bluuebunny/crossref_metadata_2025 huggingface dataset:
Porous silicon free-standing coupled microcavities
Authors: Ghulinyan M. , Oton C. J. , Gaburro Z. , Bettotti P. , Pavesi L.
Published: March 2003

We report the experimental characterization of porous silicon free-standing coupled microcavities. We have grown free-standing structures of up to 109 stacked layers. Free-standing structures are interesting because reflectance spectra can be measured on both sides of the samples. The comparison of reflectance spectra from the front and back side indicates that the porous silicon anodization process has a natural drift along the growth direction. However, we demonstrate that this drift can be compensated, showing a homogeneous structure of ten coupled microcavities, in which all ten resonance peaks are resolved in both transmission and reflection measurements.
Direct observation of inversely polarized frozen nanodomains in fatigued ferroelectric memory capacitors
Authors: Colla E. L. , Stolichnov I. , Bradely P. E. , Setter N.
Published: March 2003

The direct observation of blocked polarization domains at the electrode–ferroelectric interface of electrically fatigued ferroelectric films is reported. Blocked nanodomains are believed to be the origin of polarization fatigue in ferroelectric nonvolatile memories but have not been directly observed so far due to the required upper metal electrode which impedes the direct access to the surface of the ferroelectric film. This problem has been solved by using low temperature melting metal as removable top electrode. After fatigue and subsequent top electrode removal it was possible to observe the polarization state of the fatigued capacitor and its depth profile by means of detection of the local piezoelectric activity with a conductive atomic force microscope tip. Blocked polarization domains with opposite polarization compared to the film body could be directly observed at the upper ferroelectrics surface.
Measurement of highly transient electrical charging following high-intensity laser–solid interaction
Authors: Borghesi M. , Romagnani L. , Schiavi A. , Campbell D. H. , Haines M. G. , Willi O. , Mackinnon A. J. , Galimberti M. , Gizzi L. , Clarke R. J. , Hawkes S.
Published: March 2003

The multi-million-electron-volt proton beams accelerated during high-intensity laser–solid interactions have been used as a particle probe to investigate the electric charging of microscopic targets laser-irradiated at intensity ∼1019 W cm2. The charge-up, detected via the proton deflection with high temporal and spatial resolution, is due to the escape of energetic electrons generated during the interaction. The analysis of the data is supported by three-dimensional tracing of the proton trajectories.
Effect of numerical aperture on the spectral splitting feature near phase singularities of focused waves
Authors: Ganic Djenan , Chon James W. M. , Gu Min
Published: March 2003

We demonstrate that because of the depolarization effect associated with a high-numerical-aperture lens, the recently predicted spectral splitting phenomenon near phase singularities of focused waves [G. Gbur, T. D. Visser, and E. Wolf, Phys. Rev. Lett. 88, 013901 (2002)] disappears when the numerical aperture is higher than critical values that are different between the incident polarization direction and the axial direction.
Exchange-spring permanent magnet particles produced by spark-erosion
Authors: Hansen M. F. , Vecchio K. S. , Parker F. T. , Spada F. E. , Berkowitz A. E.
Published: March 2003

Exchange-spring permanent magnet particles of composition Pr6.93Fe85.7B5.95Nb1.39 in at. % were prepared by spark-erosion in liquid argon. The best exchange-spring properties were achieved after vacuum annealing the as-sparked powders at 700 °C for ∼5 min, and did not change significantly for anneals up to 120 min. This behavior suggests that the equilibrium dimensions of the “hard” and “soft” phases were determined by the sizes of the spark-eroded particles in which they developed. The Pr2Fe14B phase developed as spheres, likely single crystals, in an α-Fe+Fe2B matrix.
Plasma-etching-enhanced deep centers in n-GaN grown by metalorganic chemical-vapor deposition
Authors: Fang Z.-Q. , Look D. C. , Wang X.-L. , Han Jung , Khan F. A. , Adesida I.
Published: March 2003

By using deep-level transient spectroscopy (DLTS), deep centers have been characterized in unintentionally doped n-GaN samples grown by metalorganic chemical-vapor deposition and subjected to inductively coupled plasma reactive ion etching. At least six DLTS traps exist in the control sample: A1 (∼0.90 eV), Ax (∼0.72 eV), B (0.61 eV), C1 (0.44 eV), D (0.25 eV), and E1 (0.17 eV), with B dominant. Then, as the etching bias-voltage increases from −50 to −150 V, trap D increases strongly and becomes dominant, while traps A1, C (0.34 eV), and E1 increase at a slower rate. Trap B, on the other hand, is nearly unchanged. Previous electron-irradiation studies are consistent with the E1 traps being N-vacancy related. It is likely that the D traps are also, except that they are in the regions of dislocations.
Structural and mechanical properties of nanostructured metalloceramic coatings on cobalt chrome alloys
Authors: Catledge Shane A. , Vohra Yogesh K. , Woodard S. , Venugopalan R.
Published: March 2003

