75 research outputs found

    A Dual Isotope Protocol to Separate the Contributions to Phosphorus Content of Maize Shoots and Soil Phosphorus Fractions from Biosolids, Fertilizer and Soil

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    Separation of the phosphorus (P) contributions from soil, fertilizer and biosolids to plants has not been possible without the aid of radioisotopes. Dual labelling of soil with 32P and fertilizer with 33P isotopes has been used to partition the sources of P in maize (Zea mays) shoots and in soil P pools. Biosolids containing 4.1% P that had been prepared using Fe and Al were applied to a Kurosol soil from Goulburn, NSW, Australia. The biosolids were applied at five rates up to 60 dry t/ha with and without P fertilizer. Phosphorus derived from fertilizer was determined directly with 33P and that from soil by 32P reverse dilution. Phosphorus derived from biosolids was estimated as the difference between total P and that derived from the soil plus fertilizer calculated from isotope data. Yield and P content of maize shoots increased linearly with the rate of biosolids application. The proportion of P in the plant derived from biosolids also increased with application rate up to 88% for the soil receiving biosolids at 60 dry t/ha with no fertilizer. The corresponding value with fertilizer applied at 80 kg P/ha was 69%. The proportion of P in the maize shoots derived from soil and fertilizer decreased as biosolids application rate increased. Soil total P, bicarbonate extractable P, Al-P, Fe-P and Ca-P increased with biosolids application rate. The increase in plant P uptake and in bicarbonate extractable P in the soil shows that biosolids P provides a readily available source of P. A decrease in uptake of fertilizer and soil P with increasing biosolids application is attributed to the decrease in the proportion of P from these sources in the total pool of available P, rather than to immobilization of P by Fe and Al in the biosolids

    Preferential phosphorus placement improves the productivity and competitiveness of tropical pasture legumes

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    Extensive grazing systems often receive minimal fertiliser due to the risk associated with using relatively expensive inputs. Nevertheless, nutrient applications are known to improve pasture productivity, and the benefit of applying fertiliser is being more widely accepted. Two tropical pasture mixes (Digit/Desmanthus and Rhodes/Centro) were established in plastic boxes containing phosphorus (P) responsive soil to investigate shoot yield and P fertiliser recovery. The grasses and legumes were planted in separate rows, and three P treatments were applied along with the seed ('BOTH low-P' had 2kg P ha−1 banded below both components, 'BOTH high-P' had 12kg P ha−1 banded below both components and 'LEGUME superhigh-P' had 12kg P ha−1 banded below the legume only). The P applied below the legumes was labelled with 32P-radioisotope tracer. When P fertiliser was applied below both components, the grasses consistently out-yielded the legumes (avg. legume content=29%). Preferential fertiliser application below the legumes increased the average legume content of the two pasture mixes to 66%. Legume tissue P derived from applied P fertiliser increased from 20% to 77% as the P application rate was increased. However, total recovery of applied P by the legumes was relatively low in each of the treatments (≤7% of applied P). These collective results demonstrate that a preferential application of P fertiliser can benefit legume productivity, with applied P being a significant proportion of plant tissue P. Although only a small proportion of applied P was recovered within the seven-week growth period, it is expected that this fertiliser application at planting will remain beneficial for a large proportion of the growing season following pasture establishment

    Fusarium Crown Rot Reduces Water Use and Causes Yield Penalties in Wheat under Adequate and above Average Water Availability

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    The cereal disease Fusarium crown rot (FCR), caused by the fungal pathogen Fusarium pseudograminearum, is a worldwide major constraint to winter cereal production but especially in Australia's northern grain's region (NGR) of NSW and Queensland. Conventionally, FCR induced yield penalties are associated with semi-arid water-limited conditions during flowering and grain-filling. In this study, yield penalties associated with FCR infection were found to be significant under both adequate and above average water conditions which has implication for global wheat production in more favorable environments. This research was conducted to understand the impact of FCR on water availability, yield and grain quality in high protein bread and durum wheat varieties in controlled environment and replicated field experiments across three locations in the NGR over a two-year period. Under controlled conditions, FCR infection significantly decreased water use by 7.5% with an associated yield reduction of 9.5% irrespective of water treatment. Above average rainfall was experienced across all field experimental sites in both 2020 and 2021 growing seasons. The field studies demonstrated a decrease in water use of upwards of 23% at some sites and significant yield penalties across all cultivars of up to 18.4% in natural rainfed scenarios to still 13.2% with further supplementary irrigation

    Physical and chemical characteristics of feedlot pen substrate bedded with woodchip under wet climatic conditions

