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Denmead O.T.,CSIRO | Macdonald B.C.T.,Australian National University | Bryant G.,University of Wollongong | Naylor T.,University of Wollongong | And 4 more authors.
Agricultural and Forest Meteorology | Year: 2010

Climatic conditions and cultural practices in the sub-tropical and tropical high-rainfall regions in which sugarcane is grown in Australia are conducive to rapid carbon and nitrogen cycling. Previous research has identified substantial exchanges of methane (CH4) and nitrous oxide (N2O) between sugarcane soils and the atmosphere. However, that research has been mostly short-term. This paper describes recent work aimed at quantifying exchanges of CH4 and N2O from fertilised sugarcane soils over whole growing seasons. Micrometeorological and chamber techniques provided continuous measurements of gas emissions in whole-of-season studies in a burnt-cane crop on an acid sulfate soil (ASS) that was fertilised with 160kg nitrogen (N)ha-1 as urea in the south of the sugarcane belt (Site 1), and in a crop on a more representative trash-blanketed soil fertilised with 150kg urea-Nha-1 in the north (Site 2). Site 1 was a strong source of CH4 with a seasonal emission (over 342 days) of 19.9kg CH4ha-1. That rate corresponds to 0.5-5% of those expected from rice and wetlands. The many drains in the region appear to be the main source. The net annual emission of CH4 at Site 2 over 292 days was essentially zero, which contradicts predictions that trash-blankets on the soil are net CH4 sinks. Emissions of N2O from the ASS at Site 1 were extraordinarily large and prolonged, totalling 72.1kgN2Oha-1 (45.9kgNha-1) and persisting at substantial rates for 5 months. The high porosity and frequent wetting with consequent high water filled pore space and the high carbon content of the soil appear to be important drivers of N2O production. At Site 2, emissions were much smaller, totalling 7.4kgN2Oha-1 (4.7kgNha-1), most of which was emitted in less than 3 months. The emission factors for N2O (the proportion of fertiliser nitrogen emitted as N2O-N) were 21% at Site 1 and 2.8% at Site 2. Both factors exceed the default national inventory value of 1.25%. Calculations suggest that annual N2O production from Australian sugarcane soils is around 3.8ktN2O, which is about one-half a previous estimate based on short-term measurements, and although ASS constitute only about 4% of Australia's sugarcane soils, they could contribute about 25% of soil emissions of N2O from sugarcane. The uptake of 50-94tCO2ha-1 from the atmosphere by the crops at both sites was offset by emissions of CH4 and N2O to the atmosphere amounting to 22tCO2-eha-1 at Site 1 and 2tCO2-eha-1 at Site 2. © 2009 Elsevier B.V.

Manalil N.S.,Macquarie University | Junior Teo V.S.,Macquarie University | Braithwaite K.,Bureau of Sugar Experiment Stations Ltd | Brumbley S.,Bureau of Sugar Experiment Stations Ltd | And 2 more authors.
Fungal Biology | Year: 2010

Metarhizium anisopliae is a well-characterized biocontrol agent of a wide range of insects including cane grubs. In this study, a two-dimensional (2D) electrophoresis was used to display secreted proteins of M. anisopliae strain FI-1045 growing on the whole greyback cane grubs and their isolated cuticles. Hydrolytic enzymes secreted by M. anisopliae play a key role in insect cuticle-degradation and initiation of the infection process. We have identified all the 101 protein spots displayed by cross-species identification (CSI) from the fungal kingdom. Among the identified proteins were 64-kDa serine carboxypeptidase, 1,3 beta-exoglucanase, Dynamin GTPase, THZ kinase, calcineurin like phosphoesterase, and phosphatidylinositol kinase secreted by M. ansiopliae (FI-1045) in response to exposure to the greyback cane grubs and their isolated cuticles. These proteins have not been previously identified from the culture supernatant of M. anisopliae during infection. To our knowledge, this the first proteomic map established to study the extracellular proteins secreted by M. ansiopliae (FI-1045) during infection of greyback cane grubs and its cuticles. © 2010 The British Mycological Society.

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