bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of cultivar and grazing intensity in spring on shear and compression energies of dry mature subterranean clover (Trifolium subterraneum L.)
Authors: Ru Y. J. , Fortune J. A.
Published: August 2004

Twenty-six cultivars of subterranean clover were divided into 3 maturity
groups according to the flowering time and sown in 2 blocks with 4 replicates.
The plots were grazed under 2 intensities (hard and lax) during the growing
season. The proportions of leaf, petiole, stem, and burr before senescence,
dry matter digestibility (DMD), herbage availability, and seed yield in summer
were measured. The energies required to shear and compress the resultant dry
mature plant materials were determined using an Instron material testing
instrument. The results showed a large range for shear
(11·3-18·2 kJ/m2) and compression
energies (2·8-4·6 kJ/kg DM) among the 26 cultivars. Grazing
intensity in spring did not affect shear energy (P >
0·05) but increased the compression energy of dry mature subterranean
clover by 0·2 units (P < 0·05). The
energy required to shear or compress plant materials was highly correlated
with herbage availability, flowering time, proportions of leaf and petiole in
the sward, and fibre content of the plant materials, with the relationships
being modified by grazing intensity in spring. Compression energy was related
to DMD of plants (r = -0·7) and shear
energy did not account for a significant amount of variation in DMD.
Within-plant variation for seed weight and seed quality traits in white lupin (Lupinus albus L.)
Authors: Velasco L. , Mart L. M. , Haro De
Published: August 2004

The influence of the branch order on seed weight and seed quality traits was
studied in 32 bitter landraces of white lupin. Seeds from the mainstem,
first-order branches, and second-order branches were harvested separately and
the seed weight, protein content, oil content, and oil composition were
determined at each branch order. The results showed the presence of
within-plant variation for all of the traits included in this study. The seeds
from the mainstem were heavier and had lower oil and protein content than the
seeds from the branches. The seed oil from the mainstem was characterised by a
higher percentage of saturated fatty acids and oleic acid, and a lower
percentage of linoleic, linolenic, eicosenoic, and erucic acid than the seeds
from the branches. The seeds from the first branch order were heavier and had
lower oil and protein content than the seeds from the second-order. Seed oil
from the 2 branch orders only differed for the percentage of palmitic acid,
which was higher in the first-order. It is concluded that within-plant
variation in white lupin should be taken into account to avoid sampling
errors, because seeds from one branch order are imperfect as a predictor of
the composition of seeds from the others.
Forecasting regional crop production using SOI phases: an example for the Australian peanut industry
Authors: Meinke Holger , Hammer Graeme L.
Published: August 2004

Using peanuts as an example, a generic methodology is presented to
forward-estimate regional crop production and associated climatic risks based
on phases of the Southern Oscillation Index (SOI). Yield fluctuations caused
by a highly variable rainfall environment are of concern to peanut processing
and marketing o/Southern bodies the industtry could profitable to adjust
their operations stategically. Significantly , physically based
lag-relationships exist between an index of ocean/atmospher EI
Niño/southern Oscillation phenomenon and future rainfall in
Australia and elsewhere. Combining knowledge of SOI phases in November and
December with output from a dynamic simulation model allows the derivation of
yield probability distributions based on historic rainfall data. This
information is available shortly after planting a crop and at least 3-5 months
prior to harvest. The study shows that in years when the November-December SOI
phase is positive there is an 80% chance of exceeding average district
yields. Conversely, in years when the November-December SOI phase is either
negative or rapidly falling there is only a 5% chance of exceeding
average district yields, but a 95% chance of below average yields. This
information allows the industry to adjust strategically for the expected
volume of production. The study shows that simulation models can enhance SOI
signals contained in rainfall distributions by discriminating between useful
and damaging rainfall events. The methodology can be applied to other
industries and regions.
Isozyme markers in Saccharum spp. hybrids and Erianthus arundinaceus (Retz.) Jeswiet
Authors: Lee D. J. , Berding N. , Jackes B. R. , Bielig L. M.
Published: August 2004

Verification of the authenticity of the hybrid origin of progeny from
interspecific or intergeneric crossing in introgression studies in plant
improvement is essential before usage of such progeny. This study undertook to
determine whether isozyme phenotypes verified the hybrid origin of apparent
crosses between a clone of Erianthus arundinaceus (Retz.) Jeswiet and several
Saccharum spp. hybrid clones. Starch gel electrophoresis
was used to resolve 18 isozyme systems for markers that would distinguish
E. arundinaceus from
Saccharum spp. hybrid clones. Eight isozyme systems
revealed 16 bands that were present in E. arundinaceus but absent from the sugarcane parents. When
a population of putative E. arundinaceus × Saccharum spp. hybrid
progeny was screened using these isozyme systems, none of the clones expressed
the bands characteristic of E. arundinaceus. Thus, their
intergeneric nature was disproven.
Effects of sorghum ergot on grain sorghum production: a preliminary climatic analysis
Authors: Meinke Holger , Ryley Malcolm
Published: August 2004

