bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain growth and malting quality of barley. 1. Effects of heat stress and moderately high temperature
Authors: Savin Roxana , Stone Peter J. , Nicolas Marc E. , Wardlaw Ian F.
Published: August 2004

In this study, controlled-environment conditions were used to compare the
effects of moderately high and very high temperatures during grain filling on
grain growth and malting quality of barley.
Heat stress applied from 15 to 20 days after anthesis (DAA) reduced grain
weight by about 35%, whereas longer periods (15–20 days) of
moderately high temperature applied from 20 DAA to maturity reduced grain
weight by about 6%. Both heat stress and moderately high temperature
resulted in reduced grain weight through a reduction in the duration of grain
filling.
Grain composition was altered by both moderately high and very high
temperatures, although the changes were larger under very high temperatures.
In general, there was a decrease in starch content, resulting from the
reduction in both volume and number of A- and B-type starch granules. Nitrogen
concentration was significantly increased only in the 30/25°C
treatments, and changes in diastatic power were only minor. There was a
reduction in β-glucan content, together with an increase in β-glucan
degradation. However, malt extract was not significantly affected by these
stresses.
Use of in situ 15N-labelling to estimate the total below-ground nitrogen of pasture legumes in intact soil - plant systems
Authors: McNeill Ann M. , Zhu Chunya , Fillery Ian R. P.
Published: August 2004

A leaf-feeding technique for
in situ 15N-labelling of intact
soil–pasture plant systems was assessed, using subterranean clover
(Trifolium subterraneum L.) and serradella
(Ornithopus compressus L.) grown under glasshouse
conditions. Total recoveries of fed 15N were
87–100% following leaf-feeding of plants at flowering but were
lower (74–84%) following the feed at the vegetative stage.
Below-ground recovery of fed 15N ranged from 7 to
26%, with serradella partitioning a greater proportion of labelled N
below ground than subterranean clover. Additionally, plants of both species
fed at the vegetative stage accumulated a greater proportion of the
15N label below ground than did those fed at flowering.
Dry sampling procedures, which utilised freeze-drying, enabled fractionation
of the below-ground portion of the system into ‘clean’ nodulated
macro-roots with no adhering soil, residual uncleaned root, rhizosphere, and
bulk soil. Calculated specific enrichment for the ‘clean’ roots at
different depths demonstrated a relatively uniform distribution of
15N label in the subterranean clover roots, whereas the
presence of large indeterminate nodules in the crown region of serradella
roots contributed to apparent uneven distribution of label. Approximately half
of the N in the residual fraction of both species consisted of labelled
material, postulated to be mostly fine root. Additionally, 5–20%
of the rhizosphere N and 0·5–3% of the N in bulk soil was
legume root-derived, with some 15N detected in the
extractable total soluble N and microbial N pools. Rhizodeposition of N
represented approximately 10% of total plant N and 17–24%
of total below-ground N for subterranean clover, whereas values for serradella
were 20 and 34–37%, respectively. Estimated total below-ground N
of subterranean clover reached a maximum value of 177 mg N/plant at 98
days after sowing, which corresponded with a peak shoot N of 243 mg N. Maximum
below-ground N for serradella attained 196 mg N/plant 84 days after sowing
with a corresponding shoot biomass of 225 mg N. There was a decline in the
total below-ground N of serradella at maturity. Overall, recovered clean root
N represented 30–62% of estimated total below-ground N, so it was
concluded that standard root recovery procedures might be likely to
underestimate severely the total below-ground N accretion and N turnover by
legumes. The implications of these results for field estimation of total
legume N yield, biological N fixation, and the N benefit from legumes in
rotations are discussed.
Inhibiting methane production in Brahman cattle by dietary supplementation with a novel compound and the effects on growth
Authors: McCrabb G. J. , Berger K. T. , Magner T. , May C. , Hunter R. A.
Published: August 2004

Three experiments were conducted to determine the effects of dietary
supplementation with a novel antimethanogenic compound (AM) on methane
production and growth in Brahman (Bos indicus) steers.
The compound was a chemical complex of bromochloromethane (BCM) and
α-cyclodextrin, which is chemically stable when added to feed, thus
overcoming the highly volatile nature of BCM. In these experiments the AM
compound was administered to steers as a mixture with different feed
supplements.
In Expt 1 the effect on in vivo methane production of
feeding steers the AM compound was determined using a confinement-type
respiration chamber. Methane production of AM-treated steers (0 ±
2·4 mL/min) was lower (P < 0·001)
than that of control steers (205 ± 5·2 mL/min) over 28 days.
In Expt 2 we determined the effect of AM treatment over 12 weeks on growth of
steers fed on a low quality roughage diet. The most marked effect of AM
treatment was reduced (P < 0·01) voluntary
roughage dry matter intake (DMI), and reduced (P <
0·01) acetate : propionate molar ratio (A : P) in rumen fluid. Average
daily liveweight gain (ADG) (0·22 ± 0·01 kg/day) and
feed : gain ratio (F : G) (20·7 ± 1·46 kg DMI/kg
liveweight) were not significantly affected by AM treatment.
In Expt 3 we determined the effect of AM treatment over 10 weeks on growth of
steers fed on a medium quality roughage diet, in steers that were either
treated or not treated with a hormonal growth promotant (HGP; oestadiol
17β). AM treatment reduced (P < 0·05) DMI
below that of steers not treated with AM, whereas DMI was not significantly
affected by HGP treatment. Both AM (P < 0· 1)
and HGP (P < 0·05) treatments separately
reduced A : P ratio in rumen fluid. AM treatment had no significant effect on
ADG, whereas ADG of HGP-treated steers was higher (P
< 0·05) than that of steers not treated with HGP (0·76
± 0·27 v. 0·60 ±
0·027 kg/day). F : G was reduced (P <
0·01) by HGP treatment. F : G of both HGP-treated steers and those
steers not treated with HGP was reduced (P <
0·05) by AM treatment.
We conclude that feeding steers with this novel AM compound enables the potent
antimethanogenic properties of BCM to be realised under commercial conditions,
and that prolonged use over 10–12 weeks is associated with an improved
feed conversion efficiency in steers fed on better quality roughage diets.
Observations on tillering in cultivars of phalaris under rotational grazing in a year with a summer - autumn drought
Authors: Culvenor R. A.
Published: August 2004

