bluuebunny/crossref_metadata_2025 huggingface dataset:
Genotype, sowing date and plant spacing influence on high-yielding irrigated wheat in southern New South Wales. II. Growth, yield and nitrogen use
Authors: Stapper M , Fischer RA
Published: November 2005

Sowing date, sowing rate and row spacing effects were studied on irrigated wheat crops at Griffith, N.S.W. during 1983-85 using genotypes differing in maturity, stature and genetic background. The aim was to identify better management practices and genotypes through a better understanding of development and growth of wheat grown under high-yielding conditions. Maximum yield was up to 891 g/m2. The average yield reduction was 50 g/m2 or 6% per 1-week delay in anthesis after 1 October, but varied between 2 and 23%, depending on the season. Lodging was a significant problem in all three years, with less lodging for later sowing dates, earlier maturity types or shorter stature. Plant spacing, through variations in row spacing (17-45 cm) or sowing rate (50-200 kg/ha) did not significantly affect grain yields, but lodging was reduced by increased row spacing and reduced sowing rate. Dry weight at anthesis (600-1 500 g/m2) explained 65% of the variation in lodging, with severe lodging risks for weights over 900 g/m2. Harvest index improved with later sowing or earlier maturity and was, among genotypes within a sowing, negatively correlated with anthesis date, height, lodging score and final leaf number on the main stem. Nitrogen uptake usually ceased before anthesis. Genotypic differences in grain protein concentrations of more than 2% were found. Some genotypes combined high yield with high grain protein concentration (e.g. 717 g/m2, 14.1% protein). Significant genotype effects on spike density, kernel weight, kernel growth rate, and number of kernels per m2, per spike and per g chaff weight were identified, but none seemed to restrict yield. There was much compensation between traits. For example, high kernel numbers (per g chaff, spike or m2) were associated with low kernel weights and vice versa, both within and between genotypes. It was concluded that short-stature, early-maturing, low spike-bearing cultivars are most suited to high-yielding conditions from any sowing date, provided flowering occurs after late September, as such crops have a reduced lodging risk and use assimilates and N most efficiently. Genotypes were highly adaptable and many morphogenetic traits differed widely between genotypes, but were usually similar among dwarf or semidwarf, and among early or late maturing genotypes.
Genotype, sowing date and plant spacing influence on high-yielding irrigated wheat in southern New South Wales. III. Potential yields and optimum flowering dates
Authors: Stapper M , Fischer RA
Published: November 2005

Experiments were undertaken at Griffith, N.S.W., using a range of genotypes, sowing dates and plant spacing to identify management strategies and genotypes that would increase irrigated wheat yields and minimize lodging risk. Results are used in this paper in an analysis of potential yield and optimum anthesis date, as influenced by temperature, irradiance, sowing date and genotype. Lodging duration was used to predict potential yields in absence of lodging from the lodging-affected yields in the study. Lodging duration between 7 days after mid-anthesis and maturity was found to best explain early and late lodging effects on yield. Yield reductions due to lodging were up to 45%. Predicted potential yields (Yp) were 800-950 g/m2 and the end of the optimum anthesis period varied from year to year. Average temperature (T, �C) and total irradiance (+R, MJ/m2) for a preanthesis period of 500�C days (>3�C) or a maximum of 60 days explained 61% of the variation in Yp: Yp=981 - 53.4T+ 0.51 +R (g/m2). Using historical weather data and frost risk restrictions indicated an optimum anthesis period between 22 September and 10 October when average predicted yields were reasonably stable. Flowering after mid-October caused reductions in average predicted yield of 70 g/m2 or 11 % per 1-week delay in anthesis. Kernel weights decreased by 5% per 1�C above 14�C, but this decrease was also associated with increased kernel numbers. High-yields under irrigation can only be achieved consistently and efficiently with lodging resistant (short, stiff stems) or avoiding (early maturing) genotypes. Very early maturing types for late sowing dates are currently not commercially available. Adjusted management practices (e.g. relatively late sowing) and lower target yields are recommended for current lodging susceptible varieties.
Stem rust epidemics and their effects on grain yield and quality in Australian barley cultivars
Authors: Dill-Macky R , Rees RG , Platz GJ
Published: November 2005

The progress of epidemics of Puccinia graminis f. sp. tritici strain 343-Anz-1,2,3,5,6 was examined in field plots of the Australian barley cultivars Clipper, Corvette, Galleon, Grimmett, Prior and Schooner. The barley Purple Nudum, reported to possess seedling resistance to Puccinia graminis f. sp. tritici, and the susceptible wheat Oxley were also examined. Additional rust-free treatments were maintained to provide comparisons of grain yield and quality. Differences in the rate of epidemic development between cultivars were found. Moderate epidemics developed in Clipper, Schooner, Grimmett and Prior and no significant losses in yield were detected in Grimmett or Prior. Severe epidemics developed in Galleon, Corvette and Oxley and reduced grain yield by about half. Yield reductions were generally associated with reduced grain size and weight.
Comparative growth of white clover sown into pots of soil from old pastures and adjacent roadsides
Authors: McGowan AA
Published: November 2005