Until 1996 the disease ‘sorghum ergot’
(Claviceps africana and
Claviceps sorghi) was unknown in Australia. Following an
outbreak near Gatton, the disease was found throughout most of the
sorghum-producing areas in Queensland within 4 weeks. A climatic risk analysis
was conducted to assess the likely timing and frequencies of further outbreaks
of the disease across the main sorghum-producing regions of Australia. Based
on the information available, likely conditions that could lead to a disease
outbreak were formulated and a computer program developed to interrogate an
existing database of long-term, daily weather records. Case studies were
conducted for 10 key sorghum-producing locations, ranging from Narromine in
central New South Wales to Mareeba in far North Queensland and Kununurra in
Western Australia.
For grain sorghum production, crops flowering in January and February are
unlikely to be affected, regardless of location. However, in up to 30%
of years, late-sown grain sorghum crops and crops flowering before January
could be affected, depending on climatic conditions prior to and around
anthesis. The frequency and timing of these events differed strongly
temporally and spatially and appeared highest in high rainfall years and in
regions with relatively cooler temperatures and more frequent autumn rains.
Hybrid seed production (i.e. breeding programs) and forage sorghum production
are likely to be more affected due to their inherently low pollen generation,
again with strong regional variation. Further applications of the methodology,
such as the development of an early warning system, based on phases of the
Southern Oscillation Index, are discussed.
Acidification potential of ten grain legume species grown in nutrient solution
Authors: McLay C. D. A. , Barton L. , Tang C.
Published: August 2004

The paper reports the relative acidification potential of 10
N2-fixing grain legume species grown in nutrient
solution for 35 days after nodule appearance. The legumes studied were pilosus
(Lupinus pilosus Murr. P23342), yellow lupin
(Lupinus luteus L. R1171), white lupin
(Lupinus albus L. Kiev mutant), narrow-leafed lupin
(Lupinus angustifolius L. Gungurru), faba bean
(Vicia faba L. Fiord), field pea
(Pisum sativum L. Dundale), grasspea
(Lathyrus sativus L. S453), chickpea
(Cicer arietinum L. T1587), common vetch
(Vicia sativa L. Blanchefleur), and lentil
(Lens culinaris Med. ILL6002). The species varied
considerably in their acidifying ability; proton production ranged from 77 to
136 cmol/kg dry matter. Chickpea and narrow-leafed lupin had the largest
acidification potential and field pea the least. The specific acidification
(amount of protons produced per kg dry matter) was best correlated with
concentrations of excess cations, ash alkalinity, and calcium in plant across
the species but was not correlated with plant nitrogen concentration. Total
ash alkalinity or total excess cations in shoots provided a good indicator for
estimation of total proton production in these species, which were reliant on
N2fixation for their source of N. The results have
implications for the selection of legumes to be used in sustainable farming
systems.
Yield and protein responses to nitrogen, and nitrogen fertiliser requirements of grain sorghum, in relation to soil nitrate levels
Authors: Holford I. C. R. , Holland J. F. , Good A. J. , Leckie C.
Published: August 2004

Sorghum fertiliser experiments at 40 sites on the north-western slopes andplains of New South Wales demonstrated that many soils are severely deficientin nitrogen (N), but most yield responses to fertiliser N occurred on sites inthe southern part of the region. Grain yields responded to fertiliser in fewerthan half of the experiments but protein concentrations responded in about75%.There were 4 distinct types of protein response curve, and the type of curvewas related to the degree of N deficiency. In the most deficient experiments(mean protein 6·1% or less), response curves were convex to thex -axis or linear; at intermediate deficiency (mean protein7·2%), response curves were sigmoid; and at low deficiency (meanprotein 9·7%), response curves were Mitscherlich. Yield responsenever occurred where grain protein was >10%.Maximum grain yield responses and amounts of fertiliser N for maximum profit,estimated by fitting the Mitscherlich equation to response curves, weresignificantly correlated with soil nitrate N levels at various depths in thesouthern experiments, but not in the northern experiments. This difference inN responses appeared to be caused by lower rainfall and higher soil N in mostof the northern experiments. Nitrate-N levels in soils sampled to 15 or 30 cmdepth were better correlated with yield response ( r> 0·81) and fertiliser requirement (r >0·72) than N levels to deeper depths.There was little or no fertiliser N recovery in the grain in the northern experiments but substantial recovery in the south where it was generallygreater than recovery by wheat in earlier experiments in the same region.Fertiliser requirement in relation to soil nitrate-N levels was lower thanthat of these wheat experiments. This was attributed to mid-spring soilsampling for sorghum which underestimates the soil N available to the sorghum
Improved methods for predicting individual leaf area and leaf senescence in maize (Zea mays)
Authors: Birch C. J. , Hammer G. L. , Rickert K. G.
Published: August 2004

The ability to predict leaf area and leaf area index is crucial in crop
simulation models that predict crop growth and yield. Previous studies have
shown existing methods of predicting leaf area to be inadequate when applied
to a broad range of cultivars with different numbers of leaves. The objectives
of the study were to (i) develop generalised methods of
modelling individual and total plant leaf area, and leaf senescence, that do
not require constants that are specific to environments and/or genotypes,
(ii) re-examine the base, optimum, and maximum
temperatures for calculation of thermal time for leaf senescence, and
(iii) assess the method of calculation of individual
leaf area from leaf length and leaf width in experimental work. Five cultivars
of maize differing widely in maturity and adaptation were planted in October
1994 in south-eastern Queensland, and grown under non-limiting conditions of
water and plant nutrient supplies. Additional data for maize plants with low
total leaf number (12-17) grown at Katumani Research Centre, Kenya, were
included to extend the range in the total leaf number per plant.
The equation for the modified (slightly skewed) bell curve could be
generalised for modelling individual leaf area, as all coefficients in it were
related to total leaf number. Use of coefficients for individual genotypes can
be avoided, and individual and total plant leaf area can be calculated from
total leaf number. A single, logistic equation, relying on maximum plant leaf
area and thermal time from emergence, was developed to predict leaf
senescence. The base, optimum, and maximum temperatures for calculation of
thermal time for leaf senescence were 8, 34, and 40ºC, and apply for the
whole crop-cycle when used in modelling of leaf senescence. Thus, the
modelling of leaf production and senescence is simplified, improved, and
generalised. Consequently, the modelling of leaf area index (LAI) and
variables that rely on LAI will be improved.
For experimental purposes, we found that the calculation of leaf area from
leaf length and leaf width remains appropriate, though the relationship
differed slightly from previously published equations.
Simplified methods for assessing quantities of N2 fixed by Lupinus angustifolius L. and its benefits to soil nitrogen status
Authors: Evans J. , Heenan D. P.
Published: August 2004