A functionally graded nanocrystalline metalloceramic coating on cobalt–chrome alloys was investigated with thin-film x-ray diffraction (XRD), nanoindentation, and scratch adhesion testing. The gradual transition in bonding from metallic to predominantly covalent along with a nanocrystalline grain structure provides a unique material system with excellent strength, toughness, and adhesion properties. XRD analysis of the (CrTiN) coating suggests a cubic sodium chloride phase structure with a=4.2169±0.0035 Å. Nanoindentation measurements of the coating result in a hardness of 27 GPa and Young’s modulus of 320 GPa. The graded metallic/covalent nature of the coating with high plasticity also results in excellent film/substrate adhesion as shown by an average critical force of 44±5 N in scratch testing.
Corrigendum to: A long-term experiment to study the role of mulches in the physiology and macro-nutrition of strawberry grown under water stress
Authors: Kirnak Halil , Kaya Cengiz , Higgs David , Gercek Sinan
Published: March 2003

Strawberry (Fragaria × ananassa Duch) cv. ‘Oso Grande’ was grown in
the field from July 1999 to May 2000 in order to investigate the effectiveness
of different mulch types on fruit yield, quality (i.e. soluble dry matter,
fruit size), leaf nutrient compositions, and normal plant growth parameters in
strawberry grown under water stress. Treatments were: (1) bare soil +
water stressed (WS), (2) bare soil + unstressed (control), (3) black
polyethylene mulch + water stressed (BPM + WS), (4) wheat
straw mulch + water stressed (WSM + WS), (5) wheat straw
mulch plus black polyethylene mulch + water stressed (WSM +
BPM + WS). Water stress was created by irrigating plants once every 3
days at 50% A pan (Epan) evaporation, compared with the control, which
received 75% daily. WS caused reductions in all parameters, except
water-soluble dry matter concentrations in fruits, compared with the control
treatment. Both BPM and WSM improved the fruit yield, fruit size, plant dry
matter, leaf area index, and chlorophyll concentrations in leaves in the
stressed treatments, while these 2 mulches in combination (BPM + WSM)
caused further increases in these parameters. WS enhanced electrolyte leakage
by impairing membrane permeability compared with control treatment. Mulching,
especially BPM and WSM together, substantially decreased electrolyte leakage.
WS reduced leaf concentrations of all nutrients tested (N, P, K, Ca, and Mg).
However, mulching, especially BPM and WSM together, enhanced the
concentrations of these nutrients, but their concentrations were still lower
than those in the control treatment. These results clearly indicate that
mulching mitigates negative effects of water stress on plant growth and fruit
yield in field-grown strawberry, particularly in semi-arid situations.
Corrigendum to: Genetic mapping of commercially significant starch characteristics in wheat crosses
Authors: Batey I. L. , Hayden M. J. , Cai S. , Sharp P. J. , Cornish G. B. , Morell M. K. , Appels R.
Published: March 2003

Starch properties were measured on the doubled haploid progeny of 2 crosses,
one between Cranbrook and Halberd and the other between CD87 and Katepwa.
Properties studied included starch peak and final viscosity measured by Rapid
Visco Analyser, starch granule size distribution measured by laser light
scattering, starch gelatinisation temperature by differential scanning
calorimetry, and flour swelling volume. In the Cranbrook Halberd cross
(samples from 2 environments), a highly significant quantitative trait locus
(QTL) was located on chromosome 4A for both starch peak viscosity and
starch/flour swelling volume, centred around the
Wx-B1 locus. In previous studies, this locus has been
found to be linked to Japanese noodle quality. The increases in starch peak
viscosity and flour swelling volume are derived from the Halberd parent,
consistent with the fact that Halberd is null for the
Wx-B1 locus on chromosome 4A and is missing the
respective granule-bound starch synthase protein, whereas Cranbrook is a wheat
line carrying the normal 3 Wx loci. The final starch
viscosity also showed an association with the Wx-B1
locus. In the CD87 Katepwa cross, the progeny showed an association between
peak viscosity and a marker on chromosome 7A. This appeared to be near the
Wx-A1 locus. In some experiments, flour viscosity showed
a highly significant QTL on chromosome 7B, apparently at the same locus as the
late maturity - amylase derived from the Cranbrook parent. Starch
gelatinisation onset temperature indicated a significant QTL on chromosomes 2B
and 7A (LOD = 2.58 and 3.66, respectively, in interval analyses).
Starch gelatinisation peak temperatures indicated a QTL on chromosome 7A,
which, although not in the significant (P = 0.05)
class based on regression analyses, indicated a LOD score of 3.06 in interval
analyses. Heat of gelatinisation (H) indicated a suggestive QTL (LRS =
14.5 with a threshold of 14.7 for P < 0.05, LOD
= 2.65 for interval analysis), on chromosome 4A, at the
Wx-B1 locus with an increased effect coming from the
Halberd parent. The A:B granule ratio analysis indicated a significant QTL on
chromosome 4B, but this was not observed in all environments and may be due to
the fact that the QTL corresponded to the position of a major QTL controlling
plant growth.
Available phosphorus, sulfur, potassium, and other cations in a long-term grazing experiment in south-western Victoria
Authors: Cayley J. W. D. , McCaskill M. R. , Kearney G. A.
Published: March 2003