Changes in tiller numbers, timing of stem elongation, and tiller survival
under summer moisture stress were measured in phalaris
(Phalaris aquatica L.) pastures rotationally grazed at
15 wethers/ha during a study of the survival and productivity of a
semi-winter-dormant cultivar (Australian) compared with 3 winter-active
cultivars (Sirosa, Holdfast, Perla Retainer). The semi-winter-dormant cultivar
maintained higher tiller numbers per plant and per area than the 3
winter-active cultivars, was later in its reproductive stem development, and
was capable of more new tillering early in spring, but could display higher
rates of tiller death late in spring. Although stem elongation in Australian
started later in 1990, it was no less synchronous than in the winter-active
cultivars. However, Sirosa had a higher proportion of elongating tillers than
Australian under very infrequent grazing in a supplementary experiment during
1991. Cultivars did not differ in the proportion of tillers that were
decapitated during spring 1990.
Perla Retainer displayed higher summer dormancy after rainfall in January 1991
and new tillers of Perla Retainer and Holdfast survived subsequent drought
better than tillers of Australian. However, regeneration of the tiller
population of Australian after drought ended was enhanced by a slightly higher
propensity for tillering during July–September 1991.
The results suggested that maintaining grazing pressure and frequency in late
winter and early spring should enhance tiller survival and improve the
resilience of phalaris to episodes of heavy spring grazing. Later reproductive
development probably benefits grazing tolerance in semi-winter-dormant
cultivars, but the value of selecting for this in winter-active phalaris is
uncertain. In areas with harsh summers, higher summer dormancy is required for
survival combined with a capacity for tiller survival should growth occur.
However, unnecessarily high summer dormancy will reduce the growth of green
herbage and, consequently, animal production.
Nitrogen accumulation and partitioning in shoots of cotton plants infested with two-spotted spider mites
Authors: Sadras V. O. , Wilson L. J.
Published: August 2004

In cotton (Gossypium hirsutum L.), leaves are the main
site of nitrogen reduction and constitute a large reservoir of organic
nitrogen. Foliar herbivores, therefore, are likely to have detrimental effects
on the nitrogen economy of the plant. A field experiment was conducted to
investigate the effects of two-spotted spider mites
(Tetranychus urticae Koch) on the accumulation and
partitioning of nitrogen in cotton shoots. Control plants and plants infested
with mites 3 times in the growing season were compared.
Once established, mite colonies grew exponentially. After peaking at
35–64 mites/leaf, mite numbers declined sharply. Mites markedly
affected both shoot nitrogen accumulation and partitioning. The amount of
nitrogen in shoots of mite-infested plants peaked earlier than in controls,
and reached maximum values that were 50–69% of the controls.
Early infestation (at the onset of reproductive growth) had a greater effect
than infestations initiated during active reproductive growth. The
concentration of nitrogen in leaves declined faster in mite-infested plants
than in controls, mostly due to accelerated leaf senescence. This rapid
decline in leaf nitrogen concentration could be one of the factors involved in
the collapse of mite colonies in heavily infested plants. Nitrogen
concentration of stems and reproductive organs was generally greater in
mite-infested plants than in controls. Allometric analysis showed that this
was related to both the small size of mite-infested plants, and true increases
in nitrogen content probably associated with translocation from senescing
leaves.
Relationships among carcass quality characteristics between and within carcass quartering sites
Authors: Baud S. , Wade C. M. , Goddard M. E.
Published: August 2004

