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1
Zubaidi, A., G. K. McDonald e G. J. Hollamby. "Shoot growth, root growth and grain yield of bread and durum wheat in South Australia". Australian Journal of Experimental Agriculture 39, n. 6 (1999): 709. http://dx.doi.org/10.1071/ea98184.
Testo completoAbstract (sommario):
Summary. In South Australia, durum wheat yields more than bread wheat under well-watered and fertile conditions, but over much of the state’s cereal belt the yields of durum wheat, relative to bread wheat, are low. Three experiments were conducted over 3 years at 2 sites to compare the growth and yield of bread and durum wheat and to investigate some of the reasons for the differences in the relative yields of the 2 cereals. Durum wheat yielded less than bread wheat when annual rainfall was less than about 450 mm or when the site mean yield for bread wheat was less than 250 g/m2. Compared with bread wheat, durum wheat had poorer early vigour, which was associated with fewer tillers/m2, and produced fewer kernels/m2. Under favourable grain filling conditions, durum wheat produced larger kernels than bread wheat but its kernel weight was more variable across sites and seasons and consequently, the relative yields of the 2 cereals depended largely on kernel weight. For example, in a wet year, durum wheat yielded 20% more than bread wheat, despite producing 16% fewer kernels/m2, because of its larger kernels (52 v. 36 mg). In 2 drier years, kernel weights of durum and bread wheat were similar (durum and bread wheat mean kernel weights: 40 v. 37 mg; 30 v. 33 mg) and so durum was unable to overcome the limitation of fewer kernels/m2 and its yields were similar to or less than bread wheat. Root length densities of durum and bread wheat below 30 cm were low. Durum wheat had an equivalent or lower root length density than bread wheat and lower length per gram of root dry matter, indicating less finely divided roots. This suggests that durum wheat may sometimes be less able than bread wheat to utilise moisture and nutrient reserves in the subsoil because of a smaller root system. This is an undesirable characteristic for a crop that appears to be more reliant than bread wheat on producing large kernels for high yields. Efforts to improve the yield of durum wheat, either through genetic improvement or by agronomic means, should focus on reducing the levels of stress during the post anthesis period so that limitations to kernel growth are minimised. Improving the early vigour of the crop, having cultivars of the appropriate maturity and with adequate levels of resistance to root disease, and improving root growth and function in the subsoil are likely to be desirable characteristics.
2
Choct, M., R. J. Hughes e G. Annison. "Apparent metabolisable energy and chemical composition of Australian wheat in relation to environmental factors". Australian Journal of Agricultural Research 50, n. 4 (1999): 447. http://dx.doi.org/10.1071/a98155.
Testo completoAbstract (sommario):
A total of 81 wheats collected from New South Wales, Victoria, South Australia, Queensland, and Western Australia over 3 harvests were assayed for apparent metabolisable energy (AME) in broiler chickens. The non-starch polysaccharides (soluble and insoluble) and their individual sugar components, starch, and protein were also determined. The nutritive quality of wheat varied significantly (P < 0.01), especially at time of harvest, with approximately 40% having an average AME value <13 MJ/kg dry matter. The low-AME wheats usually caused copious quantities of watery and sticky droppings. The occurrence of low-AME wheats was associated more with climatic conditions during growth than with geographical region.
3
McMullen, K. G., e J. M. Virgona. "Dry matter production and grain yield from grazed wheat in southern New South Wales". Animal Production Science 49, n. 10 (2009): 769. http://dx.doi.org/10.1071/an09055.
Testo completoAbstract (sommario):
In southern New South Wales, Australia, grazing wheat during the vegetative and early reproductive growth stages (typically during winter) can provide a valuable contribution of high quality feed during a period of low pasture growth. This paper reports results from a series of experiments investigating the agronomic management of grazed wheats in southern NSW. The effect of sowing date and grazing on dry matter production and subsequent grain yield of a range of wheat cultivars was measured in five experiments in 2004 and 2005. In all experiments, results were compared with ungrazed spring wheat (cv. Diamondbird). Grain yield of the best winter cultivar was either the same or significantly greater than the spring cultivar in each of the five experiments. Within the winter wheat cultivars, there was significant variation in grain yield, protein content and screenings, depending on site and year with the cultivar Marombi out-yielding all others. Interestingly, this cultivar usually had the least dry matter post-grazing but the greatest dry matter by anthesis of the winter wheats. Generally, if sowing of the winter wheat was delayed, then the effects on yield were small or non-existent. The results are discussed with respect to the benefits of incorporating grazing cereals into cropping programs in the medium rainfall zone of southern Australia.
4
Evans, J., NA Fettell, DR Coventry, GE O'Connor, DN Walsgott, J. Mahoney e EL Armstrong. "Wheat response after temperate crop legumes in south-eastern Australia". Australian Journal of Agricultural Research 42, n. 1 (1991): 31. http://dx.doi.org/10.1071/ar9910031.
Testo completoAbstract (sommario):
At 15 sites in the cereal belt of New South Wales and Victoria, wheat after lupin or pea produced more biomass and had a greater nitrogen (N) content than wheat after wheat or barley; on average these crops assimilated 36 kg N/ha more. The improved wheat yield after lupin averaged 0 . 9 t/ha and after pea 0.7 t/ha, increases of 44 and 32% respectively. The responses were variable with site, year and legume. Soil available N was increased by both lupin and pea and the levels of surface inorganic N measured at the maturity of first year crops was often related to N in wheat grown in the following year. Of two possible sources of additional N for wheat after legumes, namely mineral N conserved in soil by lupin or pea (up to 60 kg N/ha) and the total N added in the residues of these legumes (up to 152 kg N/ha), both were considered significant to the growth of a following wheat crop. Their relative contribution to explaining variance in wheat N is analysed, and it is suggested wheat may acquire up to 40 kg N/ha from legume stubbles. Non-legume break crops also increased subsequent wheat yield but this effect was not as great as the combined effect of added N and disease break attained with crop legumes.
5
Coutts, B. A., N. E. B. Hammond, M. A. Kehoe e R. A. C. Jones. "Finding Wheat streak mosaic virus in south-west Australia". Australian Journal of Agricultural Research 59, n. 9 (2008): 836. http://dx.doi.org/10.1071/ar08034.
Testo completoAbstract (sommario):
Between 2003 and summer 2006, 33 659 samples of wheat and grasses were collected from diverse locations in south-west Australia and tested for presence of Wheat streak mosaic virus (WSMV), but none was detected. In April–early May 2006, 2840 random samples of volunteer wheat from 28 fields on 24 farms in 6 districts in the grainbelt were tested. WSMV was detected for the first time, the infected samples coming from three fields, one in the Hyden and two in the Esperance districts. In ‘follow-up’ surveys in May 2006 in the same two districts, 8983 samples of volunteer wheat or grasses were tested, and the virus was detected on further farms, two in the Hyden and four in the Esperance districts. Incidences of infection in volunteer wheat were 1–8%, but WSMV was not found in grasses. By September 2006, when 1769 samples from further visits were tested, WSMV was detected in wheat crops or volunteer wheat plants at 2/3 of the original farms, with infection also found at one of them in barley, volunteer oats, and barley grass (Hordeum sp.). When samples of the seed stocks originally used in 2005 to plant five of the fields containing infected volunteer wheat at the three original infected farms were tested, seed transmission of WSMV was detected in four of them (0.1–0.2% transmission rates). In August–October 2006, 16 436 samples were collected in a growing-season survey for WSMV in wheat trials and crops throughout the grainbelt. WSMV was detected in 33% of ‘variety’ trials, 18% of other trials, 13% of seed ‘increase’ crops, and 52% of commercial crops. Incidences of infection were <1–100% within individual crops, <1–17% in trials, and <1–3% in seed increase crops. WSMV-infected sites were concentrated in the low-rainfall zone (east) of the central grainbelt. This area received considerable summer rains in 2006, which allowed growth of a substantial ‘green ramp’ of volunteer cereals and grasses, favouring infection of subsequent wheat plantings. WSMV was also detected at low levels over a much wider area involving all rainfall zones, from Dongara in the north to Esperance in the south. All 26 122 samples collected in January–May 2006 and 515 with possible WSMV symptoms collected in August–October 2006 were also tested for High plains virus (HPV), but it was not detected.
6
Radke, J. K., A. R. Dexter e O. J. Devine. "Tillage Effects on Soil Temperature, Soil Water, and Wheat Growth in South Australia". Soil Science Society of America Journal 49, n. 6 (novembre 1985): 1542–47. http://dx.doi.org/10.2136/sssaj1985.03615995004900060042x.
Testo completo
7
Zubaidi, A., G. K. McDonald e G. J. Hollamby. "Nutrient uptake and distribution by bread and durum wheat under drought conditions in South Australia". Australian Journal of Experimental Agriculture 39, n. 6 (1999): 721. http://dx.doi.org/10.1071/ea98185.
Testo completoAbstract (sommario):
Summary. An important limitation to the production of durum wheat in South Australia is its poor adaptation to the alkaline, sodic soils of the cereal belt, which often results in nutrient imbalances in the crop. A field experiment was conducted at Palmer, South Australia, to measure the nutrient uptake and distribution between grain and straw of 3 bread wheat cultivars and 9 cultivars and breeding lines of durum wheat. The purpose of the work was to characterise the patterns of nutrient uptake and to examine whether there were major, consistent differences between bread wheat and durum wheat. Rainfall during the growing season was below average and the crops suffered from drought stress after anthesis. Plants were marginally deficient or deficient in nitrogen (N), phosphorus (P) and zinc (Zn), and boron (B) concentrations were high. Compared with bread wheat, durum wheat had a very much higher concentration of sodium (Na), higher concentrations of calcium (Ca) and sulfur (S), but lower concentrations of potassium (K), magnesium (Mg), manganese (Mn) and copper (Cu). Total amounts of P, Zn and Na in the shoot continued to increase throughout the growing season with significant increases occurring during grain filling, whereas there was little increase in the amount of N, K, B and Mn during grain filling. The maximum rate of nutrient uptake occurred before the time of maximum crop growth rate, and was in the order K (10.1 weeks after sowing), N (10.6), P (11.3), Mn (12.0), Zn (12.5) and B (14.6); maximum growth rate occurred at 14.8 weeks. There was no consistent difference between bread and durum wheat in the partitioning of nutrients to the grain. The importance of N and Zn uptake to the growth of the durum wheat genotypes was shown by significant correlations between maximum uptake rates of these nutrients and maximum crop growth rate, with the strongest correlation being with Zn. Growth rate was not correlated with uptake rates of other nutrients. A number of genotypes of durum wheat had maximum rates of Zn and Mn accumulation up to twice those of the current commercial genotypes. Some of these lines have yielded well at Zn- and Mn-deficient sites which indicates that the micronutrient efficiency of durum can be improved. Late in the season the experiment showed signs of infection by crown rot (Fusarium graminearum Schw. Group 1). Durum wheat showed more severe symptoms than bread wheat and the number of white heads in durum wheat was inversely correlated with the concentration of Zn in the shoot during the pre-anthesis period.
8
Angus, J. F., A. F. van Herwaarden, D. P. Heenan, R. A. Fischer e G. N. Howe. "The source of mineral nitrogen for cereals in south-eastern Australia". Australian Journal of Agricultural Research 49, n. 3 (1998): 511. http://dx.doi.org/10.1071/a97125.
