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1
Pate, J. S., W. H. Verboom e P. D. Galloway. "Co-occurrence of Proteaceae, laterite and related oligotrophic soils: coincidental associations or causative inter-relationships?" Australian Journal of Botany 49, n. 5 (2001): 529. http://dx.doi.org/10.1071/bt00086.
Testo completoAbstract (sommario):
This communication presents the hypothesis that certain Australian lateritic and related oligotrophic soils may have been partly derived biotically from soluble iron-rich complexes generated following secretion of low-molecular weight organic acids by phosphate-absorbing specialised proteoid (cluster) roots of proteaceous plants. Subsequent precipitation of the iron is then pictured as occurring onto the oxide rinds of developing laterite after consumption of the organic components of the complexes by soil bacteria. The hypothesis is f irst examined in relation to current theories of origins of laterites and the extent of the coincidences worldwide in past and present times between Proteaceae and oligotrophic soil types of lateritic character. The paper then provides more definitive lines of evidence supporting the hypothesis, based largely on recent studies by the authors in south-western Western Australia. This relates to (a) cases of definitive association in habitats rich in Proteaceae between zones of root proliferation and ferricrete layers in lateritic soils, (b) proximity in soil profiles between ferric deposits and current and ancestral root channels, (c) the recovery of citrate-consuming bacteria from soil profiles and specifically from ferricrete rinds and horizons accumulating sesquioxide organic matter and (d) distribution of iron and phosphorus within plant and soil profile components consistent with ferricrete rinds being generated by rhizosphere-mediated interactions of plants and microbes under conditions of severely limited availability of phosphorus. The mode of functioning of proteoid root clusters is then discussed, especially in relation to exudation of organic acid anions, uptake of phosphorus and the subsequent fate of organic anions and their metal ion complexes in the system. An empirically based scheme is presented indicating flow profiles for phosphorus and iron between soil, ferricrete rinds and bacterial and plant components. We then discuss possible carbon costs to proteaceous plant partners when accessing phosphorus under the nutrient-impoverished conditions typical of heathlands and open woodlands of Mediterranean-type ecosystems of Western Australia. The paper concludes with a critical overview of the hypothesis, particularly its implications regarding possible higher plant: microbial influences shaping soil and landscape evolution in the regions involved.
2
Wong, M. T. F., e R. J. Harper. "Use of on-ground gamma-ray spectrometry to measure plant-available potassium and other topsoil attributes". Soil Research 37, n. 2 (1999): 267. http://dx.doi.org/10.1071/s98038.
Testo completoAbstract (sommario):
The incidence of potassium (K) deficiency is increasing in crops, pastures, and forestry in south-western Australia. Although soil K can be measured using soil sampling and analysis, γ-ray spectrometry offers a potentially cheaper and spatially more precise alternative. This could be particularly useful in precision agriculture, where inputs are applied according to need rather than by general prescription. In a study of topsoils near Jerramungup, Western Australia, strong relationships (r2 = 0·9) were found between on-ground counts of γ-rays derived from 40K (γ-K) and both total K and plant-available K. The success of γ-ray spectrometry in predicting available K relied on a strong relationship (r2 = 0·9) between total K and available K which may not hold in all areas. Although the relationship between γ-K and available K held over the range of 36–1012 mg/kg, crop response to K fertilisers is only expected when the available K content is <100 mg/kg. Estimates of available K from γ-K were unreliable at this lower end of the regression curve. Separate analysis with a subset of the data with available K <100 mg/kg showed a poor relationship between γ-K and available K (r2 = 0·05; d.f. 11). The usefulness of γ-ray spectrometry may therefore be restricted to defining areas where response to fertiliser K may occur, and where further soil sampling and analysis are required to predict the fertiliser requirement. Strong relationships (r2 = 0·9) were also found between γ-K and a range of other soil attributes, including clay, silt, and organic carbon content. These relationships depended on the locally strong relationship between total K and these soil attributes. Since such relationships do not hold everywhere, the utility of γ-ray spectrometry will likewise be limited. Site-specific calibrations are required if γ-ray spectrometry is to be used for soil property mapping.
3
Wong, M. T. F., R. J. Corner e S. E. Cook. "A decision support system for mapping the site-specific potassium requirement of wheat in the field". Australian Journal of Experimental Agriculture 41, n. 5 (2001): 655. http://dx.doi.org/10.1071/ea00191.
Testo completoAbstract (sommario):
The intensely weathered nature of Western Australian cropping soils and the long history of potassium depletion by the farming system has resulted in increased incidence of potassium deficiency in wheat. There is currently no scientifically based method for potassium recommendation in Western Australia. This paper describes the use of site-specific plot-scale field trials carried out in 1995–98 and a crop response model to develop a generally applicable potassium recommendation system. Geographic information system technology was used to extend the uniform potassium recommendation system into a system for mapping spatially variable potassium requirement that takes account of crop demand and soil available potassium. The field trials were carried out on a range of soil types and showed that wheat response to potassium can be described by the Mitscherlich equation. The size of the response was dependent on the soil test value for plant available potassium and the yield of the crop. The latter is mainly dependent on rainfall in the water-limited Mediterranean environment of Western Australia. The relationships between the maximum achievable yield, crop response and soil available potassium values were quantified in order to allow the decision support system to be developed for uniform whole-paddock fertiliser recommendation. Both soil available potassium and yield are very spatially variable in Western Australia and for wheat, the coefficient of variation of yield within the paddock is often of the order of 30%. Soil property variation can be of a similar order. Maps of soil available potassium values and of spatially variable target yield determined either from (i) farmer’s estimate, (ii) yield monitors and (iii) remotely sensed normalised difference vegetation index measurements allow this decision system to map spatially variable potassium requirement. Comparison of the map of potassium requirement with measured spatially variable response to potassium showed that the decision support system performed satisfactorily.
4
Samadi, Abbas, e R. J. Gilkes. "Phosphorus Transformations and Their Relationships with Calcareous Soil Properties of Southern Western Australia". Soil Science Society of America Journal 63, n. 4 (luglio 1999): 809–15. http://dx.doi.org/10.2136/sssaj1999.634809x.
Testo completo
5
Wong, M. T. F., R. W. Bell e K. Frost. "Mapping boron deficiency risk in soils of south-west Western Australia using a weight of evidence model". Soil Research 43, n. 7 (2005): 811. http://dx.doi.org/10.1071/sr05022.
Testo completoAbstract (sommario):
The aim of this work was to develop a risk map for boron (B) deficiency in the grain cropping regions of Western Australia (WA), whilst avoiding the high costs associated with direct B measurements for an area as vast as the south-west of WA. The study firstly determined relationships between 0.01 m CaCl2-extractable soil B levels and readily available data on soil properties and parent materials for Reference Soils of south-west Australia and secondly assembled direct evidence of B deficiency risk from surveys of farmers’ crops and soils and from glasshouse experiments. Across 73 Reference Soils, there was a positive relationship between 0.01 m CaCl2-extractable soil B levels and clay (r 2 = 0.50) and pH (r 2 = 0.43) in the surface horizon. Soils containing <0.5 mg B/kg generally had <5% clay and pH CaCl2 <5.5. Plant and soil analysis surveys in farmers’ fields revealed 10–20% of fields had B levels below tentative critical levels. In a glasshouse experiment, B response in oilseed rape was obtained in 4 sandy acid soils, all developed on sandstone parent materials. From this prior evidence of B deficiency, spatial data layers for surface soil pH, subsurface pH, surface clay level, and geology in south-western Australia were weighted and combined using the Dempster-Shafer weight of evidence model to map B-deficiency risk. The weightings of evidence layers were revised to increase the correspondence between predicted areas of high risk and field areas with measured low B or B deficiency from a validation dataset. The model helps overcome the high cost associated with direct B measurements for risk mapping. A similar approach may have value for mapping risk of other deficiencies of relevance to agriculture.
6
Bolland, MDA, IR Wilson e DG Allen. "Effect of P-buffer capacity and P-retention index of soils on soil test-P, soil test P-calibrations and yield response curvature". Soil Research 32, n. 3 (1994): 503. http://dx.doi.org/10.1071/sr9940503.
Testo completoAbstract (sommario):
Twenty-three virgin Western Australian soils of different buffer capacities (BC) for phosphorus (P) were collected. The effects of BC on the relationships between Colwell soil test P and the level of P applied, yield and soil test P, and yield and the level of P applied were studied. Wheat (Triticum aestivum cv. Reeves), grown for 27 days in a glasshouse, was used. Two methods of measuring P sorption of soils, P buffer capacity (PBC) and P retention index (PRI), were used. The PBC is determined from a multi-point sorption curve. The PRI is a new, diagnostic, one-point, sorption method now widely used for commercial soil P testing in Western Australia. Both PBC and PRI produced similar results. The relationship between soil test P and the level of P applied was adequately described by a linear equation. When the slope coefficient of the linear equations was related to PBC or PRI, there was no relationship. The other two relationships were adequately described by a Mitscherlich equation. When the curvature coefficient of the Mitscherlich equation was related to PBC or PRI, the trend was for the value of the coefficient to decrease with increasing PBC or PRI. Consequently, as the capacity of the soil to sorb P increased the trend was for larger soil test P or higher levels of P application to produce the same yield.
7
Taylor, Miranda J., Keith Smettem, Gabriella Pracilio e William Verboom. "Relationships Between Soil Properties and High-Resolution Radiometrics, Central Eastern Wheatbelt, Western Australia". Exploration Geophysics 33, n. 2 (giugno 2002): 95–102. http://dx.doi.org/10.1071/eg02095.
Testo completo
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Anderson, Geoffrey, e Richard Bell. "Wheat grain-yield response to lime application: relationships with soil pH and aluminium in Western Australia". Crop and Pasture Science 70, n. 4 (2019): 295. http://dx.doi.org/10.1071/cp19033.
