1,721,074 research outputs found
Natural disease resistance in strawberry fruit and Geraldton waxflower flowers
Full text linkAntifungal activity against Botrytis cinerea and Cladosporium cladosporioides
declined with increasing fruit maturity as shown by thin layer chromatography (TLC)
bioassay. Preformed antifungal activity was also demonstrated in flower tissue.
Decline in fruit antifungal compounds was correlated with a decline in natural disease
resistance (NDR) against B. cinerea. Crude extracts of green stage I fruit contained at
least two previously unreported preformed antifungal compounds (Rf = 0.44 and 0.37)
that were not present in white and red stage fruit. These compounds were confirmed
by TLC reagent sprays not to be phenolics or alkaloids. Positive reactions to
Ehrlich’s reagent suggested that Rf = 0.37 was a teipene. The majority of antifungal
activity was found in the achenes of green stage I fruit. However, antifungal activity
was found in all tissue types (viz. pith, cortex, epidermis) of green stage I fruit. TLC
bioassays showed that all fruit stages showed antifungal activity at the origin (Rf =
0.00). The approximate area of fungal inhibition at origin in green stage 1 fruit
extracts was 90 and 70% greater than in white and red stages. TLC reagent sprays
confirmed that antifungal compounds at origin contain phenolics. This is consistent
with previously reported phenolic compounds in strawberry fruit that are inhibitory to
B. cinerea.
An investigation into the potential of enhancing NDR using different chemical
(acibenzolar), biological (Aureobasidium pullulons) and physical (UV-C) elicitors
was conducted with a view to developing an integrated pest management (EPM)
strategy. The most promising results were achieved with pre-harvest treatments of the
chemical plant activator acibenzolar. Seven glasshouse trials were conducted over a
three year period. Preharvest application of acibenzolar (0.25 - 2.0 mg AI ml'1) were
effective in suppressing grey mould on strawberry fruit harvested from winter grown
plants. Conversely, acibenzolar was ineffective at suppressing grey mould on fruit
harvested from summer grown plants. However, where acibenzolar was effective,
disease development was delayed by as much as 2 days. This delay was equivalent to
a 15-20% increase in shelf-life. If systemic acquired resistance and/or other inducible
mechanisms are to be implemented as part of an IPM strategy for controlling B.
cinerea more research is required on how environment and management factors affect
the efficacy of elicitors such as acibenzolar.
Geraldton waxflower is the most economically important native Australian cut flower
export. Infection of Geraldton waxflower by B. cinerea can lead to unacceptable
levels of flower abscission after harvest. Thus, an investigation was conducted into
the nature and identities of constitutive antifungal compounds in imported Geraldton
waxflower flower and leaf tissues. Antifungal activity against B. cinerea and C.
cladosporioides was observed in both Geraldton waxflower leaf and flower tissue.
Leaf tissue contained considerably less antifungal activity than flower tissue. Some
antifungal compounds were common to the three different waxflower cultivars
studied. Through TLC reagent sprays and NMR GC-MS spectra, these antifungal
compounds were identified as the sesquiterpenes, globulol and grandinol. There were
also at least two unidentified phenolics. Notwithstanding similarities in antifungal
profiles, it was also evident from TLC bioassays that significant variations exist
between different waxflower cultivars.
Further work is required to fully characterise the preformed antifungals compounds
found in strawberry and Gerladton waxflower tissues and to elucidate pathways
involved in their biosynthesis. In addition, work is also required to look at the full
spectrum of antifungal activity of these antifungal compounds. Such information will
allow precise definition of the roles that these compounds may play in suppression of
in strawberry and waxflower NDR against B. cinerea. In turn, this knowledge should
enable the introduction of improved and/or novel IPM strategies that enhance levels
of these compounds.Ph
Postharvest quality of conventionally and organically grown banana fruit
Full text linkQuality is increasingly important for retailers, who tend to look for more definitive assessment criteria. Taste has become a major issue over past years for consumers, who are seeking higher quality produce. For banana fruit, at least one major retailer is asking TSS measurement in addition to the usual assessment based on skin colour. At the same time organic produce sales are increasingly important for ripeners and retailers to consumers.
This study investigated variability in banana pulp with regard to sampling position from proximal, middle and distal portions. Also two different devices, the traditional pocket refractometer and the digital refractometer were evaluated. TSS was measured on juice obtained directly from the pulp, as practised by one supermarket representative, versus the more conventional method of homogenizing pulp samples in distilled water. Finally, a comparison of postharvest qualities of conventionally and organically grown banana fruit from nearby plantations in the Dominican Republic was made. This comparison involved several harvest times over the seasonal period from February to June 2001.