Carcass quality characteristics were measured on 511 steers of 4 breeds that
were destined for the Japanese market. All steers had carcass measurements
taken at the 10th/11th rib interface, while 103 steers had additional
measurements made on the same characteristics at the 5th/6th rib
interface.
Australian marbling score, longissimus muscle area,
intramuscular fat percentage, intramuscular water content, Japanese
intermuscular fat thickness, Japanese subcutaneous fat thickness, Japanese rib
thickness, and meat pH were measured in the study. These measurements allowed
the phenotypic relationships between the different carcass quality traits
measured at the 10th/11th rib interface to be calculated. Significant
positive correlations were observed among measurements of carcass fatness, and
significant negative correlations were observed between carcass fatness and
carcass water content. Angus and Murray Grey cattle had higher levels of
marbling and intramuscular fat than Hereford and Poll Hereford cattle
The data enabled Australian, USDA, and Japanese marbling standards to be
compared on the basis of intramuscular fat percentage determined by an ether
extraction process. Differences between the same carcass characteristics taken
at 5th/6th and 10/11th rib interfaces of
the longissimus dorsi were estimated from the 103 steers
measured at both sites. Correlations between the rib sites were high for
marbling, intramuscular fat, and intramuscular water, but low for
longissimus muscle area, intermuscular fat thickness,
and pH.
Water relations of white clover (Trifolium repens L.) in a drying soil, as a function of phosphorus supply and defoliation frequency
Authors: Singh DhananJay K. , Sale Peter W. G. , McKenzie Blair M.
Published: August 2004

A glasshouse pot experiment was carried out to determine how white clover
plants responded to repeated drying cycles, under conditions of varying P
supply and defoliation frequency. Measurements included leaf water potential
(Ψleaf), evapotranspiration rate, soil matric
potential (Ψsoil), an assessment of visual water
stress symptoms, and the rate of plant recovery on rewatering. The rate of
decline in Ψleaf per unit decline in
Ψsoil was greater in frequently defoliated plants.
High-P plants extracted more water per unit time, were able to maintain a
higher Ψleaf in dry soil than low-P plants,
displayed minimal water stress symptoms, and recovered completely on
rewatering. High-P, frequently defoliated clover plants displayed minimal
water stress symptoms in dry soil, whereas frequently defoliated low-P plants
showed extreme symptoms; these plants were unable to recover from severe water
stress and most plants died during the final drying cycle. Infrequently
defoliated, low-P plants partially recovered from the water stress condition,
but the recovery was slower than that for infrequently defoliated high-P
plants. The findings suggest that the combination of dry soil, low P supply,
and frequent defoliation that would result from heavy grazing would threaten
the survival of white clover plants in the field.
Phosphorus nutrition of spring wheat (Triticum aestivum L.). 2. Part I, Aust. J. Agric. Res., 1997, 48, 855-67.. Distribution of phosphorus in glasshouse-grown wheat and the diagnosis of phosphorus deficiency by plant an
Authors: Elliott D. E. , Reuter D. J. , Reddy G. D. , Abbott R. J.
Published: August 2004

In 2 glasshouse experiments, the effects of variations in phosphorus (P) level
on concentration and distribution of total and labile P within wheat plants
were examined to compare the sensitivity of various plant tests for assessing
the P status of wheat.
Total P was distributed unevenly within the plant: shoots had higher total P
concentrations than roots, and concentrations in grain were markedly higher
than in glumes or straw. Within wheat shoots, the concentration of total and
labile P varied with stage of plant growth and the type and physiological age
of the plant part analysed. In general, leaf blades had higher concentrations
than their subtending sheaths. During the vegetative phase, the highest P
concentrations were measured in immature tissues and the concentrations
decreased progressively in older plant parts, except at luxury supply where
total P was invariably higher in old leaf blades.
Critical total P concentrations (CTPC) estimated for whole shoots decreased
with advancing plant age beyond Zadoks Scale 13·5. Circumstantial
evidence suggests that this may be caused by stems of lower P concentration
progressively constituting a larger proportion of shoot biomass with
increasing age.
Critical concentrations defined for leaf blades of known physiological age
also decreased with plant age beyond Zadoks Scale 13·5 for both labile
and total P. These decreases may result from either an increase in the size of
the sampled individual leaf blades as plants age or shifts in distribution of
P within the shoot from the main culm to developing tillers (or reproductive
structures).
Total P is the preferred and easier method of analysis, and in most cases,
diagnostic and predictive CTPC were similar in defined individual leaf blades.
The estimated critical value for the labile P: total P ratio of about
30% appeared to be independent of leaf age or stage of plant ontogeny.
These data suggest that the existence of P deficiency in wheat can be
confirmed by analysing whole shoots or recently matured leaf blades for total
P. In the period up until early tillering, the P test criteria are constant
but thereafter must be related to stage of growth.
Soil organic carbon changes in cracking clay soils under cotton production as studied by carbon fractionation
Authors: Conteh A. , Blair G. J. , Lefroy R. D. B. , Macleod D. A.
Published: August 2004

This study examined soil carbon levels across a wide range of cracking clay
soils used for growing cotton in Australia by using a simple carbon
fractionation procedure. The soils studied included reference and cropped
sites. The procedure employed determines soil carbon fractions based on their
ease of oxidation to obtain the labile (CL) and
non-labile (CNL) carbon components. Based on the total
carbon (CT), labile carbon (CL),
and non-labile carbon (CNL) of a cropped soil relative
to a reference soil, various monitoring indices were developed. It was found
that cultivation has generally led to a decrease in the organic carbon status
of the soils. The effect of cultivation was found to be more pronounced in the
CL and the carbon management index (CMI) than in the
CT and CNL. The changes in the
ratio of CL to CNL as a result of
cultivation have been variable. The CMI has generally declined during
cultivation, and since the CMI has incorporated the changes taking place in
CT, CL, and
CNL, the use of this index can provide very useful
results in monitoring of organic matter status of soils.
Effect of pasture management on the contributions of fixed N to the N economy of ley-farming systems
Authors: Peoples M. B. , Gault R. R. , Scammell G. J. , Dear B. S. , Virgona J. , Sandral G. A. , Pau J. , Wolfe E. C. , Angus J. F.
Published: August 2004