Relationships between amounts of superphosphate applied to pasture and stocking rate on available nutrient status were assessed from 1979 to 2000 on a chromosol derived from basalt at Hamilton, Victoria. The pastures were stocked with sheep at low, medium, or high grazing pressures in factorial combination with 6 levels of superphosphate. Overall annual amounts of single superphosphate (8.8% P, 11% S, 19% Ca) applied ranged from 0.4 to 36 kg P/ha. Potassium chloride (KCl) was applied to all plots periodically. Average stocking rates ranged from 7 to 19 dry sheep equivalents (DSE)/ha. The nutrient status of plots was monitored by sampling the soil to a depth of 10 cm, avoiding the areas used by the sheep for camping. In 1994, samples of topsoil (0–5 cm and 5–10 cm) were taken from the camp areas and non-camp areas in each plot in order to assess 'plant-available' P, S, and extractable cations. Changes in P and S with depth to 80 cm in high and low grazing pressure treatments were also assessed. The influence of cumulative P applied on Olsen P varied with time and grazing pressure. During the first 12–15 years, the Olsen P of high grazing pressure plots was greater than that of low grazing pressure plots, but subsequently the reverse has been the case. Plant-available S also increased where more superphosphate had been applied. Levels were greater than 7 mg S/kg soil except at the lowest level of superphosphate, indicating that forms of P fertiliser with less S could be used here. After initial applications of KCl, this fertiliser was not applied for 8 years. During this time the K status fell from 270 to 120 mg K/kg soil, just above where plant responses to K are likely, emphasising the need to monitor the K status of productive pastures on these soils. Levels of exchangeable Mg2+ fell as more superphosphate was used, whereas levels of Ca2+ rose. The Olsen P of soil deeper than 10 cm was always less than 5 mg P/kg soil. P supply to deep-rooted pasture plants may thus be limiting when the topsoil is dry. These results, together with published assessments of animal production at this site, show that for pastures fertilised annually, the Olsen P associated with the most profit varied from 7 mg P/kg soil at 7 ewes/ha (10.5 DSE/ha), to 14 mg P/kg soil at 18 ewes/ha.
Matching physiological traits and ion concentrations associated with salt stress in cowpea genotypes
Authors: Murillo-Amadot Bernardo , Troyo-Diéguez Enrique , López-Aguilar Raúl , López-Cortés Alejandro , Tinoco-Ojanguri Clara L. , Jones Hamlyn G. , Kaya Cengiz
Published: March 2003

The salt tolerance of 25 cowpea genotypes (Vigna unguiculata L. Walp.) was studied during early vegetative growth. Salinity treatments were applied by irrigating with a nutrient solution containing 0, 85, and 170 mmol NaCl/L. Seedling survival decreased linearly as salinity increased, but this enabled cowpea genotypes to be ranked for salinity tolerance according to the magnitudes of slopes of regression of survival percentage on salinity. Sodium concentration was higher in roots than in shoots in all genotypes, and increased significantly in both roots and shoots as salinity increased. Chloride concentration in both roots and shoots increased with increasing salinity in all genotypes, and was higher in shoots than in roots at 85 and 170 mmol NaCl/L. In some cases, Ca, Mg, K, and P concentrations were reduced by an increase in salinity, but none of the genotypes appeared to suffer any nutrient deficiency. We observed wide differences in responses to salinity, and our results suggest that during the growth stage studied, 7 of the 25 genotppes tested could be classified as tolerant or relatively tolerant to salinity (Sonorense, CB3, CB27, Cuarenteño, CB46, Paceño, and IT82D-889).
Competition between inoculant and naturalised Rhizobium leguminosarum bv. trifolii for nodulation of annual clovers in alkaline soils
Authors: Denton M. D. , Coventry D. R. , Murphy P. J. , Howieson J. G. , Bellotti W. D.
Published: March 2003

Inoculant rhizobia typically need to compete with naturalised soil populations of rhizobia to form legume nodules. We have used the polymerase chain reaction to test the ability of seed-inoculated rhizobia to compete with naturalised populations of rhizobia and form nodules on clover (Trifolium alexandrinum, T.�purpureum, and T. resupinatum) in alkaline soil. Clover rhizobia, Rhizobium leguminosarum bv. trifolii, were identified at the strain level using either a nif-specific RP01 primer or ERIC primers. Analysis of rhizobia isolated from nodules indicated that strain TA1 competed poorly for nodule occupancy at 2 field sites (Roseworthy and Mallala, South Australia), with the exception that it nodulated T. alexandrinum at a level of 39% at the Roseworthy site in the first year of the trial. Strains CC2483g and WSM409 successfully colonised nodules when inoculated onto a particular clover species (T. resupinatum and T. purpureum, respectively) in the first year of inoculation and persisted in the soil to form nodules in the following year. Nodules frequently contained naturalised strains of rhizobia, distinct from introduced commercial strains. Dominant isolates were specific to a field site and nodulated all 3 clover species in both years of the field trial, with each isolate occupying up to 19% of the total nodules at a field site. It was hypothesised that field isolates had a better alkaline soil tolerance conferring a greater ability to nodulate clovers under these edaphic conditions. The results indicate that soil populations of rhizobia may provide a significant constraint to the introduction of current Australian commercial clover rhizobia into alkaline soils, and a more profitable strategy may be to seek rhizobial inoculants that are adapted to these soils.
Sunflower response to tillage and soil residual nitrogen in a wheat - sunflower rotation under rainfed Mediterranean conditions
Authors: López-Bellido Rafael J. , López-Bellido Luis , Castillo Juan E. , López-Bellido Francisco J.
Published: March 2003

