bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of durum wheat and triticale cultivars as affected by thermo-photoperiodic conditions
Authors: Giunta Francesco , Motzo Rosella , Virdis Adriana
Published: September 2002

The understanding of the interaction between thermo-photoperiodic conditions
and the genetic control of anthesis date is fundamental in explaining the
environmental adaptation of durum wheat and triticale cultivars. The
development of 8 durum wheat (Triticum turgidum L. var.
durum) and 2 triticale
(×Triticosecale Wittmack) cultivars was studied at
3 sowing dates (September, November, and March) by observations on apex
development, number and rate of leaf appearance, spike fertility, and number
and length of elongated internodes.
Variation in anthesis date was mostly explained by the total number of leaves,
which ranged between 8.3 and 15, and hence by the duration of the phase of
leaf primordium production. Total leaf number also affected the length ofthe
subsequent phase until flag leaf appearance. The phyllochron was influenced by
both sowing date and genotype, and was minimum in the March sowing (87
degree-days). The genotypic variability in phyllochron was due either to the
variations in leaf number or to genotypic intrinsic differences. Time to
terminal spikelet stage was related to the number of spikelets per spike and
to the number of elongated internodes, although stem length depended more on
internode length than on internode number. The number of spikelets per spike
was associated with leaf number, but their relationship was affected by the
thermal conditions during spikelet primordium initiation. No differences were
observed between wheat and triticale cultivars, apart from the number of
spikelets per spike.
Variation within and between F2-derived families for grain yield and barley malting quality
Authors: Lu M. Q. , O'Brien L. , Stuart I. M.
Published: September 2002

Variation within and between F2-derived families for
grain yield and malting quality was investigated using
F4 breeding lines derived from F2
families of 4 barley crosses. The variation between
F2-derived families was greater than within
F2-derived families for grain yield and all malting
quality attributes. Superior segregates almost exclusively came from the best
performing families. The greater similarity of lines eventually drawn from an
F2-derived family has significant implications for
selection strategies in barley breeding programs as it facilitates the early
discard of F2-derived families. To maximise the
exploitation of genetic variation as early as possible, selection for malting
quality could start in the F2 generation using near
infrared transmittance (NIT) spectroscopy and for grain yield in the
F3 generation.
Effects of lime and gypsum on growth of sweet potato in two strongly acid soils
Authors: Ila'ava Vele P , Blamey Pax , Asher Colin J
Published: September 2002

There were strong relationships between exchangeable aluminium (Al) and
relative top yield, and between soil pH and relative top yield in the Garret
and Bisinella soils. Sweet potato plants produced maximum top yields at soil
exchangeable Al <3.0 cmol ((+)/kg, with a 10% yield
reduction coinciding with a value of approximately 5.0 cmol (+)/kg.
The value was lower for the Bisinella soil than the Garret soil. In the case
of pH, maximum yield in both soils was evident at a soil pH of 5.0 with
90% of maximum yield being achieved at about pH 4.7. These results
suggest that soil pH would be a good index for Al toxicity. The close
relationships between sweet potato growth and both exchangeable Al and soil pH
need to be explored further to determine whether it will hold across a wide
range of acid soil groups.
Embryo and seed coat factors produce seed dormancy in capeweed (Arctotheca calendula)
Authors: Ellery A. J. , Chapman R.
Published: September 2002

Capeweed [Arctotheca calendula (L.) Levyns.]
is common in annual pastures of southern Australia. The physiological basis of
seed dormancy in capeweed seeds was studied to determine the likely role of
dormancy in the success of this species. Two dormancy mechanisms were
identified: one embryo-based and the other imposed on the embryo by the seed
coat. Embryo dormancy could be overcome by leaching, suggesting that this form
of dormancy was caused by a water-soluble germination inhibitor, possibly
localised in the cotyledons. Following an initial after-ripening period,
embryo dormancy was rapidly relieved under conditions experienced on the soil
surface during summer. Ungerminated embryos entered secondary dormancy in
winter. Seed coat-imposed dormancy persisted longer than primary embryo
dormancy, but was not associated with mechanical constriction of embryo
growth, or with limited water or oxygen supply to the embryo.
Embryo and seed coat dormancy mechanisms interacted to maintain a high level
of dormancy in these seeds at all times. Thus, a large proportion of seeds
produced might enter a persistent seed bank, enabling re-establishment
following years when seed production is limited by unfavourable seasonal
conditions or cropping activities.
Role of superoxide dismutase and peroxidase activities in paraquat-resistant redflower ragleaf (Crassocephalum crepidioides (Benth.) S. Moore)
Authors: Ismail B. S. , Chuah T. S. , Salmijah S. , Hussin Khatijah H.
Published: September 2002