It is often claimed that improved pastures grow better in the early years after initial establishment than after many years of fertilization and grazing. A pot experiment was conducted to compare the dry matter production of white clover and perennial ryegrass when sown into soil from old established pastures and into soil taken from adjacent roadsides which had not previously been cultivated, fertilized, sown or grazed. On 8 out of 10 sites, white clover growth was consistently poorer when sown into the paddock soil than into the roadside soil. The average growth on paddock soil from these 8 sites was only 61% that of growth on the roadside soils. With perennial ryegrass there was no similar depression; in fact, the overall average growth of grass on the paddock soils was 121% that on the roadside soils. The explanation for this difference in growth of clover on the two soil types was apparently not due to any difference in the N status of the clover plants, as at no harvest was this difference significantly reduced when N fertilizer was regularly applied to the clover. The economic importance of these findings depends on confirmation of the results in the field. Possible, but untested, explanations may lie in different levels of soil-borne pests and diseases, or a residual allelopathic effect of improved pasture species on the growth of clover on the old pasture soil.
Factors affecting the hydrogen cyanide potential of forage sorghum.
Authors: Wheeler JL , Mulcahy C , Walcott JJ , Rapp GG
Published: November 2005

The effect of seven factors, namely genotype, plant maturity, nitrogen fertilizer, phosphorus fertilizer, water stress, light intensity and temperature, on the hydrogen cyanide potential (HCNp) of forage sorghum was studied in three pot experiments. Fivefold differences occurred between genotypes in HCNp, with a breeder's line, X45106, selected for low HCNp having a maximum of 520 mg HCN kg-1 DM (dry matter) compared with 2300 and 2450 mg kg-1 DM for cvs Zulu and Silk respectively. In X45 106, HCNp (mg HCN kg-1 DM) declined curvilinearly with age d (days from sowing) (HCNp=8460- 320d+ 3.1d2) and linearly in Silk (HCNp = 9020 - 110d), but the decline in Zulu was not statistically significant. Nitrogen (equivalent to 200 kg ha-1 of N) increased HCN, (P< 0.001), but more so in full light (100 mg kg-1 compared with 1430 mg kg-1) than in 50% shade (190 mg kg-1 compared with 690 mg kg-1). In one experiment, acute water stress appeared to reduce HCNp, but this was confounded with the strong decline due to aging. In another study, acute water stress had no effect on HCNp. Neither the application of superphosphate nor change in light intensity, nor change in temperature had a direct significant effect on HCNp in these studies. Breeding and selection for low HCNp appears a promising approach to ensuring that sorghum plants will provide non-toxic forage from an early stage of growth.
Pollination biology of cashew in the Northern Territory of Australia
Authors: Heard TA , Vithanage V , Chacko EK
Published: November 2005

Aspects of the pollination biology of cashew Anacardium occidentale L. (Anacardiaceae) were investigated at a site of potential commercial production. A mean of 442.9 flowers were produced per panicle of which 32.1 (7.3%) were hermaphrodite, the remainder being male. Mean initial fruit set was 5.0 per panicle, representing a percentage fruit set of 15.5%. The absence of either male or hermaphrodite flowers at any particular stage of flowering did not limit fruit set. Diversity of insect flower visitors, attracted by nectar rewards, was great, but only a few species were common. Three species of potentially efficient pollinators were tested for their pollinator efficiency which was found to be high for honey bees, Apis mellifera, and a native fly, Ligyra sp. Only 25% of flowers were pollinated in 1987, but this increased to 98% owing to a corresponding increase in the natural populations of insect visitors. Wind and night flying insects played no role in pollination. Although 98% of flowers were pollinated, initial fruit set averaged only 15.5%. This suggests that factors other than pollination limit fruit set. However, pollination is important and the insect pollinators will need protection from insecticide applications and destruction of breeding sites.
The phosphorus nutrition of the apple tree. III. Influence of phosphate timing treatments on the performance of Jonathan/MM.104 apple trees in two years
Authors: Taylor BK , Nichols DG
Published: November 2005

Bench grafted JonathanlMM104 apple trees were grown in perlite culture in a glasshouse for up to 2 years and the effects of adding � phosphate (PO or P50 ppm nutrient solutions) in spring, summer, autumn, or during the second growing season were determined. Phosphate timing treatments produced marked differences in tree performance and P uptake. Thus, spring P significantly increased the growth of tree tops, the top/root ratio, P uptake and flowering in the second year. Summer P increased the growth of tree tops, the top/root ratio and P uptake, while autumn P increased P uptake but not tree growth in the first year. Strong carryover effects were note for all first year P treatments on the growth and P content of the trees in the second year consistent with the mobilization of P reserves. Significant interaction effects between treatments were found and P uptake in a given period was influenced by the P treatment given in the previous period. Thus, P uptake and the tree growth response were greater in P stressed trees than in high P trees. All times of application of P were effective in increasing the P status of tree parts including leaves and fruit. Tree P content at the end of the second year was dependent upon both residual and current year P treatments. These findings are briefly discussed in relation to earlier published work on the P nutrition of apple trees and also in relation to their significance to apple growers.
The control of Nezara viridula L. with introduced egg parasitoids in Australia. A review of a 'landmark' example of classical biological control
Authors: Clarke AR
Published: November 2005