Testo completoAbstract (sommario):
Soil acidity, or more specifically aluminium (Al) toxicity, is a major soil limitation to growing wheat (Triticum aestivum L.) in the south of Western Australia (SWA). Application of calcium carbonate (lime) is used to correct Al toxicity by increasing soil pH and decreasing soluble soil Al3+. Soil testing using a 0.01 m calcium chloride (CaCl2) solution can measure both soil pH (pHCaCl2) and soil Al (AlCaCl2) for recommending rates of lime application. This study aimed to determine which combination of soil pHCaCl2 or soil AlCaCl2 and sampling depth best explains the wheat grain-yield increase (response) when lime is applied. A database of 31 historical lime experiments was compiled with wheat as the indicator crop. Wheat response to lime application was presented as relative yield percentage (grain yield for the no-lime treatment divided by the highest grain yield achieved for lime treatments × 100). Soil sampling depths were 0–10, 10–20 and 20–30 cm and various combinations of these depths. For evidence that lime application had altered soil pHCaCl2, we selected the change in the lowest pHCaCl2 value of the three soil layers to a depth of 30 cm as a result of the highest lime application (ΔpHmin). When ΔpHmin <0.3, the lack of grain-yield response to lime suggested that insufficient lime had leached into the 10–30 cm soil layer to remove the soil Al limitation for these observations. Also, under high fallow-season rainfall (228 and 320 mm) and low growing-season rainfall (GSR) (<140 mm), relative yield was lower for the measured level of soil AlCaCl2 than in the other observations. Hence, after excluding observations with ΔpHmin <0.3 or GSR <140 mm (n = 19), soil AlCaCl2 provided a better definition of the relationship between soil test and wheat response (r2 range 0.48–0.74) than did soil pHCaCl2 (highest r2 0.38). The critical value (defined at relative yield = 90%) ranged from 2.5 mg Al kg–1 (for soil Al calculated according to root distribution by depth within the 0–30 cm layer) to 4.5 mg Al kg–1 (calculated from the highest AlCaCl2 value from the three soil layers to 30 cm depth). We conclude that 0.01 m CaCl2 extractable Al in the 0–30 cm layer will give the more accurate definition of the relationship between soil test and wheat response in SWA.
9
Coates, Fiona, e J. B. Kirkpatrick. "Is Geographic Range Correlated with Climatic Range in Australian Spyridium Taxa?" Australian Journal of Botany 47, n. 5 (1999): 755. http://dx.doi.org/10.1071/bt97066.
Testo completoAbstract (sommario):
The major centres of local endemism and richness at the species level and below in Spyridium Fenzl are located on the southern coast of Western Australia and in south-eastern South Australia. There are only a few Spyridium taxa with ranges that transgress the boundaries of the following four regions: south- western Western Australia; south-eastern South Australia and western Victoria; eastern Victoria, New South Wales and southern Queensland; Tasmania. Synthetic climatic variables were generated for all recorded populations of Spyridium taxa. Variabilities in these were related to the maximum geographic ranges of taxa in Australia as a whole, and within the regions, in order to test the hypothesis that narrow endemism is explained by climatic restriction since the last glacial. In Australia as a whole, local endemics are both narrowly and widely distributed climatically, as are more widespread Spyridiumtaxa, and there were no significant relationships between the climatic and geographic ranges of taxa confined to the Australian mainland regions. However, Tasmanian taxa exhibited a strong positive relationship. Restriction of range as a result of climate change is an unlikely explanation for local endemism in Spyridium in mainland Australia, where topographic and climatic gradients are generally subdued, and which apparently experienced less severe climatic oscillations during the Quaternary. However, this hypothesis cannot be rejected for Tasmania, which experienced more extreme Quaternary climatic fluctuations than the present-day areas of mediterranean climate, and hence more severe fluctuations in the area and location of climatically suitable habitats.
10
O'Rourke, Tiernan A., Tim T. Scanlon, Megan H. Ryan, Len J. Wade, Alan C. McKay, Ian T. Riley, Hua Li, Krishnapillai Sivasithamparam e Martin J. Barbetti. "Severity of root rot in mature subterranean clover and associated fungal pathogens in the wheatbelt of Western Australia". Crop and Pasture Science 60, n. 1 (2009): 43. http://dx.doi.org/10.1071/cp08187.
Testo completoAbstract (sommario):
Pasture decline is considered to be a serious challenge to agricultural productivity of subterranean clover across southern Australia. Root disease is a significant contributing factor to pasture decline. However, root disease assessments are generally carried out in the early part of the growing season and in areas predominantly sown to permanent pastures. For this reason, in spring 2004, a survey was undertaken to determine the severity of root disease in mature subterranean clover plants in pastures located in the wheatbelt of Western Australia. DNA-based soil assays were used to estimate population density in the soil of a variety of soil-borne pathogens known to commonly occur in the Mediterranean-type environments of southern Australia. The relationships between severity of disease on tap and lateral roots and root diameter, root length, nodulation, and total rainfall were determined. The survey showed, for the first time, that severe root disease is widespread in spring across the wheatbelt of Western Australia. There was a positive correlation between rainfall and tap root disease, and between tap root disease and average root diameter of the entire root system. Despite the high levels of root disease present across the sites, the DNA of most root disease pathogens assayed was detected in trace concentrations. Only Pythium Clade F showed high DNA concentrations in the soil. DNA concentrations in the soil, in particular for Phytophthora clandestina and Rhizoctonia solani AG 2.1 and AG 2.2, were higher in the smaller autumn sampling in 2006. This study suggests that the productivity of subterranean clover-based pastures is severely compromised by root rot diseases throughout the growing season in the wheatbelt of Western Australia.
11
Bolland, M. D. A., D. G. Allen e K. S. Walton. "Soil testing for phosphorus: comparing the Mehlich 3 and Colwell procedures for soils of south-western Australia". Soil Research 41, n. 6 (2003): 1185. http://dx.doi.org/10.1071/sr02153.
Testo completoAbstract (sommario):
Soil samples were collected from 14 long-term field experiments in south-western Australia to which several amounts of superphosphate or phosphate rock had been applied in a previous year. The samples were analysed for phosphorus (P) by the Colwell sodium bicarbonate procedure, presently used in Western Australia, and the Mehlich 3 procedure, being assessed as a new multi-element test for the region. For the Mehlich procedure, the concentration of total and inorganic P in the extract solution was measured. The soil test values were related to yields of crops and pasture measured later on in the year in which the soil samples were collected.The Mehlich 3 procedures (Mehlich 3 total and Mehlich 3 inorganic soil test P values) were similar, with the total values mostly being slightly larger. For soil treated with superphosphate, for each year of each experiment: (i) Mehlich 3 values were closely correlated with Colwell values; and (ii) the relationship between plant yield and soil test P (the soil P test calibration) was similar for the Colwell and Mehlich 3 procedures. However, for soil treated with phosphate rock, the Colwell procedure consistently produced lower soil test P values than the Mehlich 3 procedure, and the calibration relating plant yield to soil test P was different for the Colwell and Mehlich 3 procedures, indicating, for soils treated with phosphate rock, separate calibrations are required for the 2 procedures. We conclude that for soils of south-western Australia treated with superphosphate (most of the soils), the Mehlich 3 procedure can be used instead of the Colwell procedure to measure soil test P, providing support for the Mehlich 3 procedure to be developed as the multi-element soil test for the region.
12
Bell, Michael J., Wayne Strong, Denis Elliott e Charlie Walker. "Soil nitrogen—crop response calibration relationships and criteria for winter cereal crops grown in Australia". Crop and Pasture Science 64, n. 5 (2013): 442. http://dx.doi.org/10.1071/cp12431.
Testo completoAbstract (sommario):
More than 1200 wheat and 120 barley experiments conducted in Australia to examine yield responses to applied nitrogen (N) fertiliser are contained in a national database of field crops nutrient research (BFDC National Database). The yield responses are accompanied by various pre-plant soil test data to quantify plant-available N and other indicators of soil fertility status or mineralisable N. A web application (BFDC Interrogator), developed to access the database, enables construction of calibrations between relative crop yield ((Y0/Ymax) × 100) and N soil test value. In this paper we report the critical soil test values for 90% RY (CV90) and the associated critical ranges (CR90, defined as the 70% confidence interval around that CV90) derived from analysis of various subsets of these winter cereal experiments. Experimental programs were conducted throughout Australia’s main grain-production regions in different eras, starting from the 1960s in Queensland through to Victoria during 2000s. Improved management practices adopted during the period were reflected in increasing potential yields with research era, increasing from an average Ymax of 2.2 t/ha in Queensland in the 1960s and 1970s, to 3.4 t/ha in South Australia (SA) in the 1980s, to 4.3 t/ha in New South Wales (NSW) in the 1990s, and 4.2 t/ha in Victoria in the 2000s. Various sampling depths (0.1–1.2 m) and methods of quantifying available N (nitrate-N or mineral-N) from pre-planting soil samples were used and provided useful guides to the need for supplementary N. The most regionally consistent relationships were established using nitrate-N (kg/ha) in the top 0.6 m of the soil profile, with regional and seasonal variation in CV90 largely accounted for through impacts on experimental Ymax. The CV90 for nitrate-N within the top 0.6 m of the soil profile for wheat crops increased from 36 to 110 kg nitrate-N/ha as Ymax increased over the range 1 to >5 t/ha. Apparent variation in CV90 with seasonal moisture availability was entirely consistent with impacts on experimental Ymax. Further analyses of wheat trials with available grain protein (~45% of all experiments) established that grain yield and not grain N content was the major driver of crop N demand and CV90. Subsets of data explored the impact of crop management practices such as crop rotation or fallow length on both pre-planting profile mineral-N and CV90. Analyses showed that while management practices influenced profile mineral-N at planting and the likelihood and size of yield response to applied N fertiliser, they had no significant impact on CV90. A level of risk is involved with the use of pre-plant testing to determine the need for supplementary N application in all Australian dryland systems. In southern and western regions, where crop performance is based almost entirely on in-crop rainfall, this risk is offset by the management opportunity to split N applications during crop growth in response to changing crop yield potential. In northern cropping systems, where stored soil moisture at sowing is indicative of minimum yield potential, erratic winter rainfall increases uncertainty about actual yield potential as well as reducing the opportunity for effective in-season applications.
13
Barrett-Lennard, Edward G., Geoffrey C. Anderson, Karen W. Holmes e Aidan Sinnott. "High soil sodicity and alkalinity cause transient salinity in south-western Australia". Soil Research 54, n. 4 (2016): 407. http://dx.doi.org/10.1071/sr15052.