The constituent level of superoxide dismutase (SOD) and peroxidase (POD)
activities in susceptible (S) and resistant (R) biotypes of
Crassocephalum crepidioides, prior to and following
paraquat treatment, was examined at the 6-leaf (6–7 weeks) and 10-leaf
(9–10 weeks) stages. Earlier dose response studies had shown survival of
resistant plants at the 6- and 10-leaf stages to be 2.9 and 2.6 times that of
the susceptible biotype. At the 6-leaf stage, the SOD activity of whole leaf
extracts in the untreated R biotype was lower (86%) than that of the S
biotype. Paraquat treatment increased SOD activity in the R biotype 2-fold
relative to the control (no paraquat) but not in the S biotype. There was also
no significant difference (P > 0.05) in the SOD
activities of the 2 biotypes after each was treated with paraquat.
Furthermore, at the 10-leaf stage, paraquat treatment did not change SOD
activity in the S biotype but the activity increased 3-fold
(P < 0.05) in the treated R biotype. These
observations suggest that SOD could play a part in the mechanism of paraquat
resistance and that this is more evident at the more mature stage. The ratio
of POD activity (R/S) was relatively constant at 6- and 10-leaf stages
after paraquat treatment. POD therefore did not appear to be important in the
mechanism of paraquat resistance in C. crepidioides.
Effect of feeding tuna oil supplement protected against hydrogenation in the rumen on growth and n-3 fatty acid content of lamb fat and muscle
Authors: Kitessa S. M. , Gulati S. K. , Ashes J. R. , Scott T. W. , Fleck E.
Published: September 2002

To re-evaluate the incorporation of n-3 fatty acids into depot fats and muscle
a group of lambs were fed indoors a concentrate ration supplemented (3%
DM) with much lower levels than used previously of rumen-protected tuna oil
for 42 days. A second group of lambs were fed diets supplemented with tallow
(3% DM) to make the diets iso-caloric. There was no difference in final
liveweight, average daily gain, hot carcass yield, or dry matter intake (DMI)
between lambs fed with tallow and tuna oil-supplemented diets. Both
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels in muscle
tissue samples from tuna oil-fed lambs were thrice those in tallow-fed lambs
(1.81% v. 0.61% for EPA; 1.51
v. 0.44% total fatty acids for DHA). There were
also significant incorporations of EPA and DHA into omental and perirenal fat.
The level of linolenic acid in both muscle and adipose tissue of tuna oil fed
lambs was double that of tallow-fed lambs. Feeding protected tuna oil
significantly enhanced the n-3 fatty acid content of lamb meat.
Crop responses to lime in long-term pasture-crop rotations in a high rainfall area in south-eastern Australia
Authors: Li G. D. , Helyar K. R. , Conyers M. K. , Cullis B. R. , Cregan P. D. , Fisher R. P. , Castleman L. J. C. , Poile G. J. , Evans C. M. , Braysher B.
Published: September 2002

A long-term trial, known as ‘managing acid soils through efficient
rotations’ (MASTER), commenced in 1992 to develop and demonstrate a
cropping system that is economically viable on the highly acid soils of the
traditional permanent pasture region in south-eastern Australia, so that their
fertility is sustained or improved. There were 2 permanent pasture systems and
2 pasture–crop rotations, each with and without lime. This paper reports
the effect of lime on crop production over the first cycle (6 years). On
annual pasture–crop rotations, lime significantly increased the dry
matter production at anthesis and grain yields of wheat (cv. Dollarbird)
compared with the unlimed treatments. Averaged across years from 1992 to 1997
(excluding the severe drought year 1994), wheat crops produced 1.6 t/ha
more grain on the limed treatments than on the unlimed treatments (3.6
v. 2.0 t/ha). On perennial pasture–crop
rotations, the lime effects varied with crops grown at each phase and year.
For example, despite being tolerant of acidity, oats (cv. Yarran) responded to
lime in 1996. Likewise, triticale (cv. Abacus) responded to lime in 1997.
Wheat (cv. Dollarbird) that is moderately tolerant to acidity responded to
lime in phase 6 from 1992 to 1997 excluding 1994 (3.5 v.
1.7 t/ha). Acid-tolerant wheat varieties, triticale, and narrow-leaf
lupins are considered the most viable crops for the soil and climatic
conditions encountered in this high rainfall (5000—800 mm per annum)
area of south-eastern Australia.
A rapid PCR protocol for marker assisted detection of heterozygotes in segregating generations involving 1BL/1RS translocation and normal wheat lines
Authors: Nadella K. D. , Peake A. S. , Bariana H. S. , Cooper M. , Godwin I. D. , Carroll B. J.
Published: September 2002

A rapid and reliable polymerase chain reaction (PCR)-based protocol was developed for detecting zygosity of the 1BL/1RS translocation in hexaploid wheat. The protocol involved a multiplex PCR with 2 pairs of oligonucleotide primers, rye-specific Ris-1 primers, and consensus 5S intergenic spacer (IGS) primers, and digestion of the PCR products with the restriction enzyme, MseI. A small piece of alkali-treated intact leaf tissue is used as a template for the PCR, thereby eliminating the necessity for DNA extraction. The test is simple, highly sensitive, and rapid compared with the other detection systems of 1BS1RS heterozygotes in hexaploid wheat. PCR results were confirmed with AFLP analyses. Diagnostic tests for 1BL/1RS translocation based on Sec-1-specific ELISA, screening for chromosome arm 1RS controlled rust resistance locus Yr9, and the PCR test differed in their ability to detect heterozygotes. The PCR test and rust test detected more heterozygotes than the ELISA test. The PCR test is being used to facilitate S1 family recurrent selection in the Germplasm Enhancement Program of the Australian Northern Wheat Improvement Program. A combination of the PCR zygosity test with other markers currently being implemented in the breeding program makes this test economical for 1BL/1RS characterisation of S1 families.
IGF-I is not a useful marker for nutritional status in the growing pig under commercial conditions
Authors: Ma L. , Dunshea F. R. , Brockwell Y. M. , Inglis R. L. , Kingston D. J. , Sillence M. N.
Published: September 2002

