Browsing by Author "University of Queensland"

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Development of DNA based diagnostic systems for sugarcane pathogens : SRDC final report UQ024
(BSES, 2001) Maclean, D; Henderson, J; Croft, B
This project developed diagnostic assays for sugarcane pathogens using novel DNA detection technologies associated with the polymerase chain reaction (PCR). The bacterium Clavibacter xyli subsp. xyli (Cxx) causing ratoon stunting disease (RSD) was used as major model to compare assay platforms based on PCR-ELISA (Boehringer) and TaqManTM real time PCR (Applied Biosystems). TaqMan was more sensitive, robust, and subject to less interference than PCR-ELISA. Laboratory tests and field trials using cultured Cxx cells and xylem fluids from RSD-infected cane demonstrated that TaqMan could detect fewer than 10 bacterial cells reliably, and was >100x as sensitive as previous ELISA and phase contrast microscopy methods. Quantitative TaqMan assays appeared to be congruent with these existing methods. TaqMan assays were also developed for Fiji disease fijivirus (FDV) and sugarcane mosaic potyvirus (SCMV). BSES can readily access this advanced technology via the Real Time PCR Facility at the University of Queensland. Compared to alternative methods the TaqMan assays are inherently time-efficient, robust, highly sensitive, quantitative, and are especially well suited for rigorous quality control. These tests are recommended for ongoing evaluation for quarantine and other purposes by the Australian sugar industry. TaqMan is a robust generic technology and assays can readily be developed for further pathogens if the need arises.
High efficiency production of transgenic sugarcane plants
(1994) Bower, R; University of Queensland
The efficiency of gene transfer into embryogenic callus of sugarcane has been increased tenfold by optimisation of particle bombardment conditions, and there is a corresponding increase in stable transformation frequencies. The method routinely yields approximately 2 independent transgenic plants per cm2 of bombarded embryogenic callus for sugarcane varieties anlenable to tissue culture. Genes coprecipitated on separate plasmids are cotransformed at high efficiency, which will facilitate introduction of agronomic genes. Materials needed for recovery of transgenic plants can be halved through improved selection protocols, allowing the recovery of hundreds of independent transformed plant lines. The improved method is now in use in BSES and CSIRO as well as UQ laboratories Since the completion of this project, the transformation system has been shown to be effective on a range of major commercial varieties, and over 70 lines from seven cultivars are currently in field trials.
Nitrate retention at depth under sugarcane in Far North Queensland Wet Tropics
(2002) Rasiah, V; Armour, JD; Menzies, NW; Heiner, DH; Don, MJ
Nitrogen mass-balance studies for sugarcane grown on Ferrosols (Krasnozem) in the Far North Queensland (FNQ) wet tropics have shown 30 to 50 kg N/ha/yr of the applied fertiliser+N leached below the root-zone (<0.75 m) as nitrate-N compared to <10 kg/ha/yr transported in surface runoff. Because, large quantities of N (guesstimate of ≈ 3,000 tonnes per annum for the catchment) was leaching below the root-zone, major emphasis has been placed on its fate, particularly in relation to off-site land and water resources and ecosystem health issues and more specifically that related to the Great Barrier Reef (GBR). The leached nitrate could be adsorbed at anion exchange sites, denitrify, enter streams/rivers through lateral-flow and/or aquifers by deep drainage. Because the ferrosols in general possess the capacity to absorb and retain nitrate-N at anion exchange (AE) sites, there exists the potential reduced risk of contamination of off-site water bodies, including GBR. The issues address in the project include (i) the assessment of sub-surface nitrate loading in Ferrosols of north Queensland wet tropical coast (ii) measurement of those physical and chemical properties, which influence nitrate mobility and retention (iii) provide from inferred processes, estimates of future nitrate movement to ground and surface waters (iv) propose management strategy(s) with regional industry group(s) to address the nitrate problem (v) improve industry and community understanding of water and nutrient dynamics and the potential environmental impacts. Soil cores to 12.5 m depth were taken from 28 sites distributed across the catchment, representing 9 Ferrosol soil types under sugarcane cultivation for at least 50 yr and from rainforest. Depth incremented (0.5-1m) sub-samples from the cores were analysed for nitrate- N, cation- (CEC) and anion- (AEC) exchange capacities, pH, exchangeable cations (Ca, Mg, K., Na), soil organic C (SOC), electrical conductivity (EC), sulphate (SO4 2-) and chloride (CI-), Nitrate-N concentration under sugarcane ranged from 0 to 72.5 mg/kg compared with 0 to 0.31 mg/kg under rainforest. The average N-load, in 12 m depth, across the 19 Pin Gin soil type was 1550 kg/ha compared with 185 kg/ha unde4r 8 non-Pin Gin and 11 kg/ha in rainforest and most of the retention in the catchment and the source of this nitrate was that leached below the rootzone. Compared to the current average N-load, the average maximum potential nitrate retention capacity (MPNRC) of 10.8 t/ha for the Pin Gin and 4.7 t/ha for the non-Pin Gin indicates these soils still possess large capacity to adsorb and retain nitrate in profiles.
