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Pasture Dieback Identification Guide
No full textThis guide describes some common pasture disorders and diseases with symptoms similar to pasture dieback. However, not all pasture disorders are discussed. Seek further independent advice from a local adviser before making management decisions based on the information in this guide
Stable isotope dilution assay and HS-SPME-GCMS quantification of key aroma volatiles of Australian pineapple (Ananas comosus) cultivars
No full textPineapple aroma is one of the most important sensory quality traits that influences consumer purchasing patterns. Reported in this paper is a high throughput method to quantify in a single analysis the key volatile organic compounds that contribute to the aroma of pineapple cultivars grown in Australia. The method constituted stable isotope dilution analysis in conjunction with headspace solid-phase microextraction coupled with gas-chromatography mass spectrometry. Deuterium labelled analogues of the target analytes purchased commercially were used as internal standards. Twenty-six volatile organic compounds were targeted for quantification and the resulting calibration functions of the matrix -matched validated method had determination coefficients (R2) ranging from 0.9772 to 0.9999. The method was applied to identify the key aroma volatile compounds produced by popular pineapple cultivars such as ‘Aus Carnival’, ‘Aus Festival’, ‘Aus Jubilee’, ‘Aus Smooth (Smooth Cayenne)’ and ‘Aussie Gold (73-50)’, grown in Queensland, Australia. Pineapple cultivars varied in its content and composition of free volatile components, which were predominantly comprised of esters, followed by terpenes, alcohols, aldehydes, and ketones
Towards reducing the capital cost of manufacturing Laminated Veneer Lumbers: Investigating finger jointing solutions
Get PDFThe capital cost of setting up a Laminated Veneer Lumber (LVL) plant which produces continuous LVL billet products, through a continuous veneer assembly and hot-pressing processes, is significant. However, the utilisation of batch-type presses, similar to those employed in the plywood industry, could significantly reduce this initial cost and may provide new opportunities for small to medium scale operations. This process would produce shorter billet lengths which would need to be joined together to produce lengths viable for structural products. Scarf joints have been used commercially to join some veneer-based engineered wood products but have limitations, while finger joints are a common method for jointing sawn timber products and offer some key advantages but is not a common method to join veneer-based products. Consequently, this paper focusses on investigating the influence of key manufacturing parameters on the performance of finger jointed LVL. The effect of the joint orientation (horizontal or vertical), the finger length, the gluing pressure and the adhesive type on the joint strength and stiffness were investigated. The finger jointed LVL were tested in edge bending, flat bending and tension, and the results were compared to reference unjointed LVL. The bending performance of the finger jointed LVL was also compared to scarfed jointed LVL. In total 304 tests were performed. The results indicated that the average strength values of finger jointed LVL can reach up to 99% of the average strength of unjointed LVL and compares to scarf jointed LVL on flat bending. Horizontal joints, being more practical to produce for deep beams, performed similarly to vertical joints. The 25 mm joints were found to have no mechanical advantages over the 20 mm investigated finger joints. A gluing pressure lower than the Eurocode's recommended level for solid timber achieved sufficient bonding for the products to be utilised. The gluing pressure was also found not to influence the performance of the joint, for the range of pressures investigated. Both polyurethane and resorcinol-formaldehyde adhesives produced high performing products, with the latter displaying superior adhesive bond durability. The paper concludes that finger jointing LVL represents a viable solution to manufacture usable LVL lengths from short LVL billets, but have lower edge bending efficiency than scarf jointed LVL
Mitigate N2O emissions while maintaining sugarcane yield using enhanced efficiency fertilisers and reduced nitrogen rates
Get PDFConventional fertiliser nitrogen (N) inputs to sugarcane farming promote gaseous losses of the greenhouse gas nitrous oxide (N2O). This study investigated the effects of a nitrification inhibitor coated urea (NICU) and a 50:50 blend (N wt%) of polymer coated urea and conventional urea (PCU + U), both at a sub-recommended rate (112 kg N ha−1), on N2O emissions and productivity in a sugarcane crop. Three rates of conventional urea (70%, 100% and 130% of the recommended rate at 160 kg N ha−1) were also assessed. Nitrous oxide emissions were measured over a 7.5-month sugarcane crop using automatic chambers. High N2O emissions (> 50 g N2O–N ha−1 d−1) occurred in the first 2 months after fertiliser application, and the variability in daily emissions was best described by a combination of pH, soil nitrate concentration, soil temperature, water filled pore space and soil ammonium concentration. The blended PCU + U resulted in 62% higher, but non-significant, net fertiliser-induced N2O emissions, while NICU significantly reduced net emissions by 81%, compared to conventional urea at the same rate (112 kg N ha−1). Net emissions from conventional urea increased linearly with increasing rate, with a mean emission factor of 2.6%. Thus, applying NICU at 70% of the recommended rate achieved the greatest N2O emission reduction compared to a PCU + U blend or conventional urea at the same N rate. There was no significant reduction in yield when the fertiliser N rate was reduced to 70%. Further field trials are required to ascertain whether the use of reduced N rates and/or enhanced efficiency fertilisers can mitigate N2O emissions while maintaining or increasing productivity in the long term