A field study was carried out to determine the effects of tillage systems on sunflower yield over 9 years, and the effects of tillage systems and residual N on sunflower yield and yield components over 4 years, in a wheat–sunflower rotation under rainfed Mediterranean conditions. Tillage treatments included no tillage (NT) and conventional tillage (CT). Nitrogen fertiliser rates were 0, 50, 100, and 150 kg N/ha, applied only to wheat. A split-plot design with 4 replications was used. The weather had a marked influence on sunflower biomass and seed yield. Rainfall over October–May was directly related to seed yield. In contrast, seed oil content was inversely related to mean temperature during the flowering season (June). Sunflower yield displayed no significant reponse to residual N derived from the fertiliser N applied to the preceding wheat crop. The tillage system did not exert a consistent influence on sunflower yield; thus, continuous no-tillage may represent an economically and environmentally viable alternative to conventional tillage for sunflower production under rainfed Mediterranean conditions.
Effect of genotype and environment on proportion of seed hull and pod wall in lupin
Authors: Clements J. C. , Dracup M. , Galwey N.
Published: March 2003

Environmental and genetic effects on hull and pod wall proportions in lupin were examined by analysing data from 125 advanced genotypes at 17 year × site combinations in Western Australia. In Lupinus angustifolius the effect of genotype dominated the variance for seed hull and pod wall percentage and weight per seed, indicating strong heritability for these traits. Smaller but significant effects of site, and year × site and year × site × genotype interaction, were present for hull percentage, and year × site and year × site × genotype interaction effects were present for pod wall percentage. Hull percentage was found to be stable across branch orders within the plant canopy, but pod wall percentage increased and weight per seed decreased from main stem to higher branch orders. The average value of hull percentage was 24.0 in L. angustifolius with a range from 21.8 to 26.2%. L. albus (cv. Kiev Mutant) had a lower value than L. angustifolius at 18.1% and L. luteus cv. Wodjil gave a value of 24.5%. Hull percentage was found to decrease by approximately 0.5% for each 10 mg increase in seed weight. Hull thickness was found to correlate with site seasonal rainfall (r = 0.45*). The correlation between genotype means for hull percentage and pod wall percentage was not significant for this set of breeding lines and cultivars, indicating that selection for one will have little effect on the other. A low but significant correlation was identified between hull percentage and protein percentage (r = –0.38**) and protein + oil percentage (r = –0.46**), showing that selection for lower hull proportion could lead to higher protein and oil concentration in seed.Pod wall percentage averaged 32.0% among L. angustifolius genotypes and was 28.1% in L. albus. At 41.7%, L.�luteus had a very large proportion of dry matter in pod walls. Pod wall percentage was weakly negatively correlated with yield among 122 L. angustifolius genotypes (r = –0.19*). Pod wall percentage tended to increase with longer growing seasons. The results demonstrate the relatively narrow range in hull and pod wall percentage available in breeding lines and cultivars representing the current genetic base of Western Australian material but that the traits are highly heritable and selection is likely to be relatively easy. New sources with lower seed hull and pod wall proportions should be sought from wild and semi-domesticated germplasm or through mutagenesis to broaden the genetic base for these traits. The relationships between these traits and resistance to insects and disease are yet to be determined.
The effect of row spacing and weed density on yield loss of chickpea
Authors: Whish J. P. M. , Sindel B. M. , Jessop R. S. , Felton W. L.
Published: March 2003

The adoption of no-till farming and the desire to maintain stubble cover when sowing legumes in northern New South Wales and southern Queensland have resulted in an increase in commercial row spacing for chickpea (Cicer arietinum L.). This paper examines the effects of increasing crop row widths on weed competition in chickpea crops. Weed densities of 0, 2, 4, 8, 16, and 32 plants/m2 of wild oats (Avena sterilis ssp. ludoviciana ) and turnip weed (Rapistrum rugosum) were established with chickpea crops planted with either 32�or 64�cm row configurations in northern New South Wales during 1996 and 1997. A rectangular hyperbolic model adequately represented the loss in chickpea yield with increasing density of either weed. Even low densities of <10 plants/m2 caused large (approx. 50%) reductions in yield, particularly with turnip weed. In these experiments, weed-free yields were higher when chickpea was sown in 32�cm rows compared with 64�cm rows, but weeds caused no greater loss in crop yield with the wider row spacing. The results of this work show that the use of wide rows has minimal impact on weed competion in northern chickpea crops.
Studies of seed production in two Austrodanthonia grass cultivars
Authors: Lodge G. M.
Published: March 2003