Procedures for assessing the quantity of symbiotically fixed nitrogen (kg
N/ha) in standing crops of lupin and for estimating variation of
N2 fixation by lupins in different years were determined
empirically and described. In standing crops, N2
fixation was estimated from crop height, plant population density, and a
bioassay of soil mineral nitrogen (cereal crop N; kg N/ha). In addition it
was also estimated from rainfall, sowing date, and cereal N, which
consequently enabled prediction of seasonal variation in fixed N using
historical rainfall data. Procedures for estimating the potential contribution
of N2 fixation to soil N, and the effects of lupin and
cereal N budgets on soil N balance based on differences in fixed N and grain
N (grain yield×estimated grain N concentration) are also given. The
collective procedures are applied to a site in south-eastern Australia and the
predicted crop effects on soil N balance compared with actual field data.
Perceived limitations of the procedures are discussed.
Impact of lupins, grazed or ungrazed subterranean clover,stubble retention, and lime on soil nitrogen supplyand wheat nitrogen uptake, grain yields, and grain protein
Authors: McGhie W. J. , Heenan D. P. , Collins D.
Published: August 2004

Soil nitrogen (N), N uptake, and wheat production in relation to rotation with
wheat, lupin,or subterranean clover, mulched or grazed, were examined on a red
earth at Wagga Wagga, New South Wales. Data over 4 years (1992{95) are
presented from a long-term trial commenced in 1979.
The effects of the various rotations on wheat productivity changed with
seasonal rainfall duringthe wheat and the previous legume growing year.
Generally, low rainfall (1991 and 1994) during thelegume growing season
resulted in lower N uptake, grain protein, and grain yield by wheat grown ina
following season. The addition of N fertiliser (100 kg N/ha) to continuous
wheat increased soil N supply, N uptake, grain yield, and grain protein.
Yields from continuously cropped wheat fertilisedwith N were usually lower
than those after a lupin growing season, although total soil N levels
weresimilar. Subterranean clover produced higher total soil N and grain
protein than lupin but yields werenormally less. Lodging and take-all diseases
were higher after a growing season with subterraneanclover than after lupins
and most likely reduced grain yields. Grazing, as opposed to mowing
andmulching subterranean clover, increased soil total N, grain protein, and
usually soil mineral N, butnot grain yield. The addition of lime at 1·5
t/ha raised the soil pH(CaCl2) (0-10 cm) of the
mostacidified treatment, continuously cropped wheat fertilised with N, from
4·04 to a mean of 4·7, andincreased yields and N uptake in 1993
and 1995.
Effects of plant extracts of Bothriochloa pertusa and Urochloa mosambicensis on seed germination and seedling growth of Stylosanthes hamata cv. Verano and Stylosanthes scabra cv. Seca
Authors: Hu F. D. , Jones R. J.
Published: August 2004

Effects of osmotic stress and of aqueous plant extracts from 4 pasture species
on seed germination and seedling growth of the tropical legumes
S. hamata (L.) Taub cv. Verano and
S. scabra Vog. cv. Seca were
investigated. Allelopathic effects of plant extracts from
B. pertusa (L.) A. Camus were
measured on S. scabra cv. Seca in
terms of lower germination (35%) and shorter root length (35%).
Extracts from Urochloa mosambicensis(Hack.) Dandy cv.
Nixon had no adverse effect on Seca germination, but also reduced Seca root
length. There was no evidence to support the hypothesis that
B. pertusa had allelopathic effects
on Verano germination or seedling growth. Extracts from Verano and Seca also
reduced germination, seedling weight, and root length of Seca as well as root
length of Verano.
Root length was more sensitive than seedling length for ascertaining
allelopathic effects, as there was no osmotic potential effect on root length
up to 300 mmol/kg, whereas seedling weight and shoot length declined
linearly with increasing osmotic potential (r =
-0·92 and -0·99, respectively).
Germination responses of Verano and Seca in solutions of both mannitol and
polyethylene glycol-600 (PEG) were similar up to 300 mmol/kg, but at 600
mmol/kg Verano had a significantly higher germination in mannitol.
Since the osmotic potential of the plant extracts did not exceed 78
mmol/kg, the use of osmotically adjusted control treatments had little
effect on the conclusions drawn from using a distilled water control
treatment.
Field amelioration of acidic soils in south-east Queensland. I. Effect of amendments on soil properties
Authors: Aitken R. L. , Moody P. W. , Dickson T.
Published: August 2004