Curcumin-mediated photodynamic treatment to extend the postharvest shelf-life of strawberries
Get PDFThis study investigated the potential use of curcumin-mediated photodynamic treatment as a postharvest decontamination technique to reduce microbial load and growth and therefore extend the shelf life of strawberries. Curcumin was applied on strawberries, followed by illumination and storage at 4°C for 16 days. Strawberries were evaluated for decay, microbial load, and physicochemical properties such as weight loss, color, and firmness during storage. The findings revealed that curcumin-mediated photodynamic treatment effectively reduced the decay incidence and severity in strawberries, with 20% less decay occurrence compared to untreated fruits, which was shown to be dependent on curcumin concentration. While a complete reduction in microbial load was observed upon treatment, microbial growth remained unaffected throughout storage. Moreover, photodynamic treatment did not show any adverse impact on color properties and firmness of strawberries. This eco-friendly technique presents potential for fruit's shelf-life extension, although optimization of treatment parameters and photodynamic unit design seems to be essential
From known to unknown unknowns through pattern-oriented modelling: Driving research towards the Medawar zone
Get PDFThe metaphor of the Medawar zone describes the relationship between the difficulty of a scientific problem and the potential payoff of solving it. This zone represents the realm where questions offer high benefits relative to the effort required to address them. By harnessing the power of mechanistic modelling, scientists can navigate towards this zone, moving beyond known unknowns to discover unknown unknowns. This requires models to be realistic and reliable. Model usefulness, impact, and predictive power can be enhanced by achieving intermediate model complexity, where the trade-off between the realism and tractability of a model is optimised. To achieve these goals, we use the pattern-oriented modelling strategy (POM) to direct research into the Medawar zone by steering model structure towards intermediate complexity. We illustrate this strategy with a detailed conceptual process. Using example models from agri-ecological systems, we demonstrate how intermediate complexity can be attained through POM, and how pattern-oriented models of intermediate complexity that reproduce multiple patterns can uncover both known unknowns and unknown unknowns, which ultimately advances our understanding of complex systems and facilitates groundbreaking discoveries. In addition, we discuss the multidimensionality of the Medawar zone in the context of modelling philosophy and highlight the challenges and imperatives for achieving coherence in the modelling discipline. We emphasize the need for collaboration between end-users and modellers and the adoption of systematic modelling strategies such as POM
Internal Disorders of Mango Fruit and Their Management—Physiology, Biochemistry, and Role of Mineral Nutrients
Get PDFMango (Mangifera indica L.) is a popular fruit grown in tropical and subtropical regions. Mango has a distinctive aroma, flavour, and nutritional properties. Annual global mango production is >50 million tonnes. Major producers of mango include India, Bangladesh, China, Mexico, Pakistan, Indonesia, Brazil, Thailand, and the Philippines, and it is shipped worldwide. Harvested mango fruit are highly perishable, with a short shelf life. Physiological disorders are among the major factors limiting their postharvest quality and shelf life, including when fruit need phytosanitary treatments, such as hot water treatment, vapour heat treatment, and irradiation. This review focuses on problematic physiological disorders of mango flesh, including physiology and biochemistry. It considers factors contributing to the development and/or exacerbation of internal disorders. Improved production practices, including pruning, nutrient application, and irrigation, along with monitoring and managing environmental conditions (viz., temperature, humidity, and vapour pressure deficit), can potentially maintain fruit robustness to better tolerate otherwise stressful postharvest operations. As demand for mangoes on international markets is compromised by internal quality, robust fruit is crucial to maintaining existing and gaining new domestic and export consumer markets. Considering mango quality, a dynamic system, a more holistic approach encompassing pre-, at-, and post-harvest conditions as a continuum is needed to determine fruit predisposition and subsequent management of internal disorders
Spatial and temporal variation of marine megafauna off coastal beaches of south-eastern Queensland, Australia
Get PDFContext
Coastal beach environments provide habitats for marine megafauna, including turtles, rays, marine mammals and sharks. However, accessing these variable energy zones has been difficult for researchers by using traditional methods.