Studies were conducted in 1993–94 on 2 native grass cultivars, Austrodanthonia richardsonii (Link) H.P.�Linder (syn. Danthonia richardsonii Cashmore) cv. Taranna and A. bipartita (Link) H.P. Linder (syn. D. linkii Kunth) cv. Bunderra, to quantify the important morphological factors affecting seed production (as measured by seed weight, g/plant). Experiments also examined the influence of nitrogen (N) application and investigated the effects of time and method of harvest on seed production and subsequent germination. For both cultivars, inflorescence and floret number accounted for the highest proportion of the variation in seed production per plant (R2 = 0.873 and 0.686 for Taranna and Bunderra, respectively). Although N applied (0, 25, and 50 kg/ha) at the late vegetative or early flowering stage, or split applications at both times, had no significant effect (P > 0.05) on the seed production per plant of Taranna and Bunderra, further studies of N effects are required. In 1993 and 1994, time of inflorescence harvest and method of harvest had no significant effect on inflorescence number and seed production of Taranna and Bunderra and no significant effect on the subsequent germination of Bunderra seed. However, in 1993, harvesting at an early stage of flowering (10% of florets white and fluffy) reduced Taranna seed production by 17% compared with the mean and decreased (P < 0.05) seed germination by about 10%. In 1994, harvesting at early flowering (5% florets white and fluffy) reduced Taranna seed production by a mean of around 55% compared with harvesting at 50% maturity, and subsequent seed germination was also lower (P < 0.05) for the early harvest time. Application of 1 L/ha of paraquat (a.i. 200 g/L of paraquat dichloride) at mid-flowering to desiccate the crop in 1993 had no significant effect on the germination of Taranna and Bunderra caryopses. The implications of these data for commercial seed production are discussed.
Differential responses to selection for aluminium stress tolerance in triticale
Authors: Zhang X. G. , Jessop R. S. , Ellison the late F.
Published: March 2003

A directional selection program was initiated to select triticale genotypes with improved aluminium (Al) tolerance and presumably acid-stress tolerance. Two consecutive cycles of 2-way selection for either high or low apparent Al tolerances from a base population, Tahara, resulted in the production of 6 selected lines, whose progenies were tested for Al tolerance response in terms of root regrowth characteristics in nutrient solutions to assess selection effectiveness. In addition, 1 cycle of 2-way selection from 2 other base populations, Empat and 19th ITSN 70-4, resulted in 4 selected lines.Selective responses differed among selected lines, depending largely on the direction of the selection made and, to a lesser extent, on the genetic background of the original population. Upward selection for longer root regrowth produced progeny with more highly Al-tolerant plants. Although varying estimates of realised heritability were generated, the 2 cycles of upward selection resulted in an enhanced Al tolerance of 14.5% in the progeny A9701 derived from the base population Tahara. These results suggest that directional selection based on longer root regrowth in nutrient solutions was effective in improving Al tolerance. A pot-culture experiment showed that the second selection generation (S2) Al-tolerant lines were more productive than their moderately Al-tolerant counterparts, further implicating the effectiveness of directional selection in enhancing Al stress tolerance and plant productivity.
Interpretation and implications of genotype by environment interactions in advanced stage sugarcane selection trials in central Queensland
Authors: Kimbeng C. A. , Rattey A. R. , Hetherington M.
Published: March 2003

Data from 6 series of routine advanced stage selection trials were used to study genotype response across 'test' environments (locations and crop-years) for sugar yield in central Queensland. The objective was to determine whether genotype × environment (G × E) interactions are present for sugar yield in central Queensland and, if so, to interpret the nature of the interactions as well as determine their implications for the selection program. The relative magnitude of the G × E interaction components, namely genotype × location (G × L), genotype × crop-years (G × C), and genotype × location × crop-years (G × L × C), was studied using variance component analysis. In addition, environments were classified based on similarity with which they discriminate amongst genotypes (pattern analyses). The study revealed substantial G × E interactions for sugar yield. The magnitude of variance attributable to the second-order interaction effect, G × L × C, was higher than that of the first-order interaction effects, G × L and G × C, in a considerable number of cases. The pattern of genotypic response across environments was not consistent among the different series of trials. These results indicate that the major contributing factor or pattern underlying G × E interactions for sugar yield in central Queensland may be complex and unpredictable, making it difficult to effectively exploit G × E interactions in the breeding program. Based on logistics and resources, the current practice whereby a manageable number of genotypes (40–50) is evaluated in a subset of locations (3–4 out of 6 possible) for 2 crop-years, and only the elite ones are re-evaluated in further locations and crop-years, appears appropriate.
Growth and carcass composition of second-cross lambs. 2. Relationship between estimated breeding values of sires and their progeny performance under fast and slow growth regimes
Authors: Hall D. G. , Gilmour A. R. , Fogarty N. M. , Holst P. J.
Published: March 2003

Growth and carcass performance of 2316 ewe and cryptorchid second-cross lambs over 2 years was related to the LAMBPLAN estimated breeding values (EBVs) of their sires. The lambs (56–156 per sire) were sired by 20 Poll Dorset rams from one stud, which were selected to represent a range of EBVs for growth rate and leanness. Half of each lamb sex group was grown at a fast rate from weaning to slaughter at 40 kg liveweight for ewes or 48 kg for cryptorchids. The other half was grown at a slower rate to the same slaughter weights, 10–13 weeks later. Lamb measurements included liveweight approximately every 21 days to slaughter, and fat and muscle depth on live lambs using ultrasound and carcass fat depth. The regressions of lamb weight on sire EBV for weight increased as the lambs aged and were 0.243 ± 0.124 for fasted weight pre-slaughter and 0.158 ± 0.064 for carcass weight. Live lamb C fat depth (45 mm from the mid-line over the 12th rib), carcass C fat depth, and carcass GR (total tissue depth 110 mm from the mid-line of the carcass over the 12th rib) were all related to sire EBV for fat. The regression values for ultrasound C fat depth and carcass GR of 0.156 ± 0.049 and 0.366 ± 0.159 on the sire EBV for fat (mm/mm EBV) were higher than the expected values. The results demonstrate that over a range of sires, 2 years, 2 sexes, and different nutrition regimes there are significant advantages in progeny weight and leanness if sires are selected for high EBVs for weight and leanness.
Wool fibre diameter and follicle density are not specified simultaneously during wool follicle initiation
Authors: Adelson David L. , Hollis David E. , Brown George H.
Published: March 2003