SaveN Cane : developing selection tools for N-efficient sugarcane
(2015) Schmidt, S; Lakshmanan, P; Cox, M; Robinson, N
This project supports the sugar industry’s intensifying efforts to reduce its nitrogen (N) footprint that is caused by inefficient use of N fertiliser by the crop. The industry aims to minimise N pollution of coastal waters and emission of potent greenhouse gas nitrous oxide from soil without negatively impacting the economic sustainability of sugar production. International research addressing this pervasive problem in grain and other crops indicates that effective approaches combine agronomic innovation of N supply and nitrogen-use efficient (NUE) crop varieties. This UQ-SRA collaborative project, aimed to advance knowledge of N use efficiency of crop varieties through systematic testing of a considerable number of sugarcane clones with diverse genetic background (commercial varieties from Australia and overseas, identified water-use-efficient clones, crosses with ancestral canes). Additional value was derived from a collaboration with QLD DAFF (Andrew Robson) to advance remote sensing of crop N, and investigations of the effects of N fertiliser on soil biology (Graham Stirling-nematodes, UQ consortium-bacterial and fungal communities). Brazilian researchers (Sao Paulo State) have since established sister experiments based on this project. Clones were cultivated with low or recommended N rates (20-40 or 160-200 kg N-fertiliser per year) in two field trials (Mackay, Burdekin). The contrasting N rates were based on concepts that (i) NUE traits are only obvious in low-N environments, and (ii) ideal crop varieties will be strongly responsive to N supply and efficiently acquire N from fertiliser and indigenous soil reserves. NUE traits of 64 clones were characterised over three years (plant crop-1st ratoon crop-2ndratoon crop) by quantifying the effects of contrasting N supply on growth in early, mid and late season. Clone vigour and ratooning ability were evaluated, as was canopy development and photosynthetic performance, the ability to acquire and store nitrate, N allocation to stalks and leaves, and sugar and biomass yields. Project deliverables focused on generating knowledge on the genetic variation in N response and NUE traits and ranking of clones across environments with different soils to study the magnitude and the robustness of NUE traits. The overall deliverables and key findings include: (i) Establishment of field experimental conditions with limited N availability suitable for screeningsugarcane populations for NUE and N-related crop attributes. The field trial set-up was demonstrably effective in evaluating a considerable number of clones over a 3-year crop cycle; (ii) Knowledge of genetic variation for NUE in Australian sugarcane germplasm; (iii) NUE screening for photosynthetic performance, N uptake and accumulation attributes and yield parameters (CCS, sugar and biomass yields) identified benefits/drawback of experimental approaches; (iv) Generated data on trait variation across clones, crop stages and environments, demonstrating that environmental conditions markedly affected crop performance as evidenced by moderate (22%, Mackay) and strong (45%, Burdekin) reduction in yields with low N supply. Soil characteristics are a likely cause as clones at Mackay acquired on average 3- and 2-fold more N than at the Burdekin site over the plant-1st ratoon cycles at low and recommended N supplies; (v) Plant vigour appears to be a major determinant of NUE in sugarcane; (vii) Clones with contrasting NUE and N response have been identified for use in next-step NUE trait research; (viii) Remote sensing showed potential for screening sugarcane germplasm, but its application at early stages of crop growth requires further investigation. Taken together, the project has achieved the stated objective and fulfilled a role in SRA’s focus area of (1) optimally-adapted varieties, Plant breeding and release. The project outcomes have been communicated to the industry nationally and internationally, have been evaluated in the context of global efforts in advancing NUE in crop and cropping systems, and are in preparation for peer review and publication in highly ranked international scientific journals. The project is strongly aligned with industry interests as evidenced by interest of growers, national and international collaborators. Logical next steps towards developing N use-efficient sugarcane in the Australian breeding program include advancing understanding the basis of clone sensitivity to N and tools for rapid selection of N-responsive clones.