The history of Nezara viridula egg parasitoid introductions into Australia is critically reviewed. Using largely unpublished file material information is presented on the source of parasitoids, specific identification of parasitoids, numbers of parasitoids reared and released, and establishment and effects in the field. At least four species of egg parasitoids, in three genera, have been introduced and liberated into Australia since biological control efforts were first begun in 1933. There are records of 11 introductions involving Trissolcus basalis (Wollaston) (Egypt 1933; West Indies 1952-53; South Africa 1980; Brazil 1980; U.S.A. 1979-8 l), Trissolcus mitsukurii (Ashmead) (Japan l962), Ooencyrtus submetallicus (Howard) (West Indies 1952-53), and Telenomus chloropus (Thomson) (Japan 1962; Japan via U.S.A. 1980). Doubt is cast on the specific status of introductions from Italy (1956) and Pakistan (1 961), which are recorded in the literature as T, basalis. Evidence is presented that there is currently not enough information available to determine the specific classifications of these importations. Three programs in which Australian field populations of Trissolcus were bred and released elsewhere in Australia are also recorded. Post-release evaluation of introduced N. viridula egg parasitoids in Australia is reviewed. It is proposed that there is only circumstantial evidence to support the claim that N. viridula is under 'good' biological control by T. basalis in Australia. Areas of investigation that are of the most significance to current workers in N. viridula biological control are highlighted in the discussion.
Effect of mouse epidermal growth factor on fertility in rams
Authors: Brown BW , Mattner PE , Panaretto BA , Brown GH , Gream BD , Honnery RL
Published: November 2005

Seminal characteristics and flock fertility were studied in Merino rams treated with mouse epidermal growth factor (EGF). Intravenous infusions of 105 8g EGF/kg body weight over 24 h in five rams had no statistically significant effect on daily sperm production measured from 6-10 weeks after dosing or on the percentages of spermatozoa that were unstained (nigrosinleosin stain) or morphologically normal. At 7-8 weeks post treatment, the percentage of spermatozoa exhibiting progressive motility was significantly reduced (P<0.05). By 9-10 weeks after treatment, the seminal characteristics were normal in all rams. In 1987, eight rams and in 1988, six ofthe same rams, were joined with ewes for 6 weeks (at a rate of 2%) 12 weeks after s.c. injection of 150 8g/kg body weight. Compared with the performance of control rams, EGF had no significant effect on ram fertility, nor did it produce any teratogenic effects in their progeny or effect their survival rate.
The incidence of flystrike in sheep in relation to weather conditions, sheep husbandry, and the abundance of the Australian sheep blowfly, Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)
Authors: Wardhaugh KG , Morton R
Published: November 2005

The incidence of cutaneous myiases (flystrike) in sheep in the Southern Tablelands of New South Wales is examined in relation to the abundance of the Australian sheep blowfly, Lucilia cuprina (Wiedemann), and various management and environmental variables known to affect sheep susceptibility. Regression analysis showed that the incidence of flystrike increased with increases in the density and activity of gravid L. cuprina. Body strike was more predictable than crutch strike, and was positively correlated with monthly rainfall, cloud cover and the rate of pasture growth. Rainfall intensity was also important, with frequent, small falls of rain being more conducive to flystrike than occasional heavy showers. The combination of weather, pasture and fly effects accounted for 76% of the observed variance in body strike and 58% of that for crutch strike. Crutch strike appeared to replace body strike under dry conditions and also when fly densities were low (less than 0.5 gravid females h-1 trap-1), irrespective of weather conditions. The analysis of total strike suggested that rainfall determined overall levels of strike, whereas pasture conditions and cloud cover regulated type of strike.
Feed intake and liveweight of cattle on subtropical native pasture hays. 1. The effect of urea
Authors: Hennessy DW , Williamson PJ
Published: November 2005

Twenty Hereford weaner steers and heifers, 9-months-old and of mean liveweight (� s.e.) 152 � 6 kg, were stratified according to sex and liveweight into four groups and assigned to cells in an experimental design which aimed at studying the effects of an increased urea intake on their rumen ammonia concentration, their intake of a low N native pasture hay and on their liveweight change over 49 days. The cattle on the basal hay diet maintained low concentrations of ammonia in rumen fluid (8 mg N/L) during the study and lost weight (at 50 g/day). Urea (as 15, 23, 42 and 53 g head.day) increased significantly (P< 0.01) rumen ammonia concentration (to 152 t 10.9 mg N/L), hay intake in the final 7 days (from 2633 to 3738 � 72 g organic matter/head.day) and liveweight change (to 273 � 33 g/head.day). Hay intake of the cattle increased within 14 days of supplementation with urea which was sprayed onto portions of the hay. Urinary N content, but not faeces, was increased by the urea diets. Urea intakes also increased urea nitrogen concentrations in plasma and saliva which were correlated (r=0.87). Liveweight change was maximized at daily urea intakes of 23 g/head and these gains are discussed in terms of the suitability of urea for Hereford cattle which are fed only low N native pastures
The effect on egg shell quality of supplementing saline drinking water with sodium or ammonium bicarbonate
Authors: Yoselewitz I , Zhang D , Balnave D
Published: November 2005