Aims
This study used drone-based aerial surveys to assess spatio-temporal variation of marine megafauna across south-eastern Queensland, Australia.
Methods
Drones were operated at five south-eastern Queensland beaches. Megafauna sightings and key variables including location, month and turbidity were analysed to assess variation across locations.
Key results
Overall, 3815 individual megafauna were detected from 3273 flights. There were significant differences in the composition of megafauna assemblages throughout the year and among beaches, with megafaunal sightings in >80% of flights conducted off North Stradbroke Island.
Conclusions
Strong temporal presence was found that is congruent with other studies examining seasonality. This supports the use of drones to provide ecological data for many hard-to-study megafauna species and help inform long-term sustainable management of coastal ecosystems.
Implications
Results indicated that environmental conditions can influence the probability of sighting marine megafauna during aerial surveys
Pupal diapause in Hypocosmia pyrochroma (Lepidoptera: Pyralidae), a biological control agent for Dolichandra unguis-cati (Bignoniaceae)
Get PDFCats claw creeper leaf-tying moth Hypocosmia pyrochroma (Lepidoptera: Pyralidae) enter pupal diapause in the soil from middle of autumn (April), in response to declining photoperiod. Proportion of larvae entering pupal diapause increased with decreasing Daily Solar Radiation (DSR), and all larvae completing development in winter under low DSR entered pupal diapause. Under natural photoperiod, adults emerged from pupal diapause, from late spring (October) to middle of summer (January), with peak adult emergence in late spring (November) and early summer (December). Pupae did not undergo diapause when the entire development (eggs and all larval instars) occurred under prolonged photoperiod (14 L:10D). However, it was not possible to terminate the pupal diapause either by prolonging photoperiod or by increasing the temperate regimes. Based on larval incidence in the field it is proposed that H. pyrochroma is a bivoltine species with overlapping generations
Hyperspectral imaging predicts macadamia nut-in-shell and kernel moisture using machine vision and learning tools
Get PDFTree nuts are a convenient and nutritious food source and recently considerable attention has been placed on quality assessment to provide high quality nuts and improve consumer satisfaction. Moisture is a critical parameter for tree nut quality and is routinely monitored throughout post-harvest processing. However, current direct methods to assess nut moisture are based on using limited numbers of representative sub-sets and are destructive. This study aimed to use hyperspectral imaging and machine learning (ML) to predict moisture of individual macadamia nuts during post-harvest processing. Specifically, we aimed to compare data extraction methods (automatic vs. manual) and nut orientation (base-up, base-down and combined orientations) during imaging in predicting moisture for nut-in-shell and kernels. We also explored minimum wavelength numbers to predict moisture. Spectra were obtained from images of nuts in two orientations and extracted using manual and automatic methods prior to development of partial least squares (PLSR), artificial neural network (ANN), support vector machine (SVM) and Gaussian process regression (GPR) models. Kernel moisture prediction was more accurate using automatically extracted spectra, whereas nut-in-shell moisture prediction accuracy was similar for either method. For kernels, combining the spectra from two images of nuts in base-up and base-down orientations provided similar prediction accuracy (RMSET = 0.308 %), compared with spectra from one image (RMSET ≥ 0.341 %), and for nut-in-shell, using spectra from one image also provided similar accuracy (RMSET ≈ 1.2 %) as using both images combined. PLSR models predicted moisture with very high accuracy for both nut-in-shell (R2T = 0.96, RMSET = 1.20 %, RPD = 5.15) and kernels (R2T = 0.99, RMSET = 0.308 %, RPD = 11.05) following selection of ten important wavelength bands between 760 and 967 nm. ANN and GPR also achieved equivalent (R2T = 0.99) highest accuracy predictions for kernels, however, all wavelengths were required, which would increase computational processing time for high volume applications. The important wavelength bands required to develop accurate models for macadamia moisture prediction are consistent with other food and nut products and prediction accuracies are possible for process control applications using only 10 wavelength bands. Several ML models including PLSR, ANN and GPR are suitable for use with Vis/NIR hyperspectral images to predict macadamia moisture, however, for industrial applications where high volume through-put is required, using PLSR with limited selected wavelength bands is recommended. Overall, hyperspectral imaging combined with computer vision software and ML models showed significant potential to predict moisture concentration of macadamia during post-harvest processing