Green mature Cavendish bananas var. Grand Nain were imported from the Dominican Republic by SH Pratt’s & Co. (Luton, UK). Both the conventionally and the organically grown bananas from the same area were held at about 15 degrees C during shipping and handling. The fruit were then ripened in a postharvest laboratory in the UK with a shot of 100 muL/L ethylene applied for 48 hours at 20 ±1 degree C. They were then assessed over 12 days of shelf life at this same temperature and at 60 ±10 % relative humidity. Fruit weight (g), colour (L* and H degrees), acidity (ml of 0.1 N NaOH), firmness (N) and TSS (%Brix) were assessed every second day during shelf life. In addition, starch breakdown was visualised by dipping slices of banana in iodine solution. Sensory analysis on the ripened fruit was also made with 30 panellists for four out of six of the harvest times
Effects of 1-MCP on storage of "Queen cox" and "Bramley" apple fruit
Full text linkBetter maintenance of firmness and suppression of ethylene production in
'Queen Cox' and 'Bramley' apple [Ma/us sylvestris (L.) Mill. var. domestica (Borkh.)
Mansf.] fruit was achieved by prestorage applications of 1-MCP. 1-MCP
concentration, exposure time and exposure temperature ranges of 0.1 to
10.0 µl r1 1-MCP, 6 to 48 h and O to 20°C, respectively, were effective on fruit
subsequently stored for 2 ('Cox') and 3 ('Bramley') months in air at 3 to 4°C.
However, 1-MCP had little effect on either firmness or ethylene production after 4
('Cox') or 6 ('Bramley') months storage. Nonetheless, 1-MCP treated 'Bramley' fruit
had reduced rot and superficial scald incidence compared with untreated control fruit.
1-MCP application was most effective when applied within 24 h of harvest
· compared to 14 d later. Earlier-harvested 'Cox' and 'Bramley' apple fruit showed
better response to 1-MCP-treatment than those harvested towards the end of the
picking season. 1-MCP-treatment was shown to improve apple storage alone and in
combination with controlled atmosphere (CA) storage. Furthermore, 1-MCPtreatment maintained fruit quality during shelf-life better than CA storage alone.
Chlorophyll fluorescence was not demonstrated to be an effective method to determine
'Cox' and 'Bramley' apple fruit quality.
There was no recorded correlation between the concentration of five antifungal
compounds and 1-MCP-treatment after inoculation with Penicillium expansum or
Botrytis cinerea.
1-MCP treatment for apple storage was developed for AgroFresh Inc., the
holder of the 1-MCP patent. Part of this research was used for the UK efficacy trials
for registration of 1-MCP as an apple storage treatment. On the 18th July 2002 the US
Environmental Protection Agency (EPA) granted approval for 1-MCP to be applied to
food crops. Approval was granted in the UK in time for the 2003 apple harvest, and
for 2004 across Europe.MPhi
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Biology and management of freesia flower specking caused by Botrytis cinerea
Full text linkThere is no published research regarding postharvest infection of freesia flowers
by Botrytis cinerea. Although, infection problems have concerned freesia growers and
wholesalers in recent years. The overall objectives of this study were firstly to evaluate
the factors affecting B. cinerea postharvest disease establishment and secondly to
evaluate a range of novel potential treatments to reduce postharvest freesia infection.
These treatment options include plant activators such as acibenzolar-S-methyl and methyl
jasmonate and biotic (Aureobasidium pullulans) and abiotic (UV-C irradiation)
biological/elicitors agents.
Research was undertaken in an attempt to explain the variation in B. cinerea
incidence on cut freesia flowers as noted by the UK importer Zwetsloots & Sons Ltd. in
2000. Higher monthly rejections of freesia flower stems throughout 2000 due to B.
cinerea infection were recorded during spring (April-May), early summer (June) and
autumn (October). Comparatively higher proportions of rejected freesia stems were
associated with glasshouse temperatures ranging from 13-17°C.
In the presence of B. cinerea inoculum on freesia petal surface, temperature was
not a limiting factor for disease establishment. Incubation of artificially inoculated
freesia flowers at 12°C resulted in overall higher disease severity and lesion numbers
compared to flowers incubated at 5 or 20°C. In contrast, relative humidity was the most
important factor for postharvest infection by B. cinerea.
Elicitor based strategies for IPM using the potent activator acibenzolar provided
limited protection of freesia flowers against B. cinerea when applied postharvest.