Testo completoAbstract (sommario):
The relative importance of soil mineral nitrogen (N) available at the time of sowing ormineralised during the growing season was investigated for 6 crops of dryland wheat. The soil mineral N in the root-zone was sampled at sowing and maturity and the rate of net mineralisation in the top 10 cm was estimated by sequential sampling throughout the growing season, using an in situ method. Mineralisation during crop growth was modelled in relation to total soil N, ambient temperature, andsoil water content. Mineral N accumulated before sowing varied by a factor of 3 between the sites (from 67 to 195 kgN/ha), while the net mineralisation during crop growth varied by a factor of 2 (from 43 to 99 kgN/ha). The model indicated that 0·092% of total N was mineralised per day when temperature and water were not limiting, with rates decreasing for lower temperatures and soil water contents. When tested with independent data, the model predicted the mineralisation rate of soil growing continuous wheat crops but underestimated mineralisation of soil in a clover-wheat rotation. For crops yielding <3 t/ha, the supply of N was mostly from mineralisation during crop growth and the contribution from mineral N accumulated before sowing was relatively small. For crops yielding >4 t/ha, thesupply of N was mostly from N present in the soil at the time of sowing. The implication is that for crops to achieve their water-limited yield, they must be supplied with an amount of N greater than can be expected from mineralisation during the growing season, either from fertiliser or from mineral N accumulated earlier.
9
Latta, R. A. "Performance of spring cereal genotypes under defoliation on the Eyre Peninsula, South Australia". Crop and Pasture Science 66, n. 4 (2015): 301. http://dx.doi.org/10.1071/cp14026.
Testo completoAbstract (sommario):
In mixed cropping and livestock dryland farming systems in southern Australia, grazing of cereals during their vegetative growth stages (typically during winter) can provide a valuable contribution of high-quality feed during a period of low pasture growth. This paper reports results from a series of experiments investigating the impact of defoliation on the grain production of cereals in the Eyre Peninsula region of South Australia. The comparative dry matter production and grain yield of wheat, barley and oats cultivars, with and without defoliation, at a range of growth stages were measured in four experiments over three growing seasons, two of which were water-deficient. The barley varieties evaluated produced up to twice the dry matter of the wheat or oats cultivars to the time of defoliation. Mowing following stem elongation more than halved grain yield (1.9 to 0.9 t ha–1) relative to no defoliation in an early-maturing variety, but with less reduction in later maturing varieties. Defoliation before stem elongation in two seasons of very low growing-season rainfall (<100 mm) caused no or very little loss in grain yields, which were generally <1 t ha–1. A long-season winter wheat produced similar grain yields irrespective of defoliation and timing, but with no yield advantage over the defoliated spring cereals. The results suggest opportunities to incorporate the grazing of cereals to fill a winter feed-gap in the low-rainfall zone of southern Australia.
10
Ryan, M. H., R. M. Norton, J. A. Kirkegaard, K. M. McCormick, S. E. Knights e J. F. Angus. "Increasing mycorrhizal colonisation does not improve growth and nutrition of wheat on Vertosols in south-eastern Australia". Australian Journal of Agricultural Research 53, n. 10 (2002): 1173. http://dx.doi.org/10.1071/ar02005.
Testo completoAbstract (sommario):
Most crops host arbuscular mycorrhizal fungi (AMF). Canola and other brassicas are some of the few exceptions. This study examined AM fungal colonisation, uptake of phosphorus (P) and zinc (Zn), growth, and yield of wheat following brassicas and crops that host AMF in 5 crop-sequence experiments in southern New South Wales and Victoria. All experiments were on alkaline Vertosols, similar to soils in the northern wheatbelt on which low AM fungal colonisation of wheat following canola, or long-fallow, has been reported to induce poor crop growth. Soils with a broad range of extractable P concentrations were chosen. AM fungal colonisation of wheat was generally lower following brassicas than hosts of AMF, although this varied with year and location. The effect on wheat AM fungal colonisation levels did not vary between brassicas with differing levels and types of root glucosinolates. Low AM fungal colonisation did not affect early wheat growth, pre-anthesis P and Zn uptake, or yield. A positive relationship between AM fungal colonisation and grain Zn and P concentrations occurred in one experiment. High levels of colonisation by AMF did not protect crop roots from damage by root pathogens and high levels of pathogen damage made interpretation of results difficult in some instances. As these findings are consistent with results from an experiment on an acidic Kandosol in southern New South Wales, it appears farmers do not need to consider the degree to which wheat will be colonised by AMF when planning crop sequences in south-eastern Australia.
11
Sissons, Mike, Ben Ovenden, Dante Adorada e Andrew Milgate. "Durum wheat quality in high-input irrigation systems in south-eastern Australia". Crop and Pasture Science 65, n. 5 (2014): 411. http://dx.doi.org/10.1071/cp13431.
Testo completoAbstract (sommario):
To extend the production base of durum wheat in Australia, field trials were conducted on seven registered durum varieties across four seasons and six sites in locations where irrigation was supplied during crop growth. The purpose was to determine if the quality of the grain produced met the requirements for good milling and pasta-making quality and to understand the genotype, environment and their interaction in affecting yield and technological quality of the grain and derived pasta. High grain yields and grain protein were obtained, producing large grain weights, low screenings and low percentage of hard vitreous kernels. Yellow colour of semolina and pasta was reduced marginally but dough and other pasta technological characteristics were similar to typical dryland durum production, with some exceptions. Varieties were identified with potential for production under irrigation.
12
Fillery, IR, e KJ McInnes. "Components of the fertiliser nitrogen balance for wheat production on duplex soils". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 887. http://dx.doi.org/10.1071/ea9920887.
Testo completoAbstract (sommario):
In this paper, we review literature on the fate of fertiliser nitrogen (N) applied to duplex soils in wheat-growing regions of southern Australia, and discuss the contribution of specific N transformations to N loss. Duplex soils are characterised by the presence of soil material, within the rooting depth of crops, that possess hydraulic conductivities that are lower than those of overlying material. Denitrification and the transport of nitrate below rooting depth of crops are thought to be the chief causes of loss of fertiliser N and to contribute to poor grain yields. Ammonia volatilisation could contribute also to N loss. The fate of fertiliser N commonly applied to wheat in southern Australia has largely been evaluated using budgeting procedures using l5N, a stable isotope of N. Results from studies in south-eastem Australia, using red-brown earths, indicate that between 10 and 40% of applied 15N can be lost irrespective of time of application to wheat. Denitrification is believed to be the chief cause of loss of l5N. Similar studies on yellow duplex soils in Western Australia have shown fertiliser N loss to range from 70% to no loss of the l5N applied. The exact cause of N loss in Western Australian studies is unclear. There was circumstantial evidence for ammonia loss from surface-applied urea, and evidence of leaching of nitrates from this and other ammoniumbased fertilisers. The role of denitrification has not been clarified in Western Australian studies. In the majority of studies, recovery of 15N in aboveground biomass exceeded 40% of that applied. In addition, between 17 and 48% of applied 15N, of which 10-15% may be in root material, has been recovered in the soil organic matter pool. The predominance of the denitrification process in south-eastern Australian soils, and the inability to improve the efficiency of utilisation of 15N by delaying the time of application to wheat underscores the importance of controlling the nitrification process using inhibitors. Management options for Western Australian soils are less clear. Some agronomic experiments have demonstrated the advantage of delaying the application of fertiliser N to wheat to improve the efficiency of its utilisation. There is also evidence which suggests that N should be applied early in the growth cycle to promote tiller development and thereby increase the potential for grain yield.
13
Cooke, JW, GW Ford, RG Dumsday e ST Willatt. "Effect of fallowing practices on the growth and yield of wheat in south-eastern Australia". Australian Journal of Experimental Agriculture 25, n. 3 (1985): 614. http://dx.doi.org/10.1071/ea9850614.
Testo completoAbstract (sommario):
The effects on crop establishment, crop development and the yield of wheat of two methods of fallow preparation, at each of three lengths of fallow were investigated over 5 years on red duplex and associated soils in north-central Victoria. The two methods of preparation were: scarifying, which involved the repeated use of a tined tillage implement; and herbicide application, which involved the repeated use of non-residual herbicides to control weeds during the fallow phase. The three lengths of fallow were winter, spring and autumn, which were approximately 10, 8 and 2 months respectively. Grain yield on the scarifier treatments was 0.26 t/ha greater (P<0.10) than on the herbicide treatments. Grain yield on winter fallow was 0.46 and 0.56 t/ha greater (Pt0.01) than on spring and autumn fallows, respectively. Crop yield was positively correlated (R2= 0.49) with soil nitrate determined at the time the crop was sown, but was independent of available soil water content determined at that time. Winter fallowing conserved 15 and 29 mm more water than did spring and autumn fallowing respectively, and mineralized 26 and 28 kg/ha more nitrogen than did spring and autumn fallows respectively. Crop establishment (No. of plants/m of row) on the herbicide treatment was 89% (P< 0.05) of that on the scarifier treatment, but this was not the reason for the reduced grain yield on the herbicide treatment. The lower yields were caused by depressed crop vigour (number of spikes/m of row) which in turn was largely a consequence of the inefficient uptake of nitrogen. The yield benefits of scarifying appear to reflect the importance of the initial two or three cultivations.
14
Syme, H., T. L. Botwright Acuña, D. Abrecht e L. J. Wade. "Nitrogen contributions in a windmill grass (Chloris truncata) - wheat (Triticum aestivum L.) system in south-western Australia". Soil Research 45, n. 8 (2007): 635. http://dx.doi.org/10.1071/sr07159.
Testo completoAbstract (sommario):
Chloris truncata, a perennial grass that is native to Australia, has potential as a short-lived summer pasture in rotation with wheat and other winter crops in the low to medium rainfall zone of south-western Australia. In this paper we examine the nitrogen contributions from a C. truncata–wheat system, with the expectation that C. truncata may take up nitrate which would otherwise be lost to leaching, for later release to the following wheat crop. In glasshouse experiments, residual soil nitrate in bare soil was available for uptake and growth of wheat, with a greater response when N was applied. In contrast, wheat grown on C. truncata stubble was mostly reliant on recently mineralised nitrogen, as the previous rotation had depleted the soil of nitrate. Shoot stubble of C. truncata provided sufficient mineralised nitrogen such that the uptake of nitrogen and biomass of wheat equalled those from bare soil. Wheat grown on root stubble of C. truncata had half the biomass production of that grown on either bare soil or shoot stubble, with root + shoot stubble intermediate. In a field trial undertaken at Bruce Rock in Western Australia, nitrogen release from C. truncata stubble at low to intermediate stubble densities increased tiller production, nitrogen uptake, and growth of wheat, but not at the highest N rate in this season, which received below-average rainfall in July. These results provide initial evidence concerning how a C. truncata–wheat system could improve the N balance of the farming system, by potentially reducing the leaching loss of nitrate in autumn, and then releasing mineralised N from stubble when needed by a following wheat crop. While these results require further confirmation, especially in the field, they raise exciting prospects for an improved agronomic system, with potential benefits to N balance, carrying capacity, yield stability, and groundwater discharge. The system requires further study to quantify these processes, and explore their implications.
