bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-dimensional nanolithography using proton beam writing
Authors: van Kan J. A. , Bettiol A. A. , Watt F.
Published: August 2003

We report the utilization of a focused mega-electron-volt (MeV) proton beam to write accurate high-aspect-ratio structures at sub-100 nm dimensions. Typically, a MeV proton beam is focused to a sub-100 nm spot size and scanned over a suitable resist material. When the proton beam interacts with matter it follows an almost straight path. The secondary electrons induced by the primary proton beam have low energy and therefore limited range, resulting in minimal proximity effects. These features enable smooth three-dimensional structures to be direct written into resist materials. Initial tests have shown this technique capable of writing high aspect ratio walls of 30 nm width with sub-3 nm edge smoothness.
Nonresonant quasi-phase matching in GaAs plates by Fresnel birefringence
Authors: Haïdar Riad , Kupecek Ph. , Rosencher E.
Published: August 2003

Quasi-phase matching is usually obtained by sign reversal of nonlinear susceptibility. This leads to resonant condition on nonlinear material dimensions and/or converted frequencies. We show that this condition is alleviated using total reflection birefringence. Indeed, Fresnel dephasing at reflection can compensate for almost any phase lag between interacting waves. This nonresonant phase-matching scenario allows both large tunability and nonlinear device design tolerance.
Nucleation of superconductivity in an Al mesoscopic disk with magnetic dot
Authors: Golubović D. S. , Pogosov W. V. , Morelle M. , Moshchalkov V. V.
Published: August 2003

We have studied the nucleation of superconductivity in a mesoscopic Al disk with a Co/Pd magnetic dot placed on the top by measuring the normal/superconducting phase boundary Tc(B). The measurements have revealed a pronounced asymmetry in the phase boundary with respect to the direction of the applied magnetic field, indicating an enhancement of the critical field when an applied magnetic field is oriented parallel to the magnetization of the magnetic dot. The theoretical Tc(B) curve is in a good agreement with the experimental data.
Electron heating mode transition observed in a very high frequency capacitive discharge
Authors: Abdel-Fattah E. , Sugai H.
Published: August 2003

The effect of excitation frequency in the 13.56–60 MHz range on the electron energy distribution function (EDF) of capacitively coupled plasma is investigated. Under a fixed rf voltage (50–130 V peak-to-peak) and argon pressure (100 mTorr), a remarkable change in the EDF is observed: a Druyvesteyn type at low frequencies (≃13.56 MHz) evolves into a bi-Maxwellian type in a very high frequency (VHF) above 30 MHz. The transition frequency decreases with increasing the rf voltage. The observed frequency effect on the EDF is tentatively explained in terms of the transition of electron heating mode from the collisional ohmic heating at low frequencies into the plasma surface heating in the VHF range.
Broadband dielectric spectroscopy of (1−x)BiScO3–xPbTiO3 piezoelectrics
Authors: Porokhonskyy V. , Kamba S. , Pashkin A. , Savinov M. , Petzelt J. , Eitel R. E. , Randall C. A.
Published: August 2003

Dielectric spectra of high-temperature piezoelectric (1−x)BiScO3–xPbTiO3 of composition near the morphotropic phase boundary (x≅0.64) were investigated in the frequency range of 100 Hz–1 THz at temperatures between 10 and 900 K. Below the ferroelectric phase transition Tc≅700 K, in addition to polar phonons, two other polarization mechanisms were detected: one, centered in the 100 MHz–1 GHz range probably caused by sound generation due to ferroelectric-ferroelastic domain wall motion; another evidences dynamic disorder of some ions. The former process, characterized by the temperature-independent mean relaxation time, vanishes below ∼250 K. The latter mechanism, caused by compositional disorder, results in the nearly frequency-independent losses (1/f noise) at low temperatures.
Luminescence of GaN nanocolumns obtained by photon-assisted anodic etching
Authors: Tiginyanu I. M. , Ursaki V. V. , Zalamai V. V. , Langa S. , Hubbard S. , Pavlidis D. , Föll H.
Published: August 2003

GaN nanocolumns with transverse dimensions of about 50 nm were obtained by illumination-assisted anodic etching of epilayers grown by metalorganic chemical vapor deposition on sapphire substrates. The photoluminescence spectroscopy characterization shows that the as-grown bulk GaN layers suffer from compressive biaxial strain of 0.5 GPa. The majority of nanocolumns are fully relaxed from strain, and the room-temperature luminescence is free excitonic. The high quality of the columnar nanostructures evidenced by the enhanced intensity of the exciton luminescence and by the decrease of the yellow luminescence is explained by the peculiarities of the anodic etching processing.
Mössbauer effect probe of local Jahn–Teller distortion in Fe-doped colossal magnetoresistive manganites
Authors: Cheng Zhao-hua , Wang Zhi-hong , Di Nai-li , Kou Zhi-qi , Wang Guang-jun , Li Rui-wei , Lu Yi , Li Qing-an , Shen Bao-gen , Dunlap R. A.
Published: August 2003