The effects of different management regimes on N2
fixation by subterranean clover (Trifolium subterraneum)
in annual pastures and lucerne (Medicago sativa) in
perennial-based pastures were examined in 5 experiments and 55 commercial
paddocks, in which the pastures were grown in phased rotation with crops. The
objectives were to quantify the inputs of fixed N2 and
to determine ways of increasing nitrogen (N) inputs into ley-farming systems
of southern New South Wales and north-eastern Victoria.
Estimates of annual amounts of N2 fixed, based on
above-ground herbage production in grazed pastures, ranged from 5 to 238 kg
N/ha for subterranean clover and from 47 to 167 kg N/ha for lucerne.
Legume reliance upon N2 fixation for growth (Pfix) was
high (>65%) in most annual and perennial pastures examined. The
levels of Pfix were generally unaffected by management treatments. As a
consequence the amounts of N2 fixed were predominantly
regulated by the legume content and herbage yield of pastures rather than by
any marked differences in the ability of the legume to fix N. When all
experimental results were combined with on-farm measurements of
N2 fixation, the data indicated that lucerne and
subterranean clover fixed 22-25 kg N for every tonne of legume dry matter
produced.
Management inputs to annual pastures which improved the productivity of
subterranean clover and the amounts of N2 fixed included
applications of superphosphate and the removal of grass species with
herbicide, although the response to these treatments was not consistent across
all sites in all years. Potential inputs from N2
fixation were high in annual pastures, and improved management during a good
clover season enhanced the levels of mineral N detected in the soil profile
(0-200 cm) the following autumn by 100-200 kg N/ha. However, year-to-year
variability in annual pasture productivity and clover content resulted in
large fluctuations in amounts of N2 fixed.
Perennial pastures containing lucerne provided consistently greater annual
herbage production, had more stable legume contents, and fixed on average
90-150% more N2 than neighbouring subterranean
clover-based pastures. Even during the 1994 drought when annual pastures
failed, lucerne still managed to fix >70 kg N/ha. It is proposed that
lucerne-based pastures could represent a more reliable means of improving soil
fertility for subsequent crops than annual pastures.
Field variations in alkane signatures among plant species in ‘degraded’ and perennial pastures on the Northern Tablelands of New South Wales
Authors: Chen W. , Lefroy R. D. B. , Blair G. J. , Scott J. M.
Published: August 2004

Differences in concentrations of n-alkanes in the cuticular waxes of plants
can be used to estimate the species composition of herbage mixtures or the
diet consumed by grazing animals. The objectives of this study were
(i) to provide information on the n-alkane
(C25-C35) ‘signatures’
or patterns of pasture species occurring in ‘degraded’ and
perennial pastures of the Northern Tablelands, New South Wales, and
(ii) to examine the extent of the field variation in the
signatures.
There were considerable differences in odd-numbered alkanes and in their total
content between species. There were also significant differences in n-alkane
concentrations among species within grasses, legumes, and weeds. For the
individual odd-numbered alkanes, differences between species accounted for
87-93% of the total variance in alkane concentration over 3 samplings.
Variable results for the temporal effect suggest that time-specific herbage
samples are needed in animal diet studies. Analyses of the spatial effect
indicate that random cuts over each treatment plot can obtain representative
samples of each species.
Multivariate statistical analyses using principal component and discriminant
analyses indicated that the patterns of alkanes in species occurring on both
degraded and perennial pastures were readily distinguishable. These results
confirmed that the alkane technique could be used for estimation of diet
composition in grazing sheep on the Northern Tablelands, NSW, where
differences in n-alkane signatures between species were sufficient and
persistent over time.
The biology and management of Axonopus affinis (Chase) in Australian pastures
Authors: Henskens F. L. F.
Published: August 2004

Carpetgrass (Axonopus affinis Chase) was described in
terms of its botany, origin, distribution, seasonal growth, habitat, and
dispersal. Factors that determine its agronomic importance were examined.
Emphasis was given to management and ecological factors which influence
competition between carpetgrass and sown pasture species. It is concluded that
the management strategies that have been developed and successfully adopted in
Queensland and New South Wales need to be tested for use in irrigated pastures
in northern Victoria
Genetic variation for seasonal herbage yield, growth habit, and condensed tannins in Lotus pedunculatus Cav. and Lotus corniculatus L.
Authors: Kelman W. M. , Blumenthal M.J. , Harris C. A.
Published: August 2004