Testo completoAbstract (sommario):
Transient salinity associated with increased dispersion of clays is arguably one of the most economically important soil constraints in Australia because it occurs on land that is regularly cropped. However, this issue is rarely studied. This paper examines the occurrence of transient salinity on agricultural land in the south-west of Western Australia and the factors causing it. We analysed four soil datasets from the region, collected at scales varying from the entire south-west to a single paddock. A variety of soil parameters were correlated with increased electrical conductivity (EC1:5). The most significant relationships were invariably with measures of exchangeable sodium (Na+; 53–85% of variance accounted for), and this factor appears to be most responsible for transient salinity. Another parameter correlated with increased EC1:5 was alkalinity. This has been associated with the increased dispersion of kaolinite and consequent decreases in soil hydraulic conductivity; kaolinite is the most common clay mineral in the south-west of Western Australia. Other factors correlated with increased EC1:5 were increasing clay, increasing depth in the soil profile and decreasing rainfall. These factors are environmental indicators of transient salinity. Affected soils might be ameliorated by application of agents to increase soil hydraulic conductivity, such as gypsum and/or elemental sulfur.
14
Kew, G. A., R. J. Gilkes e D. Evans. "Relationships between fabric, water retention, and strength of hard subsoils in the south of Western Australia". Soil Research 48, n. 2 (2010): 167. http://dx.doi.org/10.1071/sr09080.
Testo completoAbstract (sommario):
Crop yield in the sandy soils of the Western Australian wheatbelt is influenced strongly by the plant-available water (PAW) and strength of subsoils. The fabric of hard subsoils of fluvial and aeolian origin has been compared with that of in situ saprolite materials that also occur as subsoils in Western Australia. A fabric classification was developed and relationships between, fabric, water retention, and strength were examined. The clay matrix of hard subsoils is denser and is less porous than in saprolite. Hard subsoils contain rounded quartz grains and transported, rounded aggregates of clay (spherites), while saprolite contains angular quartz grains in a more porous isotropic kaolin clay matrix developed by in situ weathering. At all matric potentials there were large differences in water retention between hard subsoils and saprolite. The dry and wet strengths of subsoils are lower than for saprolite but the strength of both materials is similarly affected by changes in water content and matric potential. A variety of factors including the size, shape, degree of sorting of quartz grains, distribution of dense clay matrix, and cementing by iron oxides or amorphous silica affect the strength of subsoils. The fabric classification is predictive of water retention and strength.
15
MACFARLANE, TERRY D., GALINA V. DEGTJAREVA, TAHIR H. SAMIGULLIN, CARMEN M. VALIEJO-ROMAN, CONSTANTIN I. FOMICHEV e DMITRY D. SOKOLOFF. "Althenia tzvelevii (Potamogetonaceae), a new species from SW Western Australia with bilocular anthers: morphology and molecular phylogenetic relationships". Phytotaxa 471, n. 3 (17 novembre 2020): 193–207. http://dx.doi.org/10.11646/phytotaxa.471.3.2.
Testo completoAbstract (sommario):
A new species Althenia tzvelevii is described from south western Australia. This is the second species after A. bilocularis described with bilocular anthers. Illustrations of plant morphology are provided by means of SEM images and habitat photographs are included. The phylogenetic relationships of the new species were investigated using five plastid DNA markers (matK, ndhF, rbcL, rpoB, and rpoC1), with published sequences augmented by several new sequences resulting in coverage of all described species in the genus. Althenia tzvelevii forms a clade with A. patentifolia and A. bilocularis and other relationships within the genus are clarified. The Western Australian Althenia hearnii is strongly supported as sister to the Eurasian-African clade composed by A. filiformis and A. orientalis.
16
Verboom, W. H., e J. S. Pate. "Relationships between cluster root-bearing taxa and laterite across landscapes in southwest Western Australia: an approach using airborne radiometric and digital elevation models". Plant and Soil 248, n. 1/2 (gennaio 2003): 321–33. http://dx.doi.org/10.1023/a:1022358014629.
Testo completo
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Tindale, MD, e LA Craven. "Three new species of Glycine (Fabaceae: Phaseolae) from north-western Australia, with notes on amphicarpy in the genus". Australian Systematic Botany 1, n. 4 (1988): 399. http://dx.doi.org/10.1071/sb9880399.
Testo completoAbstract (sommario):
Three new species of Glycine Willd., viz. G. albicans, G. Lactovirens and G. hirticaulis from north-western Australia are described and illustrated. Their putative relationships are presented. A key is provided to the species of Glycine in north-western Australia. Two forms of amphicarpy occur within the genus Glycine.
18
McKissock, I., R. J. Gilkes, R. J. Harper e D. J. Carter. "Relationships of water repellency to soil properties for different spatial scales of study". Soil Research 36, n. 3 (1998): 495. http://dx.doi.org/10.1071/s97071.
Testo completoAbstract (sommario):
In order to predict the occurrence of water repellency, which is a labile property, from field survey data obtained throughout the year, it is necessary to identify predictive relationships between water repellency and commonly measured soil properties. This paper evaluates these relationships for diverse soil assemblages. These soil assemblages include a set of reference soils from the south-west of Western Australia (an area of 250 000 km2), more intensively sampled suites of soils in several smaller soil{landscape associations within the south-west of Western Australia (≅1000 km2), soils from single farms (1-10 km2) and transects (≅0·001 km2), and single soil profiles (≅m2). The severity of water repellency was assessed by measuring water drop penetration time in seconds (WDPT) and was related to intrinsic properties of soils using log-transformed data. For the set of soils from the West Midland Sandplain the type of land use was also considered as a variable. There is a general tendency for WDPT to increase as organic matter content increases and decrease as the content of fine mineral material increases (clay, silt, very fine sand). However, there is no single soil property that is able to predict WDPT adequately. Furthermore, reliability of prediction decreases as the area of sampling increases. There appear to be no systematic differences in the capacity of organic matter from pasture or crop to induce water repellency, but increments of organic matter under bush increase water repellency at a greater rate than does organic matter from crop or pasture.
19
Stephens, D. J., e T. J. Lyons. "Rainfall-yield relationships across the Australian wheatbelt". Australian Journal of Agricultural Research 49, n. 2 (1998): 211. http://dx.doi.org/10.1071/a96139.
Testo completoAbstract (sommario):
A network of rainfall stations was selected across the Australian wheatbelt and monthly rainfall regressed with wheat yields from the surrounding shires for the period 1976-87. Yields were found to be strongly related to fluctuations in total rainfall amount and the seasonal distribution of rainfall through the year. These temporal relationships vary spatially and appear to be regulated by the water-holding capacity of regional soils. Sixteen agrometeorological zones were defined with similar rainfall-yield relationships. In all these, autumn rains that permit an early sowing, and finishing rains after July, are most important for higher yields. As the rainfall distribution becomes more winter-dominant, both crop yield variability and the usefulness of high winter rainfall decreases. Heavy rainfall in the month after sowing can have a negative effect in southern Australia, as plants are more prone to suffer potential yield losses from a wet soil profile. Waterlogging has a large negative effect in the south-west of Western Australia, such that the rainfall distribution can be more important than the rainfall amount. Rainfall-yield correlations are generally more positive in drier regions, and are enhanced by persistent rainfall anomalies between April and November during El Niño Southern Oscillation years.
20
Perrie, Leon R., Daniel J. Ohlsen, Lara D. Shepherd, Michael Garrett, Patrick J. Brownsey e Michael J. Bayly. "Tasmanian and Victorian populations of the fern Asplenium hookerianum result from independent dispersals from New Zealand". Australian Systematic Botany 23, n. 6 (2010): 387. http://dx.doi.org/10.1071/sb10028.
Testo completoAbstract (sommario):
The fern Asplenium hookerianum Colenso (Aspleniaceae) is indigenous to New Zealand and Australia. In New Zealand, it is widespread and genetically diverse, with 26 haplotypes previously identified for the chloroplast trnL–trnF locus. In Australia, A. hookerianum is currently known only from two small populations in Victoria and two in Tasmania. The present study assessed the diversity, relationships and biogeographic history of the Australian populations. A single trnL–trnF haplotype was identified in Tasmanian populations, and it was shared with populations in south-western New Zealand. The single haplotype found in Victorian populations was unique and most similar to a haplotype found in populations from central and eastern North Island, New Zealand. Relationships among haplotypes suggest that the two Australian haplotypes are derived within the group (not close to the root of the haplotype network) and only distantly related. This pattern is consistent with two independent dispersals of A. hookerianum from New Zealand to Australia. These findings are unique in providing evidence for more than one trans-Tasman dispersal event in a species of vascular plant.
21
Itzstein-Davey, Freea. "The representation of Proteaceae in modern pollen rain in species-rich vegetation communities in south-western Australia". Australian Journal of Botany 51, n. 2 (2003): 135. http://dx.doi.org/10.1071/bt02048.
Testo completoAbstract (sommario):
The Proteaceae family is a large Gondwanan plant family with a major centre of richness in south-western Australia. Modern pollen–vegetation relationships in the two areas of species richness in the northern and southern sandplains of south-western Australia were investigated to calibrate fossil-pollen studies concurrently conducted on Eocene, Pliocene and Quaternary sediment. Results indicated that the Proteaceae component in modern pollen rain can be quite high, contributing up to 50% of the count. Some sites showed a dominant type (such as Banksia–Dryandra), whilst others had up to six different genera represented. Exactly how and when the biodiversity of Proteaceae in south-western Australia developed is unknown. This work provides a benchmark for comparisons with studied fossil material to unravel patterns of diversity of this family in south-western Australia.
22
Bell, DT, S. Vlahos e LE Watson. "Stimulation of Seed-Germination of Understorey Species of the Northern Jarrah Forest of Western-Australia". Australian Journal of Botany 35, n. 5 (1987): 593. http://dx.doi.org/10.1071/bt9870593.