15
Steiner, JL, RCG Smith, WS Meyer e JA Adeney. "Water use, foliage temperature and yield of irrigated wheat in south-eastern Australia". Australian Journal of Agricultural Research 36, n. 1 (1985): 1. http://dx.doi.org/10.1071/ar9850001.
Testo completoAbstract (sommario):
Quantification of the relationship between evapotranspiration (Et) and yield is important for the analysis of irrigation practices. Wheat (Triticum aestivum cv. Avocet) was grown at the CSIRO Centre for Irrigation Research, Griffith, N.S.W., in 1982 with treatments of no irrigation and irrigation at 40, 70, and 90% depletion of plant available soil water. Irrigation significantly affected total dry matter, grain yield, and the yield components of number of heads per m2, number of grains per head, mass of individual grains, and harvest index. Plot grain yields, varying from 1.7 to 8.3 t ha-1, were closely related to dry matter at anthesis (r = 0.94) and number of grains per m2 (r = 0.99), indicating the importance of early growth on final yield. Regression analysis showed a significant (P < 0.01) linear relationship between Et and total or grain dry matter. The relationship of Et (mm) to grain yield (Y) (t ha-1) was described by Y = -2.010 + 0.016Et. Foliage temperatures were monitored at noon and showed promise as plant stress indicators. The mean differential between foliage and air temperature from jointing to late grain fill showed a strong negative linear relationship to grain numbers per unit soil area (r2 = 0.88) and to final yield (r2 = 0.86).
16
Acuña, Tina Botwright, Geoff Dean e Penny Riffkin. "Constraints to achieving high potential yield of wheat in a temperate, high-rainfall environment in south-eastern Australia". Crop and Pasture Science 62, n. 2 (2011): 125. http://dx.doi.org/10.1071/cp10271.
Testo completoAbstract (sommario):
Average wheat yields in the high-rainfall zone (HRZ) of southern Australia are predicted to be around 10 t ha–1, yet most regions fall short through a lack of locally adapted cultivars or abiotic stress that constrains yield. Wheat yields in Tasmania can be variable but have exceeded this potential yield in some field trials and have thus approached that of other traditionally high-yielding HRZ environments such as northern Europe. A contributing factor to high wheat yields in Tasmania is the cool-temperate climate, which tends not to have extremes in temperature (cold, heat) as may be experienced in HRZ environments elsewhere. Hence an understanding of crop growth, development and yield of wheat of locally adapted wheat cultivars in Tasmania may improve our understanding of the basis of yield formation in other HRZ in Australia. This was evaluated by conducting an analysis for adaptive response of grain yield in 10 wheat genotypes to a range of 14 environments that were favourable for wheat production or experienced constraints to growth. Crop growth and yield formation was then examined in detail for all or a subset of these genotypes in three field trials with contrasting environments, two of which included a time of sowing (TOS) treatment. Environment accounted for around 90% of the sum of squares (SS) in the multi-site analysis of yield. Six environment groups were identified using cluster analysis, two of which were clearly separated in response to frost at flowering or putative biotic stress, which constrained yield to 1.8 and 6.8 t ha–1, respectively. Waterlogging was also a significant abiotic stress in one of the TOS field trials. The late-flowering cultivar Tennant had the highest yield in the presence of waterlogging and by avoiding frost at flowering, although it suffered a yield penalty of 35 and 66%, respectively, compared with the average across environments. The highest-yielding genotypes averaged 8 t ha–1 across environments and included Alberic, the breeding line K37.18 and the new release Revenue. In the detailed experiments on crop growth and development, high grain yields of 10 t ha–1 in Mackellar appeared to be due to increased grains ear–1, resistance to barley yellow dwarf virus and possibly higher radiation-use efficiency, although the latter needs to be confirmed. There was little genotype × environment interaction for grain yield, hence wheat breeders can have a relatively high level of confidence that genetic material with high yield potential should rank consistently across Tasmanian environments. Results presented in the paper will be useful in developing management and breeding strategies to increase potential yield across the HRZ of southern Australia.
17
McDonald, G. K., J. D. Taylor, A. Verbyla e H. Kuchel. "Assessing the importance of subsoil constraints to yield of wheat and its implications for yield improvement". Crop and Pasture Science 63, n. 12 (2012): 1043. http://dx.doi.org/10.1071/cp12244.
Testo completoAbstract (sommario):
Many of the soils in the Australian cereal belt have subsoils with chemical and physical properties that restrict root growth, which limits water use and yield. On alkaline sodic soils salinity, high pH, high available boron (B), deficiencies of zinc (Zn) and manganese (Mn) and high soil strength occur commonly and aluminium (Al) toxicity restricts root growth on acid soils. While the effects of individual subsoil constraints have been studied there is some debate about the relative importance to yield of the different soil stresses across the region. To address this issue yield variation among a set of 52 varieties of bread wheat was analysed using yield data from 233 trials conducted over 12 years. The trials were conducted in all mainland States but the majority were in South Australia and Western Australia. Each variety was characterised for its response to high B, high pH, Al toxicity, salinity, deficiencies in Zn and Mn and resistance to root lesion nematode (Pratylenchus neglectus), root growth through strong soil, seminal root angle, carbon isotope discrimination (CID) and maturity. This data was then used to examine the contribution of each trait to the genetic variation in yield at each of the 233 trials. The contribution of a specific trait to the genetic variation in yield at each site was used to infer the importance of a particular constraint to yield at that site. Of the traits linked to soil constraints, salinity tolerance, (measured by Na+ exclusion) was most often associated with genetic variation in grain yield (34% of all experiments), followed by tolerance to high Al (26%) and B tolerance (21%). Tolerance to low Zn and Mn were not consistently associated with yield variation. However, maturity was the trait that was most frequently associated with yield variation (51% of experiments), although the relative importance of early and late flowering varied among the States. Yield variation was largely associated with early flowering in Western Australia and the relative importance of late flowering increased as trials moved eastward into South Australia, Victoria and New South Wales. Narrow, rather than wide, seminal root angle was more commonly associated with high yield (25% of sites) and there was little evidence of any regional pattern in the importance of root angle. CID was important in 18% of trials with a low CID being most commonly associated with high yields. The yield advantage at sites where a trait contributed significantly to yield variation ranged from ~15% for Na+ exclusion and B tolerance to 4% for tolerance to high pH. The analysis has provided an assessment of the relative importance of a range of traits associated with adaptation to environments where subsoil constraints are likely to affect yield and has indicated patterns in the importance and effects of these traits that may be linked to regional variation in rainfall and soils.
18
Sloane, D. H. G., G. S. Gill e G. K. McDonald. "The impact of agronomic manipulation of early vigour in wheat on growth and yield in South Australia". Australian Journal of Agricultural Research 55, n. 6 (2004): 645. http://dx.doi.org/10.1071/ar03170.
Testo completoAbstract (sommario):
The initial growth of wheat crops can be manipulated either by agronomic means, such as by increasing inputs of seed and fertiliser, or by genetic improvement in early vigour. Cultivars of wheat with enhanced early vigour are still not commercially available and so a series of experiments was conducted to examine the impact of increasing initial dry matter production and leaf area index by increasing sowing and nitrogen (N) rates on grain yield. Increasing the sowing rate and amount of N fertiliser applied significantly increased early dry matter production and leaf area, with the largest responses occurring when sowing rate was increased. However, there was little effect on yield. The increases in dry matter production that occurred early in the season as a result of the additional inputs diminished as the season progressed. Yield responses to the additional inputs depended on the seasonal distribution of rainfall and in particular the rainfall received in August and September when grains per m2 were being determined. Consequently, yield responses were affected more by changes in grain per m2 than by changes in grain weight, and the benefits of the improvements in early vigour were only realised when moisture availability was high during the immediate pre-anthesis and early grain filling period of growth. High rainfall in August and September increased the responses in grains per m2 from increased sowing rate and N. When N was used to increase early growth, the response in grain weight was negatively correlated with increasing pre-anthesis rainfall, but there was no relationship with rainfall when sowing rate was used to increase early growth. This effect of N, in which responses in pre-anthesis growth were offset by reductions in grain weight, is consistent with the ‘haying-off’ effect that can occur with applications of N. The results showed that increasing early vigour by increased inputs of seed and N fertiliser produce variable responses in grain yield. While improvements in vegetative growth occurred, the realisation of these gains only happened when rainfall in August and September was adequate. Basing improvements in early vigour only on agronomic manipulation appears to be associated with a relatively high level of risk, as it is difficult to control the balance between vegetative growth and the availability of soil moisture. Alternatively, the data suggest that the levels of early vigour under current agronomic practices may be adequate (>50 g/m2 shoot DM at late tillering stage), and only marginal gains may be achieved by promoting early growth by additional inputs.
19
Humphries, A. W., R. A. Latta, G. C. Auricht e W. D. Bellotti. "Over-cropping lucerne with wheat: effect of lucerne winter activity on total plant production and water use of the mixture, and wheat yield and quality". Australian Journal of Agricultural Research 55, n. 8 (2004): 839. http://dx.doi.org/10.1071/ar03250.
Testo completoAbstract (sommario):
Two field experiments in southern Australia investigated a farming system of over-cropping wheat (Triticum aestivum L.) into established lucerne (Medicago sativa subsp. L.) varieties of different winter activity ratings. The study was completed at Roseworthy, South Australia, and Katanning, Western Australia, between August 2000 and May 2003 in seasons receiving below average and average rainfall. Comparative lucerne persistence and biomass, wheat biomass, grain yield and protein contents, and soil water contents were measured. Wheat grain yield was reduced by 13–63% by over-cropping lucerne compared with wheat monoculture. Winter-dormant lucerne (winter activity Classes 0.5 and 2) reduced the yield penalty compared with winter-active varieties (Classes 6 and 10) in 2 of the 4 evaluations. The positive response to applying N at sowing in the second year of over-cropping wheat at Katanning was greatest in the most winter-dormant lucerne treatment (winter activity 0.5). Soil water contents were similar under the lucerne/wheat over-cropping and lucerne monoculture treatments irrespective of lucerne winter activity. Deficits of up to 43 mm at Roseworthy and 88 mm at Katanning were measured in the 0–200-cm soil profile at the start of the third summer of the study. The study shows that it can be more efficient in terms of land area to over-crop wheat into lucerne than to grow monocultures on separate parcels of land akin to phase farming. The improved productivity of over-cropping is associated with the separation of growth patterns of winter wheat and summer-active lucerne. This farming system offers great potential for improving sustainability and productivity in southern Australian cropping rotations.
20
Borger, Catherine P. D., Abul Hashem e Shahab Pathan. "Manipulating Crop Row Orientation to Suppress Weeds and Increase Crop Yield". Weed Science 58, n. 2 (giugno 2010): 174–78. http://dx.doi.org/10.1614/ws-09-094.1.