Replicated field trials with rates of lime ranging up to 8 t/ha were
conducted at each of 27 sites in south-east Queensland. At 16 of these sites,
single rates (2 t/ha) of gypsum or phosphogypsum were also applied. Soil
samples (0-10 cm) were collected from each plot and analysed for pH in both
water (pHw) and 0·01 M
CaCl2 (pHCa), for electrical
conductivity, exchangeable cations, and extractable Al and Mn.
Gypsum application resulted in either a general trend for, or significant
(P < 0·05), reductions in
pHw but had no significant effect on
pHCa. The relationship between rate of applied lime and
soil pH at each site permitted the calculation of pH buffer capacity for a
wide range of soil types and properties. The pH increase per t applied lime
ranged from 0·14 to 0·82 and from 0·16 to 0·63 for
pH measured in water and 0·01 M CaCl2,
respectively, reflecting the range in pH buffer capacity which was
significantly correlated with organic carbon. Multiple regression indicated
that organic carbon and clay significantly contributed to the variation in pH
buffer capacity but only around 40% of the variation could be accounted
for.
The pH values at which Al saturation was reduced to 10% ranged from
4·82 to 6·02 (pHw) and from 4·26 to
4·93 (pHCa) and indicated that if neutralising
exchangeable Al is the basis for liming, then no single target pH value will
be appropriate for all soils. However, the target pH at which Al saturation
would be reduced to 10% could be predicted from the initial pH and
initial Al saturation. The effective cation exchange capacity (ECEC) was
increased by liming at all sites and the additional exchange capacity was
occupied by Ca. This increased Ca saturation was not necessarily at the
expense of exchangeable K and Mg, which were significantly
(P < 0·05) reduced at only a few sites. The
increase in ECEC for a unit increase in pH ranged from 0·5 to 9
cmol(+)/kg and at some sites represented a doubling of the
soil"s cation exchange capacity.
Season and plant type affect the response of rice yield to nitrogen fertilisation in a semi-arid tropical environment
Authors: Borrell A. K. , Garside A. L. , Fukai S. , Reid D. J.
Published: August 2004

Production of flooded direct-seeded rice (Oryza sativa
L.) in semi-arid tropical regions of northern Australia would be enhanced by
increasing the efficiency of fertiliser nitrogen (N) use. Short-statured and
early-maturing genotypes have replaced the taller and later genotypes in
northern Australia, and they may respond differently to N. This paper reports
the results of 4 experiments comparing the response of 3 rice genotypes
differing in maturity and stature to 5 rates of applied nitrogen (0, 70, 140,
210, and 280 kg/ha) over 4 seasons (2 wet and 2 dry seasons) in the
Burdekin River Irrigation Area, northern Australia.
Grain yield varied among seasons and was negatively correlated with average
daily mean temperature during the 30-day period before anthesis. The response
of yield to N fertilisation was generally higher in the dry season. Panicle
number was correlated with grain yield in both seasons, yet responded to N
fertilisation only in the dry season. In 3 of 4 experiments, grain yield
responded to the application of up to 70 kg N/ha, yielding about 750
g/m2. In only 1 dry season experiment did grain
yield respond to the application of 140 kg N/ha, yielding about 930
g/m2. In this experiment, the response of grain yield
to N rate also varied among genotypes such that yield in the early-maturing
genotypes (Newbonnet and Lemont) was more responsive to N rates above 70
kg/ha than in the late-maturing genotype (Starbonnet).
Of the 3 genotypes examined, highest yields were attained in Newbonnet
(early-maturing, medium-statured) by combining high total dry matter
production with high harvest index, indicating that this plant type may have
an advantage in northern Australia. Yields in Lemont (early-maturing,
short-statured) and Starbonnet (late-maturing, tall-statured) were limited by
dry matter production and harvest index, respectively. There is some evidence
that increased dry matter production in Newbonnet compared with Lemont was
related to increased stem length. The evidence linking high harvest index with
increased earliness in Newbonnet compared with Starbonnet is less compelling.
Plant growth regulators cannot be used to alter significantly the commercial harvest date of Boronia heterophylla F. Muell. (Rutaceae)
Authors: Wann J. M. , Plummer J. A.
Published: August 2004

Harvest of the cut fiower crop, Boronia heterophylla F.
Muell., is restricted to a 2-week period in early spring. Extension of the
fiowering period by plant growth regulators was examined in plants growing in
the field under standard, commercial production conditions. Flowering time,
and hence harvest date, were delayed by 6{9 days following the
application of gibberellic acid and benzyl adenine
(GA4+7+BA). High concentrations of
GA4+7+BA (40, 80 mg/L) delayed flowering longer
than 20 mg/L, but reduced flower number. BA alone (4 applications of 20,
50, or 100 mg/L) reduced flower number and did not aflect harvest date.
GA3 (4 applications of 20 mg/L) prevented flowering. Paclobutrazol (100
mg/L) reduced flower number and delayed flowering by 4 days. The timing of
applications at the commencement of flower-promoting conditions, when plants
had been exposed to 10-20 nights of temperatures <10˚C (mid autumn),
appeared to be critical. A delay of harvest of 6 days is a 40%
extension of the harvest period but this may not be sufficient for commercial
production.
Chickpea in wheat-based cropping systems of northern New South Wales. III. Prediction of N2 fixation and N balance using soil nitrate at sowing and chickpea yield
Authors: Herridge D. F. , Marcellos H. , Peoples M. B. , Felton W. L. , Turner G. L.
Published: August 2004