Supplementing the town water supply of laying hens with 600 mg sodium chloride (NaCl)/L significantly decreased egg shell quality and significantly increased the incidence of egg shell defects without affecting egg production and egg weight or food and water intakes. A smaller, but still significant, increase in egg shell defects was also observed with sodium bicarbonate (NHCO3) supplementation of town water. Ammonium bicarbonate (NH4HCO3) supplementation of town water had no significant effect on egg shell defects and, when added to drinking water containing NaCl, significantly reduced the incidence of shell defects. A smaller beneficial effect was observed when NHCO3was added to saline water. Ammonium bicarbonate, when added to saline drinking water at concentrations of 250 and 450 mg/L, reduced water intake, an effect not observed when these same supplements were added to town water. This suggests that the presence of NaCl in the water may affect kidney function so that the use of NH4HCO3may have limited value, especially at higher water salinities. Shell gland fluid composition was influenced less by treatment than by whether or not hens were laying eggs with defective shells.
Morphological and phenological variation in three populations of saffron thistle (Carthamus lanatus L.) from Western Australia
Authors: Peirce JR
Published: November 2005

Saffron thistle (Carthamus lanatus L.), an erect spiny annual herb, is a weed of pasture and cereal crops in some agricultural areas of southern Australia. Cypselas (achenes or seeds) were collected from mature plants at three sites near Salmon Gums, Moorine Rock and Greenough in Western Australia and grown at South Perth. Two forms were observed and could be distinguished by differences in their phenology and the shape of cotyledons and achenes. After two generations at South Perth, germination in the presence or absence of leaching with water or after storage at daily fluctuating temperatures of 15-60�C indicated that there were differences between forms as well as between different accessions of the same form. This result suggests that genetic as well as environmental factors influence the breakdown of dormancy and promote germination. Differences in germination were detected when a single accession was sown at two sites, one in the south and the other in the north of the cereal-growing region of Western Australia. Low rainfall and temperatures in autumn were primarily responsible for slow and staggered germination at the more southern site. The protracted germination of saffron thistle in the southern cereal-growing districts creates a problem for cultural control and correct timing of herbicide applications.
Crop growth and relative growth rates of old and modern wheat cultivars
Authors: Karimi MM , Siddique KHM
Published: November 2005

An analysis of the dynamics of green area index (GAI), dry matter (DM), relative growth rate (RGR) and crop growth rate (CGR) based on growing degree days (GDD) is presented for a historical series of wheats commercially released in Western Australia. Relative to the old cultivars, modern wheats were characterized by a greater RGR during the vegetative phase. This was achieved at a lower initial GAI, which persisted as the season progressed and was associated with a higher CGR at anthesis and greater grain yield at the end of the season. In the old cultivars, a greater GAI during the mid season declined rapidly as temperatures and soil moisture stress increased in spring, resulting in a lower GAI at anthesis. Together with lower CGR at anthesis this resulted in less dry matter and grain yield at final harvest. The higher grain yield of modern wheat cultivars was achieved with a high RGR during the vegetative phase and greater CGR from ear emergence to harvest.
An improved method for artificial hybridization in annual Medicago species
Authors: Pathipanawat W , Jones RAC , Sivasithamparam K
Published: November 2005

An improved technique for successful artificial hybridization in annual medic (Medicago spp.) is described. Using a previously reported method, only four out of seven species were successfully crossed, with the percentage of success ranging from 3 to 22%. Initial modifications to this technique gave a 7-8 fold increase in the successful crossing rate in M. murex and M. polymorpha medic, from 9 to 64% with M. murex and from 10 to 82% with M. polymorpha. Further modifications to the technique resulted in a success rate of 100% in both species. The numbers of seeds per pod obtained from crosses in both species were also increased by using the modified techniques compared to the established method. Selection of larger, more mature flowers, differences in flower cutting position, as well as post pollination position were the main modifications which accounted for the greatly improved success rate. The modified technique was subsequently applied successfully to obtain for the first time inter-specific crosses involving M. polymorphax M. murex, M. polymorphax M. sphaerocarpos, M.murexx M. sphaerocarpos, M. solerolii x M. littoralis/M.truncatula hybrid, M. solerolii x M, tornata, and M. littoralis/M.truncatula hybrid x M. sphaerocarpos.
Postanthesis green area duration in a semidwarf and a standard-height wheat cultivar as affected by sink strength
Authors: Slafer GA , Savin R
Published: November 2005

Postanthesis green area duration (GAD) has been associated frequently with yield. The senescence pattern of green organs is a major component of GAD. It has been proposed that delayed or accelerated senescence is strongly controlled by environmental conditions and the level of source or sink limitation on grain growth. In particular, it has been generally reported that the removal of reproductive structures delays the senescence process. However, results reporting this effect in wheat are not conclusive. A field experiment was conducted at the experimental station of The University of Melbourne comprising a factorial combination of a semidwarf and a standard-height wheat, and two levels of sink strength. At anthesis, 20 main shoots were tagged and detillered. Ten days after anthesis all the spikelets from one side of 10 tagged ears were removed by hand. The experiment was performed under natural, and 3 h-extended photoperiods from seedling emergence to heading. The photoperiod treatments induced differing grain filling environments and differing plant characteristics at onset of grain filling. Green area senescence was similar for both sink size treatments at any combination of cultivar and grain filling condition, indicating that the dynamics of plant senescence was insensitive to a severe reduction in number of grains per spike. Therefore, GAD was not significantly affected by the reduction in sink strength. The number of grains per spike were reduced to ca. 50% due to trimming. Therefore, source-sink ratio was doubled, but no significant changes in individual grain weight were found. There was no relationship between GAD and individual grain weight, confirming that grain growth in field-grown wheat is not limited by the strength of the source. Alternatively, our results confirmed that field-grown wheat is sink-limited during grain filling and that the likely accumulation of soluble carbohydrates in leaves does not affect the onset or rate of senescence.
The field pea crop in S.W. Australia. I. Patterns of growth, biomass production and photosynthetic performance in genotypes of contrasting morphology
Authors: Armstrong EL , Pate JS
Published: November 2005