Testo completoAbstract (sommario):
Crop rows oriented at a right angle to sunlight direction (i.e., east–west within the winter cropping system in Western Australia) may suppress weed growth through greater shading of weeds in the interrow spaces. This was investigated in the districts of Merredin and Beverley, Western Australian (latitudes of 31° and 32°S) from 2002 to 2005 (four trials). Winter grain crops (wheat, barley, canola, lupines, and field peas) were sown in an east–west or north–south orientation. Within wheat and barley crops oriented east–west, weed biomass (averaged throughout all trials) was reduced by 51 and 37%, and grain yield increased by 24 and 26% (compared with crops oriented north–south). This reduction in weed biomass and increase in crop yield likely resulted from the increased light (photosynthetically active radiation) interception by crops oriented east–west (i.e., light interception by the crop canopy as opposed to the weed canopy was 28 and 18% greater in wheat and barley crops oriented east–west, compared with north–south crops). There was no consistent effect of crop row orientation in the canola, field pea, and lupine crops. It appears that manipulation of crop row orientation in wheat and barley is a useful weed-control technique that has few negative effects on the farming system (i.e., does not cost anything to implement and is more environmentally friendly than chemical weed control).
21
Yunusa, I. A. M., W. D. Bellotti, A. D. Moore, M. E. Probert, J. A. Baldock e S. M. Miyan. "An exploratory evaluation of APSIM to simulate growth and yield processes for winter cereals in rotation systems in South Australia". Australian Journal of Experimental Agriculture 44, n. 8 (2004): 787. http://dx.doi.org/10.1071/ea03121.
Testo completoAbstract (sommario):
The Agricultural Production Systems Simulator (APSIM) suite of models was used to predict dynamics in water and nitrogen in soil, as well as the growth and yield of sequential crops of wheat and barley in pasture–wheat–barley rotations, between 1995 and 1997 at Roseworthy, South Australia. The NWHEAT model satisfactorily predicted above-ground dry matter, leaf area index and grain yields for both crops in rotations with either grassy (Grass) or medic (Medic) pastures, including the lack of significant response of yield to nitrogen fertiliser applied to wheat at sowing. Simulation data for soil water, from SOILWAT2, was consistent with measured data. Simulation with SOILN2, however, largely underestimated soil nitrogen, due to excessive uptake by the simulated wheat during the season when nitrogen was abundant and water supply readily available. Thus, the soil nitrate had to be reset at sowing for the following barley crop; simulated soil nitrate agreed with the measured data in this season when this nutrient was low. For most variables of crop growth and soil water, the simulated data were mostly within 2 standard errors of the measured means. Prediction of grain protein was underestimated in all cases, including where nitrogen in the shoot was overestimated. This was possibly due to inadequate remobilisation of nitrogen from the straw and roots to the grain by the simulated crop. A satisfactory prediction of dry matter, grain yield and grain weight was obtained for wheat when the models were extended to other trials at Roseworthy (Lower North), Minnipa (Upper Eyre Peninsula) and Wunkar (Murray Mallee), based on limited soil data. Long-term simulations of wheat yields showed that, with early sowing in the Lower North, median wheat yield increased by 50 kg/ha for every kilogram of nitrogen applied at sowing, up to a maximum nitrogen rate of 50 kg/ha. In the drier districts of the Upper Eyre Peninsula and the Murray Mallee, nitrogen fertiliser of no more than 25 kg/ha, applied at sowing, was enough to achieve yield benefits in any given season. At these drier sites, crop failures occurred in 5% (Upper Eyre Peninsula) and 10% (Murray Mallee) of the seasons simulated. Median sowing dates from these simulations were 15 May for the Lower North, 30 May for the Upper Eyre Peninsula and 24 May for Murray Mallee. This suggested that sowing could be conducted at least a week earlier than currently practised in the 3 environments. This study demonstrated the capability of APSIM to predict growth and grain yield of wheat and barley, as well as the associated dynamics of soil water in the main cereal belts of South Australia.
22
Ward, P. R., J. A. Palta e H. A. Waddell. "Root and shoot growth by seedlings of annual and perennial medic, and annual and perennial wheat". Crop and Pasture Science 62, n. 5 (2011): 367. http://dx.doi.org/10.1071/cp10392.
Testo completoAbstract (sommario):
Perennial plants such as lucerne are now widely acknowledged as one means of controlling the expansion of dryland salinity in southern Australia. However, their inclusion in farming systems is limited by poor seedling vigour, thought to be associated with greater allocation of biomass to perennating organs in roots, and poor adaptation to some soils and climatic conditions in south-western Australia. For this reason, interest in other perennial options such as perennial wheat is increasing. In this research we compared early (29-day) seedling growth and root : shoot ratios for annual and perennial medics (Medicago truncatula and M. sativa), and for annual and perennial wheat (Triticum aestivum and Triticum × Agropyron cross). For the medics, the annual reached the 6-leaf stage after 29 days and produced more root and shoot biomass than lucerne (4-leaf stage after 29 days), but there was no difference in root : shoot ratio or depth of root growth. For wheat, there were no differences in root growth, shoot growth, or root : shoot ratio between the annual and perennial lines (Zadoks growth stages 23 and 21, respectively, after 29 days). The poor competitive performance of M. sativa seedlings relative to M. truncatula was not due to changed allocation of biomass to shoots, but was related more to seed size (2.7 and 5.0 mg, respectively). This does not seem to occur to the same extent in perennial wheat lines, suggesting that their seedling performance may be more competitive.
23
Sprigg, Hayden, Robert Belford, Steve Milroy, Sarita Jane Bennett e David Bowran. "Adaptations for growing wheat in the drying climate of Western Australia". Crop and Pasture Science 65, n. 7 (2014): 627. http://dx.doi.org/10.1071/cp13352.
Testo completoAbstract (sommario):
This study investigated the effects of predicted changes in rainfall distribution in marginal (≤325 mm annual rainfall) parts of the south-west Australian wheatbelt and options for management and adaptation of the wheat crop. Field experiments with rain-out shelters and irrigation were conducted in 2008 and 2009 to investigate the interactions of rainfall distribution, row spacing, genotype and timing of nitrogen application on growth, water use and grain yield of spring wheat. Water storage before seeding showed potential to maintain or increase yields despite lower in-season rainfall. Widening row spacing reduced biomass and slowed water use but did not increase grain yield, because of increased soil evaporation and water left in the soil at crop maturity. The Agricultural Production Systems Simulator (APSIM) wheat model was used to investigate the effects of recent and projected climate change on yield in relation to row spacing, phenology and nitrogen. Two climate-change scenarios were applied to historical climatic data to create two plausible future climates (‘optimistic’ and ‘pessimistic’) for the year 2030. None of the strategies tested increased wheat yield under the predicted climate scenarios. Simulated yields at wider row spacings were consistently lower due to insufficient biomass, increased soil evaporation and the inability of the crop to use all of the available water before maturity. Simulated yields of short-season genotypes were always greater than yields of longer season genotypes. Nitrogen regimes had little effect in this study. This study points to several genotypic traits that could improve the performance of wheat grown at wider row spacings. These include early vigour to reduce soil evaporation and increase competition with weeds, greater tillering/biomass to reduce limitation by sink size, and a vigorous root system with appropriate lateral spread and growth to depth to access available soil water.
24
Kitchen, J. L., G. K. McDonald, K. W. Shepherd, M. F. Lorimer e R. D. Graham. "Comparing wheat grown in South Australian organic and conventional farming systems. 1. Growth and grain yield". Australian Journal of Agricultural Research 54, n. 9 (2003): 889. http://dx.doi.org/10.1071/ar03039.
Testo completoAbstract (sommario):
Organic farming standards do not allow addition of water-soluble fertilisers and therefore it is likely that growth of organically grown crops will be limited by nutrient availability. However, in marginal rainfall conditions, when growth in conventional systems is limited by water availability, yields of organically grown crops could be comparable with those conventionally grown. Similarly, micronutrient-efficient plant varieties could be expected to perform comparatively better under organic farming conditions than they do in conventional systems, when compared with micronutrient-inefficient varieties.In this study, biomass and grain production of wheat from certified organic farming systems were compared with neighbouring conventional farming systems in 'across the fence' field trials in 1 moderate and 2 marginal rainfall areas of South Australia. Wheat varieties compared included 2 old wheat varieties developed under relatively low-input conditions (Baroota Wonder and Dirk-48) and varieties shown to be micronutrient-efficient (Janz and Trident) and inefficient (Yallaroi).The organic farming systems produced significantly less biomass than the conventional farming systems at late tillering in both the moderate and marginal rainfall areas. Grain yield was variable, but significantly lower in the organic farming system for 11 of the 14 comparisons. None of the varieties showed an adaptive advantage for 1 farming system over the other. The relative yield of the organic system, compared with the conventional system, was not associated with rainfall.
25
Zhang, Heping, Neil C. Turner, Michael L. Poole e Senthold Asseng. "High ear number is key to achieving high wheat yields in the high-rainfall zone of south-western Australia". Australian Journal of Agricultural Research 58, n. 1 (2007): 21. http://dx.doi.org/10.1071/ar05170.
Testo completoAbstract (sommario):
The growth and yield of spring wheat (Triticum aestivum L.) were examined to determine the actual and potential yields of wheat at a site in the high rainfall zone (HRZ) of south-western Australia. Spring wheat achieved yields of 5.5−5.9 t/ha in 2001 and 2003 when subsurface waterlogging was absent or minimal. These yields were close to the estimated potential, indicating that a high yield potential is achievable. In 2002 when subsurface waterlogging occurred early in the growing season, the yield of spring wheat was 40% lower than the estimated potential. The yield of wheat was significantly correlated with the number of ears per m2 (r2 = 0.81) and dry matter at anthesis (r2 = 0.73). To achieve 5–6 t/ha of yield of wheat in the HRZ, 450–550 ears per m2 and 10–11 t/ha dry matter at anthesis should be targetted. Attaining such a level of dry matter at anthesis did not have a negative effect on dry-matter accumulation during the post-anthesis period. The harvest index (0.36−0.38) of spring wheat was comparable with that in drier parts of south-western Australia, but relatively low given the high rainfall and the long growing season. This relatively low harvest index indicates that the selected cultivar bred for the low- and medium-rainfall zone in this study, when grown in the HRZ, may have genetic limitations in sink capacity arising from the low grain number per ear. We suggest that the yield of wheat in the HRZ may be increased further by increasing the sink capacity by increasing the number of grains per ear.
26
Bramley, Helen, Stephen D. Tyerman, David W. Turner e Neil C. Turner. "Root growth of lupins is more sensitive to waterlogging than wheat". Functional Plant Biology 38, n. 11 (2011): 910. http://dx.doi.org/10.1071/fp11148.
Testo completoAbstract (sommario):
In south-west Australia, winter grown crops such as wheat and lupin often experience transient waterlogging during periods of high rainfall. Wheat is believed to be more tolerant to waterlogging than lupins, but until now no direct comparisons have been made. The effects of waterlogging on root growth and anatomy were compared in wheat (Triticum aestivum L.), narrow-leafed lupin (Lupinus angustifolius L.) and yellow lupin (Lupinus luteus L.) using 1 m deep root observation chambers. Seven days of waterlogging stopped root growth in all species, except some nodal root development in wheat. Roots of both lupin species died back progressively from the tips while waterlogged. After draining the chambers, wheat root growth resumed in the apical region at a faster rate than well-drained plants, so that total root length was similar in waterlogged and well-drained plants at the end of the experiment. Root growth in yellow lupin resumed in the basal region, but was insufficient to compensate for root death during waterlogging. Narrow-leafed lupin roots did not recover; they continued to deteriorate. The survival and recovery of roots in response to waterlogging was related to anatomical features that influence internal oxygen deficiency and root hydraulic properties.