Functions quantifying relationships between N2 fixation
by legumes and other factors would be useful to farmers in the management of
legumes and nitrogen in their production systems. The 2 most critical factors
regulating N2 fixation are legume yield and soil nitrate
and both should be included as independent variables in the functions. Data
from 9 experiments in northern New South Wales on soil nitrate at sowing,
yields of shoot and grain dry matter (DM) and N of chickpea, and
δ15N of shoots of chickpea and non
N2-fixing reference crops (wheat, barley, and
uninoculated chickpea) were used to determine the percentage of chickpea N
derived from N2 fixation (P fix),
total N2 fixed, and N balance (fixed
N2 minus grain N). Data were then subjected to simple
and multivariate regression analyses with Pfix and total
N2 fixed as the dependent variables and soil nitrate,
shoot N, and grain yield as the independent variables. Simple regression
coefficients (r2) for Pfix were
0·26 with shoot N as the independent variable, 0·59 with soil
nitrate, and 0·62 with grain yield. Coefficient values were increased
in the 2-factor (multiple) regressions to 0·74
(P<0·001) for soil nitrate plus shoot N, and
0·82 (P < 0·001) for soil nitrate plus
grain yield. For total N2 fixed, the regression
coefficient was lower at 0·68 (P <
0·001), using soil nitrate plus grain yield. We tested the functions
against an independent data set with best prediction of
Pfix involving the nitrate and grain yield equation
(r2 = 0·83;
P < 0·001). Total N2
fixed was not well predicted. We concluded that further development of such
functions is warranted to refine both accuracy and precision for chickpea and
to extend the approach to other species.
Simulation of legume-cereal systems using APSIM
Authors: Probert M. E. , Carberry P. S. , McCown R. L. , Turpin J. E.
Published: August 2004

A major issue for the sustainability of cropping systems is the maintenance of
soil fertility and especially the supply of nitrogen to cereal crops. Choice
of appropriate management strategies, including the role of legumes, is
problematic, especially where climatic variation is large. Simulation models
provide the means of extrapolation from the site- and season-specific bounds
of experimental data to permit scenario analyses that can explore alternative
management options.
This paper is a status report on the capabilities of the APSIM modelling
framework to simulate legume-cereal systems. APSIM deals with water and
nitrogen constraints to crop growth and is well suited to the task of
modelling whole systems involving crop rotations. The components that are not
yet fully developed are modules for growing the legume crops and coupling
these with the module describing the dynamics of soil organic matter to obtain
sensible predictions of nitrogen supply to subsequent crops. Evidence is
provided that those parts of the system that can be represented by current
APSIM modules are predicted satisfactorily. The closest approach to a whole
system that has been simulated to date is grass or legume
(Stylosanthes hamata cv. Verano) leys followed by crops
of maize or sorghum grown in experiments at Katherine, NT. Predictions of the
yields of the leys and the cereal crops, especially the benefit from the
legume leys to a second crop, were sufficiently close to measured yields to
suggest that there are good prospects for developing useful models of other
systems involving legumes and cereals. A simulation scenario exploring a
chickpea-wheat system demonstrates how models can be used to analyse both
productivity and sustainability aspects of the system.
Effects of grazing on plant and soil nitrogen relations of pasture-crop rotations
Authors: Unkovich Murray , Sanford Paul , Pate John , Hyder Mike
Published: August 2004

Plant and soil nitrogen (N) fluxes were assessed in subterranean clover
(Trifolium subterraneum L.) based pastures set-stocked
at 8 sheep per hectare (light grazing) or grazed at a much higher, but
variable, intensity to maintain 1400 kg standing dry matter per hectare
(intensive grazing) through the addition or removal of sheep. Pasture
composition and biomass production, herbage N concentration, plant nitrate
(NO-3) utilisation, and
N2 fixation by clover were assessed at 3-weekly
intervals over the growing season. Soil ammonium
(NH+4) and
NO-3 availability were assessed at
similar intervals using soil coring and in situ incubation cores. Seasonal
pasture yield under light grazing was 11·5 t dry matter/ha compared
with 7·9 t/ha under intensive grazing, the difference being mostly
attributable to reduced grass growth under intensive grazing. However, there
was essentially no difference between the pastures in total N accumulation
(300 kg N/ha in the lightly grazed and 302 kg N/ha in the intensively
grazed pastures). The lesser dry matter production under intensive grazing was
compensated for by higher N concentration and increased clover content of the
sward, and faster clover growth late in the growing season.
N2 fixation by clover under intensive grazing (153 kg
N/ha) was slightly greater than under light grazing (131 kg N/ha).
Proportional dependence of clover on N2 fixation
(%Ndfa) was similar under intensive grazing (78%) and light
grazing (84%), despite higher continued availability of soil mineral N
under intensive grazing. Uptake of soil N by the grass component amounted to
147 kg N/ha under light grazing v. 96 kg N/ha in
the intensively grazed pasture, and for the clover was 18 and 40 kg N/ha,
respectively. Capeweed (Arctotheca calendula L.), a
common weed of south-west Australian pastures, was extraordinarily active in
absorbing, storing, and reducing soil
NO-3, especially when subjected
to intensive grazing. After the 3 years of the grazing trial, the pastures
were cultivated and cropped to oats, triticale, and canola and the biomass and
N uptake of each crop assessed. Intensive grazing in the previous pasture
resulted in increased availability of soil mineral N in the subsequent
cropping phase and accordingly augmented crop N uptake and eventual grain
protein levels relative to crops following lightly grazed pasture. The study
indicated that intensive grazing before cropping may offer a useful management
tool for improving N nutrition and yields of non-leguminous crops in
pasture-crop rotations under the conditions prevailing in the south-west of
Australia.
No lactic acid absorbed from the caecum and rumen of sheep
Authors: Rowe J. B. , Ding Z. , Godwin I. R. , Xu Y. , Ball F. M. , Atkinson S.
Published: August 2004