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    Wet winter conditions can create animal welfare issues in feedlots if the pen surface becomes a deep, wet, penetrable substrate. Feedlot pens with a clay and gravel base (N = 30) bedded with 150 mm (W15) and 300 mm (W30) depth of woodchips were compared to a control treatment with no bedding over a 109-day feeding period, while irrigated to supplement natural rainfall. The pad substrate was measured for variables which would affect cattle comfort and value of the substrate for composting. The penetrable depth of control pens was higher than both woodchip-bedded treatments from week 2, and increased until the end of the experiment. Meanwhile these scores were steady for W30 throughout the experiment, and increased for W15 only after week 10. Moisture content of the pad was higher throughout the experiment in the control pens than in the woodchip-bedded pens. In the control pens, the force required to pull a cattle leg analogue out of the pen substrate was three times that required in woodchip-bedded treatments. The W15 treatment increased C : N in the substrate to the upper limit of suitability for composting, and in W30, C : N was too high for composting after a 109-day feeding period. Overall, providing feedlot cattle with 150 or 300 mm of woodchip bedding during a 109-day feeding period improved the condition of the pad substrate for cattle comfort by reducing penetrable depth and moisture content of the substrate surface stratum, but composting value decreased in W30 over this feeding period duration

    Impact of Fusarium Crown Rot on Root System Area and Links to Genetic Variation within Commercial Wheat Varieties

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    Fusarium crown rot (FCR), caused by the fungal pathogen Fusarium pseudograminearum (Fp), is a major constraint to cereal production worldwide. The pathogen restricts the movement of solutes within the plant due to mycelial colonisation of vascular tissue. Yield loss and quality downgrades are exacerbated by this disease under water stress conditions. Plant root systems are adaptive and can alter their architecture to optimise production in response to changes in environment and plant health. This plasticity of root systems typically favours resource acquisition of primarily water and nutrients. This study examined the impact of FCR on the root system architecture of multiple commercial bread and durum wheat varieties. Root system growth was recorded in-crop in large transparent rhizoboxes allowing visualization of root architecture over time. Furthermore, electrical resistivity tomography was used to quantify spatial root activity vertically down the soil profile. Results demonstrated a significant reduction in the total root length and network area with the inoculation of FCR. Electrical resistivity measurements indicated that the spatial pattern of water use for each cultivar was influenced differently from infection with FCR over the growing season. Specifically temporal water use can be correlated with FCR tolerance of the varieties marking this investigation the first to link root architecture and water use as tolerance mechanisms to FCR infection. This research has implications for more targeted selection of FCR tolerance characteristics in breeding programs along with improved specific varietal management in-crop

    Aggressiveness of Phytophthora medicaginis on chickpea: Phenotyping method determines isolate ranking and host genotype-by-isolate interactions

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    Phytophthora medicaginis causing Phytophthora root rot of chickpea (Cicer arietinum) is an important disease, with genetic resistance using C. arietinum × Cicer echinospermum crosses as the main disease management strategy. We evaluated pathogenic variation in P. medicaginis populations with the aim of improving phenotyping methods for disease resistance. We addressed the question of individual isolate aggressiveness across four different seedling-based phenotyping methods conducted in glasshouses and one field-based phenotyping method. Our results revealed that a seedling media surface inoculation method used on a susceptible C. arietinum variety and a moderately resistant C. arietinum × C. echinospermum backcross detected the greatest variability in aggressiveness among 37 P. medicaginis isolates. Evaluations of different components of resistance, using our different phenotyping methods, revealed that differential pathogen–isolate reactions occur with some phenotyping methods. We found support for our hypotheses that the level of aggressiveness of P. medicaginis isolates depends on the phenotyping method, and that phenotyping methods interact with both isolate and host genotype reactions. Our cup-based root inoculation method showed promise as a non-field-based phenotyping method, as it provided significant correlations with genotype–isolate rankings in the field experiment for a number of disease parameters

    Improving quality of life through the routine use of the patient concerns inventory for head and neck cancer patients: main results of a cluster preference randomised controlled trial