Testo completoAbstract (sommario):
Glasshouse trials in trays of soil measured the germination response to high temperatures and the presence of charcoal in 40 non-leguminous understorey species of the northern jarrah (Eucalyptus marginata Donn ex Smith) forest. Species producing relatively low proportions of viable and germinable seeds tended to be the long-lived resprouting species where reproductive output may not be of major adaptive significance. Three species, Conostylis setosa, Trymalium ledifolium and T. spathulaturn, with seed stored in the soil, were stimulated to germinate by high temperatures. Bradysporous, obligate reseeding species showed either no temperature effect (mainly species of Dryandra) or death at high temperatures (species of Hakea, whose seeds normally are protected by woody fruits). Charred wood of Eucalyptus marginata induced an increase in the proportion of Burchardia umbellata germinating under the test conditions. Relationships of the seed germination results to aspects of r- and K- selection theory and fire management policy in the northern jarrah forest are also discussed.
23
Bolland, M. D. A., e R. J. Gilkes. "The systematic effect of soil P buffer capacity on Colwell soil P test v. plant response calibration exists only when field experiments are adjacent". Soil Research 42, n. 7 (2004): 763. http://dx.doi.org/10.1071/sr04022.
Testo completoAbstract (sommario):
Thirteen field experiments distributed throughout south-western Australia examined the relationship between percentage of maximum grain yield of wheat (Triticum aestivum L. cv. Aroona) and Colwell soil phosphorus (P) values. These calibration data were fitted to a linear equation, and the slope values for the 13 sites were compared with the P buffer capacity (PBC) of the soils. There was no systematic relationship between these variables except for 3 adjacent sites at Badgingarra and for 3 adjacent sites at Newdegate. We conclude that differences in climate and site conditions have a greater effect than PBC on Colwell soil P test calibration when widely separated sites are compared.
24
Garkaklis, Mark J., J. S. Bradley e R. D. Wooller. "The relationship between animal foraging and nutrient patchiness in south-west Australian woodland soils". Soil Research 41, n. 4 (2003): 665. http://dx.doi.org/10.1071/sr02109.
Testo completoAbstract (sommario):
The woylie (Bettongia penicillata) was once common and abundant over the southern third of the Australian continent. Since European settlement the range of this rat-kangaroo has become reduced by more than 97%, and until the early 1990s, only 3 small natural populations remained, all in south-western Australia. These medium-sized (c. 1 kg) marsupials create a large number of diggings as they forage for the hypogeous fruiting bodies of ectomycorrhizal fungi upon which they feed. The effect of such foraging activity on the availability of plant nutrients in the vicinity of such diggings was evaluated in simulated digging experiments. Available nitrate, ammonium, and sulfur decreased significantly 3 years after diggings were constructed and had filled in, whereas phosphorus, potassium, iron, and organic carbon remained unchanged. The results suggest that preferential water infiltration via woylie diggings leads to a decrease in those soil nutrients that are susceptible to leaching and indicates that digging vertebrates may influence the distribution of surface soil nutrients.
25
Snowball, R., e AD Robson. "Relationship Between Soil Properties and the Growth of Legumes on Acid Wodjil Soils in Western Australia". Australian Journal of Botany 33, n. 3 (1985): 299. http://dx.doi.org/10.1071/bt9850299.
Testo completoAbstract (sommario):
The relationship between vegetation and soil properties in part of the eastern wheatbelt of Western Australia was investigated. Soil in the Burracoppin Reserve supporting wodjil vegetation (Acacia beauverdiana, A. signata and Allocasuarina corniculata) had a very low pH in the 4.3-5.0 cm surface soil layer, a very low level of mineralizable N and a low chloride content compared to soils supporting Eucalyptus spp. All soils were low in exchangeable potassium and bicarbonate-extractable phosphorus. Acacia signata and Trifolium subterraneum were grown on a soil from Merredin supporting wodjil vegetation. Neither species responded markedly to lime when grown on the surface soil (0-5 cm). However, growth of both species on the subsoil (30-40 cm) was enhanced with the addition of lime. Increased growth of A. signata was probably associated with the alleviation of manganese toxicity which had been induced in this experiment. By contrast, increased growth of T. subterraneum was probably associated with the alleviation of aluminium toxicity.
26
Gerritse, RG. "Effect of reaction-rate on leaching of phosphate through sandy soils of Western-Australia". Soil Research 33, n. 1 (1995): 211. http://dx.doi.org/10.1071/sr9950211.
Testo completoAbstract (sommario):
The effect of reaction rate on the mobility of phosphate in soils was measured from breakthrough curves in the leachate from small columns of soil, following step increases in the input concentration of phosphate. Average mobilities of phosphate in columns of soil, following a step increase in the input concentration, decrease with decreasing rate of flow and with increasing distance travelled and appear to be linearly correlated on a log-log scale with both flow rate and distance travelled. An empirical equation, describing these relationships, fits data from leaching experiments at flow rates between 30 and 600 cm/day in columns of soil ~10-30 cm in length. Two coefficients are required and are obtained by curve fitting breakthrough curves, calculated with a numerical computer simulation model, to experimental breakthrough curves. The fitted equation enables extrapolation to flow rates and distances travelled that are more relevant to a field situation.
27
Bolland, M. D. A., e D. P. Windsor. "Converting reactive iron, reactive aluminium, and phosphorus retention index (PRI) to the phosphorus buffering index (PBI) for sandy soils of south-western Australia". Soil Research 45, n. 4 (2007): 262. http://dx.doi.org/10.1071/sr07026.
Testo completoAbstract (sommario):
The recently developed phosphorus (P) buffering index (PBI) is now the national single-point P sorption index to rank the capacity of soil to sorb P. However, before PBI was developed, P sorption was routinely measured by 2 simple procedures in Western Australia: (i) since the mid 1970s, reactive iron (Fe), which is the concentration of Fe extracted from soil by ammonium oxalate; and (ii) since the mid 1980s, the P retention index (PRI), a single-point P sorption index. Both reactive Fe and aluminium (Al) extracted from soil by ammonium oxalalate (reactive Al) have been measured in experiments conducted in Western Australia. Because PBI is now routinely measured in Western Australia there is the need to convert historical reactive Fe, reactive Al, and PRI values to PBI values. In this study we used soil samples collected from 2 field studies and a study of 96 paddocks, all on sandy soil types common in the region, to measure PBI, reactive Fe, reactive Al (not measured in the paddock study), and PRI. We related PBI (dimensionless), as the dependent (y-axis), to reactive Fe (mg/kg), reactive Al (mg/kg), or PRI (mL/g), as the independent (x-axis). The relationships for all data were good for reactive Al (47 data points from the 2 field studies) and PRI (133 data points for the 2 field studies and the paddock study): --> However, the relationships was poor for reactive Fe (133 data points) and differed for each of the 2 field studies and the paddock study, so no consistent, reliable approach for converting reactive Fe to PBI values could be determined. We recommend that reactive Fe is no longer used in the region, and that only PBI is used to estimate P sorption.
28
Bolland, MDA. "Residual value for wheat of phosphorus from calciphos, Duchess rock phosphate and triple superphosphate on a lateritic soil in south-western Australia". Australian Journal of Experimental Agriculture 25, n. 1 (1985): 198. http://dx.doi.org/10.1071/ea9850198.
Testo completoAbstract (sommario):
The residual values of phosphorus from triple superphosphate and from three rock phosphates were compared in a 4-year field experiment with wheat, grown on a phosphorus deficient lateritic soil in south-western Australia. The three rock phosphate fertilizers were an apatitic rock phosphate originating from the Duchess deposit in north-western Queensland, and calcined (500�C) Christmas Island C-grade ore as a powder and as pellets. Five rates of each fertilizer were applied at the commencement of the experiment and their effectiveness was calculated from data on yield of dried plant tops, grain yield, and bicarbonate soluble phosphorus extracted from the soil. Triple superphosphate was the most effective phosphorus fertilizer initially, but its effectiveness decreased markedly with time. The effectiveness of the three rock phosphates was initially very low, and remained approximately constant for the duration of the experiment. The yield of dried plant tops depended upon their phosphorus content and this relationship was independent of the phosphorus fertilizer used.
29
McLaughlin, M. J., N. A. Maier, R. L.Correll, M. K. Smart, L. A. Sparrow e A. McKay. "Prediction of cadmium concentrations in potato tubers (Solanum tuberosum L.) by pre-plant soil and irrigation water analyses". Soil Research 37, n. 1 (1999): 191. http://dx.doi.org/10.1071/s98031.
Testo completoAbstract (sommario):
Potato tubers can accumulate high concentrations of cadmium (Cd) in edible portions, so that techniques to determine high risk Cd environments are required by growers. The use of combined soil and irrigation water analyses prior to crop planting was investigated as a means to predict risks of Cd accumulation in tubers. Soils and irrigation waters were analysed at 134 sites in the major potato production areas in Western Australia, South Australia, Tasmania, Victoria, and New South Wales. Irrigation waters were analysed for electrical conductivity (EC), major cations, and anions. Cadmium was extracted from soil using aqua regia (1 : 3 HNO3: HCl), EDTA (ethylenediamine-N,N,N′,N′-tetraacetate), DTPA (diethylene-triamine-pentaacetate), 0·01 M CaCl2, 0·01 M Ca(NO3)2, 0·1 M CaCl2, and 1·0 M NH4NO3. The preferred test procedure was validated in a subsequent sampling and analysis program at 39 sites. Irrigation water quality (EC or Cl concentration), measured prior to planting, explained the greatest variation in tuber Cd concentrations. Of the soil test procedures, only Cd extracted by 0·01 M CaCl2 significantly improved the predictive capacity of water EC. These 2 measures explained >55% of the variance in tuber Cd concentrations. The data set were transformed to generate a probability curve for exceeding Cd concentrations of either 0·05 or 0·1 mg/kg fresh weight, the latter being the current maximum permitted concentration (MPC) in Australia for potato tubers. The probability of producing potato tubers exceeding 0·05 and 0·1 mg/kg fresh weight was >50% once irrigation water EC increased above 1·4 and 3·0 dS/m, respectively. Using the relationships developed, growers should be able to quantify Cd risks by a simple test of irrigation water EC prior to planting and, if further precision is needed, also determine CaCl2-extractable Cd in soil.
30
Hall, D. J. M., R. A. Sudmeyer, C. K. McLernon e R. J. Short. "Characterisation of a windbreak system on the south coast of Western Australia. 3. Soil water and hydrology". Australian Journal of Experimental Agriculture 42, n. 6 (2002): 729. http://dx.doi.org/10.1071/ea02009.