Although the highly negative correlation between wool fibre diameter and wool follicle density has been known for some time, the source of this relationship in terms of the developmental mechanisms involved has been unclear. By comparing follicle rudiment dimensions (measured in the fetus) with fibre diameter values (measured in the same animal as an adult), we present data indicating that this inverse relationship arises largely after follicle initiation. Our data indicate that this is because fibre diameter is largely specified post-initiation, during the period of wool follicle growth and morphogenesis. This result was unexpected, and has permitted us to speculate upon the hierarchy and relationship of genes that control follicle initiation and fibre diameter.
Seed softening, imbibition time, and seedling establishmentin yellow serradella
Authors: Taylor G. B. , Revell C. K.
Published: March 2003

The first (preconditioning) and final stages of seed softening were studied over a 4-year period in 4 lines of yellow serradella (Ornithopus compressus L.): cvv. Santorini and Charano, and accessions GEH72-1A and GRC5045-2-2. Pods grown in 1997 were collected in December (start of summer) and placed on the soil surface or buried at a depth of 1 cm. Measurements of seed softening between years were made from pod samples removed in June each year. The progress of preconditioning and seed softening within the first 3 years was determined from samples taken at the end of February. Numbers of soft and viable seeds were determined from each sampling. Preconditioned seeds were identified by subjecting seeds to 7 gradual diurnal temperature cycles of 48/15°C in darkness before testing for permeability.

Seed softening was markedly accelerated by pod burial in all 4 lines, with most buried seeds of GEH72-1A and Santorini softening during the first year. Seed softening was slower in GRC5045-2-2 and Charano, approaching a constant annual rate over the 4 years of the experiment. Despite this marked effect of burial the differences between lines in rates of softening of buried seeds were sufficient to have important implications for persistence under some management systems.

Most seeds of all lines softened between February and June, indicating that shallow pod burial could be delayed in these lines until at least the end of February to promote the final stage of seed softening. Although large numbers of seeds of GEH72-1A and GRC5045-2-2 had preconditioned at the soil surface by the end of February, few went on to complete the softening process by June, when most had lost their preconditioned state. Treatment at 48/15°C was less successful in identifying preconditioned seeds of Santorini and Charano.

Rates of imbibition differed markedly between lines. Most soft seeds of GEH72-1A and GRC5045-2-2 imbibed within days, whereas they took weeks in Santorini and an intermediate time in Charano. Seedling age distributions in the 4 lines in June closely reflected the times their soft seeds took to imbibe in the laboratory. Imbibition time can be an important germination regulating mechanism having implications that may be either favourable or unfavourable depending on rainfall distribution around the break of season and the system of management.
Screening and selection of faba bean (Vicia faba L.) germplasm resistant to Bean leafroll virus
Authors: Makkouk Khaled M. , Kumari Safaa G. , van Leur Joop A. G.
Published: March 2003

Three hundred and fifty-eight faba bean accessions, originating from 28 countries in 5 continents, were evaluated for their reaction to a Syrian isolate (SV64-95) of Bean leafroll virus (BLRV, family Luteoviridae). Selection for resistance was based on: (i) visual evaluation for symptom expression (disease severity); (ii) virus concentration in the plant tissues, based on the intensity of reaction in the tissue-blot immunoassay; and (iii) seed yield. A large variability in resistance to BLRV was found both between and within faba bean accessions. Progenies of single plants, selected for resistance under inbreeding conditions, were evaluated for another 2-year period. Repeated reselection of inoculated plants, in the absence of outcrossing, significantly increased the proportion of resistant plants. The most resistant selections were made from populations originating from Afghanistan, China, Colombia, Pakistan, Russia, Sudan, Switzerland, Tunisia, Turkey, and Yemen.
Within-field variation in wheat quality: implications for precision agricultural management
Authors: Skerritt J. H. , Adams M. L. , Cook S. E. , Naglis G.
Published: March 2003