Plasma hormone concentrations were measured in gilts after fasting, long-term
protein restriction, or supplementation. In 11-week-old pigs fasted overnight,
plasma insulin, glucagon, gastrin, urea, and glucose were increased 30 min
after re-feeding (P < 0.05), whereas IGF-I did not
change. In 16-week-old gilts fed a standard commercial diet [14.6%
crude protein (CP)], or a high-protein diet (16.7% CP) for 4
weeks, the high-protein diet increased weight gain (13%;
P < 0.05) and carcass weight (4%;
P < 0.05), but did not alter plasma IGF-I, insulin,
or glucagon. In 10-week-old gilts fed high-protein diets (19.4% and
18.3% CP), or low-protein diets (15.5% and 13.3% CP) for
12 weeks during the grower and finisher phases, respectively, the low-protein
diet decreased weight gain (18%; P < 0.001)
and carcass weight (11%; P < 0.01), with a
marked increase in plasma glucagon (P < 0.05), no
change in insulin, and only a trend towards decreased IGF-I
(P = 0.1). The pigs were more sensitive to
altered dietary protein at 10 weeks of age than at 16 weeks. Plasma IGF-I was
not responsive to the short-term effects of feeding or the long-term effects
of dietary protein. Glucagon could provide a useful marker for nutritional
status in young pigs, provided that time of feeding is taken into account.
The root growth response to heterogeneous nitrate supply differs for Lupinus angustifolius and Lupinus pilosus
Authors: Dunbabin V. , Rengel Z. , Diggle A.
Published: September 2002

Little is known about the ability of legume root systems to respond to the
heterogeneous supply of nitrate. A split-root nutrient solution experiment was
set up to compare the root growth response of 2 lupin species,
Lupinus angustifolius L. (dominant tap root and primary
lateral system) and L. pilosus Murr. (minor tap root and
well-developed lateral root system), to differentially supplied nitrate. These
2 species represent the extremes of the root morphology types present across
the lupin germplasm.
Nutrient solution containing low (250 M) or high (750 M) nitrate was supplied
either uniformly, or split (high and low) between the upper and lower root
system. The average growth rate and total root length of
L. pilosus was 1.7 times that of
L. angustifolius. For both species, the increased
proliferation of roots in a high nitrate zone was accompanied by a decrease in
root growth in the low nitrate zone, giving approximately the same total
growth as the uniform low nitrate treatment. This correlative growth rate
response was 15% larger for the first-order branches of
L. pilosus than L. angustifolius.
While few second-order branches grew for
L. angustifolius, the second-order laterals of
L. pilosus showed a 2-fold correlative root growth and
branching response to the split treatments, with no difference in growth
between the uniform high and low nitrate treatments. The second-order laterals
thus proliferated in response to the differential supply of nitrate and not
the absolute concentration. While the growth rate and branching of the
second-order laterals of L. pilosus exhibited a typical
correlative response, first-order branching was inhibited in all split
treatments, regardless of whether the roots were in the high or low nitrate
zone. This response was not seen in L. angustifolius.
The difference in the root growth response of the 2 root system types to
differentially supplied nitrate suggests a potential in the lupin germplasm
for developing a line capable of greater nitrate capture from the soil
profile.
Soil water extraction by dryland crops, annual pastures, and lucerne in south-eastern Australia
Authors: Angus J. F. , Gault R. R. , Peoples M. B. , Stapper M. , van Herwaarden A. F.
Published: September 2002

The extraction of soil water by dryland crops and pastures in south-eastern
Australia was examined in 3 studies. The first was a review of 13 published
measurements of soil water-use under wheat at several locations in southern
New South Wales. Of these, 8 showed significantly more water extracted by
crops managed with increased nitrogen supply or growing after a break crop.
The mean additional soil water extraction in response to break crops was 31 mm
and to additional N was 11 mm.
The second study used the SIMTAG model to simulate growth and water-use by
wheat in relation to crop management at Wagga Wagga. The model was set up to
simulate crops that produced either average district yields or the potential
yields achievable with good management. When simulated over 50 years of
weather data, the combined water loss as drainage and runoff was predicted to
be 67 mm/year for poorly managed crops and 37 mm for well-managed crops.
Water outflow was concentrated in 70% of years for the poorly managed
crops and 56% for the well-managed crops. In those years the mean
losses were estimated to be 95 mm and 66 mm, respectively.
The third study reports soil water measured twice each year during a phased
pasture–crop sequence over 6.5 years at Junee. Mean water content of the
top 2.0 m of soil under a lucerne pasture averaged 211 mm less than under a
subterranean clover-based annual pasture and 101 mm less than under
well-managed crops.
Collectively, these results suggest that lucerne pastures and improved crop
management can result in greater use of rainfall than the previous farming
systems based on annual pastures, fallows, and poorly managed crops. The
tactical use of lucerne-based pastures in sequence with well-managed crops can
help the dewatering of the soil andreduce or eliminate the risk of groundwater
recharge.
Manipulation of thyroid hormones in ruminants - a tool to understand their physiological role and identify their potential for increasing production efficiency
Authors: Villar D. , Rhind S. M. , Arthur J. R. , Goddard P. J.
Published: September 2002