Lotus pedunculatus (greater lotus) and
L. corniculatus (birdsfoot trefoil) are perennial
forages with potential to improve the legume content of pastures in
south-eastern Australia. A collection of 39 accessions of each species was
grown at 3 localities to assess the degree of genetic and genotype locality
interaction components of variance for herbage yield, plant height, and width,
the rate of reproductive development, and condensed tannin concentration as a
prelude to forming strategies for genetic improvement. Rhizome development in
L. pedunculatus and seed yields in both species were
recorded at a single locality. The genetic variance component for herbage
yield, plant height, and condensed tannins was significant for all characters,
whereas the genotype × locality variance component was generally of
lower magnitude. Grouping of accessions by geographic origin revealed
important associations between characters. These associations were supported
by strong positive genetic correlations. In
L. pedunculatus, Portuguese accessions combined high
autumn herbage yield with a tall plant type, a sparsely rhizomatous growth
habit, high seed yield, and high condensed tannins. In
L. corniculatus, prostrate growth habit was associated
with high condensed tannins in accessions from Spain but was associated with
low condensed tannins in Russian accessions. Principal components analysis of
data for geographic groups of L. pedunculatus showed a
positive association between means and variances, suggesting that selection
within groups should be effective in producing cultivars with high herbage
yield and low condensed tannins. In
L.corniculatus, the positive
genetic correlation between herbage yield and plant height suggested that
hybridisation and selection would be required to produce a cultivar that would
be more persistent under grazing.
Effects on growth rate and utilisation of amino acids in weaner pigs fed diets containing whole proteins and free amino acids in combination with different energy sources
Authors: Farrell D. J. , Officer D. I. , Batterham E. S.
Published: August 2004

This experiment was designed to determine the effects of 3 protein and 3
energy (carbohydrate) sources on the growth rate of weaner piglets and their
eciency of nutrient utilisation. All 3 energy sources and 2 of the protein
sources [casein plus free amino acids (casein), free amino acids alone
(FAA)] were chosen because they were suitable for studies measuring amino
acid utilisation. The third protein source, based predominantly on peptide
protein, was a combination casein-fish meal-soyabean meal (CFS). The
combinations of carbohydrates tested were sucrose alone, sucrose plus 150 g
lactose/kg, and wheat starch plus 150 g sucrose plus 150 g lactose/kg.
The experiment was a randomised complete block design based on a 33 factorial
arrangement with 5 blocks and 9 pigs per block. Piglets given CFS as the
protein source exhibited greater (P < 0·001)
weight gain than those consuming casein or FAA (494 v.
415 and 345 g/day) and deposited protein more eciently
(P < 0·001) (e.g. crude protein
retention/ileal-digestible protein intake, 0·65
v. 0·56 and 0·49). The apparent
digestibility of nitrogen (N) and amino acids was lower for the CFS-fed
piglets (0·83 and 0·88) than for those given casein (0·92
and 0·95) or FAA (0·94 and 0·96). The daily weight gains
of piglets given diets containing starch, sucrose, and lactose were
9-10% lower (P < 0·05) than those
consuming either sucrose or sucrose plus lactose (391 v.
433 and 430 g/day). The energy sources, however, had no effect on ileal
digestibility of amino acids or empty body composition. Neither casein nor FAA
diets were found to be acceptable sources of amino acids for studies on amino
acid utilisation. Sucrose and sucrose plus lactose were excellent energy
sources for piglets. In contrast, wheat starch was found to be unsuitable for
inclusion in synthetic weaner diets for piglets with a liveweight of 5-20 kg.
Effects of seed size and maturity on the growth and yield of faba bean (Vicia faba L.)
Authors: Agung S. , McDonald G. K.
Published: August 2004

The importance of seed size and flowering time to yield in faba bean has not
been well defined for many of the faba bean growing areas of southern
Australia. The objective of this work was to examine the relative importance
of these traits to yield of dryland faba bean at 2 sites in South Australia.
Grain yield, seed growth rate, the partitioning of dry matter to the seed, and
water use efficiency for dry matter production and yield of faba bean
cultivars differing in seed size and maturity were measured. Early-,
intermediate-, and late-flowering accessions in each of 3 seed size classes,
large (>1200 mg/seed), medium (800-1200 mg), and small (<800 mg),
were grown at the Waite Institute (623 mm average annual rainfall) and
Charlick Experiment Station (509 mm). A small-seeded and intermediate
flowering cultivar, Fiord, which is well adapted in South Australia was also
included.
Dry matter production and grain yields at the Waite Institute were higher than
at Charlick and the difference tended to be greater in the large-seeded
accessions. Average yields at the 2 sites were about 400 g/m 2 and were
not consistently related to seed size, although the highest yielding accession
at both sites was large-seeded. Among the small- and medium-sized seed
accessions, the early-flowering accession yielded more than late-flowering
accessions, but among the large-seeded accessions there was no relationship
between flowering time and yield. Although there were significant differences
between accessions and sites in individual yield components, yield was not
significantly correlated with any particular component. There was strong
compensation between seed number and seed size and high yields were obtained
from a range of seed sizes. In contrast there was a positive relationship
between dry matter production and yield. Partitioning of dry matter during pod
filling and harvest index differed little between genotypes. Yield was
therefore related to biomass accumulation, and whether this was partitioned
between a small number of large seeds or a large number of small seeds was not
an important factor.
Genotype×environment interactions and some considerations of their implications for wheat breeding in Australia This review is one of a series commissioned by the Advisory Committee of the Journal.
Authors: Basford K. E. , Cooper M.
Published: August 2004

