12903 research outputs found
Sort by
The function of source-sink relationships in grapevines on grape and wine production
No full textThe production and storage of carbohydrates in grapevines is influenced by vineyard management and environmental conditions. The general pattern of seasonal perennial reserve utilisation is characterized by a decrease following bud-break, and then an increase that can begin any time between flowering and leaf-fall. Stored carbohydrate reserves support early shoot growth and the availability of reserves can influence reproductive development, including grape composition. The crop load impacts on grape maturation and carbohydrates allocated to the perennial structure, whereas the length of the period after harvest and its conditions, determine the replenishment of carbohydrate reserves for the following season. The availability of assimilates from leaves or reserves is crucial for berry sugar accumulation and metabolite production, ultimately reflected in must fermentation and the final wine. Further knowledge of carbohydrate dynamics and the influence of cultural practises on these source-sink relationships is critical to enhance grape and wine production. Several studies were conducted under warm climatic conditions to understand the source-sink relationships of grapevines, by investigating the seasonal carbohydrate dynamics, conducting experiments under controlled conditions and incorporating various vineyard management practices. In a major field experiment, crop load, canopy size, or water supply was altered on ‘Shiraz’ and ‘Chardonnay’ grapevines, affecting winter carbohydrate reserve status and fruit productivity. However, these practices did not substantially alter the seasonal pattern of reserve dynamics, suggesting that developmental stage or seasonal climatic factors have a stronger influence. In contrast, the impact of varying source-sink biomass significantly impacted on fruit composition, including sugar accumulation. These results were also reflected in the composition and sensory attributes of experimental wines, with influence on wine quality being more pronounced for ‘Shiraz’ than ‘Chardonnay’. Further detailed evaluations of carbohydrate dynamics during grape maturation are required to clarify the impact of management practises on vine carbon balance and implications for wine production
The use of fixed shelling percentage biases genotype selection in hybrid maize multi-environment yield trials
No full textContext or problem Phenotyping is an integral part of plant breeding operations. In many cases the trait measured is not identical to the target trait for reasons of speed and or cost. This is a form of indirect selection, where correlation between the trait measured and the target phenotype influences the rate of genetic gain. Low correlations lead to slow rates of genetic gain. In sub-Saharan African maize breeding programs, maize grain yield in breeding experimental plots is measured as a field weight (FW), which includes the grain and cob. The weight of grain from each plot is estimated as a standard proportion of grain to total ear weight using a shelling percentage of 80 %. This approach assumes that there is no genetic, environment or genetic by environment interaction in shelling percentage which, if present, would contribute to slower rates of genetic gain for grain yield. Objective or research question This study investigated the magnitude of genetic and environmental variation in shelling percentage and its impact on selection in six hybrid maize multi-environment yield trials in Ethiopia over two seasons. Methods The data of shelled grain weight (SW) and cob weight (CW) from the trials were analyzed using a bivariate linear mixed model. Results Genetic variances for both traits varied across the six testing sites ranging from 0.199 to 2.975 for SW and from 0.029 to 0.245 for CW. The genetic correlations between pairs of sites for SW and CW also varied, indicating the existence of genotype by environment interaction for these traits. Additionally, the bivariate regressions between FW and SW indicated there was substantial genetic deviation around the 80 % shelling response, and this relationship was impacted by environmental influences. Conclusion The use of a constant relationship of 80 % shelling biases grain yield prediction in multi-environment hybrid maize yield trials and thus reduces the rate of genetic gain in maize breeding programs. Implications or significance Taking into account the variations in the shelling percentage of the genotypes across sites in predicting grain yield from field weight improves the accuracy of genotype selection and the rate of genetic gain in maize breeding programs
A review of the benefits and limitations of waste nutrient treatment in aquaculture pond facilities