The local structure of the Fe-doped La1−xCaxMnO3 (x=0.00–1.00) compounds has been investigated by means of Mössbauer spectroscopy. Fe57 Mössbauer spectra provide direct evidence of Jahn–Teller distortion in these manganites. On the basis of the Mössbauer results, the Jahn–Teller coupling was estimated. It is noteworthy that the Ca-concentration dependence of the Jahn–Teller coupling strength is very consistent with the magnetic phase diagram. Our results reveal that Mössbauer spectroscopy cannot only detect the local structural distortion, but also provide a technique to investigate the Jahn–Teller coupling of Fe-doped La1−xCaxMnO3 colossal magnetoresistive perovskites.
Imaging helical potassium hexaniobate nanotubes
Authors: Du G. H. , Peng L.-M. , Chen Q. , Zhang S. , Zhou W. Z.
Published: August 2003

Potassium hexaniobate nanotubes have been synthesized at room temperature and characterized by high-resolution transmission electron microscopy (HRTEM) and energy-dispersive x-ray analysis. It is shown that HRTEM images may be used effectively to determine the helicity of the nanotubes, and, in particular, it is found that almost all nanotubes have their axes pointing within a few degrees from the [100] direction of the K4Nb6O17 structure.
MeV-order proton and carbon ion acceleration by irradiation of 60 fs TW laser pulses on thin copper tape
Authors: Fujii Takashi , Oishi Yuji , Nayuki Takuya , Takizawa Yasushi , Nemoto Koshichi , Kayoiji Tsutomu , Horioka Kazuhiko , Okano Yasuaki , Hironaka Yoichiro , Nakamura Kazutaka G. , Kondo Ken-ichi
Published: August 2003

We obtained high-energy ions by irradiating 60 fs laser pulses onto a copper tape target of 5 μm thickness. The proton was accelerated with energy of 1.2 MeV at laser intensity of 6.8×1018 W/cm2. The equivalent Boltzmann temperature of the proton was 185 keV which was less than the ponderomotive potential (650 keV) of an electromagnetic standing wave in a laser field. Moreover, we observed the acceleration of carbon ions with energy of more than 0.4 MeV at laser intensity of 3.4×1018 W/cm2.
Biochemical sensors based on polymer microrings with sharp asymmetrical resonance
Authors: Chao Chung-Yen , Guo L. Jay
Published: August 2003

Photonic microresonators have great potential in the application of highly sensitive sensors due to high Q-factor resonances and steep slopes between zero and unity transmission. A microring resonator with increased resonance slopes is proposed by introducing two partially reflecting elements implemented by waveguide offsets. This configuration produces a Fano-resonant line shape and can greatly enhance the sensitivity of the sensor. Polystyrene microring resonators were fabricated by the nanoimprinting technique, and the optical spectra were measured in glucose solutions of different concentrations. The shift in resonant wavelength and variation of the normalized transmitted intensity are linearly related to the concentration of the glucose solution.
Structural anisotropy in GaN films grown on vicinal 4H-SiC surfaces by metallorganic molecular-beam epitaxy
Authors: Kato Jun-ichi , Tanaka Satoru , Yamada Satoshi , Suemune Ikuo
Published: August 2003

GaN grown directly on 4H-SiC substrates by metallorganic molecular-beam epitaxy is investigated in terms of nucleation, coalescence, and growth front evolution. The effects of SiC surface configurations such as step and terrace structures on GaN film growth physics are examined in detail. Comparative studies using on-axis and vicinal SiC surfaces indicate distinguishable differences in structural and morphological characteristics. An anisotropic x-ray characteristic is observed for the GaN film deposited on the vicinal stepped SiC surfaces. This is due to preferential nucleation and coalescence of GaN islands along step edges, which are induced by the confinement of adatoms on the narrow terraces on the vicinal SiC surface.
Predicting the development of photoperiod 'insensitive' winter wheats in south-central New South Wales
Authors: Penrose L. D. J. , Fettell N. A. , Richards R. A. , Carpenter D. J.
Published: August 2003

The aim of this study was to determine the effect of vernalisation on the field development of vernalisation responsive wheats in south-central New South Wales, and to develop equations with which to predict their timing of ear emergence in this region. To achieve this, a 'phasic development' approach was taken by considering relationships between temperature and photoperiod and the duration of the leaf, spikelet, and stem development phases in 3 photoperiod 'insensitive' vernalisation responsive wheat cultivars. The responsiveness to vernalisation of these cultivars covered much of the range that has been reported in wheat. This study was conducted at 3 sites and over 6 sowing times (17 field environments), covering the geographic and commercial range in sowing time for wheat grown in this region of Australia. An initial step in this study was to obtain measures of development duration that were independent of site and sowing date over our 17 field environments. Thus, appropriate photo-thermal units of time were sought using a photoperiod and vernalisation insensitive control wheat. The appropriate base temperatures and photoperiods we found for these photo-thermal units were not entirely consistent with those found in previous studies. Phase durations of our vernalisation responsive wheat cultivars were measured in these units.Vernalisation was found to be the predominant factor determining duration of both the leaf and spikelet phases in our vernalisation responsive wheat cultivars. The relationship we found between accumulated vernalisation and the duration of the leaf phase was similar to the relationship found in an earlier study in a controlled environment. This relationship differed from those currently used in 'phasic development' models for wheat. There appeared to be some latitude in the range of vernalising temperatures that could be used to estimate vernalisation in our field environments. Duration of the stem phase was strongly influenced by photoperiod, and showed greatest complexity of control, to the extent that site-specific effects could not be removed from equations predicting the duration of this phase.Simplified regression equations appeared to predict time of ear emergence reasonably well over the range of environments considered in our study, with the exception of a few cultivar × sowing time combinations for which wheat would not be commercially sown in the region. The ability to predict time of ear emergence may allow plant breeders to evaluate development controls that might extend the range of environments over which winter wheats may be commercially sown in south-central New South Wales.
Prediction of vernalisation in three Australian Vrn responsive wheats
Authors: Penrose L. D. J. , Rawson H. M. , Zajac M.
Published: August 2003