Manipulations of thyroid hormone secretion and function can be used to cure
thyroidal deficiencies or overactivity and as a tool to investigate their
physiological roles and identify potential protocols for enhancing animal
performance. An essential approach to the investigation of thyroid hormone
action involves the induction of hypothyroidal states. Methods of inducing
hypothyroidal states in ruminants include thyroidectomy and treatment with
thionamides. There are few data concerning the induction of an optimal degree
of hypothyroidism for the study of thyroid function in ruminants, unlike the
situation in rodents. The effects of hypothyroidism on the physiology of
ruminants, and the relative merits of thyroidectomy or of treatment with
thionamides to manipulate thyroid hormone profiles in them, are reviewed and
discussed. Thyroidectomy in ruminants induces an acute, irreversible,
hypothyroidal state. It also has indirect, predominantly adverse, effects on
many physiological processes and impairs health. Thus, thyroidectomised (THX)
animals cannot be sustained for long-term studies without thyroid hormone
replacement. Antithyroid drugs of the thionamide class, on the other hand,
have been used with success to induce varying degrees of hypothyroidism,
predominantly less severe than those induced by thyroidectomy. The changes
induced by drugs are reversible upon withdrawal of treatment. However,
treatment may require daily administration of the drug for several weeks
before stable plasma concentrations of thyroid hormone are achieved.
Furthermore, at high doses, these drugs can have toxic side effects. It is
concluded that the treatment regime of choice will depend on the objectives of
the individual study. Knowledge of the activities of thyroid hormone
metabolising, deiodinase enzymes in the target tissues is also required if the
actions of some of these drugs, their physiological roles in modulation of the
thyroid hormones, and, crucially, their potential effects on animal health and
production are to be properly understood and exploited.
Heritability estimates and genetic and phenotypic correlations of lamb production parameters with hogget liveweight and fleece traits in Western Australian Merino sheep
Authors: Cloete S. W. P. , Greeff J. C. , Lewer R. P.
Published: September 2002

Heritability estimates (h2) for weight of lamb weaned
and number of lambs weaned totalled over 3 reproduction opportunities were
estimated in a multi-bloodline Western Australian medium wool resource flock.
These traits were defined to give an indication of lifetime lamb production
(the ewes were retained in the breeding flock for a maximum of 4 lambing
opportunities). Both reproduction traits were highly variable, as suggested by
coefficients of variation of approximately 50%. The between-bloodline
variance ratio was significant (P < 0.05), but failed
to exceed 5% of the total across-bloodline phenotypic variation.
Within-bloodline h2 ( s.e.) was estimated at 0.154 0.040
for total weight of lamb weaned, and at 0.141 0.040 for total number of lambs
weaned. Within-bloodline genetic correlations of both traits with hogget
liveweight were positive and significant (P < 0.05;
0.58 0.11 and 0.26 0.13, respectively). Within-bloodline genetic correlations
of the reproduction traits with wool production were generally positive, being
0.26 0.11 for the correlation between total weight of lamb weaned and clean
fleece weight, and 0.29 0.15 for the correlation between total number of lambs
weaned and clean fleece weight. Clean yield was genetically unrelated to both
measures of reproductivity. The genetic correlation of total weight of lamb
weaned per breeding ewe with fibre diameter was positive in sign, but smaller
than twice its standard error (0.17 0.10). The corresponding estimate for
total number of lambs weaned was 0.16 0.12. It was concluded that the
reproduction traits investigated would respond to selection in Western
Australian Merinos if it should form part of a breeding strategy. Genetic
correlations with hogget liveweight and wool traits were generally favourable.
The rate of reduction in carotenoid concentration in fat of steers fed a low carotenoid ration, and the role of increasing carcass fatness
Authors: Knight T. W. , Death A. F. , Lambert M. G. , McDougall D. B.
Published: September 2002

Experiments were carried out on steers to determine the effects of different
allowances of a low carotenoid ration on fat yellowness and the interval from
starting on the ration to significant decreases in fat yellowness. In Expt 1,
forty 17–18-month-old steers were fed a ration of maize grain, maize
silage, and soybean meal containing 6 mg β-carotene/kg DM, and were
slaughtered 0, 28, 42, or 70 days after starting on the ration. Significant
decreases in fat yellowness and carotenoid concentration in the fat occurred
70 days after starting on the ration. The exception was subcutaneous fat,
which had a significant reduction of carotenoid concentration after only 28
days. Decreases in fat yellowness coincided with and were of a similar
magnitude to increases in fat deposits. In Expt 2, 3 groups
(n = 13) of 24–26-month-old steers were fed
a ration of maize grain and pasture silage, which contained 33 mg
β-carotene/kg DM. The ration was fed to steers for 63 days at 1 of 3
allowances with the aim of gaining weight rapidly (FASTGN), gaining weight
slowly (SLOWGN), or losing weight (WTLOSS). A fourth group of steers
(n = 9) was slaughtered at the beginning of the
experiment. The growth rates of the steers over the 63 days were 1.72, 0.71,
and –0.03 kg/head.day for FASTGN, SLOWGN, and WTLOSS, respectively.
Fat yellowness and carotenoid concentration in the fat depots were lower
(P < 0.05) for FASTGN than for WTLOSS and steers
slaughtered at the beginning of the experiment, with no differences between
the latter 2 groups. The SLOWGN were intermediate with higher fat yellowness
or carotenoid concentration in some fat depots than for FASTGN and lower than
for WTLOSS in other fat depots. In both experiments there were negative
correlations between plasma cholesterol (PChol) concentration and fat
yellowness and carotenoid concentration, and positive correlations between
these traits and plasma carotenoid concentration (PCar). PCar :PChol ratio was
a better predictor of fat yellowness and carotenoid concentration than PCar or
PChol concentration alone. The conclusions were that reduction in fat
yellowness was largely caused by a dilution of existing fat with whiter fat
and the rate of change in fat yellowness depended on the rate of fat
deposition. The results suggest that carotenoids do not come out of fat once
deposited there but further experiments are required to confirm this
suggestion.
Genetic purity analysis of hybrid broccoli (Brassica oleracea var. italica) seeds using RAPD PCR
Authors: Crockett Phillip A. , Singh Mohan B. , Lee C. K. , Bhalla Prem L
Published: September 2002