Biological yield and photosynthetic performance of six field pea genotypes of contrasting foliar morphology and growth habit were studied in a water-limited field environment at Wongan Hills, Western Australia. Dundale and Wirrega were tall, indeterminate, scrambling and conventionally leaved; Dinkum, L82 and L80 (semi-leafless) and Progreta (tare-leaved) were semi-dwarf and more erect. Green area index (green leaf area per unit of ground area), green area duration (time integral of green area), crop growth rate (rate of dry matter accumulation per unit ground area) during early spring, net photosynthetic rate (CO2 exchange rate per unit green area or unit green weight) and net assimilation rate (rate of dry matter accumulation per unit green area) all influenced crop productivity. Shoot and root biomass was highest in Wirrega, due mainly to superior green area index, extended green area duration and maintenance of high growth rate during pod fill. Inverse relationships amongst genotypes were evident between green area index and net assimilation rate, and between green area index and CO2 exchange rate of green area. Total net photosynthesis of the tendrils of semi-leafless types was similar to that of leaflets of conventional types, due mainly to larger biomass of tendrils compensating for poor photosynthetic rates. The poor growth of semi-leafless and tare-leaved types was attributed to lower vigour, green area, ground cover and photosynthate production. Future selection of such types for water-limited environments should concentrate on increasing shoot height, node number per plant, stipule and tendril size and photosynthetic efficiency of green area.
The field pea crop in S.W. Australia. II. Effects of contrasting morphology and environment on reproductive performance
Authors: Armstrong EL , Pate JS
Published: November 2005

Reproductive performance of six field pea genotypes was assessed at three contrasting field sites in Western Australia and under optimal conditions in a glasshouse using comparative data on phenology, branching pattern, green area indices, number distribution and fruiting success of reproductive nodes and final seed yields per plant or unit crop area. Two genotypes (Dundale and Wirrega) were tall, indeterminate and conventionally leaved, the other four semi-dwarf and more erect. Three of the latter were semi-leafless (Dinkurn, L82 and L80) and the other tare-leaved (Progreta). Seed yields at the field sites increased generally in relation to rainfall during the growing season (May-October), viz. Avondale (267 mm), Wongan Hills (350 mm), Mt Barker (421 mm). Superior performance at Mt Barker was related to greater biomass and green area index and higher number of reproductive nodes and pods per plant, but not to increased branches per plant, pods per node, seeds per pod or seed size. Improved harvest index, larger seeds and greater reproductive yield from basal and aerial branches were responsible for the trellised well-watered and fertilized glasshouse plants mostly outyielding those at the field sites. Field-site specific superiority of certain genotypes over others was evident, e.g. the top ranking performance of the deeper-rooted, late maturing Wirrega at the drier sites of Avondale or Wongan Hills and the much improved performance of the semi-leafless types in the extended cool and moist season of Mt Barker. Poor seed yields of tall types relative to their vegetative biomass were pronounced at Mt Barker due to poor fruit set and seed filling in the severely lodged and self-shaded canopies. Data are discussed in relation to previous cultivar evaluations and ideotype prescriptions by other workers in Australia or overseas.
Effects of sowing seed with different levels of infection, plant density and the growth stage at which plants first develop symptoms on cucumber mosaic-virus infection of narrow-leafed lupins (Lupinus angustifolius)
Authors: Bwye AM , Jones RAC , Proudlove W
Published: November 2005

During 1990-92, narrow-leafed lupins (Lupinus angustifolius) cv. Gungurru, were grown in six field experiments in which plots were sown with healthy seed or seed that carried 0.5-5% infection with cucumber mosaic virus (CMV). Seed-infected plants were the primary source for subsequent virus spread by aphids. The rate of CMV spread and the extent of infection in plots depended on the level of infection in the seed sown, the proportion of infected seeds that successfully developed into established plants and the time of arrival and number of aphid vectors. In general, higher seed infection levels, better establishment of seed-infected plants and early aphid arrival favoured greater virus spread, yield loss and infection in the harvested seed. In 1991, in two experiments, late arrival of aphids resulted in minimal CMV spread, no effect on yield and much less infection in the harvested seed than in the seed sown. In the other four experiments, significant yield losses (25-42%) always resulted when seed with 5% or 3% infection was sown. Sowing 1% infected seed resulted in significantly decreased yields in two experiments, while 0.75% and 0.5% infected seed caused significant losses in one experiment (16-19% losses). Yield decreases were due to both fewer seeds being formed and decreased seed size. Levels of infection in harvested seed did not exceed 15%. In a further field experiment in 1991, individual plants that developed CMV symptoms before initiation of flowering or during flowering had significantly smaller yields than those that developed symptoms after flowering had finished. In four field experiments during 1990-91, 10-15% CMV-infected lupin seed was sown at rates of 20-150 kg ha-1 to generate a range of plant densities. The numbers of seed-infected plants were recorded at different times. The extent of loss of seed-infected plants due to shading by neighbouring healthy plants depended on plant density and the time when canopy closure developed. Where no canopy formed there was little or no loss of seed-infected plants, while early canopy formation at high plant density was most effective in removing them. Current-season spread was also decreased by early canopy formation and high plant density, but this effect was smaller when aphids arrived early. This work supports recommendations for management of CMV infection in lupins by sowing seed with low infection (<0.5%) to minimize infection sources, and sowing early at high seeding rates to remove seed-infected plants through improved canopy formation.
Infection of alternative hosts associated with annual medics (Medicago spp.) by alfalfa mosaic virus and its persistence between growing seasons
Authors: McKirdy SJ , Jones RAC
Published: November 2005