This study sought to better estimate vernalisation in winter wheats, so that their early development and time of anthesis can be better predicted. For this, an accurate relationship between temperature and the effectiveness of vernalisation is required. Using previously published data, our study found that the relationship between temperature and effectiveness of vernalisation can be suitably described by a quadratic function. In contrast, most previous studies used linear interpolation functions to describe vernalising effectiveness. These consist of a series of linear functions of temperature over adjoining temperature ranges. An advantage of quadratic functions is that they allow effectiveness of vernalisation to be described in terms of underlying physiological processes, and require the estimation of fewer parameters to predict wheat development. Our study found the cardinal temperatures for vernalisation to be –3�C, 6.5�C, and 15.9�C, that is for the lower, optimum, and maximum temperatures respectively. To allow for different upper temperature limits for vernalisation, 2 quadratic temperature-vernalising effectiveness functions were used to predict accumulated daily vernalisation at 3 field sites. These predictions of daily vernalisation were compared with corresponding estimates produced with 3 previously proposed linear interpolation functions. Varying degrees of agreement were found between estimates produced by the 2 types of vernalising effectiveness functions. Equations that have been developed to predict floral initiation in winter wheats have not been previously evaluated in Australian field environments. These equations utilise the same underlying relationship between accumulated daily vernalisation and a measure of floral initiation, often the appearance of double ridges. Two of these equations were used to predict the appearance of double ridges for a field-grown Australian winter wheat, JF87%014. Neither equation could satisfactorily predict the timing of the double ridge development stage for this wheat, whatever vernalising effectiveness function was used to predict vernalisation in the field. Both equations had greatest difficulty in predicting the double ridge stage, in environments where vernalisation most delayed development. This finding suggests that equations currently predicting floral initiation in winter wheats do not utilise an accurate relationship between accumulated vernalisation and floral initiation. An alternative method of predicting anthesis in winter wheats is to predict final leaf number, but this approach has not been reliably applied in environments where vernalising temperatures vary.
Influence of genotype and environment on oil and protein concentrations of canola (Brassica napus L.) grown across southern Australia
Authors: Si Ping , Mailer Rodney J. , Galwey Nick , Turner David W.
Published: August 2003

Improvement of oil and protein concentrations is a primary breeding objective for canola (Brassica napus L.) grown in the low rainfall areas across southern Australia. This study investigates the relative influences of genotype and environment on the relationship between seed oil concentration and protein concentration of meal, and between seed components. The study also estimates the magnitude of genetic and genotype × environment variances in oil and protein concentrations in a set of interstate field evaluation experiments of genotypes with early and mid-season maturity conducted across southern Australia in 1996 and 1997.The oil concentration of seed ranged from 36 to 46% across maturity groups, locations, and years. The range of protein concentration of meal was 30–46%. Environment had a much larger impact than genotype on oil concentration of seed and protein concentration of meal. Several genotypes in this study had higher concentrations of oil in the seed and protein in the meal than the commercial cultivars used as controls. Significant (P < 0.05) genetic variance (σg2) and significant genotype × year × location interaction (σgyl2) was present in these 2 quality traits. However, the variance components for the interaction of genotype with location (σgl2) and with year (σgy2) were not significant (P > 0.05), indicating that ranking of genotypes remained constant across locations averaged over many years and across years averaged over many locations, respectively. A significant negative correlation (r�=�–0.73) between seed oil concentration and protein concentration of meal was observed across locations in 1997. Among the genotypes tested, there was no genetic correlation between these 2 traits, suggesting that seed oil concentration and protein concentration of meal can be increased simultaneously by selection. Increase in oil concentration of seed and protein concentration of meal was at the expense of seed residue.
Corrigendum to: A comparative study for yield performance and adaptation of some Australian and CIMMYT/ICARDA wheat genotypes grown at selected locations in Australia and the WANA region
Authors: Sivapalan S. , O'Brien L. , Ortiz-Ferrara G. , Hollamby G. J. , Barclay I. , Martin P. J.
Published: August 2003

A regional adaptation analysis was conducted to provide a basis for effective and efficient wheat germplasm exchange between Australia and the WANA region. A set of 38 Australian and CIMMYT/ICARDA genotypes was tested for grain yield in 29 environments in Australia and the WANA region for 3 years commencing in 1994–95 season. Classification analysis of grain yield data identified 9 genotypic groups and 5 environmental groups with similar patterns in yield performance within each group. Genotypes with similar origin and pedigree were similar in yield performance across environments in Australia and the WANA region. Environmental conditions across both regions showed similarity in discriminating genotypes for their yield performance. Genotypes Attila, Spear, Excalibur, and 82Y:1186 were highest yielding in Australia and the WANA region. However, genotypes Nesser, Pfau/Seri//Bow, Hartog, Vulcan, and Sunland showed wide adaptation across both regions. Genotypes Cranbrook, Genaro 81, Seri 82, Kauz, SUN 190A, and Pgo/Seri 82 showed specific adaptation to favourable environments. Genotypes in each group, based on yield performance, showed differing degrees of yield stability. Pfau/Seri//Bow has the potential for release for commercial production in Australia and the WANA region. The genotypes Pfau/Seri//Bow, Hartog, Sunland, and Vulcan could be used in trials in both regions as indicator varieties to evaluate new breeding lines for mutual exchange between the 2 sets of breeding programs.
Drainage and change in soil water storage below the root-zone under long fallow and continuous cropping sequences in the Victorian Mallee
Authors: O'Connell Mark G. , O'Leary Garry J. , Connor David J.
Published: August 2003