Get PDFManaging waste nutrients from intensive freshwater and marine pond aquaculture is a global challenge. Nutrient-enriched water released from farms can have detrimental effects on aquatic ecosystem health. There are a range of treatment options for discharge water from fish and crustacean ponds, and this review examines the benefits and limitations of these options. Much of the nutrient waste is derived from the addition of formulated feed. In recent years, reduction in waste from feeds and feeding has been largely incremental. In terms of treatment, there are low-cost approaches, such as settlement ponds, but they are inefficient at reducing nutrients. Biological systems, using aquatic plants, microalgae and filter feeders to reduce nutrient release from farms have variable levels of effectiveness. Establishing wetlands requires considerable additional land area, and success to date has been highly variable. Overall, this review found no simple cost-effective solution for managing nutrient enriched water from ponds. This is due, in many cases, to challenges with treating the large volumes of discharge water with relatively low nutrient concentrations. This means that more technologically advanced and reliable treatment options, for example, bioreactors, are prohibitively expensive. However, some systems, such as use of recirculation systems typically increase nutrient concentrations, and hence the efficiency and effectiveness of more expensive treatment methods. Biofloc systems can also provide a mechanism for in-situ nutrient treatment as well as a supplementary food source for animals. Overall, there is scope to improve treatment of waste nutrients, but significant modifications to many production systems are needed to achieve this
Gum Arabic edible coating embedded aqueous plant extracts: Interactive effects of partaking components and its effectiveness on cold storage of fresh-cut capsicum
Get PDFThis study investigated the interactive effects of components in gum Arabic-based coating enriched with aqueous extracts of Syzygium aqueum, Diploglottis bracteata, and Tasmannia lanceolata on properties of edible coating/film. Response surface methodology was employed to optimize the films based on their physical and permeability properties. It was shown that the concentration of the components significantly influenced these characteristics. The coating demonstrated strong antimicrobial activity against Pseudomonas viridiflava, a main cause of soft rot in vegetables, when using 5.00% S. aqueum, 5.00% D. bracteata, and 9.35% T. lanceolata with lower concentrations of gum Arabic and MCT oil. The optimized coating was applied to fresh-cut red capsicum, and its effects were evaluated. The coating effectively inhibited microbial growth, maintaining low bacterial load (ca. 3 log CFU. g−1) until day 10 of storage. Sensory evaluations also showed positive liking scores for appearance, aroma, and flavor, indicating that the coating enhanced the overall sensory experience of the capsicum. Despite these positive outcomes, challenges regarding moisture retention and firmness preservation during storage were identified. The coating did not adequately preserve these qualities, highlighting the need for further research to optimize the formulation for commercial applications. Nonetheless, incorporating plant extracts in the gum Arabic-based coating holds promise for extending the shelf life of fresh-cut capsicum while improving its sensory attributes
Identification and evolution of ICE-PmuST394: a novel integrative conjugative element in Pasteurella multocida ST394
Get PDFThe emergence of macrolide and tetracycline resistance within Pasteurella multocida isolated from feedlot cattle and the dominance of ST394 in Australia was reported recently.To establish the genetic context of the resistance genes in P. multocida 17BRD-035, the ST394 reference genome, and conduct a molecular risk assessment of their ability to disperse laterally.A bioinformatic analysis of the P. multocida 17BRD-035 genome was conducted to determine if integrative conjugative elements (ICEs) carrying resistance genes, which hamper antibiotic treatment options locally, are in circulation in Australian feedlots.A novel element, ICE-PmuST394, was characterized in P. multocida 17BRD-035. It was also identified in three other isolates (two ST394s and a ST125) in Australia and is likely present in a genome representing P. multocida ST79 from the USA. ICE-PmuST394 houses a resistance module carrying two variants of the blaROB gene, blaROB-1 and blaROB-13, and the macrolide esterase gene, estT. The resistance gene combination on ICE-PmuST394 confers resistance to ampicillin and tilmicosin, but not to tulathromycin and tildipirosin. Our analysis suggests that ICE-PmuST394 is circulating both by clonal expansion and horizontal transfer but is currently restricted to a single feedlot in Australia.ICE-PmuST394 carries a limited number of unusual antimicrobial resistance genes but has hotspots that facilitate genomic recombination. The element is therefore amenable to hosting more resistance genes, and therefore its presence (or dispersal) should be regularly monitored. The element has a unique molecular marker, which could be exploited for genomic surveillance purposes locally and globally
Evaluating novel biodegradable polymer matrix fertilizers for nitrogen-efficient agriculture