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    Funding: UK National Institute for Health Research (NIHR) under its Research for Patient Benefit (RfPB) Programme (Grant Reference Number PB-PG-0215-36047).Purpose The patient concerns inventory (PCI) is a prompt list allowing head and neck cancer (HNC) patients to discuss issues that otherwise might be overlooked. This trial evaluated the effectiveness of using the PCI at routine outpatient clinics for one year after treatment on health-related QOL (HRQOL). Methods   A pragmatic cluster preference randomised control trial with 15 consultants, 8 ‘using’ and 7 ‘not using’ the PCI intervention. Patients treated with curative intent (all sites, disease stages, treatments) were eligible. Results   Consultants saw a median (inter-quartile range) 16 (13–26) patients, with 140 PCI and 148 control patients. Of the pre-specified outcomes, the 12-month results for the mean University of Washington Quality of Life (UW-QOLv4) social-emotional subscale score suggested a small clinical effect of intervention of 4.6 units (95% CI 0.2, 9.0), p = 0.04 after full adjustment for pre-stated case-mix. Results for UW-QOLv4 overall quality of life being less than good at 12 months (primary outcome) also favoured the PCI with a risk ratio of 0.83 (95% CI 0.66, 1.06) and absolute risk 4.8% (− 2.9%, 12.9%) but without achieving statistical significance. Other non-a-priori analyses, including all 12 UWQOL domains and at consultant level also suggested better HRQOL with PCI. Consultation times were unaffected and the number of items selected decreased over time. Conclusion   This novel trial supports the integration of the PCI approach into routine consultations as a simple low-cost means of benefiting HNC patients. It adds to a growing body of evidence supporting the use of patient prompt lists more generally.Publisher PDFPeer reviewe

    Improving quality of life through the routine use of the patient concerns inventory for head and neck cancer patients : baseline results in a cluster preference randomised controlled trial

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    Funding: RfPB on behalf of the NIHR (PB-PG-0215-36047). This paper presents independent research funded by the National Institute for Health Research (NIHR) under its Research for Patient Benefit (RfPB) Programme (Grant Reference Number PB-PG-0215-36047).Purpose The main aim of this paper is to present baseline demographic and clinical characteristics and HRQOL in the two groups of the Patient Concerns Inventory (PCI) trial. The baseline PCI data will also be described. Methods This is a pragmatic cluster preference randomised control trial with 15 consultant clusters from two sites either ‘using' (n = 8) or ‘not using’ (n = 7) the PCI at a clinic for all of their trial patients. The PCI is a 56-item prompt list that helps patients raise concerns that otherwise might be missed. Eligibility was head and neck cancer patients treated with curative intent (all sites, stage of disease, treatments). Results From 511 patients first identified as eligible when screening for the multi-disciplinary tumour board meetings, 288 attended a first routine outpatient baseline study clinic after completion of their treatment, median (IQR) of 103 (71–162) days. At baseline, the two trial groups were similar in demographic and clinical characteristics as well as in HRQOL measures apart from differences in tumour location, tumour staging and mode of treatment. These exceptions were cluster (consultant) related to Maxillofacial and ENT consultants seeing different types of cases. Consultation times were similar, with PCI group times taking about 1 min longer on average (95% CL for the difference between means was from − 0.7 to + 2.2 min). Conclusion Using the PCI in routine post-treatment head and neck cancer clinics do not elongate consultations. Recruitment has finished but 12-month follow-up is still ongoing.Publisher PDFPeer reviewe

    Differences in phosphorus acquisition and critical phosphorus requirements among nine Desmanthus spp. genotypes

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    The extensive grazing systems of northern Australia are dominated by C4 grasses and are established in N- and P-responsive soils that receive minimal nutrient input. Under these conditions, tropical pasture legumes are expected to improve the quality of grazing forage and fix atmospheric N2. However, legume persistence is relatively poor, which may be due to a presumed disparity in P requirements among tropical pasture species. This disparity suggests that P-efficient legumes may improve legume persistence, yet the P requirements of many tropical pasture legumes remain unquantified. Nine Desmanthus spp. genotypes were grown in pots to determine differences in shoot yield and root morphology in response to soil P supply (0-100 mg applied P kg-1 soil; 5-63 mg Colwell P kg-1 soil). The shoot yield of each genotype increased in response to increased P supply. When P supply was adequate for maximum plant growth, the shoot yield of the best genotype (3.5 g DM pot-1; JCU 9) was 1.7-fold larger than that of the next most productive genotype. There were also substantial differences in the critical external P requirements of the genotypes (29.4-64.0 mg P kg-1 soil), although these differences did not always reflect the efficiency of dry matter production per unit of applied P fertiliser. Differences in shoot yield and P acquisition were positively associated with differences in the development of root length. The results indicated that P-efficient genotypes of Desmanthus spp. can be identified for improved growth in the P-responsive pastures of northern Australia. These genotypes may compete more effectively with C4 grasses and form resilient pasture swards as climate patterns change
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