27
Nuttall, J. G., R. D. Armstrong e D. J. Connor. "Early growth of wheat is more sensitive to salinity than boron at levels encountered in alkaline soils of south-eastern Australia". Australian Journal of Experimental Agriculture 46, n. 11 (2006): 1507. http://dx.doi.org/10.1071/ea04264.
Testo completoAbstract (sommario):
The early vegetative growth of 3 wheat (Triticum aestivum L.) cultivars, Frame, BT Schomburgk and Schomburgk, was evaluated over a range of soil salinity and soluble boron (B) concentrations in pots. Additions of boric acid and mixed salts to a sandy clay soil produced extractable B levels of 2, 13, 24, 51 and 129 mg/kg and salinities (ECe) of 0.8, 8, 15, 23 and 29 dS/m. In both cases, the levels produced in the first 4 treatments corresponded well with those commonly observed in subsoils of the southern Mallee. Within the ranges tested, wheat cultivars had relatively greater tolerance to B toxicity than to salinity. Significant differences in tolerance also existed among the 3 cultivars for B, but not for mixed salts. For Frame, BT Schomburgk and Schomburgk, critical concentrations of soil soluble B were estimated at 53, 32 and 27 mg/kg, respectively, in the absence of salinity. For salinity tolerance, the 3 wheat cultivars could all tolerate an ECe up to about 9 dS/m equally well. In combination with B, salinity still dictated overall response in growth with the interactive effect of B being to increase sensitivity of plants at low levels of salt. Shoot B concentrations in Frame ranged from 15 to 947 mg/kg for increasing soil B treatments but these responses did not correlate well with growth reduction. Shoot Na contents ranged from 0.02 to 0.58%, but was not a reliable indicator of Na+ toxicity due to interactive effects of B: increasing B reduced Na+ uptake. Generally, differences in B tolerance among the cultivars highlighted the existence of genetic variation in adaptation of wheat to high levels of soil B; however, this does not appear to be the case for salt tolerance in wheat. Because high levels of B and salt usually co-exist in the field, plant tolerance to these limitations need to exist in combination.
28
Sprague, S. J., J. A. Kirkegaard, H. Dove, J. M. Graham, S. E. McDonald e W. M. Kelman. "Integrating dual-purpose wheat and canola into high-rainfall livestock systems in south-eastern Australia. 1. Crop forage and grain yield". Crop and Pasture Science 66, n. 4 (2015): 365. http://dx.doi.org/10.1071/cp14200.
Testo completoAbstract (sommario):
The development of guidelines for successful dual-purpose (graze and grain) use of wheat and canola in Australia’s high-rainfall zones (HRZ) has mostly emerged from separate wheat- and canola-focused research. Less attention has been placed on the benefits of integrating dual-purpose wheat and canola into pasture-based grazing enterprises. We conducted a farming systems experiment during 2010–11 to evaluate the benefits of integrating wheat and canola as dual-purpose crops into a pasture-based grazing system in Australia’s south-eastern tablelands. We compared forage production and grain yield in three separate crop–livestock systems in which the sheep grazed long-season wheat, winter canola or a combination of these. Initial growth rates were higher in early-autumn-sown canola than wheat in 2010, but were much lower although similar in both crops in 2011. Significant forage was available from both canola (3.1–3.4 t ha–1) and wheat (2.3–2.4 t ha–1) at the onset of grazing, but winter growth rates of wheat were higher than those of canola, leading to increased sheep grazing days (SGD). In the favourable 2010 season, dual-purpose wheat and canola separately provided 2393 and 2095 SGD ha–1, and yielded 5.0 and 1.9 t ha–1 grain, respectively, with an apparent nitrogen limitation in canola. In the drier season of 2011, grazing was reduced to 1455 and 735 SGD ha–1 in wheat and canola, respectively. Wheat yield was reduced from 5.9 to 5.4 t ha–1 grain by grazing, whereas canola yield was unaffected (3.6 t ha–1). In both years, grazing did not affect harvest index or oil content of canola, but harvest index was higher in grazed wheat crops. The yield of wheat and canola crops grazed in sequence did not differ from yield in treatments where animals grazed only a single crop, but the total overall grazing window when crops were grazed sequentially increased by 1054 and 618 SGD ha–1 in wheat, and by 1352 and 1338 SGD ha–1 in canola in 2010 and 2011, respectively. The major benefits of including crops that can be grazed sequentially were the widening of the grazing window and other operational windows (sowing, harvest), along with the rotational benefits for wheat by including canola in the system. Additional benefits to pastures may include eliminating the need to re-sow, because a more productive pasture composition is maintained under lower grazing pressure while stock are on crops, and reduced weed invasion. The commercial availability of new, herbicide-tolerant winter canola varieties provides significant opportunities to underpin the performance of dual-purpose crop sequences on mixed farms in the high-rainfall zone.
29
Bell, Lindsay W., Julianne M. Lilley, James R. Hunt e John A. Kirkegaard. "Corrigendum to: Optimising grain yield and grazing potential of crops across Australia’s high-rainfall zone: a simulation analysis. 1. Wheat". Crop and Pasture Science 67, n. 1 (2016): 117. http://dx.doi.org/10.1071/cp14230_co.
Testo completoAbstract (sommario):
Interest is growing in the potential to expand cropping into Australia's high-rainfall zone (HRZ). Dual-purpose crops are suited to the longer growing seasons in these environments to provide both early grazing for livestock and later regrow to produce grain. Grain yield and grazing potential of wheats of four different maturity types were simulated over 50 years at 13 locations across Australia's HRZ, and sowing date, nitrogen (N) availability and crop density effects were explored. Potential grazing days on wheat were obtained by simulating sheep grazing crops to Zadoks growth stage Z30 at 25 dry sheep equivalents (DSE)/ha. Optimal sowing dates for each maturity type at each location were matched to the flowering window during which risk of frost and heat stress was lowest. Overall, we found significant national potential for dual-purpose use of winter wheat cultivars across Australia's HRZ, with opportunities identified in all regions. Simulated mean wheat yields exceeded 6t/ha at most locations, with highest mean grain yields (8–10t/ha) in southern Victoria, and lower yields (5–7t/ha) in the south-west of Western Australia (WA) and central and northern New South Wales (NSW). Highest grazing days were from winter cultivars sown early (March–mid-April), which could provide 1700–3000 DSE-days/ha of grazing across HRZ locations; this was 2–3 times higher than could be obtained from grazing spring cultivars (200–800 DSE-days/ha). Sowing date was critical to maximise both grazing and grain yield potential from winter cultivars; each 1-week delay in sowing after 8 March reduced grazing by 200–250 DSE-days/ha and grain yield by 0.45t/ha. However, in Mediterranean climates, a lower frequency of early sowing opportunities before mid-April (
30
Nuttall, J. G., G. J. O'Leary, N. Khimashia, S. Asseng, G. Fitzgerald e R. Norton. "‘Haying-off' in wheat is predicted to increase under a future climate in south-eastern Australia". Crop and Pasture Science 63, n. 7 (2012): 593. http://dx.doi.org/10.1071/cp12062.
Testo completoAbstract (sommario):
Under a future climate for south-eastern Australia there is the likelihood that the net effect of elevated CO2, (eCO2) lower growing-season rainfall and high temperature will increase haying-off thus limit production of rain-fed wheat crops. We used a modelling approach to assess the impact of an expected future climate on wheat growth across four cropping regions in Victoria. A wheat model, APSIM-Nwheat, was performance tested against three datasets: (i) a field experiment at Wagga Wagga, NSW; (ii) the Australian Grains Free Air Carbon dioxide Enrichment (AGFACE) experiment at Horsham, Victoria; and (iii) a broad-acre wheat crop survey in western Victoria. For down-scaled climate predictions for 2050, average rainfall during October, which coincides with crop flowering, decreased by 32, 29, 26, and 18% for the semiarid regions of the northern Mallee, the southern Mallee, Wimmera, and higher rainfall zone, (HRZ) in the Western District, respectively. Mean annual minimum and maximum temperature over the four regions increased by 1.9 and 2.2°C, respectively. A pair-wise comparison of the yield/anthesis biomass ratio across climate scenarios, used for assessing haying-off response, revealed that there was a 39, 49 and 47% increase in frequency of haying-off for the northern Mallee, southern Mallee and Wimmera, respectively, when crops were sown near the historically optimal time (1 June). This translated to a reduction in yield from 1.6 to 1.4 t/ha (northern Mallee), 2.5 to 2.2 t/ha (southern Mallee) and 3.7 to 3.6 t/ha (Wimmera) under a future climate. Sowing earlier (1 May) reduced the impact of a future climate on haying-off where decreases in yield/anthesis biomass ratio were 24, 28 and 23% for the respective regions. Heavy textured soils exacerbated the impact of a future climate on haying-off within the Wimmera. Within the HRZ of the Western District crops were not water limited during grain filling, so no evidence of haying-off existed where average crop yields increased by 5% under a future climate (6.4–6.7 t/ha). The simulated effect of eCO2 alone (FACE conditions) increased average yields from 18 to 38% for the semiarid regions but not in the HRZ and there was no evidence of haying-off. For a future climate, sowing earlier limited the impact of hotter, drier conditions by reducing pre-anthesis plant growth, grain set and resource depletion and shifted the grain-filling phase earlier, which reduced the impact of future drier conditions in spring. Overall, earlier sowing in a Mediterranean-type environment appears to be an important management strategy for maintaining wheat production in semiarid cropping regions into the future, although this has to be balanced with other agronomic considerations such as frost risk and weed control.
31
Roget, DK. "Decline in root rot (Rhizoctonia solani AG-8) in wheat in a tillage and rotation experiment at Avon, South Australia". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 1009. http://dx.doi.org/10.1071/ea9951009.
Testo completoAbstract (sommario):
Studies of a tillage x rotation field experiment begun in 1978 at Avon, South Australia, have demonstrated a decline in rhizoctonia root rot of wheat. In direct-drilled treatments the severity of rhizoctonia root rot culminated in 1983, with patches of poor plant growth accounting for up to 46% of the crop area, and then declined to negligible levels by 1990. Disease severity was significantly less in cultivated than direct-drilled treatments. In cultivated treatments the onset of decline was more difficult to determine, but by 1990 there was negligible rhizoctonia root rot in either tillage treatment, with no increase in disease from 1990 to 1994. Decline in rhizoctonia root rot occurred largely independent of rotation, although there were significant differences in root damage and patch area between rotations, with disease generally being more severe in wheat following pasture than following peas, medic, or wheat. When inoculum of R. solani was added to soil collected from the experimental site in 1985, wheat grown in soil from direct-drilled plots had significantly less disease than wheat grown in soil from cultivated treatments, indicating a possible development of suppression.
32
Zhang, Heping, Neil C. Turner e Michael L. Poole. "Yield of wheat and canola in the high rainfall zone of south-western Australia in years with and without a transient perched water table". Australian Journal of Agricultural Research 55, n. 4 (2004): 461. http://dx.doi.org/10.1071/ar03122.