A field study investigated drainage and changes in soil water storage below the root-zone of annual crops on a sandy loam soil in the Victorian Mallee for 8 years. It was designed to compare the effects of the common long (18-month) fallow in a 3-year rotation (fallow–wheat–pea, FWP) with a rotation in which the fallow was replaced with mustard (Brassica juncea), viz. mustard–wheat–pea (MWP). Drainage was measured over 2 periods (1993–98 and 1998–2001) using 9 in situ drainage lysimeters in each rotation. The first period of ~5 years was drier than average (mean annual rainfall 298 cf. 339 mm) and drainage was low and variable. Drainage was greater under the fallow rotation (average 0.24 mm/year) than under the non-fallow rotation (average <0.01 mm/year). The result for the fallow rotation did, however, include one lysimeter that recorded substantial drainage (10.6 mm over the 5 years). During the second period of measurement (~3 years), rainfall was above average (mean annual rainfall 356 cf. 339�mm) and drainage was greater. On average, drainage from the fallow rotation was 6.7 mm/year compared with the non-fallow rotation at 4.0 mm/year. There was again substantial variation between lysimeters. One lysimeter under MWP recorded 31.4 mm/year, and as in the earlier drier period, there were many lysimeters that recorded no drainage. During the drier first period (1993–98), changes in soil water storage between 1.5 and 5.5 m depth confirmed the tendency of the fallow rotation to increase deep drainage. Despite increases and decreases in subsoil water storage during the study, the cumulative change in water storage was positive and greatest under FWP (range: 2.8–14.8 mm/year, ave. 9.6 mm/year) compared with MWP (range: 5.3–9.8 mm/year, ave. 7.4 mm/year) cropping sequences. Overall, the long fallow system has the potential to increase deep drainage by approximately 2 mm/year compared with a fully cropped system, over a wide annual rainfall range (134–438 mm). Further, this experiment reinforces the focus for the reduction of fallow practices for dryland salinity control in the Mallee region.
Estimating spatially variable deep drainage across a central-eastern wheatbelt catchment, Western Australia
Authors: Pracilio G. , Asseng S. , Cook S. E. , Hodgson G. , Wong M. T. F. , Adams M. L. , Hatton T. J.
Published: August 2003

The management of excess water (recharge or deep drainage) is one of many important issues required to address dryland salinity. To provide information on site-specific risk of deep drainage at a landholder scale, spatially variable deep drainage beneath an annual crop was estimated for a catchment of approximately 25 000 ha. The method coupled the results from one-dimensional crop simulation modelling (Agricultural Production Systems Simulator) with probabilistic soil mapping (Expector). Annual deep drainage over the catchment averaged 18 mm, representing 5% of rainfall. The annual deep drainage for the most probable soil types averaged 25 mm for acid loamy sand, 19 mm for yellow duplex, 14 mm for loamy sand, and 12 mm for red duplex. Groundwater modelling (Flowtube) highlighted that the groundwater table below the flat valley is not likely to be lowered with the introduction of perennial vegetation upslope. However, scenario spatial modelling indicated that replacing vegetation in areas of the most drainage-prone soil types, acid loamy sand (22% of catchment) and acid loamy sand plus yellow duplex (together at 48% of catchment area), was predicted to reduce annual average deep drainage by 38 and 60%, respectively. Mapping deep drainage by this method is of value to land managers who want to reduce deep drainage by locating priority areas for the establishment of perennial vegetation.
The effect of spraying a growth promoting bacterium on the yield, growth and nutrient element composition of leaves of apricot (Prunus armeniaca L. cv. Hacihaliloglu)
Authors: Esitken Ahmet , Karlidag Hüseyin , Ercisli Sezai , Turan Metin , Sahin Fikrettin
Published: August 2003

Experiments were conducted during 2000 and 2001 to determine the effects of floral and foliar application of the bacterial strain Bacillus OSU 142 on the yield, growth and nutrient element composition of leaves of the apricot cultivar Hacihaliloglu grown in the Malatya province of Turkey. In 2000, trees were sprayed with a bacterial suspension at full bloom, and 30 and 60 days after full bloom. This experiment demonstrated significant differences in yield, shoot length and nutrient element composition of leaves only on trees treated at the full bloom stage. In view of this, the bacterial application was performed only at full bloom in 2001.The average increase in yield in 2000 and 2001 was 30% and 90%, respectively, compared with the untreated control. Shoot length development was significantly higher when trees were treated with OSU 142 at full bloom stage in both years. Similarly, N, P, K, Ca and Mg contents of leaves were higher on OSU 142-treated trees than on the untreated control. The results of this study suggest that OSU 142 has the potential to increase the yield of apricot trees.
Effect of organic amendments and solarisation on Fusarium wilt in susceptible banana plantlets, transplanted into naturally infested soil
Authors: Nasir N. , Pittaway P. A. , Pegg K. G.
Published: August 2003