Determination of genetic purity of F1-hybrid seeds is aquality control requirement in the production of hybrid Brassica vegetableseeds. Hybrid varieties of these vegetable crops have arisen from a limitedgermplasm base, making discrimination of parental and hybrid lines verylaborious and troublesome. The use of RAPD PCR for evaluating seed purity in acommercial F1-hybrid broccoli a single cultivar bywithholding water. In Expt 2, plants of EP and MK were grown together in thesame container and received water daily with gradation in intensity of waterdeficit achieved by varying the daily water ration per container.All cultivars in each experiment exhibited commonly reported responses towater deficit, characterised by diminished evaporative surface area andincreased root : shoot ratio. The response of MK was primarily morphologicaland MK plants had smaller plant size, higher root : shoot ratio, and a lowergrowth rate compared with temperate cultivars. By contrast, response oftemperate cultivars was primarily physiological; stomatal conductance oftemperate cultivars was lower and these cultivars had a greater tendency forleaf lamina osmotic a
Quality traits of wheat determined by small-scale dough testing methods
Authors: Békés F. , Gras P. W. , Anderssen R. S. , Appels R.
Published: September 2002

The dough properties of flours from the grain of 172 doubled haploid lines of
a Cranbrook Halberd cross, grown at 3 locations, were determined with
traditional and small-scale dough testing equipment. The experiments were
aimed at determining the genetic factors that underpin the flour processing
properties of wheat flour. Seven mixing parameters determined on a 2-g
Mixograph™, as well as the maximum resistance (RMAX) and extensibility
(EXT) measured on a Micro-Extension Tester, were identified as quality traits
for genetic mapping studies, to identify the underlying quantitative trait
loci (QTL). For each of the 3 locations in which the wheat lines were grown,
relationships between the quality parameters and genetic markers were
constructed for the populations. The associations of HMW- and LMW-glutenin
allele combinations with the quality traits were investigated using ANOVA,
linear parametric, and non-parametric methods. Of particular interest were
qualitative and quantitative assessments of the extremes of the quality traits
in each population. The relative contributions of the glutenincoding loci to
quality were determined and it was found that the growing conditions to which
wheat lines were subjected significantly affected the analyses. The nature and
extent of these variations could not be explained by changes in protein
content alone, and were related to environmentally induced alterations in the
protein composition. From a comparison of the measurements made with the
small-scale Mixograph™ with those from both the Extensograph™ and
a Micro-Extension Tester, it was concluded that the same information about
RMAX and EXT obtained from traditional extension testing could be obtained
using small-scale dough tests. The data provided a direct validation for the
application of small-scale testing for the screening of large populations. The
comparisons of large and small scale testing procedures also provided the
basis defining a new trait, ‘M-extensibility’, which is obtained
from protein content and selected Mixograph data. This parameter was able to
be measured more accurately and was shown to be closely related to the
traditional extensibility measurement, and thus very useful for
molecular/genetic analysis. The M-extensibility trait could be mapped as a
major QTL to LMW-glutenin subunit loci on chromosomes 1B and 1D.
Changes in pH and organic carbon were minimal in a long-term field study in the Western District of Victoria
Authors: Cayley J. W. D. , McCaskill M. R. , Kearney G. A.
Published: September 2002

Changes in soil pH from a long-term experiment at Hamilton, Vic., associated
with time, fertiliser application, and stocking rate were assessed. The pH was
measured in a 1 :5 suspension of soil in water (pHW)
from 1980 onwards and in a 1:5 suspension of soil in 0.01 M
CaCl2 (pHCa) from 1984 onwards.
Topsoils (0–10 cm) were sampled regularly from 1980 to 1999, and the
soil profile to a depth of 80 cm in 1994. The site was sown to perennial
ryegrass, phalaris, and subterranean clover in 1977. Treatments fertilised
with different amounts of superphosphate were grazed by sheep at stocking
rates of 7–19 dry sheep equivalents (DSE)/ha. Average applications
of phosphorus (P) ranged from 0.5 to 38.7 kg P/ha.year.
The pHCa of the topsoil in 1984 was 4.9. It decreased at
an average rate of 0.005 pHCa or 0.008
pHW units/year, with little variation due to
fertiliser or stocking rate. Measurements in 1994 revealed subtle but
statistically significant (P < 0.01) trends in soil
pHCa that were associated with grazing pressure, inputs
of fertiliser, and whether or not areas sampled were used by the sheep for
camping. The top 0–5 cm of soil was slightly less acidic (+0.07
pHCa units) in the camp areas compared with non-camp
areas. Below 5 cm to a depth of 80 cm, camp areas were more acidic
(–0.19 pHCa units). At the highest stocking rates,
heavier applications of superphosphate were associated with greater subsoil
acidity: –0.06 pHCa units per 100 kg phosphorus
(P) applied. There was no relationship at medium stocking rates. At low
stocking rates, higher P applications were associated with more alkaline
subsoils. Net removal of product from 1979 to 1994 (wool and meat removed from
plots and excreta transferred to camps) was estimated to be equivalent to
140–380 kg/ha of lime over this 15-year period. The organic carbon
(OC) content of the topsoil did not change over 20 years of records from 1979,
and was unaffected by inputs of P. In 1994, the OC content of the 0–5 cm
layer of topsoil was greater than the 5–10 cm layer (mean values
5.5% and 3.8% respectively; P < 0.001).
The OC content of camp areas was higher than that of non-camp areas, this
difference being more pronounced in the 0–5 cm layer
(P < 0.01).
It was concluded that the rate of change of pH was slow because of the high pH
buffering capacity of the soil, the small amount of alkalinity removed in
product, and the generally high perennial grass content of the pastures. Soils
shown to be at greatest risk of acidification from this study were those under
camp areas, and where high fertiliser rates were applied to pastures with a
low perennial grass content. Rotational grazing should diminish these problems
by reducing the concentration of excreta in camp areas, and favouring
perennials over annuals in both camp and non-camp areas. Inputs of lime may
eventually be needed to compensate for the acidifying effect of product
removal.
Albumin polymorphism and mapping of a dimeric a-amylase inhibitor in wheat
Authors: Singh J. , Appels R. , Sharp P. J. , Skerritt J. H.
Published: September 2002