Testo completoAbstract (sommario):
The yields of wheat and canola in 2 successive years with and without the development of a perched watertable were compared in the high rainfall zone of south-western Australia. In 2001, no perched watertable was observed and wheat and canola yields were close to their estimated potentials. In 2002, a perched watertable developed at less than 30 cm below the soil surface for more than 8 days and at less than 50 cm below the soil surface for at least 30 days at the tillering stage of wheat and at the rosette stage of canola. The air-filled porosity of the soil fell below the critical value of 10% at 10 and 30 cm depth for about 40 days. This reduced the maximum leaf area index of canola by 46% and of wheat by 30%, and reduced the shoot dry matter of wheat at flowering by 27% and by 40% at podding in canola compared with those in 2001. The growth of the wheat roots was constrained at depths from 50-90 cm from the soil surface in 2002 compared with 2001. However, the roots of canola and wheat were able to grow to at least 1.4 m in both 2001 and 2002. In both years, a much higher proportion (>10%) of roots was present in the clay subsoil compared with previous reports in south-western Australia and enabled the crops to utilise a greater amount of water from the clay subsoil. The wheat yield in 2002 was 37% lower than in 2001 and well below the potential, largely as a result of a reduced tiller number per plant and ears per unit area. Despite the greater reduction in dry matter in canola than in wheat in 2002, the seed yield of canola was 17% higher in 2002 than in 2001. Canola, an indeterminate crop, was able to respond to the late rain that occurred in 2002 compared with 2001 and produced a significantly higher seed number per unit area. In 2002, grain size in wheat was 25% larger than in 2001, but this increase was insufficient to compensate for the yield loss resulting from the fewer ears per unit area. It is concluded that early transient perched watertable induced subsurface waterlogging, and that the subsurface waterlogging can be a major constraint to crop growth in the high rainfall region of southwestern Australia, and that reducing waterlogging could be a key to achieving higher crop production.
33
Officer, S. J., V. M. Dunbabin, R. D. Armstrong, R. M. Norton e G. A. Kearney. "Wheat roots proliferate in response to nitrogen and phosphorus fertilisers in Sodosol and Vertosol soils of south-eastern Australia". Soil Research 47, n. 1 (2009): 91. http://dx.doi.org/10.1071/sr08089.
Testo completoAbstract (sommario):
Root growth responses to separately placed of bands of N and P fertiliser were examined at the 3-leaf (GS13) and stem extension growth stages (GS30) for wheat (Triticum aestivum L. cv. Yitpi) growing in 2 major alkaline soil types from the rainfed (375–420 mm) grain production regions of south-eastern Australia. Intact cores of a Sodosol and a Vertosol were destructively sampled and changes in root length density (RLD) and root diameter distribution within the soil profile were examined using restricted maximum likelihood analysis and principal component analysis, respectively. At GS13, RLD increased in the Vertosol when only P was applied, although there was no shoot growth response. The root response to P consisted of a spatially generalised increase in RLD, rather than a specific increase in the vicinity of the P fertiliser band. There was a substantially greater, but still generalised, increase in RLD in the Vertosol when both N and P fertiliser were applied, although there was no response to N fertiliser (without P). The distribution of root length in diameter classes changed with depth in the profile at GS13 but was otherwise similar, regardless of soil types and fertiliser treatment. The root responses to fertiliser at GS30 also consisted of a generalised proliferation of RLD in the topsoil, with no detectable fertiliser-specific changes in the location or structure of the root system. Shoot and root growth increased to a similar level at GS30 when plants were supplied with N, irrespective of P, and root diameter distributions were again insensitive to fertiliser treatment. Plants responded to N by increasing the RLD of relatively fine roots (100–250 μm), which was a P style of acquisition strategy that was possibly triggered by moisture limitations. Consequently, the root responses to fertiliser under realistic semi-arid conditions did not follow expectations based on nutrient acquisition studies. Instead, wheat plants responded to N or P fertiliser with a generalised proliferation of fine roots, apparently to better compete for finite water and nutrients.
34
Pankhurst, CE, HJ McDonald e BG Hawke. "Influence of soil-water matric potential on the control of Pythium root infection of wheat with metalaxyl in two contrasting soils of South Australia". Australian Journal of Experimental Agriculture 35, n. 5 (1995): 603. http://dx.doi.org/10.1071/ea9950603.
Testo completoAbstract (sommario):
Under prevailing climatic conditions, treatment of winter-sown wheat with metalaxyl (seed dressing, granule, or soil drench applications) significantly limited seed infection by Pythium species but did not give a significant yield response in separate field trials conducted on 2 contrasting soil types in South Australia. However, following irrigation of trial plots (which raised the soil-water matric potential from about -0.09 MPa to -0.02 MPa) during the first 3 weeks of wheat growth in 1989, metalaxyl granule treatment was effective in limiting seed and root infection by the 2 dominant Pythium species present, P. irregulare and P. echinulatum, and gave a significant increase in grain yield on both soil types. This effect of soil-water matric potential was confirmed in growth cabinet experiments in which metalaxyl was shown to be more effective in controlling infection of wheat by P. irregulare in both soil types when the soil-water matric potential was maintained at -0.02 MPa than at a soil-water matric potential of -0.1 MPa.
35
Browne, Nicholas, e Bikal Pokharel. "South Australia's power sector: renewables, batteries and the future role of gas". APPEA Journal 58, n. 2 (2018): 505. http://dx.doi.org/10.1071/aj17063.
Testo completoAbstract (sommario):
The South Australia experience is noteworthy in a global power mix set to increasingly shift to renewable energy. The rapid growth of renewables raises intermittency challenges and has already changed the power mix with coal phased out and gas utilisation reduced. However, despite this reduction, gas still remains the most important way to ensure uninterrupted power supply. Meanwhile, South Australia is experimenting with numerous new technologies, in addition to reintroducing diesel generation, in an attempt to ensure security of power supply. Currently, these technologies are not economic compared to gas. Looking ahead South Australia is projected to have installed renewable energy capacity exceed its peak demand by 2020. This paper asks what needs to be considered given the increasing role of renewables in the energy mix? Can battery technology combined with renewables offer a commercial solution for replacing either base load or peak load gas plants? What is required for system security to 2035? If renewables and batteries are proven commercial then what are the implications for gas? To answer these questions, this paper will assess the extent to which renewable and battery technology costs will fall in South Australia. We will compare renewable and gas cost projections for 2018, 2025 and 2035. Using proprietary dispatch modelling we will then assess what the growth in renewables means for annually, monthly and daily gas demand. Demand will undoubtedly decline and become more volatile. This poses challenges. We will assess whether and how current gas contracting terms need to change to ensure that gas has a continued role in ensuring system security in South Australia.
36
Perry, MW, e DJ Miers. "A re-evaluation of chlormequat application to wheat in Western Australia". Australian Journal of Experimental Agriculture 26, n. 3 (1986): 361. http://dx.doi.org/10.1071/ea9860361.
Testo completoAbstract (sommario):
The effect of chlormequat on the grain yield of wheat was investigated in 24 field experiments between 1981 and 1983. Two times of application (at the 3.5- and 6-leaf growth stages-Zadoks decimal score 13.5 and 16.0) and rates of application up to 0.75 kg/ha a.i. were tested with two chlormequat formulations, Cycocel 750 and Bettaquat. Chlormequat application reduced crop height in all trials, but crop lodging did not occur in any trial. Statistically significant yield responses to rate of application alone were obtained in only three of 24 trials, with maximum yield occurring at 0.19-0.37 kg/ha a.i. and with some indication of a yield depression at 0.75 kg/ha a.i. A significant effect of time of application was observed in only two trials, but the results conflicted. In one trial there was a significant interaction between rate and time, with a response to rate of chlormequat only at the 6-leaf stage. No differences were detected between chlormequat formulations. In individual trials, the mean grain yield from the chlormequat treatments ranged from 92.9 to 116.5% of the control. However, averaging over all trials in each year, chlormequat treatments yielded 102.5, 99.3 and 100.0% of the control, respectively, in the three years. Our results confirm that low application rates of chlormequat, applied early in crop development, can increase grain yield. However, over the 24 trials, the effects of chlormequat were too small and inconsistent to warrant its use to increase wheat grain yields under natural rainfall in south-western Australia.
37
Ma, G., P. Rengasamy e A. J. Rathjen. "Phytotoxicity of aluminium to wheat plants in high-pH solutions". Australian Journal of Experimental Agriculture 43, n. 5 (2003): 497. http://dx.doi.org/10.1071/ea01153.
Testo completoAbstract (sommario):
Phytotoxicity of aluminium in acid soils is well known. At pH ≥6.3, aluminate [Al(OH)4–] is the principal hydroxo-aluminium species in soil solutions; however, its phytotoxicity has not received much attention. Sodic subsoils in Australia are generally alkaline and have pH above 9. During our survey of 8 subsoils in South Australia, we found aluminate ions at concentrations greater than 0.8 mg/L (29.7 μmol/L of aluminium) in soil solutions when pH was greater than 9, with corresponding high uptake of aluminium by wheat plants. We studied the phytotoxicity of aluminium to wheat plants in solution culture by maintaining the pH of alkaline solutions at 9.2.Relative root lengths of wheat plants, compared with those in reverse-osmosis deionised water, were significantly reduced in alkaline solutions and CO2-free air indicated toxicity of hydroxy, carbonate and bicarbonate ions. Further reduction of root lengths due to aluminate toxicity was also evident. Relative root lengths of wheat plants, when comparing between +aluminium and –aluminium treatments, were reduced up to 50% in alkaline solutions containing as low as 1 mg/L of aluminium. Aluminium accumulated mainly in the roots, thereby reducing their growth. In bicarbonate solutions, aluminium toxicity under alkaline pH was highly significant (P<0.001). However, at the same level of added aluminium in carbonate solutions, relative root length was not reduced. This study concludes that when aluminium species are present at a concentration of about 1 mg/L in soil solutions with pH greater than 9, the growth of wheat plants could be significantly affected.
38
Dove, H., J. A. Kirkegaard, W. M. Kelman, S. J. Sprague, S. E. McDonald e J. M. Graham. "Integrating dual-purpose wheat and canola into high-rainfall livestock systems in south-eastern Australia. 2. Pasture and livestock production". Crop and Pasture Science 66, n. 4 (2015): 377. http://dx.doi.org/10.1071/cp14201.
Testo completoAbstract (sommario):
In south-eastern Australia, low winter temperatures often reduce pasture growth and thus winter herbage supply relative to livestock requirements. Grazing of vegetative grain crops in winter is one strategy that might overcome this feed gap. In a study with young sheep over two seasons near Canberra, ACT, we compared pasture-only grazing with three separate crop–livestock systems in which the sheep grazed long-season wheat, winter canola or a combination of these, for intervals over the period May–August. We measured forage biomass, sheep grazing days (SGD) and liveweight accumulated per ha. Crop-grazing treatments resulted in much more winter forage for grazing sheep (t DM ha–1): in 2010, one crop 2.5–3.0, two crops 3.5 v. pasture only 1; in 2011, one crop 2, two crops 3 v. pasture only 1.4. In the first season, grazing one crop resulted in ~2000 extra SGD ha–1 and the accumulation of more liveweight per ha than in the pasture-only treatment; grazing of two crops resulted in >3500 extra SGD ha–1. Equivalent values in the second, drier season were: one crop, ~1000 extra SGD ha–1; two crops, 2600 extra SGD ha–1. Spelling of pastures during crop grazing led to extra pasture growth, such that in each of the two seasons, 40% of the total benefit in extra SGD per ha came from the extra pasture. The results indicate that, like grazed wheat, grazed canola can provide valuable winter forage, especially when used together with wheat. The data also provide the first quantification of the effect of crop grazing on pasture spelling and subsequent pasture supply, and suggest value in the incorporation of grazing wheat and canola into grazing systems in the high-rainfall zone.