Testo completoAbstract (sommario):
This paper describes changes in soil water and ground water at various distances from a Pinus pinaster windbreak in south-western Australia. Soil water contents were measured by neutron moisture meter and time domain reflectometry at distances from a windbreak ranging from 1 to 20 tree heights (H). Within 3 H of the windbreak, soil water storage was reduced by 100–153 mm/1.8 m when compared to unsheltered conditions (20 H) over the 4 years of the experiment. Beyond 3 H, no significant differences in soil water storage were found which could be related to microclimate modification. Relationships between surface soil water storage (mm/0.4 m) at <6�H and 12–24 H were 1 : 1 regardless of the technique used. Similarly, soil water depletion within the crop rootzone (mm/0.6 m) was similar at distances >3 H. Reductions in the depth and duration of perched water levels occurred within 4 H of the windbreak. Despite this, the windbreaks had no effect on the regional ground-water levels.
31
Powell, Jocelyn M., David A. Morrison, Paul A. Gadek, Darren M. Crayn e Christopher J. Quinn. "Relationships and Generic Concepts within Styphelieae (Epacridaceae)". Australian Systematic Botany 10, n. 1 (1997): 15. http://dx.doi.org/10.1071/sb95044.
Testo completoAbstract (sommario):
A morphological data base of 30 characters has been assembled for 33 terminal taxa in the tribe Styphelieae sensu Powell et al. (1996), as well as four outgroup taxa representing the other major affinity groups previously identified within the Epacridaceae on morphological and molecular data. Heuristic and bootstrap analyses provided strong support for the tribe, but indicated a need to modify several long-established generic concepts. Four genera are shown here to be polyphyletic. Six new monotypic genera should be segregated from Astroloma. Brachyloma should be divided into three segregates. Two distinct affinity groups warranting generic status were identified within Cyathodes. The separation of the monotypic Western Australian genus, Croninia, from Leucopogon s.l. is supported, and four other separate entities are here recognised: four species from section Heteranthus Benth. should be united with Lissanthe, and the other three segregates warrant generic status. In addition, Monotoca is paraphyletic, and should be redefined to incorporate Oligarrhena, while a new genus, ‘Pseudactinia’, is required to accommodate two new species from Western Australia. There seems little justification for maintaining the distinction between Trochocarpa and Decatoca. The pattern of intergeneric relationships resolved suggests that Astroloma s.l., Coleanthera, Conostephium, Croninia, Melichrus, Styphelia and much of Leucopogon s.l. constitute an affinity group, and that Brachyloma s. str. and B. scortechinii are basal within the tribe, but there is only weak support for these aspects of the topology within the data.
32
Bolland, MDA. "Residual value of phosphorus from superphosphate for wheat grown on soils of contrasting texture near Esperance, Western Australia." Australian Journal of Experimental Agriculture 26, n. 2 (1986): 209. http://dx.doi.org/10.1071/ea9860209.
Testo completoAbstract (sommario):
The residual value for wheat of phosphorus (P) from superphosphate was measured in field experiments on two texture-contrast (duplex) soils near Esperance, Western Australia. Superphosphate was applied to previously untreated plots once only, in 1980, 198 1, 1982 or 1983. The residual value of this P was measured in 1983 relative to P applied in 1983. Results were similar for both soils. Superphosphate applied in previous years did not produce the same yield as superphosphate applied in the current year. As calculated from yield response, relative effectiveness was 65, 42 or 32% after 1, 2 and 3 years, respectively. Yield depended on P content of plant tops, and this relationship was independent of time of P application. As the period of contact of P with the soil increased, less P was taken up by the plants, and this limited yield. As calculated from the P content of plant tops, relative effectiveness was 60, 30 or 23% after 1, 2 and 3 years, respectively. The amount of P extracted from the soil by 0.5M sodium bicarbonate decreased by about 54% from day 210 to day 575 after application of superphosphate, by a further 35% from day 575 to day 940, and by 15% from day 940 to day 1305. Bicarbonate-extractable P determined on soil samples collected mid January 1983 gave a good prediction of yields measured in the spring of that year
33
Baek, C. W., e N. Coles. "The influence of antecedent soil moisture conditions on the rainfall–runoff threshold value of a roaded catchment used for water harvesting". Water Supply 13, n. 5 (1 settembre 2013): 1202–8. http://dx.doi.org/10.2166/ws.2013.128.
Testo completoAbstract (sommario):
A roaded catchment (RC) is a representative type of artificial catchment for rainwater harvesting. The rainfall–runoff threshold value of the RC is the main factor which influences the system efficiency and cost. Antecedent soil moisture condition is an important factor which impacts on the determination of the rainfall–runoff threshold value. In this study, rainfall–antecedent soil moisture condition–runoff relationships and the potential efficiency of RCs are presented. Rainfall and runoff data monitored at research sites in Merredin and Mount Barker are used to determine this relationship. Two antecedent moisture criteria; Antecedent Moisture Conditions (AMC) and Average Antecedent Precipitation (AAP) are used to analyse the relationship between previous rainfall and soil moisture for each RC. Monitored results show that AMC is not that suitable to show the relationship between rainfall and antecedent soil moisture condition of the RC in the dryland of Western Australia and it is recommended to use AAP to determine this relationship.
34
Wakelin-King, Gresley. "Using geomorphology to assess contour furrowing in western New South Wales, Australia". Rangeland Journal 33, n. 2 (2011): 153. http://dx.doi.org/10.1071/rj10080.
Testo completoAbstract (sommario):
This study examines landscape rehabilitation treatments installed 20–40 years ago in the Western Catchment of NSW. Treatment outcomes were assessed using geomorphic criteria, because geomorphic processes are fundamental to ecological permanence. Contour furrowing creates artificial runoff-runon sets which intercept runoff (resistance to flow by windrows microrelief and surface roughness) and promote infiltration (artificial permeability by ripping). As originally conceived, after windrows subside, flow resistance would be afforded by surface roughness under belts of vegetation. This study shows that rehabilitation treatments have a more complex relationship with the landscape than this would suggest, and that the final effect of the treatment depends on the geomorphic processes natural to the site. Treatment design should therefore be site-specific. The relevant aspects of treatment design are site location, runoff : runon ratio (expressed as furrow spacing and furrow length), furrow placement, and post-treatment management. Some long-term successes are documented. In ironstone ridge country affected by impermeable hard-setting soils, furrowing creates artificial permeability, allowing plant germination; plant material in the soil reverses hard-setting and establishes self-sustaining permeability. In stony gilgai country furrowing through vegetated patches can aid in re-establishing vegetation, but furrowing through stony runoff patches only diminishes, rather than improves, landscape function. Other landscape types will have different key attributes. In all cases, selection of appropriate sites for rehabilitation treatment is of primary importance. The 1990s NSW Soil Conservation Service best-practice included a specialised furrower, surveying techniques for accurate furrow placement along the contour, staggered gaps along each furrow line to reduce risks of gullying by windrow breakthrough, and post-treatment management of total grazing pressure. New guidelines for treatment design developed from this study include determining for each site the optimum runoff:runon ratio (which varies according to climate, gradient, vegetation, and regolith), and matching furrow spacing and furrow/gap length to local runoff:runon ratios. In stony gilgai country, furrow placement should be along the contour but within non-stony patches; elsewhere, placement should be rigorously along the contour. In ironstone ridge country, a greater runoff:runon ratio, commensurate with the area’s apparently larger patch scale, can be achieved by having more gap than furrow along each furrow line. No single rehabilitation technique will fit all landscape types, and these guidelines will ideally be developed further with investigation of other landscapes.
35
Mendham, D. S., A. M. O'Connell e T. S. Grove. "Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation". Soil Research 40, n. 5 (2002): 859. http://dx.doi.org/10.1071/sr01092.
Testo completoAbstract (sommario):
The influence of land-use management on Walkley-Black soil carbon (C) concentration, 3 concentrations of permanganate oxidisable C (33, 167, and 333 mm), microbial biomass, and soil respiration in a laboratory incubation was tested in surface soil from 10 sites in south-western Australia. The sites ranged in total C concentration from 1.9 to 8.3%, and represented a broad climatic and soil-type distribution across south-western Australia. At each of the sites, 0-10 cm soil was collected from plots in pasture (20-71 years old), Eucalyptus globulus plantation (7-10 years old, established on ex-pasture), and native vegetation. Soil profiles and position in the landscape for each of the land-use types were matched as closely as possible at each site to minimise influences other than land use. Total C was highly correlated with clay content. Land use caused no significant change in the relationship between total C and soil texture, and land use had little effect on total C concentration. Permanganate-oxidisable C was highly correlated with Walkley-Black organic C (R2�>�0.90) for all 3 concentrations that were investigated. Only the most dilute concentration of permanganate-oxidisable C (33 mm) was sensitive enough to detect small changes in soil organic matter with land use (P = 0.045). Microbial biomass and respiration at 25 kPa matric potential moisture content and 35°C temperature were used as biological indicators of soil organic matter lability. Cumulative respired C was more sensitive to land use than Walkley-Black organic C, with lower respiration in native soils compared with managed soils with low C concentrations, but higher than the managed soils at sites with high C concentrations. Microbial biomass was not significantly affected by land use. Microbial biomass and cumulative respired C were strongly influenced by soil texture, with the microbial quotient (proportion of microbial biomass in total carbon) and the proportion of total C respired significantly lower in soils with higher silt and clay contents. Land use had no significant effect on these relationships. Overall, land use caused only minor differences in the biological and chemical indicators of organic matter quality across a broad range of sites in south-western Australia.
36
Bolland, M. D. A., W. J. Cox e B. J. Codling. "Soil and tissue tests to predict pasture yield responses to applications of potassium fertiliser in high-rainfall areas of south-western Australia". Australian Journal of Experimental Agriculture 42, n. 2 (2002): 149. http://dx.doi.org/10.1071/ea01060.