Under conditions of natural alfalfa mosaic virus (AMV) spread, five plant species found associated with annual Medicago spp. (medics) were infected commonly and another seven sporadically. Ten of these were new records. Because seed of herbaceous plant hosts provides a possible route for virus persistence through dry summer conditions, AMV seed transmission was tested for in alternative hosts. Of ten species systemically infected by sap inoculation with AMV, seed transmission was detected in Melilotus indica (l0%), Ornithopus compressus (0 1%) and Stachys arvensis (2%). Seed of seven naturally infected potential alternative host species was tested, and seed transmission found in Crassula decumbens (0. 1%), M. indica (3%), 0. compressus (0.2%), S. arvensis (0.4%) and Trifolium subterraneum (2%). Carry-over of AMV through seed transmission was detected in seedlings of Hypochaeris glabra (0.2%) and M. indica (0.6-0.8%) that germinated naturally in the field. In grazed, self-regenerated Medicago murex and M. polymorpha swards sown in 1987, the virus persisted for at least seven growing seasons. Levels of infection in M. polymorpha seed produced each year declined, but levels in the general seed bank remained higher due to presence of older seed. It is concluded that under the conditions of broadacre agriculture in the Mediterranean-type climate of Western Australia, seed transmission in C. decumbens, H. glabra and volunteer 0. compressus is an alternative means by which AMV can persist over summer to act as sources of AMV for spread within annual medic pastures. However, persistence through seed of the annual medic cultivars sown and of naturalized annual Medicago species is the principal means of persistence. AMV persists readily from year to year following sowing of infected seed and is likely to cause a recurrent disease problem in annual medic pastures.
Infection of subterranean clover swards with bean yellow mosaic potyvirus: losses in herbage and seed yields and patterns of virus spread
Authors: Jones RAC
Published: November 2005

During 1989-92, subterranean clover ( Trifolium subterraneum L.) was grown in field experiments in which swards of six cultivars were infected with bean yellow mosaic potyvirus (BYMV) by transplanting small BYMV-infected subterranean clover plants into them. The swards were then grazed by sheep or mown to simulate grazing. The infected transplants were the primary virus source for subsequent spread by aphids. Spread initially centred on infected transplants resulting in circular expanding infected patches. Later, secondary patches, isolated affected plants and more generalized infection sometimes developed. The extent of spread within swards from the transplants varied with cultivar, BYMV isolate, site and year. Final BYMV incidence ranged from 12% of plants symptom-affected by isolate MI in cv. Junee in 1991 to 100% by isolate SMB in cv. Leura in 1992. BYMV spread mostly occurred in spring and was increased around the edges of areas of bare ground in swards. In two experiments at one site in which 'mini swards' of cvv. Green Range, Karridale and Leura were mown repeatedly, BYMV-infection decreased herbage yields (dry weights) by 12-16% while seed yields were decreased significantly (by 37-40010) in one experiment. In a grazing experiment at a second site with swards of cvv. Esperance and Karridale, BYMV-infection decreased overall yields of herbage by 18-39% and seed by 11-12%; herbage yield losses within symptom-affected patches were 28-49%. In a further grazing experiment at this site with swards of cvv. Junee and Karridale, BYMV-induced losses determined from symptom-affected patches were 21-29% for herbage and 15-25% for seed. In a grazing experiment with swards of cvv. Denmark and ~ e u r a ' at a third site, BYMV-induced overall herbage yield decreases of 8-12% were still recorded despite extensive BYMV spread to control swards; yield losses within symptom-affected patches were 18-25% for herbage and 35-47% for seed. Seed yield losses were due to decreased seed size (mean seed weight), fewer seeds being produced, or both. Estimates of the effects of different levels of BYMV infection on herbage yields in partially infected grazed swards were obtained for cvv. Denmark, Karridale and Leura by plotting individual quadrat data for herbage dry weights against % symptom-affected plants. Losses increased in proportion to the level of infection, but their magnitude also varied with cultivar and experiment. It is concluded that BYMV infection of subterranean clover pastures is cause for concern, not only as regards herbage yield losses but also as regards depletion of the seed bank, which, when compounded year by year, results in pasture deterioration. Early and prolonged aphid activity, reseeding the pasture with susceptible cultivars, heavy grazing and extended growing seasons are all likely to magnify BYMV-induced losses.
Genetic structure of the scald pathogen (Rhynchosporium secalis) in South East Australia: implications for control strategies
Authors: Burdon JJ , Abbott DC , Brown AHD , Brown JS
Published: November 2005