A comparative study of the absorption of lactic acid, volatile fatty acids
(VFA), glucose, and ammonia from caecal and rumen pouches was undertaken in
anaesthetised sheep. Test solutions varying in pH, osmolarity, lactic acid
concentration, and with fixed concentrations of VFA, ammonia, and glucose
(100, 7, and 4 mmol/L, respectively) were introduced into the clean,
surgically sealed pouches. Studies were undertaken in 9 sheep, each with 2
pouches in the caecum and 1 in the rumen. Samples were taken at 10-min
intervals for 50 min to determine rate of absorption. Neither L-lactic acid
nor D-lactic acid was absorbed from the caecal or rumen pouch and there was a
slight increase in both isomers of lactic acid (0·39%/min of
L-lactic acid and 0·24%/min of D-lactic acid averaged for
the caecum and rumen values) which was presumably due to conversion of
propionic acid and tissue metabolism during the experiment. The rate of
increase per unit area in the caecum (0·06
µmol/cm2·min) was much greater than
that in the rumen (0·015
µmol/cm2·min) based on the average of
L- and D-lactic acid. The absorption rates of acetic, propionic, and butyric
acids from the caecum (0·49, 0·17, and 0·08
µmol/cm2 ·min, respectively) and the
rumen (0·48, 0·16, and 0·08
µmol/cm2· min, respectively), based on
absorptive surface area of the pouches, were very similar. Glucose was
apparently absorbed from rumen pouches (0·18
µmol/cm2 ·min), but not from caecal
pouches (-0·01 µmol/cm2·min).
The mean absorption rate of ammonia from caecal pouches (0·60 µg
N/cm2·min) was 2·5 times greater than
that from rumen pouches (0·24 µg
N/cm2·min) (P <
0·0001). The mean absorption rate of ammonia for the caecal and rumen
pouches was about 2·6 times higher at pH 6·5
(0·99%/min) than that at pH 4·5
(0·38%/min) (P < 0·0001) at
the same osmolarity and lactic acid concentration. A decrease in pH, osmotic
pressure, or the concentration of lactic acid resulted in corresponding
increases in the absorption of VFA.
Yield response of narrow-leafed lupin plants to variations in pod number
Authors: Palta J. A. , Ludwig C.
Published: August 2004

The effect of pod number on the seed yield and components of seed yield was
examined for narrow-leafed lupin (Lupinus angustifolius
L.) grown at a plant density of 36 plants/m2 in both
the glasshouse and the field. Diflerent numbers of pods per plant in the
glasshouse-grown lupin were generated by the application of
N6-benzylaminopurine (BAP) to a specific number of
flowers to ensure artificially that they set pods, and the subsequent removal
of the remaining untreated flowers. Pod number ranged from 6 to 65
pods/plant in the glasshouse and was naturally distributed from 2 to 22
pods/plant in the field. Increases in seed yield per plant occurred as pod
number per plant increased from 2 to 30 pods. No further increases in seed
yield resulted when pod number per plant increased from 30 to 55 pods. Seed
yield per plant was depressed as pod number increased from 55 to 65 pods. Seed
size fell as pod number per plant increased over 20 pods and was less affected
once the number of seeds per pod was reduced. The reduction in seed number per
pod resulted from an increase in the number of seeds that aborted during seed
filling. The data suggest that at a plant density of 36
plants/m2 there is potential for improving seed
yield per plant by increasing the number of pods that reach maturity, provided
it does not exceed 30 pods/plant. However, if consideration is given to
producing large seeds, often preferred by buyers, the number of pods per plant
should not exceed 20 pods.
Radiation use efficiency increases when the diffuse component of incident radiation is enhanced under shade
Authors: Healey K. D. , Hammer G. L. , Rickert K. G. , Bange M. P.
Published: August 2004

Theoretical analyses have shown the radiation use efficiency of maize,
soybean, and peanut to increase with a decrease in the level of incident
radiation and an increase in the proportion of diffuse radiation. This study
compared the growth and radiation use efficiency of
Panicum maximum cv. Petrie (green panic) and
Bothriochloa insculpta cv. Bisset (creeping bluegrass)
beneath shading treatments (birdguard and solarweave shadecloths) with that in
full sunlight. A level of incident radiation reduced by 25% under
birdguard shadecloth decreased final yield and final leaf area index,but
increased canopy leaf nitrogen concentration and radiation use efficiency
(19-14%) (compared withthe full sun treatment). A similar level of
reduced incident radiation under solarweave shadecloth (which provided an
increased proportion of diffiuse radiation), increased final yield and
radiation use efficiency (46-50%). An understanding of the effects of
composition of incident radiation on radiation use efficiency of tropical
grasses enables more accurate estimation of potential pasture growth in shaded
environments. It also has impact upon crop production in glasshouses and
greenhouses.
Animal x testing environment interaction on postweaning liveweight gains of young bulls
Authors: Schoeman S. J. , Jordaan G. G.
Published: August 2004