39
Norton, R. M., e N. G. Wachsmann. "Nitrogen use and crop type affect the water use of annual crops in south-eastern Australia". Australian Journal of Agricultural Research 57, n. 3 (2006): 257. http://dx.doi.org/10.1071/ar05056.
Testo completoAbstract (sommario):
The effect of management and crop selection on water use and profile drying was investigated using 2 series of experiments conducted in the Victorian Wimmera. The effect of applied nitrogen on growth and water use of canola was assessed from 3 field experiments on a Vertosol soil. Across these sites, 140 kg N/ha increased crop water use by a mean of 30 mm, and the biological response averaged 3.68 t/ha of shoot dry matter and seed yield increased by 73% from 1.46 to 2.52 t/ha. The additional nitrogen enabled roots to go deeper into the soil and also to extract water to higher tensions, but the increases in water use were far less than the growth and yield responses. Estimated average soil evaporation was 120 mm across these experiments, but ranged from 26 to 57% of total water use. It was concluded that increased crop vigour in response to applied nitrogen does increase total water use, but the main way that water-use efficiency increases is through reduced soil evaporation. In a second series of experiments, the growth, yield, and water use of wheat, canola, linseed, mustard, and safflower were compared across 4 sites with differing soil moisture contents. Wheat was the highest yielding crop at all sites. Mustard and canola produced similar amounts of biomass and seed yields, whereas linseed produced seed yields that were generally less than the brassica oilseeds. Safflower grew well and produced large amounts of biomass at all sites, but this increased growth did not necessarily translate into increased seed yields. Safflower yielded less seed than all other crops at the 2 dry sites, but yields were similar to canola at the wetter sites. On 2 drier sites, soil water extraction occurred to approximately 1 m for all crops, and all available water was used within that zone by all crops. Where the soil was wet beyond 1 m, safflower was able to extract water from deeper in the profile than the other crops and generated a soil water deficit of about 100 mm more than the other crops at maturity. This deficit persisted into the subsequent autumn–winter period. The potential of using safflower as a management option to extract water from deep in the profile, and so create a soil buffer, is discussed.
40
Rebetzke, G. J., e R. A. Richards. "Genetic improvement of early vigour in wheat". Australian Journal of Agricultural Research 50, n. 3 (1999): 291. http://dx.doi.org/10.1071/a98125.
Testo completoAbstract (sommario):
Grain yield potential of Australian wheat crops is often limited because of inadequate water for crop growth and grain filling. Greater early vigour, defined here as the amount of leaf area produced early in the season, should improve the water-use efficiency and yield of wheat crops grown in Mediterranean-type climates such as occurs in southern Australia. In order to maximise selection efficiency for early vigour in breeding programs, the magnitude and form of genetic variation for early vigour and its components was investigated for 2 contrasting wheat populations. The first population comprised 28 Australian and overseas wheat varieties evaluated in a serial sowing study in Canberra. The second population contained 50 random F 2:4 and F 2:6 families derived from a convergent cross of elite CIMMYT wheat lines evaluated in Canberra, and in the field at Condobolin, New South Wales. For the first population, environmental effects on leaf breadth and length, and to a lesser extent, phyllochron interval, produced significant (P < 0.05) changes in leaf area. Large and significant (P < 0.05) differences were observed among Australian and overseas wheats for early vigour and its components. Australian varieties were among the least vigorous of the lines tested, with a number of overseas varieties producing about 75% greater leaf area than representative Australian wheats. Increased leaf area was genetically correlated with increases in leaf breadth and length, and a longer phyllochron interval. Significant (P < 0.05) genotype ´ environment interaction reduced broad-sense heritability (%) for early vigour (H ± s.e., 87 ± 26) compared with leaf breadth (96 ± 25) and length (97 ± 27). Narrow-sense heritability (%) in the second population was small for leaf area (h2 ± s.e., 30 ± 6) and plant biomass (35 ± 7), but high for leaf breadth (76 ± 14) and length (67 ± 16). Genetic correlations were strong and positive for leaf area with plant biomass, leaf breadth and length, specific leaf area and coleoptile tiller frequency, whereas faster leaf and primary tiller production were negatively correlated with leaf area. The high heritability for leaf breadth coupled with its strong genetic correlation with leaf area (rg = 0.56-0.57) indicated that selection for leaf breadth should produce genetic gain in leaf area similar to selection for leaf area per se. However, the ease with which leaf breadth can be measured indicates that selection for this character either by itself, or in combination with coleoptile tiller production, should provide a rapid and non-destructive screening for early vigour in segregating wheat populations. The availability of genetic variation for early vigour and correlated traits should enable direct or indirect selection for greater leaf area in segregating wheat populations.
41
Cooper, J. L. "The effect of biosolids on cereals in central New South Wales, Australia. 1. Crop growth and yield". Australian Journal of Experimental Agriculture 45, n. 4 (2005): 435. http://dx.doi.org/10.1071/ea03099.
Testo completoAbstract (sommario):
Two forms of biosolids, with and without lime, were applied to acid soils at 2 sites in central New South Wales. Wheat and triticale were then grown on these sites to determine the effect of biosolids on crop growth and yield. The forms of biosolids used were dewatered sewage sludge cake, and N-Viro Soil which is a lime amended sewage sludge. Dewatered sewage sludge cake was applied at rates of 0, 6, 12 and 24 dry Mg/ha, and N-Viro soil at 0, 1.5, 3.0 and 4.5 dry Mg/ha. Biosolids produced grain yield increases of over 50% at both sites, with the largest yield increases at the highest rate of dewatered sewage sludge. Continued cropping at 1 of the sites showed that significant yield increases were still obtained 3 years after the initial application. The addition of lime and N-Viro Soil raised soil pH, and produced small but long lasting yield increases. However, the main benefit of biosolids seems to have come from the nutrients they supplied rather than changes in soil pH.
42
Cammarano, Davide, Glenn Fitzgerald, Bruno Basso, Deli Chen, Peter Grace e Garry O'Leary. "Remote estimation of chlorophyll on two wheat cultivars in two rainfed environments". Crop and Pasture Science 62, n. 4 (2011): 269. http://dx.doi.org/10.1071/cp10100.
Testo completoAbstract (sommario):
For this study we hypothesise that the use of canopy chlorophyll content index (CCCI) and crop greenness will be useful in assessing crop nutritional status and provide a robust management tool by growth stage DC30 for fertiliser application across multiple sites without being confounded by soil and biomass differences. The objectives of this study were: (i) to study the robustness of the CCCI and greenness as a measure of crop N content at two different locations, and (ii) to validate the model developed for crop nitrogen (N) determination. Data were collected from two rain-fed field sites cropped to wheat, one in Southern Italy (Foggia) and the other in the south-eastern wheat belt of Australia (Horsham). Data collection was conducted during the growing season in 2006–07 (December–June) for the Italian site and during the 2006 and 2007 (June–December) growing seasons for the Australian site. Measurements included crop biophysical properties (leaf area index (LAI), biomass, crop N concentration), hyperspectral remote sensing data, and SPAD (chlorophyll meter) determination. An independent dataset including SPAD, biomass, and remotely sensed data from Horsham (Australia) was used to test the validity of the model developed. Results showed that there is good correlation between SPAD and crop N content. The relationship between greenness (measured as LAI*SPAD) and CCCI was fitted with an exponential model and was not affected by biomass accumulation or soil reflectance (r2 = 0.85; y = 15.1e4.5424x; P < 0.001). When this model was tested on the independent dataset it yielded good results for the estimation of greenness (y = 1.22x − 54.87; r2 = 0.90; P < 0.001; root mean square error 32.2; relative error 15%). In conclusion, SPAD measurements combined with LAI could be used as a crop nutritional management tool by DC30 for fertiliser application across multiple sites.
43
Fischer, RA, Y. Kono e GN Howe. "Direct drilling effects on early growth of wheat: studies in intact soil cores". Australian Journal of Experimental Agriculture 34, n. 2 (1994): 223. http://dx.doi.org/10.1071/ea9940223.
Testo completoAbstract (sommario):
Tillage experiments with wheat (Triticum aestivum L.) were conducted at 2 sites in south-eastern Australia: one cool and wet (Murrumbateman), the other warmer and drier (Yanco). Following crop residue removal, direct drilling treatments with complete surface disturbance to 3 cm depth of the medium-textured topsoils (D), or with disturbance only in the narrow seeding slots (DN), were compared with drilling into a surface prepared by cultivating to about 7 cm depth (control). At the 4.5 leaf stage, seedlings from D and DN treatments had less shoot dry weight than the control except at Murrumbateman under very wet post-seeding conditions. Simulation of the above tillage treatments in intact soil Cores from both sites kept under controlled temperature and moisture conditions confirmed that DN treatment, with only 11% of the volume of soil disturbance of the control, reduced early growth, especially at Yanco and if post-sowing conditions were drier. Reduced shoot growth was associated with relatively larger effects on the extent of root exploration. Treatment D, with 43% of the volume of disturbed soil, did not reduce shoot growth relative to the control under any circumstances. Although results suggest a minimum volume of disturbed soil for maximum growth, interactions with biotic stresses as reported recently cannot be ruled out.
44
Brennan, R. F., e M. D. A. Bolland. "Comparing copper requirements of field pea and wheat grown on alkaline soils". Australian Journal of Experimental Agriculture 44, n. 9 (2004): 913. http://dx.doi.org/10.1071/ea03091.
Testo completoAbstract (sommario):
Copper (Cu) is a common deficiency of spring wheat (Triticum aestivum L.), the major crop grown in south-western Australia. The Cu requirements of wheat are well known for soils in the region, but are not known for field pea (Pisum sativum L.) grown in rotation with wheat on alkaline soils in the region. The Cu requirements of field pea and spring wheat were compared in a glasshouse experiment, using 2 alkaline soils from south-western Australia. The Cu was either incubated in moist soil at 22°C for 100 days before sowing (incubated Cu) or applied just before sowing (current Cu). Comparative Cu requirements were determined from yields of 43-day-old dried shoots for: (i) Cu already present in the soil (indigenous Cu); (ii) the amount of added Cu required to produce the same percentage of the maximum (relative) yield of dried shoots; and (iii) the Cu content of dried shoots (Cu concentration multiplied by yield of dried shoots). The critical concentrations of Cu in youngest mature growth and in dried shoots were also determined. As determined from yield of shoots, both species used indigenous Cu about equally effectively. Compared with spring wheat, field pea was about 12% less effective at using current and incubated Cu to produce dried shoots. It was about 15% less effective at using current and incubated Cu to increase Cu content in dried shoots. Relative to current Cu, the effectiveness of incubated Cu declined by about 60% for both wheat and field pea in both soils. The critical Cu concentration in the youngest tissue, associated with 90% of the relative yield, was 1.4 mg Cu/kg for spring wheat and 2.0 mg Cu/kg for field pea. The critical value for the rest of the dried shoots was about 3.0 mg Cu/kg for both species.