A survey of electrophoretic variation in 89 isolates of Rhynchosporium secalis collected from cultivated and wild barley grass in Victoria, New South Wales and Tasmania detected an average of 2.5 alleles at each of 11 loci in 5 enzyme systems. At five loci, two alleles each occurred at frequencies exceeding 0.2. Comparison of the frequency of alleles at these loci showed little association with host or geographic origin, pathogenicity of the isolates or with the allelic state at other loci. Given that this pathogen reproduces asexually only, this lack of association confirms previous suggestions that some means of asexual recombination is important in this pathogen. Furthermore, the results suggest that the most effective means whereby long-term control over R. secalis will be achieved is through the use of both pathotype-specific and field resistance complemented by other strategies like the use of fungicides and possibly varietal mixtures.
The N2-fixing capacity of peanut cultivars with differing assimilate partitioning characteristics
Authors: Bell MJ , Wright GC
Published: November 2005

The contribution of symbiotic N2 fixation to the total N budget of irrigated crops of peanut (Arachis hypogaea L.) during vegetative and reproductive growth was investigated using four peanut cultivars with differing patterns of dry matter (DM) partitioning to developing pods. Estimates of NZ fixation were obtained with the 15N natural abundance procedure by using a non-nodulating peanut genotype as a non-N2-fixing reference plant. Partitioning was assessed on the basis of vegetative DM equivalents, with adjustments to pod DM based on relative synthesis costs of vegetative and pod DM. Cultivars differed in crop duration, DM production and yield of pods and kernels. Despite large differences in derived DM partitioning coefficients among cultivars (0.68 to 1.03), both total crop N and fixed N increased as a constant proportion of accumulated, energy-adjusted DM. Crop duration was the primary factor determining both total crop N and fixed N. In addition to fixation, all cultivars continued to accumulate soil mineral N throughout the season. However, in all cultivars except TMV-2, crop N uptake during reproductive growth was insufficient to meet the demands of developing pods and N was renlobilized from vegetative plant parts. Remobilized N was almost exclusively N derived originally from N2 fixation. Despite relatively high levels of N2 fixation (from 140 to 210 kg N ha-1, depending on crop duration), all cultivars except Virginia Bunch showed a negative apparent N balance when the amounts of N2 fixed were compared to N removed in pods at final harvest. This was primarily due to high N harvest indices (0.62 to 0.73), and is likely to be a feature of many recently released, high yielding cultivars.
Seed manganese affects the early growth of lupins in manganese-deficient conditions
Authors: Crosbie J , Longnecker NE , Robson AD
Published: November 2005

Poor crop establishment and split seed associated with manganese (Mn) deficiency are major problems in the production of narrow-leafed lupins (Lupinus angustifolius L.) in Western Australia. A survey of Western Australian seed producers indicated that Mn concentrations in lupin seeds ranged from 8 to 62 mg kg-1, with the majority of the seed containing less than 20 mg kg-1. We studied seedling growth of lupins (cultivars Gungurru and Danja) in nutrient solution, from seed with Mn concentrations ranging from 8 (Seed8) to 223 (Seed 223) mg kg-1. Without added Mn, the final weight of plants grown from Seed8 was 39% for shoots and 30% for roots, compared to maximum growth (Seed62). With adequate external Mn supply, there was no effect of seed Mn on growth of plants grown from undamaged seedlings. Shoot weight of Gungurru lupins 42 days after imbibing increased with increasing seed Mn concentration up to about 55 mg kg-1 when grown without added Mn. Growth of Danja plants increased similarly with increasing seed Mn concentration.
Effect of cultivar on uptake of cadmium by potato tubers
Authors: McLaughlin MJ , Williams CMJ , McKay A , Kirkham R , Gunton J , Jackson KJ , Thompson R , Dowling B , Partington D , Smart MK , Tiller KG
Published: November 2005

Cadmium (Cd) accumulation in tubers by commercial potato cultivars was assessed at 12 sites around Australia having differing soil and environmental conditions. At all but two sites there were significant differences in tuber Cd concentrations between cultivars. Some major commercial cultivars had tuber Cd concentrations only half that of others. Advanced breeding lines showed further potential to reduce Cd accumulation. Mean tuber Cd concentrations of the 14 most common cultivars, averaged across all sites, ranged from 30 to 50 8g kg-1 fresh weight (FW), below the maximum permitted concentration (MPC) of 50 8g kg-1 of Cd (FW). However, at some sites certain cultivars exceeded the MPC. A modified joint regression analysis of the data indicated that no cultivars have consistently low or consistently high tuber Cd concentrations across a range of environments. While differences between cultivars were significant, the range in Cd concentrations found between sites was generally greater than the range in Cd concentrations between cultivars at any one site. Thus soil and other site factors (e.g. irrigation water quality, climate, etc.) play a dominant role in controlling Cd accumulation by current commercial cultivars and there is a need to breed new cultivars resistant to Cd accumulation under a wide range of environments.
A glasshouse evaluation of sulfur fertilizer sources for crops and pastures. I. Flooded and non-flooded rice
Authors: Dana M , Lefroy RDB , Blair GJ
Published: November 2005