Any new protein or DNA marker is potentially useful to add detail to already
constructed genetic chromosome maps and may be valuable in breeding programs
wherever polymorphism exists. Non-gluten proteins represent
15–20% of total wheat grain proteins. Isoelectric focusing of
wheat (Triticum aestivum L. em Thell.) proteins on
ultrathin gels showed high resolution and was found to be a useful tool in the
differentiation of wheat varieties. Seventeen hexaploid wheat varieties were
screened to investigate polymorphism of albumin proteins using isoelectric
focusing. Polymorphism was observed for albumin polypeptides of pI 5.20, 5.85,
6.25, and 7.1, and 8.0. The polymorphic protein of pI 7.1 was mapped by
analysing doubled haploid populations from the intervarietal crosses,
Cranbrook x Halberd and Synthetic x Opata 85. This protein locus was
designated as Iha-B1.2, and is located on the short arm
of chromosome 3B.
The effects of temperature elevation and water deprivation on lamb physiology, welfare, and meat quality
Authors: Lowe Tim E. , Gregory Neville G. , Fisher Andrew D. , Payne Steven R.
Published: September 2002

Romney-cross ewe lambs (n = 27) were subjected to controlled environmental conditions to induce acute heat stress. The goals of the study were to: (1) determine appropriate physiological indicators of acute heat stress, (2) determine threshold rectal temperatures (Tr) for catecholamine and cortisol release, (3) determine effects on meat quality, and (4) assess the effect of dehydration on the above measures. There were 3 treatments: control (ambient temperature and humidity), heat stress (33°C, and 85-100% humidity), and heat stress combined with water deprivation. The duration of the treatment period was 12 h. Respiration rate (Rf) and rectal temperature (Tr) were highly correlated with increasing temperature humidity index (THI) (r > 0.75, P < 0.001), whereas heart rate was less responsive to THI (r = 0.30, P < 0.05). The welfare of these lambs was at risk at Tr greater than 40.5°C, a point at which respiration rate was maximal and unable to prevent further increases in Tr. Plasma cortisol concentrations were increased in heat-stressed lambs after Tr reached approximately 40.7°C. Plasma catecholamines were only elevated in lambs when Tr was greater than 42°C. The majority of lambs subjected to heat stress had a Tr less than 42°C, and there were no significant effects on meat quality. Despite exhibiting increases in plasma protein concentrations, there were no indications that dehydrated lambs were under additional stress during heat challenge in comparison with hydrated lambs.
Outbreaks of house mice in Australia: limitation by a key resource
Authors: White T. C. R.
Published: September 2002

Plagues of mice are generated in cereal-growing areas when mice can sustain
breeding at high levels for much longer than usual. They may do this when,
after good early rains, they have access to abundant
ripening seeds, followed by large quantities of
prematurely germinating seeds in seedheads soaked by
further rain just prior to harvest. Both ripening and germinating seeds,
unlike mature seeds, contain high levels of soluble amino acids that are
necessary for successful breeding. Results from work on birds and other
animals support this hypothesis.
Effect of dietary free lipid on anaerobic fungi and digestion in the rumen of sheep
Authors: Faichney G. J. , Gordon G. L. R. , Welch R. J. , Rintoul A. J.
Published: September 2002

Six 2-year-old Border Leicester Merino wethers were offered diets containing
75% mixed wheaten and lucerne hays (2:1), 10% rolled barley, and
15% unprotected and protected cottonseed kernel supplement mixed to
provide 2.1, 4.0, or 5.9% free lipid in a total lipid content of
7% of the dry matter.
Rumen anaerobic fungi were undetectable with 5.9% free lipid but were
present at normal levels with 4 and 2.1% free lipid. In association
with the absence of anaerobic fungi, protozoal numbers tended to be lower but
bacterial counts increased. Lignin degradation was substantially reduced (by
45–60%) and digestion of hemicelluloses (by 7%) and
cellulose (by 9%) was also reduced. As rumen digestion of
hemicelluloses was reduced by 40% and of cellulose by 14%,
digestion in the large intestine partially compensated for the effect of free
lipid on rumen digestion. Acetate:propionate ratios decreased as free lipid
content increased but the calculated reduction in methane emissions suggested
that they only partly compensated for the reduction in energy digestion caused
by the free lipid.
It was concluded that there is a threshold level, >4% but
<6%, for polyunsaturated free lipid above which rumen anaerobic
fungi cannot be maintained and fibre digestion will be reduced.
The future of pollinators for Australian agriculture
Authors: Cunningham Saul A. , FitzGibbon Frances , Heard Tim A.
Published: September 2002