Despite extensive research since pathogenicity was first established in 1919, no cultural or chemical control strategy has proven effective against Fusarium wilt of bananas. The efficacy of cultural control is attributed to the suppression of pathogen activity. Yet, amending naturally infested soil with aged chicken manure has been shown to enhance disease severity, without any change in the activity of the pathogen Fusarium oxysporum f. sp. cubense (Foc) in the soil. In this study, the effect of amending soil with composted sawdust, and of solarising soil, was compared with the effect of amending soil with chicken manure. Bioassays comparing the activity of Foc in the soil with the extent of invasion of banana pseudostem tissue by Foc were used to investigate why strategies targetting pathogen survival have not proven successful in controlling this disease.The enhancement of Foc invasion of the banana plantlets was reproduced with the addition of chicken manure to the naturally infested soil. However, changes in the activity of Foc in the soil were not associated with changes in the frequency of invasion of the plantlets. Invasion of banana pseudostems in the sawdust and solarisation treatments was not significantly different from invasion in the respective control treatments, despite a reduction in the activity of Foc in the sawdust-amended soil and an enhancement in the solarised soil. Moreover, the increase in Foc activity in the solarised soil recorded during the bioassays occurred despite the effectiveness of solarisation in reducing the survival of Foc in pre-colonised banana root tips buried in the soil. Changes in the frequency of invasion were associated with changes in the availability of mineral nitrogen, particularly ammonium N. These results suggest that the physiological response of banana cultivars to ammonium N may be associated with their susceptibility to Fusarium wilt. Accordingly, cultural strategies for controlling Panama disease will only be effective if they enhance the ability of the host to resist invasion.
Effects of below-ground nitrogen on N balances of field-grown fababean, chickpea, and barley
Authors: Khan Dil F. , Peoples Mark B. , Schwenke Graeme D. , Felton Warwick L. , Chen Deli , Herridge David F.
Published: August 2003

The objectives of this study were to quantify below-ground nitrogen (BGN) of rainfed fababean (Vicia faba), chickpea (Cicer arietinum), and barley (Hordeum vulgare) and to use the values to determine N balances for the 3 crops. The BGN fraction of legumes in particular represents a potentially important pool of N that has often been grossly underestimated or ignored in calculating such balances. A field experiment was conducted at Breeza on the Liverpool Plains, New South Wales, in which BGN of fababean, chickpea, and barley was estimated using 15N methodologies. Plants were grown in 0.32-m2 microplots and labelled with 15N on 5 occasions during vegetative growth with a total of 1.0 mL of 0.5% 15N urea (98 atom% 15N) using leaf-flap (fababean), leaf-tip (barley), or cut petiole (chickpea) shoot-labelling procedures. At peak biomass (146–170 days after sowing), all plant material and soil to 45 cm depth was sampled from one microplot in each replicate plot and analysed for dry matter (DM), %N, and 15N. At plant maturity, the remaining 3 microplots in each replicate plot were harvested for shoot and grain DM and N. With fababean, 15N enrichments of intact roots and shoots were reasonably uniform at 537‰ and 674‰, respectively. Microplot soil at 0–25 cm depth had a 15N enrichment of 18‰ (natural abundance of 6.1‰). The 25–45 cm soil enrichment was 8.7‰ (natural abundance of 6.3‰). In contrast, 15N enrichment of chickpea shoots was about twice that of recovered roots (685‰ v. 331‰), and the soil enrichment was relatively high (30‰ and 8.8‰ for the 0–25 and 25–45 cm depths, respectively). The 15N enrichments of barley shoots and recovered roots were 2272‰ and 1632‰, respectively, with soil enrichments of 34‰ and 10.7‰ for the 0–25 and 25–45 cm depths, respectively. Estimates of BGN as a percentage of total plant N, after adjusting the 15N shoot-labelling values of fababean and chickpea for uneven distribution of 15N-depleted nodules, were 24% for fababean, 68% for chickpea, and 36% for barley. The BGN values were combined with N2 fixation (fababean and chickpea only) and shoot and grain yield data (all 3 species) to construct N budgets. The inclusion of BGN in the budgets increased N balances by 38 kg N/ha to +36 kg N/ha for fababean and by 93 kg N/ha to +94 kg N/ha for chickpea. As there was no external (N2 fixation) input of N to barley, the inclusion of BGN made no difference to the N balance of the crop of –74 kg N/ha. Such values confirm the importance of BGN of N2-fixing legumes in the N economies of cropping systems.
Early stage selection for commercial cane sugar (CCS) in sugarcane clones: effects of time of sampling and irrigation
Authors: Jackson Phillip A. , Morgan Terry E.
Published: August 2003

Commercially recoverable sugar content in sugarcane (CCS, expressed as a percentage) is a key selection criterion in sugarcane breeding programs. In some sugarcane breeding programs there may be significant operational advantages in measuring CCS early in the crop growth cycle, well before commercial harvesting would normally commence, and in restricting growth by withholding irrigation to reduce cane yield and lodging. Two field experiments were conducted to investigate these effects. The experiments included clones representative of genotypes routinely assessed in the earliest stages of clonal selection in breeding programs. Differences among genotypes for CCS were expressed early when cane had very low CCS (in February or March), and then rates of increase in CCS following that time were similar in most genotypes. Therefore, time of sampling had little effect on ranking of genotypes for CCS, and selection for high CCS could be effective early in the year. Irrigation regime also had little effect on ranking of the clones for CCS, indicating that mild water stress could be imposed with no adverse effect on selection results. The results are discussed in relation to optimising selection procedures and systems in early stage selection trials in sugarcane breeding programs, and better understanding the physiological basis of genetic variation in CCS.
Influence of size of rainfall events on water-driven processes. I. Water budget of wheat crops in south-eastern Australia
Authors: Sadras Víctor O.
Published: August 2003