In pot experiments using flooded and non-flooded soil, rice cv. IR-43 was given gypsum (G), elemental S (E), urea-S melt (US), sulfur-coated urea (SCU), S-coated triple superphosphate (HF), S-bentonite (SB) and 3 S-coated triple superphosphate products in which the adhesives were UNE1, UNE2 and UNE3. A 2nd rice crop was grown in the same pots with basal nutrients applied at the same rate as for the 1st crop but without S. Highest grain yields in the 1st crop were obtained with G, UNE1 and UNE3 under flooded conditions, and G, UNE1, UNE3, SCU and E under non-flooded conditions. Fertilizer S uptake was highest from G under flooded conditions and uptake was higher with UNE1 and UNE3 than E. Yield and fertilizer S uptake in the 2nd crop were generally inversely related to those in the 1st crop.
A glasshouse evaluation of sulfur fertilizer sources for crops and pastures. III. Soluble and non-soluble sulfur and phosphorus sources for pastures
Authors: Lefroy RDB , Dana M , Blair GJ
Published: November 2005

Decreasing terms of trade of animal producers and increasing awareness of environmental problems associated with fertilizer use has resulted in increased emphasis on improving fertilizer use efficiency. Elemental S and reactive phosphate rock offer two sources of fertilizers with slower nutrient release rates than gypsum or monocalcium phosphate. A randomized block experiment was conducted under glasshouse conditions. Undisturbed soil cores of an Aquic Haplustalf soil were oversown with perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens, L.), and a factorial combination of two S sources (elemental S and gypsum), two P sources (triple superphosphate, (TSP), or North Carolina reactive phosphate rock (RPR), two methods of S and P application (S mixed with granulated TSP or RPR and S coated onto TSP or granulated RPR). An unfertilized control (C) was included in order to calculate fertilizer S recovery using the 35S reverse dilution technique. Pots were either watered to field capacity (NL) or watered to 25% excess to promote leaching (L). Harvests of tops were made at 4 or 8 weekly intervals up to 96 weeks after application when the pots were destructively harvested. Yields were lower in the leached than the unleached pots between weeks 8 and 44 where TSP or G was applied. Clover yields were initially highest with G, but elemental S gave more sustained production. Yields and P content of tops were lower with RPR than TSP up to week 36. Recovery of fertilizer S was higher in the TSP than RPR treatments up to week 24. Leaching losses of S were higher from G than elemental S sources up to week 17 and were higher where TSP was the P source. Manipulation of P and S source has been shown to improve the efficiency of utilization of the applied fertilizers.
A glasshouse evaluation of sulfur fertilizer sources for crops and pastures. IV. Water solubility and physical losses and sulfur and phosphorus from S-coated triple superphosphates
Authors: Dana M , Lefroy RDB , Blair GJ
Published: November 2005

Coated fertilizers must retain the coating during transport and handling, but the nutrients in the coat must be released readily in the soil to meet plant demand. Three experimental fertilizers where S is adhered to TSP granules using UNE1, UNE3 or UNE2 adhesive were compared with a commercial S coated TSP, Hifert (HF) Goldphos-10. Fertilizer S loss from the granule was measured in a rotating drum friabilator. The highest particle loss was recorded with HF, and there were no significant differences recorded between UNE1, UNE2 and UNE3. Release of S from the coated fertilizers was measured by placing the fertilizers between 500 8m nylon mesh and leaching with distilled water at 20 mL min-1 for up to 96 h. In all products there was a rapid release of S in the first 24 h and a slower release thereafter. S release was fastest from UNEl and UNE3, and the amount of Ca and P released from the granule was also highest with these two products. Granules were scanned in the electron microscope, and electron microprobe both before and after leaching. Dispersion in distilled water was also recorded. The microprobe scan confirmed the leaching data with more S remaining in the granule with HF than UNEl or UNE3. These data confirm earlier studies that the method of adhesion of S to TSP can markedly alter the agronomic performance of the fertilizer.
Effect of placement and source of sulfur in flooded and non-flooded rice cropping systems
Authors: Chaitep W , Lefroy RDB , Blair GJ
Published: November 2005

Many rice-growing areas in developing countries are becoming S deficient. A glasshouse experiment was conducted to study the effect of water regimes in successive crops (nonflooded : non-flooded, flooded : flooded and flooded : non-flooded), surface (S) and deep (D) placement of sulfur fertilizer and S sources (elemental S (E) and sulfate S (S)) on the growth of rice. A soil of granitic origin was used and 35S-labelled sulfur fertilizers were used to investigate S uptake by plants and the dynamics of S in soils. Among the sulfur sources, surface-applied gypsum produced the highest total yield, which was 83.6 g pot-1 under flooded conditions. Total yields under flooded conditions were ranked in order SS > SE > DS > DE > control. In the first crop, the highest 35S recovery in the plant was 67.8% from the non-flooded SE, compared with 51.7% in the DE treatment. Deep-placed elemental S (DE) became more effective than SS and SE for the subsequent rice crop, both in terms of plant dry-matter yield and fertilizer 35S content. The highest 35S recovery in the second crop was 29.5% in the previous DE treatment in the flooded: non-flooded system. This compares with 7.5% in the SS treatment in the same cropping system.