45
Tew, Michelle, Kim M. Dalziel, Dennis J. Petrie e Philip M. Clarke. "Growth of linked hospital data use in Australia: a systematic review". Australian Health Review 41, n. 4 (2017): 394. http://dx.doi.org/10.1071/ah16034.
Testo completoAbstract (sommario):
Objective The aim of the present study was to quantify and understand the utilisation of linked hospital data for research purposes across Australia over the past two decades. Methods A systematic review was undertaken guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2009 checklist. Medline OVID, PsycINFO, Embase, EconLit and Scopus were searched to identify articles published from 1946 to December 2014. Information on publication year, state(s) involved, type of data linkage, disease area and purpose was extracted. Results The search identified 3314 articles, of which 606 were included; these generated 629 records of hospital data linkage use across all Australian states and territories. The major contributions were from Western Australia (WA; 51%) and New South Wales (NSW; 32%) with the remaining states and territories having significantly fewer publications (total contribution only 17%). WA’s contribution resulted from a steady increase from the late 1990s, whereas NSW’s contribution is mostly from a rapid increase from 2010. Current data linkage is primarily used in epidemiological research (73%). Conclusion More than 80% of publications were from WA and NSW, whereas other states significantly lag behind. The observable growth in these two states clearly demonstrates the underutilised opportunities for data linkage to add value in health services research in the other states. What is known about the topic? Linking administrative hospital data to other data has the potential to be a cost-effective method to significantly improve health policy. Over the past two decades, Australia has made significant investments in improving its data linkage capabilities. However, several articles have highlighted the many barriers involved in using linked hospital data. What does this paper add? This paper quantitatively evaluates the performance across all Australian states in terms of the use of their administrative hospital data for research purposes. The performance of states varies considerably, with WA and NSW the clear stand-out performers and limited outputs currently seen for the other Australian states and territories. What are the implications for practitioners? Given the significant investments made into data linkage, it is important to continue to evaluate and monitor the performance of the states in terms of translating this investment into outputs. Where the outputs do not match the investment, it is important to identify and overcome those barriers limiting the gains from this investment. More generally, there is a need to think about how we improve the effective and efficient use of data linkage investments in Australia.
46
Pembleton, K. G., R. P. Rawnsley, J. L. Jacobs, F. J. Mickan, G. N. O'Brien, B. R. Cullen e T. Ramilan. "Evaluating the accuracy of the Agricultural Production Systems Simulator (APSIM) simulating growth, development, and herbage nutritive characteristics of forage crops grown in the south-eastern dairy regions of Australia". Crop and Pasture Science 64, n. 2 (2013): 147. http://dx.doi.org/10.1071/cp12372.
Testo completoAbstract (sommario):
Pasture-based dairy farms are a complex system involving interactions between soils, pastures, forage crops, and livestock as well as the economic and social aspects of the business. Consequently, biophysical and farm systems models are becoming important tools to study pasture-based dairy systems. However, there is currently a paucity of modelling tools available for the simulation of one key component of the system—forage crops. This study evaluated the accuracy of the Agricultural Production Systems Simulator (APSIM) in simulating dry matter (DM) yield, phenology, and herbage nutritive characteristics of forage crops grown in the dairy regions of south-eastern Australia. Simulation results were compared with data for forage wheat (Triticum aestivum L.), oats (Avena sativa L.), forage rape (Brassica napus L.), forage sorghum (Sorghum bicolor (L.) Moench), and maize (Zea mays L.) collated from previous field research and demonstration activities undertaken across the dairy regions of south-eastern Australia. This study showed that APSIM adequately predicted the DM yield of forage crops, as evidenced by the range of values for the coefficient of determination (0.58–0.95), correlation coefficient (0.76–0.94), and bias correction factor (0.97–1.00). Crop phenology for maize, forage wheat, and oats was predicted with similar accuracy to forage crop DM yield, whereas the phenology of forage rape and forage sorghum was poorly predicted (R2 values 0.38 and 0.80, correlation coefficient 0.62 and –0.90, and bias correction factors 0.67 and 0.28, respectively). Herbage nutritive characteristics for all crop species were poorly predicted. While the selection of a model to explore an aspect of agricultural production will depend on the specific problem being addressed, the performance of APSIM in simulating forage crop DM yield and, in many cases, crop phenology, coupled with its ease of use, open access, and science-based mechanistic methods of simulating agricultural and crop processes, makes it an ideal model for exploring the influence of management and environment on forage crops grown on dairy farms in south-eastern Australia. Potential future model developments and improvements are discussed in the context of the results of this validation analysis.
47
Larg, Allison, John R. Moss e Nicola Spurrier. "Relative contribution of overweight and obesity to rising public hospital in-patient expenditure in South Australia". Australian Health Review 43, n. 2 (2019): 148. http://dx.doi.org/10.1071/ah17147.
Testo completoAbstract (sommario):
Objective Arguments to fund obesity prevention have often focused on the growing hospital costs of associated diseases. However, the relative contribution of overweight and obesity to public hospital expenditure growth is not well understood. This paper examines the effect of overweight and obesity on acute public hospital in-patient expenditure in South Australia over time compared with other expenditure drivers. Methods Annual inflation-adjusted acute public admitted expenditure attributable to a high body mass index was estimated for 2007–08 and 2011–12 and compared with other expenditure drivers. Results Expenditure attributable to overweight and obesity increased by A$45million, from 4.7% to 5.4% of total acute public in-patient expenditure. This increase accounted for 7.8% of the A$583million total expenditure growth, whereas the largest component of total growth (62.4%) was a real increase in the average cost per separation. Conclusions The relatively minor contribution of overweight and obesity to expenditure growth over the time period examined invites reflection on arguments to boost preventive spending that centre upon reducing hospital costs. These arguments may inadvertently detract attention from the considerable health and social burdens of overweight and obesity and from unrelated sources of expenditure growth that reduce opportunities for state governments to fund obesity prevention programs despite their comparative benefits to population health. What is known about the topic? Stand-alone estimates suggest that overweight and obesity are placing a considerable financial burden on the Australian public healthcare system. What does this paper add? Our findings challenge common perceptions about the relative importance of overweight and obesity in the context of rising public in-patient expenditure in Australia. What are the implications for practitioners? Consistent serial estimates of overweight- and obesity-attributable expenditure enable its tracking and comparison with other potentially controllable expenditure drivers that may also warrant attention. Explicit consideration of population health trade-offs in expenditure-related decisions, including in enterprise bargaining, would enhance transparency in priority setting.
48
McDonald, Glenn, William Bovill, Julian Taylor e Robert Wheeler. "Responses to phosphorus among wheat genotypes". Crop and Pasture Science 66, n. 5 (2015): 430. http://dx.doi.org/10.1071/cp14191.
Testo completoAbstract (sommario):
Phosphorus (P) recovery and P-use efficiency (PUE) by wheat are low, and genetic improvement in PUE is a potential means of improving the effectiveness of P in farming systems. We examined variation in response to P in wheat to identify genotypes that showed consistent responsiveness to P fertiliser in the field and which may be the target of future studies, and examined differences in P uptake and partitioning. The response to P was studied among a diverse set of bread wheat germplasm at three sites in South Australia between 2009 and 2012. Up to 53 varieties and breeding lines were grown at two rates of P, 0 kg/ha and 30 kg/ha. Grain yield at 0 kg P/ha and response to P varied independently among genotypes. There were large effects of site and season on the response to P, but some genotypes showed consistently low and others high response to P. Analysis of a subset of lines revealed large responses in vegetative growth to P but the response diminished as crops matured, and variation in early vegetative growth was unrelated to the responses in biomass at maturity or grain yield. Genotypic variation in grain yield was more strongly related to variation in P utilisation efficiency than to variation in P uptake among wheat genotypes, which was associated with differences in P harvest index (PHI). Although breeding has improved yield, there has been no significant genetic gain in total P uptake; rather, improvements in PUE have been associated with an increase in P utilisation efficiency and PHI.
49
Officer, S. J., R. D. Armstrong e R. M. Norton. "Plant availability of phosphorus from fluid fertiliser is maintained under soil moisture deficit in non-calcareous soils of south-eastern Australia". Soil Research 47, n. 1 (2009): 103. http://dx.doi.org/10.1071/sr08090.
Testo completoAbstract (sommario):
Low soil moisture and phosphorus (P) deficiencies restrict grain production in south-eastern Australia. The effect of the soil moisture regime on the plant availability of P from fluid mono-ammonium phosphate (MAP) fertiliser was examined during vegetative growth of wheat and canola in P-responsive soils from the Wimmera, Mallee, and high rainfall zone (Glenelg) regions of Victoria. Three plant growth experiments were performed. In Experiment 1, wheat growth and P uptake increased synergistically as soil moisture increased above permanent wilting point (PWP) and as P rate increased. In Experiment 2, the uptake of P from MAP fertiliser of wheat growing under a soil moisture deficit was examined using radioactive (32P) labelling. A factorial design compared uptake from intact soil cores of 3 soil types (Vertosol, Sodosol, Chromosol), 2 depths of fertiliser placement (40 and 80 mm), and either 0 or 25 kg P/ha. Results showed distinct plant responses to both the presence and depth of MAP fertiliser. Banding MAP close to the seed was most efficient in terms of recovery of the fertiliser P, regardless of the soil moisture conditions. Soil moisture regime affected the plant uptake of soil P, rather than fertiliser P, with more soil P taken up by the plants when soil moisture increased. The plant availability of the residual MAP fertiliser in the soil was subsequently examined in Experiment 3. The availability of the residual MAP to canola seedlings was equivalent to 8 kg P/ha of freshly applied MAP. Following both crops (9 months), Colwell P values indicated no further residual MAP availability in soil that had been under the wet regime, and only a small residual value in soil from the dry regime. Banded application of fluid MAP close to the seed and into soil that is above PWP is recommended, even when a relatively dry season is expected, although the residual value to following crops may be limited.
50
Harris, John. "Is LNG the panacea for Australia's natural gas?" APPEA Journal 50, n. 2 (2010): 713. http://dx.doi.org/10.1071/aj09077.
Testo completoAbstract (sommario):
Australia already has abundant natural gas reserves. To what extent will LNG exports grow? What is the potential for future conventional gas discoveries? Is there a potential round of additional CBM-sourced LNG projects? Could shale gas contribute to supply? There are already a significant number of proposed LNG projects in Australia. How many more projects might emerge to add to the current tally? In the longer term, Australia has the potential to surpass Qatar as the world’s leading LNG exporter but which markets can help Australia realise that potential? With growing Asian demand for LNG, and buyers historically accustomed to oil-linked long term contracts, the prospects for LNG appear good. But are they? To what extent can growth in Asian gas demand absorb Australian LNG, which itself has to compete with other LNG projects? If Asian demand is satiated, what are the alternative markets? North America provides another potential outlet for Australian LNG exports, but how do the project economics stack up relative to Asia? Does South America offer market opportunities and if so can countries there absorb a meaningful volume of Australian LNG? A detailed consideration of project costs and the outlook for gas prices in Asia and the Americas can help shed light on this question. It can also set Australia’s LNG projects in context relative to its competitors. If LNG is not the panacea for Australia’s natural gas, will alternative monetisation options emerge, and what might they be?