Power laws relating the number of events N (s) and their sizes s, i.e. N (s) ~ s–τ, are widespread in natural and social systems. Two hypotheses were tested: (1) power laws can be used to characterise rainfall patterns irrespective of the amount, seasonality, and rainfall mechanisms; and (2) crop water budget components favoured by large rainfall events, i.e. runoff and drainage, are negatively associated with τ, whereas soil evaporation, which is favoured by small rainfall events, is positively associated with τ. Hypothesis 1 was tested using long-term records of daily rainfall in 114 geographically widespread Australian locations from 12 to 43�S, and from 115 to 154�E, with median annual rainfall from 113 to 3437 mm, and Walsh and Lawler's seasonality index from 0.07 (very equable rainfall regime) to 1.1 (most rain in 3 months or less). Coefficients of determination of the linear regression between log-transformed number and size of rainfall events ranged from 0.90 to 0.98 (P < 0.0001). A single value of τ described well the rainfall patterns in 50 out of the 114 locations, whereas some degree of curvilinearity suggested that a multidimensional model would be more suitable in the other locations. Hypothesis 2 was tested in a factorial modelling experiment combining 44 years and 39 southern Australian locations in a latitudinal band (33–36�S) between 134 and 147�E. Simulated water budget components of wheat crops on a sandy loam soil included runoff (R), drainage beyond the root-zone (D), and evapotranspiration (ET) and its components. Seasonal rainfall (range from 176 to 381 mm) and τ (range from 2.84 to 3.76) were unrelated. Simulated ET, R, and D increased, and the soil evaporation : ET ratio (E/ET) decreased with increasing rainfall. For a given amount of seasonal rainfall, processes favoured by large rainfall events, including runoff and drainage, were more frequent and more intense in locations with smaller τ, whereas E/ET increased with larger τ. Despite some limitations, power laws provided a statistical description of rainfall patterns that is agronomically meaningful, with parameter τ accounting for the effect of size of rainfall events on the fate of water in crops.
Influence of size of rainfall events on water-driven processes. II. Soil nitrogen mineralisation in a semi-arid environment
Authors: Sadras Victor O. , Baldock Jeffrey A.
Published: August 2003

Power laws describe the relationships between the number N (s) and the size s of daily rainfall events, i.e. N (s) ~ s–τ, with higher τ corresponding to sites or seasons with greater frequency of small rainfall events. This paper tested the hypothesis that the rate of soil nitrogen mineralisation increases with increasing exponent τ, as affected by both spatial and temporal sources of variation. Rates of nitrogen mineralisation in an uncropped sandy loam soil were calculated using a simulation model with detailed nitrogen and water balances, and long-term weather data for 6 Australian locations in a range of annual rainfall from 260 to 360 mm. Daily rates of mineralisation were calculated using actual rainfall, and variable or fixed temperature and evaporative demand. The annual pattern of mineralisation rate, calculated as a function of rainfall and variable temperature and evaporative demand, was bimodal with peaks in April and November. These peaks disappeared and differences among locations were reduced when the effects of temperature and evaporative demand were removed. Under constant temperature and evaporative demand, mineralisation rates between April and November were 68% greater than rates between December and March. In the former period, characterised by a high frequency of small rainfall events, monthly mineralisation rate was a direct function of the amount of rainfall. In contrast, mineralisation was independent of the amount of rainfall during the period of larger, less frequent rainfall events from December to March. Parameter τ accounted for 75% of the variation in mineralisation rate in the period December–March and it also accounted for a substantial part of the variation between periods.
Screening wheat genotypes for tolerance of soil acidity
Authors: Tang C. , Nuruzzaman M. , Rengel Z.
Published: August 2003

A soil-based screening method was used to test tolerance of wheat genotypes to acidity. Plants were grown for 6 days in an acid soil with the pH adjusted to 3.9–5.8. The number and length of roots were measured. To validate the method, 12 wheat cultivars of known acidity tolerance and one acid-sensitive barley cultivar were grown on an acid soil in the field with or without amelioration of subsoil acidity. The relative yields of these wheat genotypes on the soil with subsoil acidity ranged from 50 to 89% of yields on soil without subsoil acidity, and were correlated with root growth parameters obtained in the glasshouse. The best correlation was obtained between relative yields in the field (y) and root length per plant (x) at pH 3.9 in the glasshouse (y = –43 + 52*log x, r = 0.95) or root length per plant at pH 3.9 as a percentage of root length at pH 4.8 (y = 1.2 + 46*log x, r = 0.94). Following validation of the glasshouse screening method in the field, 115 wheat genotypes, including cultivars and breeding lines, were screened in the glasshouse. A substantial genotypic variation in acidity tolerance was found, with root length per plant at pH 3.9 ranging from 66 to > 350 mm. Many Western Australian breeding lines displayed better tolerance than existing tolerant wheat cultivars. The screening system can be instrumental in breeding wheat for increased tolerance to acid soils.
Effects of phytase supplementation of phosphorus-adequate,
lysine-deficient, wheat-based diets on growth performance
of weaner pigs
Authors: Selle P. H. , Cadogan D. J. , Bryden W. L.
Published: August 2003