Postweaning liveweight gain records of 1610 young bulls obtained both in
feedlot and under pasture were used to estimate (co)variance components using
a multivariate restricted maximum likelihood analysis. The pedigree file
included 3477 animals. Heritability estimates for liveweights and gain in both
environments correspond to most previously reported estimates. The genetic
correlation of gain between the 2 environments was -0·12, suggesting a
large genotype testing environment interaction and re-ranking of animal
breeding values across environments. Results of this analysis suggest the need
for environment-specific breeding values for postweaning gain.
Seed production in cluster clover (Trifolium glomeratum L.). 1. Flowering time, abortion, seed size, and hardseededness along branches
Authors: Smith F. P. , Cocks P. S. , Ewing M. A.
Published: August 2004

Seed production in cluster clover (Trifolium glomeratum
L.) was investigated at the level of the individual inflorescence. Plants were
grown in nursery rows under non-limiting conditions until 150 days after
sowing, at which time irrigation was stopped to truncate the growing season.
The number of florets, and the number, mass, and impermeability of seeds, were
determined for each inflorescence along the main branches, and were related to
the date and node of flowering. The interval between subsequent flowers
increased (3·4 days at node 2 v. 7·3 days
at node 7) and the rate of floret abortion increased (14% at node 1
v. 49% at node 7) with successive inflorescences
along the branch, even while moisture conditions remained favourable. These
effects are attributed to resource limitation during the latter stages of
plant growth. On the other hand, seeds per floret and seed mass were
unaffected by the node of flowering but declined rapidly once irrigation
ceased. Hardseededness was not affected by either node of flowering or date of
flowering, before or after the cessation of irrigation. Mean initial
hardseededness from inflorescences produced after irrigation ceased was
slightly higher than that from earlier formed inflorescences
(99·6% v. 94·1%,
P < 0·001).
The results highlight the importance of reproductive timing in an environment
with a limited growing season, since seed production fell rapidly once water
conditions became unfavourable. They suggest that seed production in cluster
clover is near to its potential while conditions remain favourable, although
resource limitation may reduce the rate of flowering and increase floret
abortion as the plant matures. Although unfavourable water conditions may
sharply reduce production of viable seeds, in cluster clover the initial
impermeability of those seeds is not affected, possibly a benefit of rapid
seed formation.
Long-term softening of surface and buried hard seeds of yellow serradella grown in a range of environments
Authors: Revell C. K. , Taylor G. B. , Cocks P. S.
Published: August 2004

A 3-year field experiment was conducted to investigate seed softening in
yellow serradella (Ornithopus compressus L.) in a low
rainfall Mediterranean environment at Merredin, Western Australia. The study
examined seeds of 4 accessions of serradella from separate growing sites
(Pindar, Merredin, and Badgingarra), and included the effect of pod burial
(only for accessions grown at Merredin). Pods were placed on the soil surface
in December 1992 and sampled in March, June, and October for the next 3 years.
Burial treatments (2 and 6 cm beneath the surface) commenced in June 1993
after pods had been on the soil surface for one summer. Samples were collected
in June for the next 2 years. Softening of seeds over the first summer in the
field was compared with that obtained in the laboratory with 16 weeks at a
diurnally alternating temperature of 60/15ºC.
Few seeds of any accession softened (generally <6%) at the soil
surface during the first summer but the rate of softening increased over the
next 2 years. The highest annual rate of softening was about 55% in the
third year in accessions GEH72-1A and GEH72-2A. Accession of serradella
hadmore influence on pattern of seed softening than site at which seeds were
produced. Burial of pods at 2 cm markedly accelerated seed softening in all
strains, particularly GEH72-1A and cv. Madeira, in which over 95% of
hard seeds softened during the first year of burial. Softening at 6 cm was
similar to that at the soil surface. Shallow burial of pods, as would occur
during cereal cropping in one year,could improve regeneration of serradella,
but reduce the longevity of its seed bank.
Laboratory treatment at 60/15ºC generally over-estimated field
softening during the first summer.The spread of germination in time in
laboratory tests differed between accessions and was much wider in GEH72-2A
than in others, extending up to 35 days. Such behaviour could provide
insurance against total seedling loss following false breaks of season.
Adaptation of lentil (Lens culinaris Medik.) to Mediterranean-type environments: effect of time of sowing on growth, yield, and water use
Authors: Siddique K. H. M. , Loss S. P. , Pritchard D. L. , Regan K. L. , Tennant D. , Jettner R. L. , Wilkinson D.
Published: August 2004

This study examined the adaptation of lentil
(Lens culinaris Medik. cv. Digger) to dryland
Mediterranean-type environments of southern Australia and determined the
effect of time of sowing on growth, yield, and water use. Phenology, canopy
development, radiation absorption, dry matter production and partitioning,
seed yield, and water use were measured from a range of sowing times at a
number of field locations in south-western Australia in 1994, 1995, and 1996.
Contrary to previous results with poorly adapted cultivars, our study showed
that lentil is well adapted to low to medium rainfall regions (300-500
mm/year) of south-western Australia and that seed yields greater than
1·0 t/ha and up to 2·5 t/ha can be achieved when sown
early. Even in the dry season of 1994 when May-October rainfall was <200
mm, yields of approximately 1·0 t/ha were produced from early
sowings. Seed yields were reduced with delayed sowing at rates of 4-29
kg/ha · day. Sowing in late April or early May allowed a longer
period for vegetative and reproductive growth, rapid canopy development,
greater absorption of photosynthetically active radiation, more water use,
and, hence, greater dry matter production, seed yield, and water use
efficiency than when sowing was delayed. Early-sown lentils began flowering
and filling seeds earlier in the growing season, at a time when vapour
pressure deficits and air temperatures were lower, and used more water in the
post-flowering period when compared to those treatments where sowing was
delayed. The values of water use efficiency for dry matter and grain
production, and transpiration efficiency, for early-sown lentil (up to 30
kg/ha · mm, 11 kg/ha · mm, and 20 kg/ha · mm,
respectively) were comparable to those reported for cereal and other grain
legume crops in similar environments. The development of earlier flowering
cultivars than Digger with greater dry matter production together with
improved agronomic packages will increase and stabilise lentil yields in low
rainfall environments of southern Australia.
Partition of nutrients in moderately fat ewes compared with lean ewes given ad libitum access to feed in late pregnancy
Authors: McNeill D. M. , Kelly R. W. , Williams I. H.
Published: August 2004