Get PDFEnhanced efficiency fertilizers (EEFs) can reduce nitrogen (N) losses in temperate agriculture but are less effective in the tropics. We aimed to design a new EEF and evaluate their performance in simple-to-complex tests with tropical soils and crops. We melt-extruded urea at different loadings into biodegradable polymer matrix composites using biodegradable polyhydroxyalkanoate (PHA) or polybutylene adipate-co-terephthalate (PBAT) polymers with urea distributed throughout the pellet. These contrast with commercially coated EEF that have a polymer-coated urea core. We hypothesized that matrix fertilizers would have an intermediate N release rate compared to fast release from urea or slow release from coated EEF. Nitrogen release rates in water and sand–soil columns confirmed that the matrix fertilizer formulations had a more progressive N release than a coated EEF. A more complex picture emerged from testing sorghum [Sorghum bicolor (L.) Moench] grown to maturity in large soil pots, as the different formulations resulted in minor differences in plant N accumulation and grain production. This confirms the need to consider soil interactions, microbial processes, crop physiology, and phenology for evaluating fertilizer performance. Promisingly, crop δ15N signatures emerged as an integrated measure of efficacy, tracking likely N conversions and losses. The three complementary evaluations combine the advantages of standardized high-throughput screening and more resource-intensive and realistic testing in a plant-soil system. We conclude that melt-blended biodegradable polymer matrix fertilizers show promise as EEF because they can be designed toward more abiotically or more microbially driven N release by selecting biopolymer type and N loading rate
Wavelength variation of the depth of penetration of Near Infrared radiation in Hass avocado fruit
Get PDFThis study reports on the wavelength dependence of near infrared (NIR) radiation penetration depth into 'Hass' avocado fruit for both transmission and reflectance modes in the wavelength range from 12820−4000 cm−1 (780−2500 nm). For transmission mode, depths of penetration less than 3 mm occurred in the 5369 to 7413 cm−1 (1862−1348 nm) range, while the maximum depth of penetration of approximately 12 mm occurred in the region 11293 to 11987 cm−1 (885−834 nm). Two other wavelength regions were identified with significant depth of penetration in transmission mode, one around 9272 cm−1 (1078 nm) and the second at approximately 7899 cm−1 (1265 nm) with approximately 10 mm and 4.5 mm penetration respectively. In reflectance mode, despite the difference in the optical paths sampled, qualitatively similar trends in wavelength dependence of the depth of penetration were observed, with a lower penetration depth of 3.3 mm occurring around 9311 cm−1 (1074 nm) and maximum depth of penetration of approximately 4.8 mm occurring in the 11625 to 11987 cm−1 (860−834 nm) region
Genome sequence and annotation of Pyramidobacter sp. strain YE332, isolated from a cattle rumen fermentation of Leucaena leaf
Get PDFWe report the 2.78-Mb circular genome sequence of Pyramidobacter sp. strain YE332, isolated from a fermentation of bovine rumen fluid, supplied with leaf material from Leucaena leucocephala cv. Cunningham. This genome sequence consists of 2,795,328 bp with 60% G + C content, 2,573 predicted coding DNA sequences, and 70 RNAs
Binding of the plant-derived toxin simplexin to bovine protein kinase C: insights from molecular dynamics
No full textPimelea poisoning of cattle is toxicologically linked to the activation of bovine protein kinase C (PKC) by the plant-derived toxin simplexin. To understand the affinity of PKC for simplexin, we performed molecular dynamics (MD) studies of simplexin, simplexin analogues, and several other activators of PKC. Binding enthalpy calculations indicated that simplexin had the strongest affinity for PKCα-C1B among the activators studied. Key to simplexin's affinity is its ability to form more hydrogen bonds to PKC, compared to the other activators. The C-3 carbonyl group and C-20 hydroxyl group of simplexin were identified as especially important for stabilizing the PKC binding interaction. The hydrophobic alkyl chain of simplexin induces deep membrane embedding of the PKC–simplexin complex, enhancing the protein–ligand hydrogen bonding. Our findings align with previous experiments on structure–activity relationships (SAR) for simplexin analogues, and provide insights that may guide the development of interventions or treatments for Pimelea poisoning
Further refinement of helicopter capture for Australian chital deer (Axis axis)
Get PDFThis study improves a technique to capture wild chital deer (Axis axis) in northern Australia by darting from a helicopter. We quantified several metrics, including the frequency of adverse animal welfare events. Mortality at the time of capture was 15%, but no animals died post-release, and the frequencies of hyperthermia and hypoxaemia were lower than in previous operations. This study can be used as a template for iterative refinement of high-risk capture methodologies