different ages
demonstrated that selection for flight speed was effective in modifying flight
speed scores of progeny. Correlated responses to divergent selection for
flight speed scores indicated that, under extensive grazing systems, the
economic value of temperament arose mainly through a reduction in production
costs.
There were significant differences in temperament scores between sire breeds
used in the crossbreeding experiment at Duckponds, but there were no
differences between lines at Belmont. From these results, it is possible that
Continental breeds either have specific, negative combining ability when
crossed with Brahmans, or themselves have temperaments that are no better than
those of Bos indicus. Treatment to control
gastrointestinal parasites (worms) had a significant (P
< 0.001) negative effect on flight speed.
Water use and water-use efficiency of chickpea and lentil in a Mediterranean environment
Authors: Zhang H. , Pala M. , Oweis T. , Harris H.
Published: September 2002

Water supply is a major constraint to crop production for both chickpea and
lentil in West Asia and North Africa, both of which have a Mediterranean
climate. This study examined water use and water-use efficiency of chickpea
and lentil from 3 experiments over 12 seasons, 1986–87 to 1997–98,
in northern Syria. The strongest determinant of grain yield of chickpea and
lentil and their water use under rainfed conditions is rainfall and its
distribution. Large inter-seasonal fluctuations in weather resulted in larger
inter-seasonal fluctuations in water use, and therefore in production of
legumes. Seasonal evapotranspiration (ET) was significantly correlated with
seasonal rainfall for both chickpea and lentil. Mean ET over 12 seasons was
268 mm for chickpea and 259 mm for lentil. The depth of extraction was, on
average, 120 cm for chickpea and 80 cm for lentil. The average extractable
soil water was 125 mm for chickpea and 90 mm for lentil over 12 seasons. For
lentil, water-use efficiency for dry matter (WUEdm) and for seed yield (WUEgr)
was 13.7 and 3.8 kg/ha.mm, respectively; for chickpea, WUEdm and WUEgr,
8.7 and 3.2 kg/ha.mm, respectively. Supplemental irrigation can
significantly increase grain yield of both chickpea and lentil. However, there
was less increase in grain yield in the wet seasons than in the dry seasons.
Estimated soil evaporation was 80 mm for lentil and 105 mm for chickpea. The
average transpiration efficiency was 7.1 kg/ha.mm for lentil and 6.4
kg/ha.mm for chickpea. Estimated potential transpiration efficiency for
seed yield was 11.8 kg/ha.mm for lentil and 12.2 kg/ha.mm for
chickpea. Both the average water-use efficiency and potential transpiration
efficiency for lentil and chickpea were lower than those for cereals. Despite
this, the rotation benefits and higher economic return provide the potential
for these legumes to replace fallow or to break continuous cereal cropping in
the region's farming system.
Relationships between in vivo and in vitro lipid metabolism in lactating goats
Authors: Dunshea F. R. , Trigg T. E. , Chandler K. D. , Bell A. W.
Published: September 2002

Multiparous Sannen dairy goats were used to compare
in vivo and in vitro lipid
metabolism. Goats were infused simultaneously with a mixture of
[2-3H]-glycerol and of
[1-14C]-palmitic, -stearic, and -oleic acid
complexed in plasma in early (Day 11, n = 4), mid
(Day 37, n = 4), and late (Day 80,
n = 3) lactation to determine
in vivo lipid kinetics. Perirenal adipose tissue
biopsies were obtained and used to measure in vitro
lipid kinetics under both basal and norepinephrine-stimulated conditions.
Plasma non-esterified fatty acid (NEFA) concentrations and NEFA entry rate
were higher (P < 0.05) during early compared with mid
and late lactation. Plasma glucose and glycerol concentrations and glycerol
entry rate were not different between stages of lactation. Although variable,
in vitro lipogenesis increased more than 10-fold
(P = 0.077) between early and late lactation,
whereas there were no significant differences between NEFA and glycerol
release at any stage of lactation. In vitro lipid
metabolism, when expressed per gram of adipose tissue, was poorly correlated
with in vivo lipid. However, when
in vitro NEFA release was extrapolated to the whole
animal the correlations were markedly improved. These data demonstrate that
the reduction in lipid reserves which occurs during early lactation is the
result of increased NEFA mobilisation and reduced lipogenesis rather than
increased lipolysis. Although more variable than in vivo
measures of lipid metabolism, in vitro metabolism of
adipose tissue can reflect metabolic status.