Testo completoAbstract (sommario):
Dairy and beef pastures in the high (>800 mm annual average) rainfall areas of south-western Australia, based on subterranean clover (Trifolium subterraneum) and annual ryegrass (Lolium rigidum), grow on acidic to neutral deep (>40 cm) sands, up to 40 cm sand over loam or clay, or where loam or clay occur at the surface. Potassium deficiency is common, particularly for the sandy soils, requiring regular applications of fertiliser potassium for profitable pasture production. A large study was undertaken to assess 6 soil-test procedures, and tissue testing of dried herbage, as predictors of when fertiliser potassium was required for these pastures. The 100 field experiments, each conducted for 1 year, measured dried-herbage production separately for clover and ryegrass in response to applied fertiliser potassium (potassium chloride). Significant (P<0.05) increases in yield to applied potassium (yield response) were obtained in 42 experiments for clover and 6 experiments for ryegrass, indicating that grass roots were more able to access potassium from the soil than clover roots. When percentage of the maximum (relative) yield was related to soil-test potassium values for the top 10 cm of soil, the best relationships were obtained for the exchangeable (1 mol/L NH4Cl) and Colwell (0.5 mol/L NaHCO3-extracted) soil-test procedures for potassium. Both procedures accounted for about 42% of the variation for clover, 15% for ryegrass, and 32% for clover + grass. The Colwell procedure for the top 10 cm of soil is now the standard soil-test method for potassium used in Western Australia. No increases in clover yields to applied potassium were obtained for Colwell potassium at >100 mg/kg soil. There was always a clover-yield increase to applied potassium for Colwell potassium at <30 mg/kg soil. Corresponding potassium concentrations for ryegrass were >50 and <30 mg/kg soil. At potassium concentrations 30–100 mg/kg soil for clover and 30–50 mg/kg soil for ryegrass, the Colwell procedure did not reliably predict yield response, because from nil to large yield responses to applied potassium occurred. The Colwell procedure appears to extract the most labile potassium in the soil, including soluble potassium in soil solution and potassium balancing negative charge sites on soil constituents. In some soils, Colwell potassium was low indicating deficiency, yet plant roots may have accessed potassum deeper in the soil profile. Where the Colwell procedure does not reliably predict soil potassium status, tissue testing may help. The relationship between relative yield and tissue-test potassium varied markedly for different harvests in each year of the experiments, and for different experiments. For clover, the concentration of potassium in dried herbage that was related to 90% of the maximum, potassium non-limiting yield (critical potassium) was at the concentration of about 15 g/kg dried herbage for plants up to 8 weeks old, and at <10 g/kg dried herbage for plants older than 10–12 weeks. For ryegrass, there were insufficient data to provide reliable estimates of critical potassium.
37
Samadi, Abbas, e R. J. Gilkes. "Forms of phosphorus in virgin and fertilised calcareous soils of Western Australia". Soil Research 36, n. 4 (1998): 585. http://dx.doi.org/10.1071/s97060.
Testo completoAbstract (sommario):
Total phosphorus (P), inorganic P (Pi), organic P, and several Pi fractions were determined for 8 fertilised calcareous soils under agriculture and their virgin analogues under natural bush to ascertain changes due to agricultural development. The relationships between soil properties and forms of P were also determined. In general, agricultural development of soils resulted in increases in total P (average 105% increase), Pi (154%), organic P (49%), Olsen P (200%), Colwell P (100%), and all Pi fractions compared with their virgin analogues. For the virgin soils, the abundance of the Pi fractions was in the order: Al-P>O-P (occluded P)>Fe-P>Ca10-P = Ca2-P>Ca8-P, which changed to Al-P>Ca8-P>Ca2-P>Ca10-P>Fe-P>O-P for fertilised soils. The average contribution of each fraction to the increase in total Pi was Al-P (29%), Ca8-P (26%), Ca2-P (18%), Fe-P (13%), Ca10-P (13%), and O-P (4%). The change in Ca8-P was closely correlated with the content of the active fraction of calcite in the soil (ACCE). The increase in Fe-P associated with agriculture was highly correlated with citrate-dithionite-bicarbonate (CDB) extractable Fe (Fed) and acid-ammonium oxalate extractable Fe (Feo). The increase in Al-P was correlated with the ratio of acid-ammonium oxalate extractable Al (Alo) to Feo. Both Olsen and Colwell NaHCO3-extractable P were highly correlated with Ca2-, Al-, Fe-, and Ca10-P, and total P values. Multiple regression analysis indicated that Ca2-P and Ca10-P were major contributors to available P as determined by the Olsen and Colwell soil tests.
38
Franklin, Donald C., e Richard A. Noske. "Nectar sources used by birds in monsoonal north-western Australia: a regional survey". Australian Journal of Botany 48, n. 4 (2000): 461. http://dx.doi.org/10.1071/bt98089.
Testo completoAbstract (sommario):
We document the flora that provides nectar for birds in monsoonal north-western Australia, and examine the relationship between floral morphology and bird morphology in the region. Twenty-four regular nectarivores (21 honeyeaters, two lorikeets, one white-eye) and 29 opportunist species have been observed probing the flowers of 116 species of plants from 28 families. Amongst the nectar sources, the Myrtaceae is dominant in both the number of species and frequency of use, followed distantly by the Proteaceae and Loranthaceae. Variation between bird species in patterns of use of different floral structures primarily reflected the habitats occupied rather than shared or co-evolved morphology. Woodland birds made particular use of staminiferous cups, mangal specialists particular use of open sepaliferous and petaliferous flowers, and forest specialists and habitat generalists intermediate use of these flower types. Bird–flower relationships in monsoonal Australia may be generalised because of a combination of the dominance of mass-flowering myrtaceous trees, aridity during past glacials that may have eliminated specialists from the system, and perhaps also because many nectar sources are shared with bats.
39
Kaur, Parwinder, Krishnapillai Sivasithamparam e Martin J. Barbetti. "Host Range and Phylogenetic Relationships of Albugo candida from Cruciferous Hosts in Western Australia, with Special Reference to Brassica juncea". Plant Disease 95, n. 6 (giugno 2011): 712–18. http://dx.doi.org/10.1094/pdis-10-10-0765.
Testo completoAbstract (sommario):
White rust, caused by Albugo candida, is a serious pathogen of Brassica juncea (Indian mustard) worldwide and poses a potential hazard to the presently developing canola-quality B. juncea industry in Australia. Nine isolates of A. candida, representing strains collected from B. juncea, B. rapa, B. oleracea, B. tournefortii, Raphanus raphanistrum, R. sativa, Eruca vesicaria subsp. sativa, Capsella bursa-pastoris and Sisymbrium irio, from different locations in Western Australia (W.A.), were tested on cruciferous host differentials to characterize their pathogenicity. In particular, these studies were aimed to determine the hazard to the newly emerging B. juncea industry in Australia from races or pathotypes of A. candida present. Pathogenicity tests with appropriate differentials demonstrated the presence in W.A. of a unique strain from B. rapa that did not show characteristics of either race 7A or 7V and clearly is a distinct new pathogenic strain within race 7. Different strains collected from W.A. differed in their host range, with the strains from B. tournefortii and S. irio being highly host specific, failing to be pathogenic on any other differentials. B. tournefortii was host to a strain attacking B. juncea and E. vesicaria subsp. sativa. The strain from R. raphanistrum showed a relatively wide host range among the differentials tested. B. tournefortii, C. bursa-pastoris, R. raphanistrum, and S. irio are common weeds within grain belt and horticultural regions in Australia. The B. oleracea isolate (race 9) was pathogenic to B. juncea ‘Vulcan’ whereas the isolate from B. juncea (race 2V) was not pathogenic on B. oleracea. Similarly, the strain from C. bursa pastoris (race 4) was pathogenic on B. juncea Vulcan but the B. juncea strain was not pathogenic on C. bursa pastoris. In contrast, the strain from R. sativus (race 1) was pathogenic on B. juncea and the B. juncea strain was also pathogenic on R. sativus. Field isolates from B. rapa, B. tournefortii, E. vesicaria subsp. sativa, and S. irio were all nonpathogenic on B. juncea. Isolates from B. juncea and R. raphanistrum were pathogenic on B. napus (FAN 189). For the nine A. candida isolates from W.A., complete rDNA internal transcribed spacer region nucleotide sequence analysis showed a nucleotide identity range of 72.4 to 100% in comparison with previous Australian collections of A. candida and those previously reported in Europe and Asia. The B. tournefortii isolate of A. candida from W.A. formed a distinct clade on its own, with an identity range of 77.4 to 80.5% compared with the other isolates. Isolates from R. raphanistrum and R. sativus from W.A. were least similar to the other isolates, with a nucleotide identity similarity of only 72.4%. Characterization of the races of A. candida in Western Australia adds to the current knowledge regarding the diversity of this pathogen, allows choice of Brassica spp. or cultivars with resistance to races across different regions, and highlights the particular cruciferous weeds involved in pathogen inoculum carryover between successive cruciferous crops, particularly B. juncea crops.
40
Anderson, Geoffrey C., Ken I. Peverill e Ross F. Brennan. "Soil sulfur—crop response calibration relationships and criteria for field crops grown in Australia". Crop and Pasture Science 64, n. 5 (2013): 523. http://dx.doi.org/10.1071/cp13244.