In this study, 9 Western Australian fields sown to dryland wheat were monitored using precision agricultural techniques, in order to understand implications for processing quality of the grain. Four fields received variable inputs of N fertiliser, and 6 received variable seed rates. In most cases, there was a very large variation within-field in grain yield, protein content, and protein quality, and such variation was related to variation in soil acidity, soil nitrate, and soil organic carbon, and specific weed and pest problems in some fields, as well as variation in the inputs. Grain protein content was positively correlated with soil nitrate levels in 6 of the 7 fields for which soil analyses were carried out. For several of the larger fields, separate harvesting of zones within the fields having differences in grain protein content would have enabled a greater proportion of the grain to be in a higher return quality grade. In 7 of the 9 fields, variation in protein quality (sodium dodecyl sulfate-sedimentation volume, SDS-SV) was greater than variation in protein content. The different measures of protein quality (SDS-SV, polymeric protein (glutenin) content, and glutenin molecular weight distribution) sometimes followed similar spatial trends, but in many cases did not. Therefore, total protein estimates are probably suitable measures for predicting within-field variation in protein quality. In none of the 9 fields was there overall a negative relationship between grain yield and protein content, although limited moisture availability can affect such relationships. The results suggest that the use of precision agricultural methods to manipulate inputs such as fertiliser, lime, or seed rates to increase yield does not have a negative effect on protein content. Farmers, therefore, can use precision agricultural methods along with other approaches to maximise wheat yield and grain protein content/quality at the same time.
Selection for persistence under grazing in winter-active populations of the perennial grass, Phalaris aquatica L. (phalaris)
Authors: Culvenor R. A. , Dobbie M. J. , Wood J. T. , Forrester R. I.
Published: March 2003

Winter-active cultivars of phalaris (Phalaris aquatica L.) have the potential to be more productive than semi-winter-dormant cultivars but may be less persistent under the stress of heavy grazing. The feasibility of improving persistence of winter-active phalaris was examined by subjecting plots of half-sib families from several winter-active populations to 2 cycles of heavy grazing pressure by sheep. Because variation among families in initial density influenced final density score in both cycles, persistence was assessed by 2 methods, final density with initial density as a covariate and the ratio of final over initial density.In Cycle 1, significant family variance was observed in a broadly based population after 3 years of continuous grazing. Changes in persistence were smaller but still significant among the families comprising cv. Holdfast after 2 years of rotational grazing on limed but not on unlimed acid soil. In Cycle 2, 4 populations selected in Cycle 1 and elsewhere were screened under continuous grazing at 2 sites, one lower in soil pH and phosphorus than the other. Family by site interaction for final density was significant (P < 0.05) for one population only and this arose before grazing commenced. The selected populations displayed higher density and persistence than control winter-active cultivars. Estimates of predicted heritability were generally high but not always significant at P < 0.05. Overall they were considered to indicate that differences in persistence between families were present and heritable. This was supported by the observation that generations of 2 populations selected in Cycle 1 were higher in final density and persistence than the base generations, although differences in persistence as distinct from final density were not always at the P = 0.05 significance level. The ratio of final over initial density scores was considered less appropriate than the covariate method of estimating persistence in this cycle because plots that established at very low density and increased slightly thereafter resulted in high error variance and biased selection towards families that established at low density.
Increasing mycorrhizal colonisation does not improve growth and nutrition of wheat on Vertosols in south-eastern Australia
Authors: Ryan M. H. , Norton R. M. , Kirkegaard J. A. , McCormick K. M. , Knights S. E. , Angus J. F.
Published: March 2003

Most crops host arbuscular mycorrhizal fungi (AMF). Canola and other brassicas are some of the few exceptions. This study examined AM fungal colonisation, uptake of phosphorus (P) and zinc (Zn), growth, and yield of wheat following brassicas and crops that host AMF in 5 crop-sequence experiments in southern New South Wales and Victoria. All experiments were on alkaline Vertosols, similar to soils in the northern wheatbelt on which low AM fungal colonisation of wheat following canola, or long-fallow, has been reported to induce poor crop growth. Soils with a broad range of extractable P concentrations were chosen. AM fungal colonisation of wheat was generally lower following brassicas than hosts of AMF, although this varied with year and location. The effect on wheat AM fungal colonisation levels did not vary between brassicas with differing levels and types of root glucosinolates. Low AM fungal colonisation did not affect early wheat growth, pre-anthesis P and Zn uptake, or yield. A positive relationship between AM fungal colonisation and grain Zn and P concentrations occurred in one experiment. High levels of colonisation by AMF did not protect crop roots from damage by root pathogens and high levels of pathogen damage made interpretation of results difficult in some instances. As these findings are consistent with results from an experiment on an acidic Kandosol in southern New South Wales, it appears farmers do not need to consider the degree to which wheat will be colonised by AMF when planning crop sequences in south-eastern Australia.
Field evaluation of early vigour for genetic improvement of grain yield in wheat
Authors: Botwright T. L. , Condon A. G. , Rebetzke G. J. , Richards R. A.
Published: March 2003