Sugar Research and Development Corporation final report Increasing sugar cane yields by improvements in soil structure
(1998) Hughes, M; Nielsen, P; Grabski, A
A project to increase sugar cane yields by improvements in soil structure was conducted at Broadwater, NSW. It was instigated in response to the poor physical structure of many cane soils and poor root development in many sugar cane crops resulting in low cane yields. A number of alternative management practices were tested and cane and sugar yield as well as appropriate soil parameters were measured. The main findings were that ridging had the biggest effects on cane and sugar yields and on soil bulk density, soil moisture (drier in the top 30 cm and wetter at depth), and a leaching of Cl, Na and S when in excess amounts. Ridging also resulted in a stable inter-row and hence far less damage during wet harvests. Intensity of tillage had some small effect on yields and soil structure; it is not clear if these would have increased over a longer period of time. The main effect of soybean production during the fallow period was due to nitrogen input. There were some small but positive effects on subsequent cane root growth soil organic carbon and soil bulk density. Mole drains and deep ripping provided no clear advantage over laser levelling alone.
The bacterial biocontrol agent pasteuria penetrans can help control root-knot nematode on sugarcane
(ASSCT, 2018) Bhuiyan, SA; Stirling, GR; Garlick, K; Anderson, J; Wickramasinghe, P; Wong, E
ROOT-KNOT NEMATODE (Meloidogyne javanica) is one of the most damaging pests of sugarcane, often causing heavy losses in coarse-textured sandy soils. The bacterial parasite Pasteuria penetrans is a potentially useful biocontrol agent and in a 2015–16 survey it was found at relatively high levels in three of the 126 sugarcane fields surveyed. Soil was collected from one of the heavily-infested fields and a pot experiment established to compare root-knot nematode multiplication in naturally infested soil and in soil where the endospores of P. penetrans had been killed by autoclaving. After 37 weeks, the root-knot nematode population was very high in the autoclaved soil but numbers of root-knot nematode eggs and second-stage juveniles were 99% lower in the soil that was naturally-infested with P. penetrans. A subsequent pot experiment with mass-produced endospores showed that when soil contained more than 6 000 endospores/g soil, root galling was not as severe as in non-infested soil and the number of root-knot nematode eggs was reduced by 71–82%. These results indicate that when high endospore concentrations are continually maintained in the root zone, P. penetrans will markedly reduce populations of one of the most important nematode pests of sugarcane.
The fast fluorescence kinetics; a sensitive tool for early detection of water stress in sugarcane : ASSCT peer reviewed paper
(ASSCT, 2016) Olsen, DJ; Shafei, R; Botha, FC
Water stress is a major constraint for sugarcane production in many regions of the world, including Australia. Sensitive and non-destructive early measurement of the crop response to water stress would be of great value for producers, advisors, and researchers. Chlorophyll-a (Chla) fluorescence is well established as a tool for measurement of photosynthetic efficiency. Changes in the kinetics of Chla fluorescence can provide valuable insight into the structure and function of the photosynthetic apparatus and chloroplast membrane integrity. The parameter Fv/Fm is often used to describe the effect of stress on the quantum yield of photosystem two (PSII). In this study the polyphasic OJIP fluorescence transient was used to evaluate the response of the sugarcane photosynthetic electron transport system. Chlorophyll fluorescence was measured on three leaves in the canopy of KQ228A over a five-day water stress period, and the response analysed using the OJIP-test. The results show that several of the parameters that can be derived from the OJIP test are more sensitive and a better reflection of water stress than the Fv/Fm ratio. Evidently PSII is much more sensitive to water stress than photosystem one (PSI). In late stages of stress there are signs of a loss in membrane integrity and a disruption of water splitting in PSII.