Testo completoAbstract (sommario):
Accurate definition of the sulfur (S) soil test–crop grain yield increase (response) relationship is required before soil S test measurements can be used to if there are likely to be responses to S fertilisers. An analysis was done using the Better Fertiliser Decision for Crops (BFDC) National Database using a web application (BFDC Interrogator) to develop calibration relationships between soil S tests (KCl-40 and MCP) using a selection of sampling depths and grain relative yields (RY). Critical soil test values (CSTV) and critical soil test ranges (CSTR) were defined at RY 90%. The ability of the KCl-40 extractable S soil test to predict grain yield response to applied S fertiliser was examined for wheat (Triticum aestivum L.) grown in Western Australia (WA), New South Wales (NSW), and Victoria and canola (Brassica napus L.) grown in WA and NSW. A smaller dataset using MCPi-extractable S was also assessed. The WA-grown wheat KCl-40 S CSTV, using sampling depth to 30 cm for soil types Chromosols (Coloured), Chromosols (Sesqui-Nodular), Kandosols (Grey and Yellow), Tenosols (Brown and Yellow), and Tenosols (Grey, Sesqui-Nodular), was 2.8 mg kg–1 with an associated CSTR 2.4–3.2 mg kg–1 and a correlation coefficient (r) 0.87. Similarly, KCl-40 S CSTV was defined using sampling depth to 10 cm for these selected soil types and for wheat grown on Vertosols in NSW. The accuracy of the KCl-40 S CSTV for canola grown in WA was improved using a sampling to a depth of 30 cm instead of 10 cm for all soil types. The canola KCl-40 S CSTV using sampling depth to 30 cm for these soil types was 7.2 mg kg–1 with an associated CSTR 6.8–7.5 and an r value 0.70. A similar KCl-40 S CSTV of 7.0 mg kg–1 was defined using a sampling depth of 10 cm, but the CSTR was higher (6.4–7.7 mg kg–1) and the r value lower (0.43). A lower KCl-40 S CSTV of 3.9 mg kg–1 or 31.0 kg ha–1 using a sampling depth of 60 cm was defined for canola grown in NSW using a limited number of S-rate calibration treatment series. Both MCPi (r = 0.32) and KCl-40 (r <0.20) soil S test–NSW canola response relationships using a 0–10 cm sampling depth were weak. The wheat KCl-40 S CSTR of 2.4–3.2 mg kg–1 can be used widely on soil types where soil sulfate is not leached during the growing season. However, both the WA canola CSTR of 6.4–7.2 mg kg–1 using a sampling depth of 30 cm and NSW canola CSTR of 25–39 kg ha–1 or 3.1–4.9 mg kg–1 using a sampling depth of 60 cm can be considered in regions outside of WA and NSW.
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Towers, Isaac R., e John M. Dwyer. "Regional climate and local-scale biotic acceptance explain native–exotic richness relationships in Australian annual plant communities". Proceedings of the Royal Society B: Biological Sciences 285, n. 1886 (5 settembre 2018): 20181328. http://dx.doi.org/10.1098/rspb.2018.1328.
Testo completoAbstract (sommario):
Native and exotic species richness is expected to be negatively related at small spatial scales where individuals interact, and positive at larger spatial scales as a greater variety of habitats are sampled. However, a range of native–exotic richness relationships (NERRs) have been reported, including positive at small scales and negative at larger scales. We present a hierarchical metacommunity framework to explain how contrasting NERRs may emerge across scales and study systems, and then apply this framework to NERRs in an invaded winter annual plant system in southwest Western Australia. We analysed NERRs at increasing spatial scales from neighbourhoods (0.09 m 2 ) to communities (225 m 2 ) to metacommunities (greater than 10 ha) within a multilevel structural equation model. In contrast to many previous studies, native and exotic richness were positively related at the neighbourhood scale and were not significantly associated at larger scales. Heterogeneity in soil surface properties was weakly, but positively, associated with native and exotic richness at the community scale. Metacommunity exotic richness increased strongly with regional temperature and moisture availability, but relationships for native richness were negative and much weaker. Thus, we show that neutral NERRs can emerge at larger scales owing to differential climatic filtering of native and exotic species pools.
42
Graham, J. F., B. R. Cullen, G. M. Lodge, M. H. Andrew, B. P. Christy, P. J. Holst, X. Wang, S. R. Murphy e A. N. Thompson. "SGS Animal Production Theme: effect of grazing system on animal productivity and sustainability across southern Australia". Australian Journal of Experimental Agriculture 43, n. 8 (2003): 977. http://dx.doi.org/10.1071/ea02197.
Testo completoAbstract (sommario):
The effects of various grazing management systems on sown, naturalised, and native pastures were studied at 6 different locations in the temperate high rainfall zone (HRZ, >600 mm rainfall/year) of southern Australia, as part of the Sustainable Grazing Systems (SGS) Program. The treatments examined had different pasture species and fertiliser management, with grazing method ranging from set stocking (continuous grazing) to rotation with rests based on pre- and post-grazing herbage mass or season and plant phenology. Sites were located at: Albany, Western Australia; Manilla, Barraba, Nundle, New South Wales; (grazed by wethers); and Carcoar, New South Wales; Maindample, Ruffy, north-east Victoria; Vasey, western Victoria; (grazed by ewes and lambs).Grazing method significantly (P<0.001) influenced stocking rate (expressed as dry sheep equivalents (DSE)/ha), but effects were not consistent across sites. At Vasey the stocking rate of the rotation treatments ranged from 5 to 23% higher than the set stocked treatments depending upon year. For all sites, significant factors (P<0.001) affecting stocking rate were soil Olsen P, soil pH, grazing management (resting), legume percent, and an index of growing season effectiveness. Although total annual rainfall had a significant effect (P<0.002) in an initial analysis, its influence became non-significant (P>0.05), when a growing season index (P<0.001) was used. Non-significant (P>0.05) factors included solar radiation, annual average temperature, fertiliser applied in the current year, and average annual perennial and broadleaf percent composition. The implications of these data for productivity and sustainability (as assessed by perenniality and water use) were encouraging. Generally, there were positive relationships between increased stocking rate and the probability of achieving a zero mm soil water surplus in winter, and between increased productivity and the proportion of perennial grass species where extremes of treatments were compared at each site. The results indicate that stocking rate can be increased without jeopardising sustainability, that grazing management can bring about more sustainable pastures, that there is scope to increase productivity particularly through increasing soil fertility, and growing season length can be used to predict potential carrying capacity. These are positive outcomes that graziers in the HRZ of southern Australia can use to enhance productivity (thus profitability) and sustainability.
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Brennan, Ross F., e Michael J. Bell. "Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia". Crop and Pasture Science 64, n. 5 (2013): 514. http://dx.doi.org/10.1071/cp13006.
Testo completoAbstract (sommario):
The Better Fertiliser Decision for Crops (BFDC) National Database holds historic data for 356 potassium (K) fertiliser rate experiments (431 treatment series) for different rain-fed grain crops and soil types across Australia. Bicarbonate-extractable K (Colwell soil-test K) is the most extensively used soil test reported in the database. Data are available for several crop species grown on a range of soil types from all states except Tasmania. Species represented and number of treatment series in the database are: wheat (Triticum aestivum L.), 254; barley (Hordeum vulgare L.), 5; canola (Brassica napus L.), 130; lupin (Lupinus angustifolius L.), 32; sunflower (Helianthus annuus L.), 10; sorghum (Sorghum bicolor L.), 5; and faba bean (Vicia faba L.), 2. About 77% of the available soil-test K (STK) data on wheat, canola, and lupin are from Western Australia. The usual sampling depth of 0–10 cm is recorded for all treatment series within the database, while 68% of experiments have STK information from other soil horizons down the profile, usually in 10-cm increments. The BFDC Interrogator, a comprehensive data search and calibration support tool developed for use with the BFDC National Database, was used to examine STK–yield relationships for each crop across Australia, with more detailed analysis by state/region and then by soil type if data were available. The BFDC Interrogator was used to determine a critical STK concentration to achieve 90% of the maximum relative yield (90%RY) for each crop species, with a critical range (determined by the 70% confidence limit for the 90%RY) also reported. The STK for 90%RY for wheat was 40–41 mg/kg on Tenosols and Chromosols, ~49 mg/kg on Kandosols, and ~64 mg/kg on Brown Ferrosols. There was some evidence of critical values increasing with increasing crop yield and on soils with no acidity constraints to root growth, with effects presumably driven by increased crop K demand. The STK for 90%RY for canola, grown mainly on Tenosols, was similar to that for wheat, ranging from 43 to 46 mg K/kg, but for lupin, also grown mainly on Tenosols, the STK for 90%RY was a relatively low ~25 mg K/kg. Data for sunflower were limited and the STK for 90%RY was poorly defined. A comparison of critical STK concentrations for different crops grown on Tenosols suggested that critical ranges for 90%RY of lupin (22–27 mg K/kg) were significantly lower than that for wheat (32–52 mg K/kg) and canola (44–49 mg K/kg). Critical STK values were not determined for sorghum and faba bean.
44
Regan, K. L., K. H. M. Siddique e L. D. Martin. "Response of kabuli chickpea (Cicer arietinum L.) to sowing rate in Mediterranean-type environments of south-western Australia". Australian Journal of Experimental Agriculture 43, n. 1 (2003): 87. http://dx.doi.org/10.1071/ea01200.
Testo completoAbstract (sommario):
The effect of sowing rate (60–320 kg/ha) on the growth and seed yield of kabuli chickpea (cv. Kaniva) was assessed at 11 sites for 4 seasons in the cropping regions of south-western Australia. The economic optimum plant density and yield potential were estimated using an asymptotic model fitted to the data and calculating the sowing rate above which the cost of additional seed was equivalent to the revenue that could be achieved from the extra seed yield produced, assuming a 10 and 50% opportunity cost. On average for all sites and seasons, plant densities ranged from 10 plants/m2 when sown at 60 kg/ha to 43�plants/m2 when sown at 320 kg/ha. Assuming a mean seed weight of 400 mg and a germination of 80%, then on average 75% of viable seeds sown (or 60% of sown seeds) established as plants. The poor establishment rates are thought to be associated with reduced viability caused by mechanical damage, storage conditions, fungal infection in the soil, and unfavourable seed bed moisture and temperatures. In general, there was a positive relationship between sowing rate and seed yield. Seed yield increases at higher sowing rates were mainly associated with the greater number of plants per unit area. There were fewer pods per plant at higher sowing rates, but there were more pods per unit area. Changing the sowing rate had little effect on mean seed weight and the number of seeds per pod. The economic optimum plant density varied from 8 to 68 plants/m2, depending on the location, but the mean (27�plants/m2) was within the range currently recommended in southern Australia (25–35 plants/m2). Due to the low establishment rates observed in this study, we estimate a sowing rate greater (160–185 kg/ha) than currently suggested (110–160 kg/ha) to achieve this density. There was a strong relationship between economic optimum plant density and seed yield potential (r2 = 0.66, P<0.01), which allows an estimation of the most profitable sowing rate, depending on the seed yield potential of the site. For most crops yielding about 1.0 t/ha in southern Australia, a plant density of 25 plants/m2 is most profitable, while in higher-yielding situations (>1.5 t/ha) plant densities >35�plants/m2 will produce the most profit.