The effects of microbial phytase supplementation of phosphorus-adequate, wheat-based diets with
available lysine : energy density ratios ranging from 0.75 to 0.90 g available lysine/MJ DE on growth performance of weaner pigs were investigated in 3 studies. In the first study, increasing levels of dietary phytate depressed growth rates (P < 0.08) and efficiency of feed conversion (P < 0.01) and phytase supplementation enhanced growth rates
(P < 0.05) and tended to improve feed efficiency (P < 0.15). There were no significant interactions between dietary phytate and phytase inclusion to support the hypothesis that dietary substrate levels of phytate govern responses to phytase. However, in this and other studies, percentage increases in efficiency of feed conversion generated by phytase were positively correlated to dietary phytate concentrations to a significant extent (P < 0.005), so it is possible that dietary substrate levels are of importance to the magnitude of responses following phytase supplementation.
Diets with 3 levels of protein, expressed as 0.80, 0.85, and 0.90 g available lysine/MJ DE, were offered to pigs without and with phytase in the second study. Protein/amino acid levels or lysine : energy density ratios did not influence growth performance, which was not expected. However, phytase tended to increase growth rates (P < 0.08) and improved feed efficiency (P < 0.01). Although it is believed that phytase may have a positive influence on protein utilisation, this was not demonstrated in this experiment. In the third study, the simultaneous inclusion of phytase and xylanase feed enzymes in wheat-based weaner diets did not increase growth performance responses in comparison with phytase alone. Individually, phytase improved feed efficiency (P < 0.05) and numerically increased growth rates (P < 0.25). Although responses in growth performance of weaner pigs following
phytase supplementation lacked consistency, they were generally positive and indicative of anti-nutritive properties of phytate that are unrelated to P availability. That these positive responses were observed in diets with suboptimal available lysine : energy density ratios is consistent with the possibility that phytate has a negative influence on protein utilisation, which is ameliorated by phytase. However, these antinutritive effects and their underlying mechanisms need to be better defined if full advantage of the potential protein-sparing effects of microbial phytase is to be taken.
Limitations to carrot (Daucus carota L.) productivity when grown with reduced rates of frequent irrigation on a free-draining, sandy soil
Authors: Gibberd Mark R. , McKay Allan G. , Calder Tim C. , Turner Neil C.
Published: August 2003

To determine the influence of reduced irrigation input, carrot (Daucus carota L. cv. Ivor) plants were grown on a coarse-textured, sandy soil during summer near Perth, Western Australia. Irrigation was applied daily with sprinklers at 5 rates ranging from 47 to 151% replacement of daily pan evaporation (Ep). A reduction in irrigation from the industry standard of 151% Ep to 124 or 97% Ep resulted in a 17% increase in water use efficiency (WUE) when calculated as total root yield/water applied. However, the percentage of total roots that were marketable declined with reduction in irrigation, being 73, 56, and 63% at 151, 124, and 97% Ep, respectively. This minimised any increase in WUE when calculated on a marketable yield basis. Further reductions in irrigation to 47 and 73% Ep resulted in large reductions in yield, WUE, and the percentage of marketable roots. Leaf biomass was not significantly different between the 151 and 124% Ep treatments and was reduced by 55 and 85% at 73 and 47% Ep, respectively. Soil water tension (ψs) varied from 4 to 80 kPa among the irrigation treatments. Pre-dawn leaf water potential (ψl) was most sensitive to ψs over a ψs range of 0–20 kPa and the influence of ψs on ψl was small (400 kPa) compared with the diurnal variations in ψl of up to 1400 kPa, which occurred independently of significant changes in bulk soil ψs. There was no significant effect of irrigation on the osmotic potential of leaf sap and there was no evidence of osmotic adjustment. For all irrigation treatments, photosynthesis (Pn) peaked in the early morning (0830 hours) at rates of 17–20 μmol CO2/m2.s, after which Pn decreased to a transient minimum value at midday. The diurnal decline in Pn was positively correlated with ψl for all treatments, and minimum values of Pn varied from 12.5 to 7.8 μmol CO2/m2.s for plants grown with 151 and 47% of Ep, respectively. When grown under frequently applied, suboptimal irrigation, carrot productivity is predominately limited by a reduction in leaf growth rates that limits leaf area and matches transpiration requirements with water availability. Furthermore, even under conditions of water deficit, the aerial environment imposes a greater constraint to Pn than soil water availability.
Isozyme characterisation of Vicia faba germplasm: genetic interpretation and applications
Authors: Avila C. M. , Atienza S. G. , Moreno M. T. , Torres A. M.
Published: August 2003