The effect of a difference in voluntary feed intake on fetal weight was tested
in lean v. moderately fat ewes (0·15
v. 0·32 kg/kg fat-free empty body weight), by
giving them ad libitum access to feed from Day 110 to
146 of pregnancy when both had placentas of a similar size (at Day 146: 437
v. 467 g, s.e.m. = 49·5,
P > 0·05). Although the lean ewes ate
29% more than the fatter ewes above their estimated requirements
(1258±106·9 v. 978±105·8
g/ewe · day, P = 0·08) fetal
weights were not affected (4744 v. 4590 g, s.e.m.
= 282·1, P > 0·05). Instead, the
lean ewes partitioned more of their intake into body fat than the fatter ewes
(0·13 v. 0·01 kg/kg fat-free empty
body weight, P < 0·05). The results support
the concept that the placenta places an upper limit to the uptake of nutrients
by the fetus.
Effect of 1-naphthaleneacetic acid concentrations and the number of applications on the yield components, yield, and fibre properties of Egyptian cotton (Gossypium barbadense L.)
Authors: Sawan Z. M. , Sakr R. A. , Momtaz O. A.
Published: August 2004

Field experiments were performed in 2 successive seasons at the experimental
station, Faculty of Agriculture, Cairo University, Giza, Egypt, on the
Egyptian cotton cultivar Giza 75 (Gossypium barbadense
L.). Cotton plants were sprayed with the growth regulator 1-naphthaleneacetic
acid (NAA) once (after 90 days), twice (90 and 105 days), or 3 times (90, 105,
and 120 days after sowing), during the square initiation and bolling stage, at
concentrations of 5, 10, 15, 20 or 25 mg/L, respectively. The volume of
solution was the same for all treatments, 960 L/ha. The control plants
were sprayed with water only. The effect of the previous treatments on yield
components, lint yield, and fibre properties was studied. The application of
NAA increased the number of opened bolls per plant, boll weight, seed index,
and lint yield per ha. Lint percentage, fibre length parameters, and
micronaire value were not significantly affected by NAA. Flat bundle strength
was significantly increased when NAA was applied once at 10-25 mg/L. The
application of NAA twice or 3 times at 15-20 mg/L tended to give the best
results on yield components and lint yield of the Egyptian cotton plants.
Effects of photon flux density on photosynthesis, growth, flowering, and oil content in Boronia
Authors: Wann J. M. , Orifici R. , Spadek Z. E. , Plummer J. A.
Published: August 2004

Boronia heterophylla is cultivated for cut flowers and
B. megastigma for volatile oil production. Both species
are endemic to south-western Western Australia and their natural habitat is
often shaded by a canopy of Melaleuca parviflora or
Eucalyptus marginata. Shade tents were used to examine
the influence of reduced photon flux density (PFD) on photosynthesis, growth,
and flower production in B. heterophylla and
B. megastigma. Volatile oil content was also examined in
B. megastigma. Photosynthesis in field-grown
B. heterophylla was saturated at 16·2 µmol
CO2/m 2·s under a PFD
of 1022 µmol/m 2·s (75% full
sunlight). Flower number was highest under 75% full sunlight but the
number of harvestable stems was the same under 75% and full sunlight.
More flowers were produced by B. megastigma plants grown
under 75% full sunlight. Content of α-pinene and limonene
decreased with decreasing light intensity, whereas β-ionone and docecyl
acetate increased with decreasing light intensity
Effects of sowing date, nitrogen application, and sowing rate on oat quality
Authors: Zhou M. X. , Glennie-Holmes M. , Robards K. , Roberts G. L. , Helliwell S.
Published: August 2004

Processors of oats for human food use in Australia may have to use grain grown
under widely different agronomic conditions. To assess the effect of agronomic
conditions on the quality of oats, field trials were conducted in New South
Wales, Australia, in 1995 with Bimbil, Carbeen, Coolabah, and Euro (feed
varieties); Cooba, Mortlock, and Echidna (food varieties); and Yarran, a
variety particularly unsuitable for human food use. In 3 separate experiments,
the effects of nitrogen (N) application, sowing date, and sowing rate on the
quality of the oats were examined. N and late sowing caused an increase in
protein content and a decrease in moisture content, whereas other grain
qualities were little affected. Sowing rate had significant effects on grain
quality. As the sowing rate was increased, kernel size, groat percentage, and
protein content were increased and moisture content was decreased. The pasting
properties of groat flour were affected by all treatments, particularly sowing
rate. Late sowing date increased the final viscosity and pasting temperature
of the oats. High sowing rates increased the final viscosity and pasting
temperature and prolonged the time to peak viscosity. Although management had
significant effects on oat quality, variety was still the main cause of the
differences.