Genotype×environment (G×E) interactions complicate selection forbroad adaptation, while their nature and causes need to be understood toutilise and exploit them in selection for specific adaptation. This invitedreview combines an assessment of the literature with the experience we havegained from involvement in wheat breeding and associated research programs toassess (1) the implications of G×E interactions for wheat breeding inAustralia, (2) the impact that research into G E interactions has had onbreeding strategy, and (3) the evidence for impact from this research efforton genetic improvement of crop adaptation. The role of analytical methodologyin this process is considered and some important issues are discussed.There are sufficient examples drawn from wheat breeding in Australia tosuggest that progress in dealing with G×E interactions can be made andseveral of these are presented. They show that impact in plant breedingfollows from achieving an appropriate level of understanding of theenvironmental and genetic factors causing the interactions as well as anassessment of their importance in the target genotype-environment system. Anaccurate definition of the environmental factor(s) contributing to theG×E interactions has been particularly important in determining therelevance of observed differences in plant adaptation to the target populationof environments. From the combination of biological and statistical studies, amore comprehensive understanding of G×E interactions has emerged andcontributed to new concepts and procedures for dealing with them.Distinguishing between what are repeatable and non-repeatable interactions isa key step. Genuine cases of positive specific adaptation observed inmulti-environment trials (METs) can be exploited by appropriately targetedselection strategies, while non-repeatable interactions are accommodated byselection for broad adaptation.The investigation of G×E interactions for grain yield of wheat inAustralia has matured to the point where an understanding of some of theircauses has enabled wheat breeders to exploit positive components of specificadaptation. The experience that has been gained in achieving these advancesindicates the importance of establishing a MET system that is relevant to thetarget population of environments of the breeding program. The investment ofadequate resources into effective design, conduct, analysis, andinterpretation of METs remains critical to continued progress from selectionin complex genotype-environment systems that present large G× Einteractions. Wheat breeders who understand their genetic material and thetarget population of environments can then use the generated information baseto achieve impact from their breeding programs.
Inter- and intra-specific variation in accumulation of cadmium by peanut, soybean, and navybean
Authors: McLaughlin M. J. , Bell M. J. , Wright G. C. , Cruickshank A.
Published: August 2004

Production of summer grain legumes like peanut, soybean, and navybean is
expanding into irrigated or high rainfall areas on more acid, lighter textured
soils in coastal areas of north-eastern Australia. A history of intensive use
of phosphatic fertilisers, combined with soil properties which generally
enhance phytoavailability of cadmium (Cd), have produced concerns about the
likely quality of grain legumes produced in these areas. This paper reports
field and pot experiments which examine the effect of grain legume species and
variety on Cd accumulation when grown across a range of soil types. Results
clearly show that both peanut and soybean accumulate Cd in seeds at levels
greater than the maximum permitted concentration (MPC, 0·05 mg
Cd/kg) even on soils with relatively low total or available Cd
concentrations (<0·5 mg/kg). The relative risk of MPC exceedance
in marketable seeds or kernels was peanut > soybean > navybean, with the
differences between peanut and navybean apparently correlated with differences
in total plant Cd uptake. Cadmium concentrations in plant tops always exceeded
that in seeds or kernel, and the testa in peanut kernel was shown to contain
Cd concentrations that were 50 times greater than that in the embryonic axis
and cotyledons.
Significant (P < 0·05) variation in Cd content
(at least 2-fold) was recorded among peanut varieties, with lesser variation
evident among a limited sample of commercial navybean varieties. Comparison of
results for 11 peanut varieties grown at each of 2 locations suggested strong
genotype environment interactions determining kernel Cd concentration.
Highly significant (P < 0·01) linear
relationships were established between soil Cd in the cultivated layer (0-20
cm; 0·1 M CaCl2 extraction) and seed Cd content
in field-grown soybean. However, despite observations of an apparent
relationship between soil Cd (CaCl2 extraction) and
peanut kernel Cd in pot studies, relationships between soil Cd in the
cultivated layer and kernel Cd could not be reproduced in field trials. Kernel
Cd concentrations from field-grown peanut plants were generally higher than
those from pot trials, despite using soil collected from the cultivated layer
(0-20 cm) of the field site for the potting medium. The presence of
significant levels of Cd to approximately 60 cm in the soil profile and a
general decline in pHw with depth suggest the lack of
correlation between soil test Cd in the top 20 cm and kernel Cd in field-grown
plants may be at least partly due to Cd uptake from deeper soil layers.
Field amelioration of acidic soils in south-east Queensland. III. Relationships of maize yield response to lime and unamended soil properties
Authors: Moody P. W. , Dickson T. , Aitken R. L.
Published: August 2004