45
Bolland, MDA. "Efficiency with which yellow serradella and subterranean clover use superphosphate on a deep sandy soil near Esperance, Western Australia". Australian Journal of Experimental Agriculture 26, n. 6 (1986): 675. http://dx.doi.org/10.1071/ea9860675.
Testo completoAbstract (sommario):
In 1984, the efficiency with which an early- and a late-flowering yellow serradella (cv. Pitman and strain DP4 respectively) and a subterranean clover (cv. Seaton Park) utilise phosphorus (P) from superphosphate was compared on a deep sandy soil near Esperance, W.A. Phosphorus applications ranged from 0 to 90 kg/ha P. For each legume there was an approximately linear relationship between the amount of P applied and either the yield of dry herbage and seed, or the P content of dry herbage. The efficiency with which each legume utilised applied P (kg/ha) was determined by calculating the slope of the relationships between dry matter production, or phosphorus content of this dry matter, and the amount of phosphorus applied; this varied according to the growth stage at which the legumes were sampled. Strain DP4 utilised P more efficiently to produce dry herbage, and Seaton Park to produce seed. Pitman was the least efficient at utilising P for dry herbage production in September, and Seaton Park in early October. For dry herbage production in September and early October, the relationship between yield and P content was similar for all 3 legumes, and yield depended on the amount of P present in the herbage. For each legume, the rate of phosphorus applied had no effect on seedling emergence, the period between sowing and commencement of flowering, senescence or the weight per seed.
46
Butcher, Ryonen. "New taxa of 'leafless' Tetratheca (Elaeocarpaceae, formerly Tremandraceae) from Western Australia." Australian Systematic Botany 20, n. 2 (2007): 139. http://dx.doi.org/10.1071/sb06015.
Testo completoAbstract (sommario):
The relationships among rare ‘leafless’ species of Tetratheca Sm. occurring on banded ironstone ranges near Koolyanobbing, Western Australia, and allied, unclassified, populations from Eneabba, Newdegate and the Die Hardy Range have been assessed by molecular characters. These findings, in conjunction with morphological investigations, have identified a new species and two new subspecies from within the ‘T. aphylla group’ and these are formally described here. Tetratheca nephelioides R.Butcher, is geographically restricted to the Eneabba area and has close morphological affinity to T. aphylla F.Muell. Tetratheca aphylla subsp. megacarpa R.Butcher, is restricted to the Newdegate area, some 300 km south of the only known populations of T. aphylla subsp. aphylla in the Helena and Aurora Range. Tetratheca paynterae Alford subsp. cremnobata R.Butcher is restricted to the Die Hardy Range, c. 10 km north-east of the only known population of T. paynterae subsp. paynterae at ‘Windarling’. All of these taxa are recognised as Declared Rare Flora. In the process of updating the existing key to ‘leafless’ species of Tetratheca to include these new taxa, two additional new species were identified from within collections of T. nuda Lindl. These are described here as T. angulata R.Butcher and T. applanata R.Butcher. Images and distribution maps for all taxa are provided.
47
Braaten, Christine C., P. Brandon Matheny, Debra L. Viess, Michael G. Wood, Joseph H. Williams e Neale L. Bougher. "Two new species of Inocybe from Australia and North America that include novel secotioid forms". Botany 92, n. 1 (gennaio 2014): 9–22. http://dx.doi.org/10.1139/cjb-2013-0195.
Testo completoAbstract (sommario):
The secotioid form of fruit bodies of mushroom-forming fungi may be an intermediate evolutionary modification of epigeous agaricoid or pileate–stipitate forms (i.e., with pileus, spore-bearing tissues, and stipe) and typically hypogeous, gasteroid- or truffle-forming species, in which the fruit bodies have been reduced to enclosed structures containing modified spore-producing tissues. To date, only a single secotioid species (Auritella geoaustralis Matheny & Bougher ex Matheny & Bougher) has been described in the ectomycorrhizal family Inocybaceae, a hyperdiverse clade of ca. 500–700 species with a cosmopolitan distribution. Fieldwork in Australia and western North America, however, has revealed two novel secotioid forms of Inocybe (Fr.) Fr., the first to be formally described in the genus. In this investigation, we analyze their phylogenetic relationships using molecular sequence data from multiple unlinked loci to test whether these are environmental variants of agaricoid forms or represent independent lineages. Results of phylogenetic analyses suggest these fungi have converged to the secotioid form independently. However, the California secotioid taxon (Inocybe multifolia f. cryptophylla f. nov.) is a phenotypic variant of the newly described agaricoid taxon (Inocybe multifolia sp. nov.). Similarly, the Australian secotioid form (Inocybe bicornis f. secotioides f. nov.) is nested within a clade of otherwise agaricoid forms of a second novel species (Inocybe bicornis sp. nov.) described from southwest Western Australia. Overall, four species with sequestrate forms within Inocybaceae can now be recognized, three of which are distributed in Australia and one in western North America, in the genera Auritella and Inocybe.
48
McDougall, K. L., R. J. Hobbs e G. E. St J. Hardy. "Distribution of understorey species in forest affected by Phytophthora cinnamomi in south-western Western Australia". Australian Journal of Botany 53, n. 8 (2005): 813. http://dx.doi.org/10.1071/bt04203.
Testo completoAbstract (sommario):
The introduced soil-borne pathogen Phytophthora cinnamomi Rands infects and kills a large number of species in the jarrah (Eucalyptus marginata Donn. ex Smith) forest of Western Australia, causing great floristic and structural change. Many of the floristic changes can be explained simply by the known susceptibility of species to infection. Some common species, however, are rarely found at infested sites but are thought to be resistant to infection. It has been postulated that such species may be affected by the change in habitat caused by the death of trees, and not by P. cinnamomi directly. If this were the case, such species should cluster around surviving trees at infested sites. The occurrence of a susceptible species in the vicinity of trees surviving at infested sites has also been reported. To investigate the spatial relationship between trees and understorey species, the positions of trees and selected perennial understorey species were mapped at two sites in jarrah forest long-affected by P. cinnamomi. Random sets of plants and trees were generated and used in simulations to test whether understorey species grew closer to trees than expected. Many understorey species, both resistant and susceptible to infection by P. cinnamomi, were found to grow closer than expected to trees currently growing at the sites and closer to the trees that would have been present at the time of infestation. This suggests that not only do these trees enable some resistant species to persist at infested sites but that they also offer protection to some susceptible species against damage by P. cinnamomi. The proximity of many understorey species to trees that are likely to have appeared at the study sites since the first infestation indicates that the maintenance and enhancement of tree cover at infested sites in the jarrah forest may limit the damage caused by P. cinnamomi and assist in the protection of biodiversity.
49
El-Tarabily, A., Giles E. St J. Hardy e Krishnapillai Sivasithamparam. "Effects of Host Age on Development of Cavity Spot Disease of Carrots Caused by Pythium coloratum in Western Australia Khaled". Australian Journal of Botany 45, n. 4 (1997): 727. http://dx.doi.org/10.1071/bt96045.
Testo completoAbstract (sommario):
Three experiments were conducted with Pythium coloratum Vaartaja, a causal agent of cavity spot disease of carrots in Western Australia, to study the relationships between host age, time of infection and development of cavity spot lesions. Pythium coloratum was isolated frequently from 3-6-week-old asymptomatic roots of carrots grown in soils infested naturally or artificially with the pathogen. Carrots grown in containers of soil artificially infested with P. coloratum, but not those in naturally infested field soil, developed cavity spot lesions after 6 weeks. Early infection of carrot seedlings at or before 3 weeks by P. coloratum in artificially infested soils followed by their transfer to pathogen-free soil was sufficient to cause cavity spot disease at the time of harvest (16 weeks). The disease levels in this treatment were not different from those transferred to P. coloratum-infested soil. There was no significant (P > 0.05) association between carrot age and the ability of P. coloratum to infect the roots and to cause cavity spot lesions at harvest.
50
McPharlin, IR, RC Jeffery e DH Pitman. "Phosphorus requirements of winter-planted lettuce (Lactuca sativa L.) on a Karrakatta sand and the residual value of phosphate as determined by soil test". Australian Journal of Experimental Agriculture 36, n. 7 (1996): 897. http://dx.doi.org/10.1071/ea9960897.
Testo completoAbstract (sommario):
The phosphorus (P) requirements of crisphead lettuce (Lactuca sativa L. cv. Oxley) was measured over 2 consecutive winter plantings using superphosphate that was freshly applied and applied 9 months before planting, at 0-600 kg/ha on a newly cleared Karrakatta sand of low natural P fertility. There was a significant (P<0.001) head yield response to level of applied P in both years. Phosphorus uptake by whole plants and plant shoots was related to level of applied P in Mitscherlich relationships (R2 = 0.88). Phosphorus recovery efficiency (fertiliser P uptake by shoots/P applied, both in kg/ha) by shoots decreased from 0.16 at 50 to 0.04 at 600 kg applied P/ha. Phosphorus recovery efficiency by whole plants (shoots plus roots) decreased from 0.18 at 50 to 0.05 at 600 kg P/ha. The level of freshly applied P required for either 95 or 99% of maximum relative yield over the 2 years (maximum yield, 86 t/ha) was 276 and 427 kg P/ha (Mitscherlich relationship, R2 = 0.95), respectively at <10 �g/g soil test P (newly cleared sites). The marketable yield was 82 and 95% of total yield at 276 and 427 kg P/ha respectively. Bicarbonate-soluble P extracted from the top 15 cm of soil was determined on residual P sites over 2 years where P was applied at 0-600 kg/ha. These soil test levels were related to head yield in a Mitscherlich relationship (R2 = 0.88). The critical soil test P values required for either 95 or 99% of maximum relative yield, over the 2 years, were 80 and 115 �g/g, respectively. Phosphorus in the wrapper leaf at early heading required for 95 or 99% of maximum yield was 0.59 � 0.03 and 0.61 � 0.03% (spline regression, R2 = 0.80), respectively. Soil and plant testing could be used to assist in reducing fertiliser costs, improving utilisation of freshly- and previously-applied fertiliser P by lettuce and reducing P losses to water systems on the Swan Coastal Plain in Western Australia.