Eighteen isozyme systems were assayed to characterise 147 accessions of Vicia faba L. from different origins, including the 4 known botanical types (major, equina, minor, and paucijuga). The most polymorphic isozyme systems were aspartate aminotransferase (AAT), fructokinase (FK), phosphogluconate dehydrogenase (PGD), peroxidase (PRX), and super-oxide dismutase (SOD), which provide a discriminatory tool for evaluating and characterising collections. The study also detected possible contamination or some degree of heterozygosity within certain inbred lines. New alleles were detected for the isozyme systems AAT, aconitase (ACO), and PRX. To our knowledge, this is the first time that the fructose-bisphosphate aldolase (FBA) system is described in V. faba. The use of allozymic variation in germplasm identification and characterisation, breeding programs, and other genetic studies on the species is discussed.
Evaluation of vegetative growth traits and their relation to time to first flowering of olive seedlings
Authors: Pritsa T. S. , Voyiatzis D. G. , Voyiatzi C. J. , Sotiriou M. S.
Published: August 2003

The aim of this work was to assess growth traits during the initial developmental stages of olive seedlings, which could be correlated to time to first flowering, facilitating fast selection in olive breeding programs. The experimental material consisted of 232 olive seedlings derived from controlled crosses of 'Kalamon' with self (KA × KA), with 'Amphissis' (KA × AM), and with 'Koroneiki' (KA × KO) and from open pollination of 'Kalamon', 'Amphissis', 'Koroneiki', 'Chalkidikis', and 'Manzanillo'. Vegetative traits of the seedlings, including canopy height and diameter, length of lateral vegetation, number of leaves, mean and total leaf area per plant, leaf shape characteristics, and specific leaf area (SLA), were recorded until 15 months after sowing. The first seedlings to initiate flowers, 4 years after sowing, were also recorded. The existence of correlations between the above growth traits and time to first flowering was investigated. In single-branched seedlings 6 months after sowing, height measured at this stage was significantly correlated with the mean and total leaf area per plant, specific leaf area, and other vegetative traits measured 15 months after sowing. Seedlings with high values of these parameters were the first to initiate flowers 33 months later. Our results indicated that pre-selection of olive seedlings for earliness of first flowering is possible, based on vegetative characteristics assessed very early in their development.
Do farming practices influence the incidence of Childers canegrubs, Antitrogus parvulus Britton (Coleoptera : Scarabaeidae)?
Authors: Allsopp Peter G. , Fischer Timothy W. A. , Bade George S. , Dall David J.
Published: August 2003

The impact of farming practices on numbers of Childers canegrubs was determined in southern Queensland by a survey of 441 field–year combinations that related practices to the numbers of second- and third-instar larvae in those fields, and by a field experiment that tested combinations of insecticide application, cultivation practices, and crop-residue retention on numbers of larvae and associated entomopathogens. There were significant differences in levels of infestation among years, soil types, crop ages, cultivars grown, insecticide-use strategies, crop-replacement strategies, intensity and frequency of tillage during crop replacement, and irrigation strategies. In the field trial, numbers of third-instar larvae declined as the larvae aged, probably through infection by the fungus Metarhizium anisopliae and the protozoan Adelina sp. Application at planting of the controlled-release insecticide suSCon Blue had an immediate effect on the number of larvae carried over from the previous crop cycle and this effect continued into the second-ratoon crop. The insecticide application increased cane and sugar yields, particularly in the first-ratoon crop. More intensive pre-planting tillage initially reduced numbers of larvae, but the effect did not continue into the ratoon crops. Management of crop residues had no consistent effect on numbers of larvae, but cane yields were higher and sugar content lower in the second-ratoon crop when residues were retained, and led to higher sugar yields where suSCon Blue had been applied. In general, long breaks between successive sugarcane crops, coupled with intensive tillage in that break and application of controlled-release insecticide, will reduce subsequent populations of larvae. The alternative strategy of herbicide destruction of the previous crop, long fallow with minimum tillage, replanting without controlled-release insecticide, and prudent use of transient insecticides in heavily infested ratoon crops will also minimise numbers and may allow better survival of entomopathogens. These strategies have been integrated into management practices attractive to growers.
Tiller dynamics of perennial ryegrass cultivars derived from different New Zealand ecotypes: effects of cultivar, season, nitrogen fertiliser, and irrigation
Authors: Bahmani I. , Thom E. R. , Matthew C. , Hooper R. J. , Lemaire G.
Published: August 2003

A field study was made of the tiller dynamics of the New Zealand perennial ryegrass (Lolium perenne L.) cultivars Grasslands Ruanui, selected from a Hawke's Bay ecotype, and Ellett, selected from the Mangere ecotype. The work tested whether nitrogen (N) fertiliser or irrigation (Irr) could manipulate the persistence strategies of these morphologically distinct perennial ryegrass ecotypes, represented by these cultivars. Tiller births and deaths, and tiller survival, were monitored over 2 years, under rotational grazing by dairy cows. Patterns of cultivar tiller birth and death were similar. Much of the temporal change in tiller population density was shown to be a response to increasing or decreasing herbage mass associated with seasonal feed surplus or deficit. The probability of tiller survival between observation dates varied markedly with date, and was lowest in autumn. The cultivar effect on tiller survival was small but a significant (P < 0.05) cultivar × date interaction was detected, with survival probability for Ellett tending to be higher than for Grasslands Ruanui in March–April 1997 but lower from July 1997 until March 1998. A cohort effect on tiller survival was also identified, in that tillers formed in January, July, and August 1997 had lower survival probability than those formed at other times. N-treated plots produced 34% more tillers than did untreated plots, and irrigation had no effect on overall tiller density. N and Irr treatments had variable effects on tiller survival. Size density compensation theory and analysis of survival probability are introduced to aid the interpretation of tiller dynamics data.