Maize (Zea mays) grain yield responses to rates of lime
were measured at 19 sites onseveral soil types in south-east Queensland. At
some sites, one rate of gypsum or phosphogypsum was also applied. Relative
grain yield (100 mean yield of nil lime treatment/maximum yield) was
correlated with each of soil pH (1 : 5 water and 1 : 5 0·01 M
CaCl2), soil solution pH, exchangeable (1 M KCl) Al, exchangeable (1 M
NH4Cl) Ca, Al saturation of the effective cation
exchange capacity (ECEC), Ca saturation of the ECEC, and 0·01 M
CaCl2 extractable Mn and Al. Across all soil types,
Mitscherlich fits indicated that most of the variation in relative grain yield
was accounted for by either Ca saturation
(R2 = 0·62) or soil
solution pH (R2 =
0·61), although soil pH(water)
(R2 =0·53), Al
saturation (R2 =
0·46), exchangeable Ca (R2
= 0·42), soil pH(CaCl2)
(R2 = 0·40), and
CaCl2-extractable Mn
(R2 = 0·33) also
accounted for significant (P < 0·05) amounts
of variation.
These results demonstrate that one or both of Al and Mn toxicities were having
an impact on yieldat different sites. The contrast between the lack of
responses to gypsum/phosphogypsum at mostlime responsive sites and the
observation that Ca saturation was well correlated with relative grainyield
suggested an ameliorating effect of Ca on Al toxicity. This effect was
captured by an index,Al saturation/Ca saturation, which was well
correlated with relative grain yield
(R2 = 0·66 for a
Mitscherlich fit).
A step-up regression approach indicated that most variation in relative grain
yield (RY) could beaccounted for by the following equation:

The assessment of factors likely to limit yield on strongly acidic soils of
the region will therefore needto include indices of Al and Mn toxicities as
well as Ca status.
Soil pH integrated the effects of these factors on yield, and as a single
index, was shown to bean effective diagnostic tool. Relative grain yields of
90% were associated with pH values in the soil solution, 1 : 5 water
and 1 : 5 0·01 M CaCl2 of 4·5, 5·2,
and 4·4, respectively.
Root and shoot response of field-grown lettuce and broccoli to a compact subsoil
Authors: Montagu K. D. , Conroy J. P. , Francis G. S.
Published: August 2004

The direct effect of subsoil compaction on the root and shoot growth of
lettuce (Lactuca sativa ‘Classic’) and
broccoli (Brassica oleracea L. Italica
‘Bushido’) was investigated in field experiments. Possible
secondary effects of the compact subsoil were minimised through careful supply
of water and nutrients to the soil. Roots were sampled at 3 times to determine
the timing and extent of root growth into the compact subsoil. The compact
treatment had a distinct layer of high strength soil at
0·17-0·35 m, maximum soil strength of 3·1 MPa at
0·27 m. In the loosened treatment, deep ripping reduced the maximum
subsoil strength to 1·9 MPa at 0·35 m. The roots of both crops
penetrated the compact subsoil approximately half-way through the vegetative
growth phase of the shoots. Root growth was restricted by the compact subsoil,
with root length densities 60-75% lower than in the loosened subsoil.
As a result, only 6-13% of the total root system was present in the
compact subsoil. The reduced root length in the subsoil was compensated for by
increased root growth in the topsoil, for the broccoli crop only. The compact
subsoil had no effect on the shoot growth or yield of either vegetable crop
when water and nutrientswere well supplied. This may have been due to the
small proportion of roots growing in compact soil and/or the advanced
vegetative growth stage of the shoots when the roots grew into the compact
subsoil. Consequently, under dield conditions, a compact subsoil had no direct
effect on vegetable crop shoot growth or yield.
Alternative crops for duplex soils: growth and water use of some cereal, legume, and oilseed crops, and pastures
Authors: Gregory P. J.
Published: August 2004

Lupin is the major break crop used by farmers in Western Australia but neither
lupin nor wheat uses much water from the B horizon of the widespread duplex
soils. This study investigated the productivity and water use of a range of
crops and pastures during 2 seasons on a shallow duplex soil, with a sandy
layer 30-40 cm deep, at East Beverley, WA. The aims of the work were to
evaluate the crops as alternative break crops to lupin on these soils, and to
establish whether roots could proliferate in the clay layer, promoting both
water extraction from the subsoil by that crop and improving yields of
subsequent wheat crops.
During the winter of the first season, a perched watertable developed for
almost 3 months and some crops (especially lentil) grew poorly. Yields in the
second season were generally good (lupin was close to the calculated potential
yield and canola and Indian mustard were >2 t/ha), establishing that
successful crops of oilseeds and grain legumes can be grown on this soil
provided that there is adequate water without topsoil waterlogging. Yields of
subsequent wheat crops were largest when following legume crops (40% in
one season and 135% in the second compared with wheat following wheat
or barley) but were also significantly greater following oilseeds (22%
and 102%).
Roots of cereals and pastures reached 80 cm in both seasons, whereas those of
the oilseeds reached 60-80 cm depending on crop and season. Rooting depth of
legumes varied from 70-80 cm for field pea to 30-50 cm for chickpea and faba
bean, with lupin extending to 60 cm in both seasons. As with shoot mass, root
mass differed between seasons, although on average, in mid September cereals
and oilseeds had a smaller proportion (0·12 and 0·14) of total
mass below ground than the legumes (0·24) and pasture species
(0·18). Only a few millimetres of water was extracted from the subsoil
by any crop in either season and there was no evidence that tap-rooted legumes
or oilseeds were better able than other crops either to exploit subsoil water
for their own use or to create pores that subsequent wheat crops might
exploit.
Morphological development of forage chicory under defoliation in the field and glasshouse
Authors: Li G. D. , Hodgson J. , Kemp P. D.
Published: August 2004