Agriculture in Australia is highly dependent on insect pollination, in particular from the introduced western honeybee, Apis mellifera. Most agricultural pollination is provided as an unpaid service by feral A. mellifera and native insects. A smaller proportion of agricultural pollination is provided as a paid service by beekeepers. Insect pollination is threatened by misuse of insecticides and the loss of remnant vegetation, but most potently by the likelihood that the honeybee mite, Varroa destructor, will enter the country. Now is the time to prepare for the effect of these changes, and international experience with pollinator decline should serve as a guide. We need to protect and manage our remnant vegetation to protect wild pollinators. Insurance against declining A. mellifera will come through the development of management practices for alternative pollinator species. By developing native insects as pollinators we can avoid the risks associated with the importation of additional introduced species.
Conservation and use of global plant genetic resources for insect resistance
Authors: Quisenberry S. S. , Clement S. L.
Published: September 2002

Insect and mite damage accounts for a significant level (30−70%) of total crop production losses. Conservation and use of plant genetic resources are required to endow crops with pest resistance, as well as to enhance crop yields and nutritional qualities. Advancements in molecular genetic technologies have the potential to facilitate the introgression of insect resistance genes from conserved and unadapted germplasm into cultivated crops. Long−term food security and the sustainability of agricultural productivity worldwide can be enhanced with the conservation and use of global plant genetic resources.
Exploiting novel germplasm
Authors: Heslop-Harrison J. S. (Pat)
Published: September 2002

Only 0.1% of the world's plant species are grown as crops, and even within these crop species, only a small proportion of the total genetic variability is used in commercial varieties. Here, I address 6 inter-related questions about why it might be desirable to exploit novel germplasm in breeding programs: to exploit plant diversity, to meet continuing breeding objectives in major crops, to develop new crops, to meet new needs from existing crops, to ensure all the world's people benefit from breeding programs, and to ensure the sustainability of crop production. Both species which are rarely cultivated, and genes from accessions and species related to existing crops, can be exploited to meet the need for improvement of agricultural production. Molecular and statistical methods have the potential to speed introduction of novel germplasm—allowing quantitative assessment of diversity, characterisation of desirable genes, tracking of chromosomes, genes, or gene combinations through breeding programs, selection of rare recombination events, and direct gene transfer through transformation. But the challenges of maintaining desirable characters in varieties incorporating novel germplasm, overcoming genetic stability problems, and ensuring safety are considerable.
Frequency of feeding and form of lucerne hay as factors affecting voluntary intake, digestibility, feeding behaviour, and marker kinetics in ewes
Authors: de Vega A. , Gasa J. , Guada J. A. , Castrillo C.
Published: September 2002

The effects of the form (chopped or ground and pelleted) of a lucerne hay, and
its frequency of feeding (once daily with restricted access, twice daily, or
once every 2 h) on voluntary intake, digestibility, feeding behaviour, and
marker kinetics was studied on 12 Rasa Aragonesa ewe lambs. The results showed
that differences between animals fed twice daily or continuously were small
and only found in intake and feeding behaviour, whereas feeding once daily
with restricted access to the meal resulted in a much lower dry matter and
digestible organic matter intake, which in turn affected significantly both
the feeding behaviour of the animals and the total mean retention time of
liquid and solid markers, but did not influence digestibility coefficients. It
is concluded that continuous feeding does not seem to be necessary when
studies on marker kinetics based on faecal marker excretion curves are carried
out in sheep fed at intake levels close to ad libitum.
Grinding and pelleting resulted in a higher dry matter intake and a reduction
in organic matter digestibility, which resulted in a higher digestible organic
matter intake. Feeding behaviour and rate of passage of Co-EDTA were also
affected, although Cr did not show any tendency to pass faster when attached
to the pelleted diet.
The influence of climate, soil, and management on the composition of native grass pastures on the central, southern, and Monaro tablelands of New South Wales
Authors: Garden D. L. , Dowling P. M . , Eddy D. A. , Nicol H. I.
Published: September 2002

Pastures on 126 properties on the central, southern, and Monaro tablelands
were surveyed to determine their botanical composition. Data on climate,
soils, pasture sowing, fertiliser history, and stock management were collected
to relate current composition to environmental factors and previous
management. Native grass-based pastures were found to be widespread, and in
many cases, pastures were dominated by native grasses, despite many decades of
pasture improvement. Seventeen genera of native perennial grasses comprising
over 35 species were identified. The most common species on the central
tablelands were Austrodanthonia spp.,
Bothriochloa macra, and
Microlaena stipoides; on the southern tablelands,
Austrodanthoniaspp. and
M. stipoides; and on the Monaro,
Poa spp., Austrodanthonia spp.,
Themeda australis, and Austrostipa
spp. Soil type was the most important factor affecting species distribution,
and other soil attributes such as texture, pH, P, and N were also important.
Environmental (rainfall) and management (superphosphate application, stock
type, stocking rate) factors also influenced distribution. The significant
areas of native grass pastures that were found suggest a decline in sown
species and a recolonisation of sown pastures with native grasses. The
potential for manipulation of botanical composition of these grasslands is
discussed, together with their value for production and sustainability.
Crop responses to sulfonylurea residues in soils of the subtropical grain region of Australia
Authors: Walker S. R. , Barnes J. E. , Osten V. A. , Churchett J. D. , McCosker M.
Published: September 2002