Improved early vigour in wheat (Triticum aestivum L.) has been proposed as an important trait for increasing grain yield through greater water-use efficiency in rainfed, Mediterranean-type environments. Three years of field trials were undertaken in Western Australia at 2 sites, Merredin (low rainfall, 244 mm in the growing season) and Wongan Hills (medium rainfall, 308 mm), to examine the influence of increased early vigour on crop growth and yield. The effect of breeding for greater early vigour was tested in 1998 and 1999 using 3 high vigour and 3 low vigour BC2:F5 lines of the cultivar Amery backcrossed to a 'high vigour' donor. Averaged across environments, the high vigour backcross lines had a 10% increase in early vigour (i.e. leaf area/plant) at 50 DAS compared with the low vigour lines. Differences in yield across environments were associated with variation in total rainfall, rainfall distribution, and soil properties. In the wetter of the 2 years (1999), greater early vigour translated to increased yield of c. 12%, averaged across environments, but there was no difference in yield in either environment in the drier year (1998). Potential deleterious effects of the recurrent parent on yield were eliminated in field trials in 1999 and 2000 by manipulating early vigour through varying grain size (25, 35, or 50 mg) or seeding density (50, 200, or 400 plants/m2) of Amery at sowing. Large grain increased the embryo size and early vigour at 50 DAS in both environments in 1999. This translated to greater biomass production at anthesis and maturity to increase grain yield at Wongan Hills in 1999. In contrast, there was no relationship between grain size, biomass production, and yield at Merredin in 1999 or at either site in 2000. Sowing density treatments also had no effect on yield in 2000. In conclusion, there is potential to increase yield of wheat by selecting for greater early vigour in a wheat breeding program. The expression of vigour in field conditions and the translation of this improvement to higher yields is, however, dependent on the environment. Current yield limitations arising through backcrossing with a high vigour, yet poor yielding donor, need to be addressed.
Awnedness affects grain yield and kernel weight in near-isogenic lines of durum wheat
Authors: Motzo Rosella , Giunta Francesco
Published: March 2003

The importance of awns in durum wheat (Triticum turgidum L. var. durum) has to be evaluated whenever an increase in grain yield is expected due to a greater photosynthetic capacity of the awned ear. Awned and awnless isolines of durum wheat were compared in a 3-year field trial in Sardinia (Italy). Ear and flag-leaf size, radiation interception, canopy temperature, yield, and yield components were measured.Awns increased the ear surface area from 36 to 59%, depending on their length, which ranged from 5.5 to 13.8 cm. This resulted in an average 4% more radiation intercepted by the awned ears. Canopy temperature was 0.9�C lower, on average, in the awned isolines, and was negatively correlated with kernel weight (r = –0.85**, n = 10), although consistent and marked effects of awns on canopy temperature were only observed in the long-awned lines. Awns positively affected grain yield, with an average increase of 10 and 16%, respectively, in the 2 years in which they affected kernel weight. The irrelevant effect of awns on yield in the year characterised by a severe drought was a consequence of their early desiccation.The effects of awns on grain yield and kernel weight strongly depend on the genetic background, on awn length and functionality, and on the environmental conditions during grain filling.
Genetic and environmental variation for grain quality traits routinely evaluated in southern Australian wheat breeding programs
Authors: Eagles H. A. , Hollamby G. J. , Eastwood R. F.
Published: March 2003

Milling yield, maximum dough resistance (Rmax), dough extensibility, flour protein concentration (flour protein), particle size index (PSI), water absorption, and dough development time are important determinants of grain quality and are routinely evaluated in Australian wheat breeding programs. Information on allelic variation at the 6 loci determining glutenin proteins is also regularly obtained and used to predict Rmax and extensibility. For each character, except dough development time, 4029 observations on 2377 lines and 94 environments were analysed to estimate genotypic and environmental variances, heritabilities, genotypic and environmental correlations, and the effects of glutenin genes. A subset was analysed for dough development time.

Milling yield, Rmax, extensibility, PSI, water absorption, and dough development time had intra-class correlation coefficients, or broad-sense heritabilities, between 0.66 and 0.76, and extensibility had a value of 0.52, with flour protein at 0.36. Genotypic and environmental correlations between extensibility and flour protein were high at +0.78 and +0.85, respectively. Rmax had a genotypic correlation with dough development time of +0.67, which was substantially due to pleiotropic effects of glutenin genes.

Rmax, extensibility, PSI, and dough development time were influenced by glutenin genes. For Rmax about 50% of the genotypic variance could be explained by glutenin genes. For extensibility about 50% could be explained by flour protein, with 50% of the remainder by the inclusion of glutenin genes. For dough development time about 15% could be explained by flour protein, with a further 30% by glutenin genes. For PSI, about 40% of the genotypic variation could be accounted for by glutenin genes after the removal of the effects of flour protein and milling yield. We concluded that dough development time could be added to Rmax and extensibility as a trait that can be usefully predicted by the glutenin genes, but more work is required for PSI.
Macadamia yield and quality responses to phosphorus
Authors: Stephenson R. A. , Gallagher E. C. , Pepper P. M.
Published: March 2003

Phosphorus fertiliser was applied to mature macadamia trees on 3 plantations with relatively low soil P in south-eastern Queensland at rates of 0, 10, 20, 40, 80, 160, and 320 kg P/ha at El Briale and Como Park and 0, 15, 30, 60, 120, 240, and 480 kg P/ha at Haylock. High rates of P were being applied to macadamias throughout the Australian industry and this study was designed to provide a basis for determining optimum application rates and critical soil P levels. Soil P was 33–199.5, 38.1–267.0, and 62.3–253.0 mg/kg at El Briale, Como Park, and Haylock, respectively. A tentative critical soil P concentration of 84–88 mg/kg was indicated, based on relative yields at El Briale and Haylock. Yield responsiveness to applied P was greatest at Haylock on a heavy soil that may have adsorbed P more readily, and had a higher P buffer capacity, than the lighter soils at the other sites. Leaf P was unresponsive to applied P, and hence soil P in this study. This is of concern since leaf P is used extensively to guide nutrition management. Further work is required to clarify relationships between leaf and soil P concentrations.