Four field and 2 glasshouse experiments were carried out to study the
morphological development of forage chicory under defoliation from 1993 to
1996 at Massey University, Palmerston North, New Zealand. ‘Grasslands
Puna’ chicory (Cichorium intybus L.) was used in
all experiments except the last one, where 3 cultivars, ‘Grasslands
Puna’, ‘PG90’, and ‘Orchies’, were compared.
Puna chicory produced 2 separate growths from the crown, one in spring and the
other in autumn, when left ungrazed. Defoliation stimulated the development of
secondary shoots but suppressed the development of the primary shoot. Axillary
shoots, however, developed fully regardless of whether plants were defoliated.
The main source of feed from chicory for livestock was primary leaves during
spring, and secondary and axillary leaves during summer and autumn. Orchies
produced more primary leaves than Puna an PG90 because it had a larger crown,
but there were no differences in the number of secondary shoots among
cultivars. The development of axillary shoots varied with cultivars.
A new approach to quantifying the N benefit from pasture legumes to succeeding wheat
Authors: McNeill Ann M. , Zhu Chunya , Fillery Ian R. P.
Published: August 2004

Vegetative subterranean clover (Trifolium subterraneum
L.) and serradella (Ornithopus compressus L.), growing
in 1-m soil columns under glasshouse conditions during 1994, were fed
15N tracer by immersion of individual leaves (5 per
plant) in a 0·4% (w/w) solution of labelled urea
(99·6 atom% 15N). Four replicate
soil-plant systems were harvested in late October 1994 at legume peak biomass
(41 days after labelling) and in early December 1994 at maturity (90 days
after labelling). The shoots were removed and the soil columns fractionated
into clean macro-root, residual (root/soil) fraction, and bulk soil; the
shoots from the remaining replicates were also harvested at maturity leaving
the labelled soil columns intact. These intact columns were kept dry for 5
months during the summer then rewetted and planted with wheat in June 1995.
Four replicate soil-plant systems were harvested at planting, tillering,
anthesis, and maturity of the wheat and fractionated as before.
Mean recovery of fed 15N by the plant{soil systems
was 42% for subterranean clover and 64% for serradella.
Proportional distribution of the recovered 15N was
similar for both plant-soil systems: 67-69% recovered above-ground and
31-33% recovered below-ground for subterranean clover compared with
71-75% above-ground and 25-29% below-ground for serradella.
Uniform labelling of below-ground nitrogen (BG N) enabled estimation of total
BG N accumulation, under undisturbed conditions, for the two pasture species.
Less than 60% of the total legume BG N for both species was recovered
as macro-root, with up to 17% recovered in the residual fraction and
33-51% in the bulk soil. Subterranean clover increased its total amount
of BG N from 174 to 218 mg/plant between peak biomass and maturity with
>65% of this located in the top 10 cm of the soil. Total BG N for
serradella was similar at peak biomass (172 mg/plant) and not only
decreased slightly by maturity (160 mg/plant) but was also redistributed
to depth between the 2 sampling times. The ratio of shoot N to total BG N at
peak biomass was 1 : 0·68 for subterranean clover and 1 : 0·60
for serradella.
Recovery of labelled legume BG N at harvest by wheat following subterranean
clover was 25% and after serradella was 18%. Root residues from
subterranean clover appeared to decompose more rapidly than those from
serradella, manifest by rapid uptake by the succeeding wheat so that
66% of the total N benefit had accrued by tillering, whereas only
44% of the N benefit from serradella roots had accrued by tillering and
72% by anthesis.
Using precision farming technologies to improve management of soil and fertiliser nitrogen
Authors: Blackmer A. M. , White S. E.
Published: August 2004

Advances in technology are making global positioning systems, on-the-go yield
monitors, geographic information systems, remote sensing, communication
networks, and variable-rate application techniques available to crop
producers. There is, however, no established methodology for using these
technologies in agricultural research to develop basic knowledge needed to
improve crop production practices. This report describes how these new
technologies are being used to develop recommendations for N management during
non-irrigated corn production in the corn belt of the USA. The discussion
begins with relevant background information about the prevailing N-management
practices for this crop and some challenges posed by the advent of the new
technologies. This is followed by a description of the various methods being
used to collect data in field trials. An example of a field trial is then
presented and the potential importance of management-induced variability is
illustrated. This is followed by some general observations derived from the
results of many field studies. The discussion concludes with speculation about
the nature of N fertiliser prescriptions during crop production with precision
farming technologies
Oxygen stress of 'Granny Smith' apples in relation to superficial scald, ethanol, α-farnesene, and conjugated trienes
Authors: Ghahramani Farhad , Scott Kevin J.
Published: August 2004

Granny Smith apples were exposed to 2 levels of oxygen stress, <1%
O2 at 0°C or <0 ·01%
O2 at 20°C before storage at 0°C. Stress
duration was 2-16 weeks at 0°C and 1-10 days at 20°C.
The severity of superficial scald decreased as the period of
O2 stress was increased. The amount of ethanol in the
juice increased as the period of O2 stress increased.
The accumulation of a-farnesene and conjugated trienes in the wax proceeded in
all treatments but the amount of increase become less as the period of
O2 stress was extended. Superficial scald was eliminated
with an 8-day period of O2 stress at 20°C before
cold storage or with 16 weeks O2 stress at 0°C.
It is suggested that control of scald by O2 stress may
be due to increased production of ethanol and consequent reduction of
a-farnesene and conjugated trienes accumulation.