Crop response following applications of sulfonylurea herbicides can vary
considerably across the grain region of subtropical Australia. The aim of the
study was to develop recommendations for safe re-cropping following
chlorsulfuron, triasulfuron, and metsulfuron-methyl specific for the different
soils and climates of this region. Seedling dry matter (SDM) and grain yield
were measured at 17 sites over 4 seasons. Soils were ferrosols (pH
5.5–6.8), sodosols (pH 6.6–7.1), and vertosols (pH 7.8–9.0).
Sorghum and sunflower were sown at plant-backs between 2 and 20 months, and
chickpea at 10–13 months, after applications of sulfonylurea herbicides.
Seedling response of the summer crops to these herbicides was substantially
different for the 3 soils. Crop response in theferrosols was largely
unaffected by plant-back, soil, or climatic factors after a minimum of
2–3 months. In contrast, response of summer crops in the vertosols and
sodosols was strongly affected by plant-backs for up to 10 months, and SDM was
more affected in sodosols than in vertosols. Predictive relationships between
SDM and plant-back, cumulative temperature, and measured chlorsulfuron
residues were developed for sowing summer crops in these soils. In ferrosols
and vertosols, chickpea was unaffected by any treatment following plant-back
of 10–12 months. These findings indicate that shorter re-cropping is
possible in this region than currently recommended. However, the decision
should be based not only on plant-back, but on soil type, cumulative
temperature, and possibly even residue level in soil. These more specific
recommendations will improve the safety and flexibility of re-cropping
following applications of sulfonylurea herbicides in this region.
Yellow lupin (Lupinus luteus) tolerates waterlogging better than narrow-leafed lupin (L. angustifolius) II. Leaf gas exchange, plant water status, and nitrogen accumulation
Authors: Davies C. L. , Turner D. W. , Dracup M.
Published: September 2002

Yellow lupin (Lupinus luteus) may have potential as a
legume crop in waterlogging-prone areas of Western Australia. To elucidate the
physiological response of yellow lupin and the widely grown narrow-leafed
lupin (L. angustifolius) to transient waterlogging we
conducted experiments in controlled environments. Narrow-leafed lupin and
yellow lupin were grown in pots and waterlogged for 14 days from 28 to 42, or
56 to 70 days after sowing, each being followed by a 14-day recovery period.
Root and shoot growth responses, leaf gas exchange, water relations, and N
accumulation were assessed.
During the period of waterlogging, net nitrogen accumulation ceased in both
species at both ages. During recovery, yellow lupin accumulated more nitrogen
than narrow-leafed lupin. Waterlogging reduced leaf gas exchange more with
older plants than with younger plants, and more so with narrow-leafed lupin
than yellow lupin. Some components of leaf gas exchange, particularly leaf
conductance, were reduced by up to 80%. Waterlogging had no effect on
leaf water potential of yellow lupin but reduced it in narrow-leafed lupin,
from about –450 to –1100 kPa, especially during the recovery
period.
Yellow lupin was more adapted to transient waterlogging than narrow-leafed
lupin because it maintained its leaf water status, it accumulated more
nitrogen during recovery, and its photosynthetic activity recovered quickly
afterremoval of waterlogging.
Elevated CO2 during pod filling increased seed yield but not harvest index in indeterminate narrow-leafed lupin
Authors: Palta J. A. , Ludwig C.
Published: September 2002

Indeterminate narrow-leafed lupin (Lupinus angustifolius
L. cv. Merrit) was exposed to enriched atmospheric CO2
during pod-filling to enhance the availability of carbon resources for
pod-filling in order to determine whether or not seed-filling, yield, and
harvest index are limited by the availability of photosynthetic assimilate.
Plants were grown in a glasshouse and the flowers painted with an aqueous
solution containing either N6-benzylaminopurine (BAP) or
no BAP to generate 2 different numbers of pods per plant. From the time when
pods began to fill seeds (≥5 mg/seed) until maturity, plants were
exposed to either ambient (350–360 L/L) or enriched (700 L/L)
CO2 by enclosing them in 2 transparent, box-shaped
tunnels with similar temperatures, light, and water conditions. Whether or not
BAP was applied to flowers, CO2 enrichment increased the
final number of pods and the number of pods that filled large seeds (≥150
mg) by 20–22 pods/plant. Enriched CO2 reduced
to zero the number of pods that had small seeds (≥30–80 mg) and
reduced the number of pods with unfilled seeds from 16 to 1 pod/plant.
This increased seed yield per plant by 44–66%, but did not affect
the harvest index. Harvest index was unchanged because enriched
CO2, while increasing pod-filling, also increased pod
set and dry matter accumulation on the developing branches. This indicates
that an increased availability of carbon resources during-pod filling changed
the allocation of assimilates by filling small seeds and producing new
branches. The 47–56% increase in dry matter per plant was
reflected in the increase in seed yield, which occurred largely through an
increased number of pods and seeds per plant. These data support the idea that
seed-filling and hence seed yield in well-nodulated, indeterminate
narrow-leafed lupin is limited by carbon resources at the stage when the plant
is most source-limited, which is during podset and pod-filling.