Acibenzolar significantly reduced disease severity, lesion numbers and lesion diameters
compared to the untreated control when applied at 0.15 g A. 1. U1.
Methyl jasmonate (MeJA) applied as gas, pulse and spray generally suppressed B.
cinerea disease on cut freesia flowers. Disease severity, lesion numbers and lesion
diameters of flowers gassed with 0.1 μL MeJA L"' were reduced by 56,43 and 37%,
respectively compared to untreated control flowers. Gaseous MeJA treated freesia
flowers at 0.1 μL L"1 increased PPO activity by 57% compared to untreated controls 24h
after MeJA treatment. After 36h of incubation at 20°C, disease severity, lesion numbers and lesion diameters of gaseous MeJA treated flowers were reduced by 68,56 and 50%,
respectively, compared to the untreated controls. However, PAL activity in MeJA treated
freesia flowers did not decrease significantly over time compared to untreated control 12h
post-inoculation and thereafter. These findings suggest that MeJA treatment might
suppress the action of PAL in the phenylpropanoid pathway and consequently block SA
production.
UV-C irradiation might be used in an integrated postharvest disease management
program for freesia flowers. UV-C irradiation after artificial inoculation resulted in
markedly reduced B. cinerea disease severity scores and lesion numbers. In detail, UV-C
irradiation of cut freesia flowers with 0.5,1,2.5 and 5 kJ m''` reduced disease severity by
up to 44,70,74 and 59% and lesion numbers by up to 37,62,68 and 60%, respectively.
UV-C irradiation at 1 kJ M-2 before artificial inoculation slightly reduced disease severity
and lesion numbers possibly by inducing defence responses. However, the limited
disease suppression suggested that apparently B. cinerea could overcome the UV-C
induced effect.
The effect of preharvest treatments on freesia crops with acibenzolar was
investigated in glasshouse trials in view to suppress postharvest B. cinerea infection via
SAR induction. Acibenzolar was effective in selected treatments and conditions.
Disease pressure varied over the 3 years and over varieties tested. However, it was
unclear whether acibenzolar induced systemic and/or local defence responses. The latter
was supported by biochemical investigations in 2001 which suggested that acibenzolar
did not induce PAL activity.
In contrast, preharvest MeJA treatment resulted in markedly systemic protection
of treated flowers compared to untreated ones. MeJA efficacy was dependent on variety
and on postharvest incubation temperatures. Disease severity, lesion numbers and lesion
diameters on MeJA treated freesia var. `Dukaat' flowers incubated at 20°C were reduced
by 56,61, and 49% compared to controls, respectively. Also, disease severity, lesion
numbers and lesion diameters on MeJA treated `Cote d'Azur' flowers incubated at 20°C
were reduced by 36,26, and 49% compared to controls, respectively
Factors Affecting the Adoption of Digital Tools and Systems in Australian Horticulture Industries
No full textGlobally, up to one-third of food is lost or wasted in part due to poor cold chain management practices. Just as the “green revolution” innovations of the 1960s changed agriculture, the current “digital revolution” could help agriculture overcome this food waste challenge. Horticulture, with its intensive production systems, higher level of loss and wastage, and high value, is well placed to gain from this digital revolution and the adoption of digital technologies. Ensuring optimal temperature management is the single most important factor in maintaining fresh produce quality and reducing waste. Careful management of temperature is important because temperatures above or below the biologically safe temperature range damage fresh products. Anecdotally, in places such as Australia, it is claimed that cold chain management practices are inadequate, and the use of temperature monitoring tools is limited. Limited research has been conducted to understand and explain why the horticulture industry at large is failing to adopt technologies to support better cold chain practices.
Using a sequential multi-methods qualitative research approach, this dissertation provides insights into the challenges of the adoption of temperature monitoring technologies in Australian horticulture supply chains. The Technology Acceptance Model (TAM) by Davis (1989b) is the theoretical foundation guiding this qualitative study. My original contributions to knowledge are twofold. First, this study explored the lived experiences of horticulture supply chain members in Australia when adopting temperature monitoring technologies to support cold chain practices. Second, the study sought to understand the applicability of TAM to general horticulture supply chain settings.
During the first stage of the research, 30 in-depth interviews with businesses operating in the mango industry provided a detailed description of factors deterring, as well as supporting, adoption. These findings were then verified in the second stage of the research using a multiple case study approach examining three horticulture supply chains. Analysis of the data indicates serious cold chain breakdowns in Australian horticulture supply chains, largely because of poor temperature monitoring due to the prevalent belief that minor temperature variations have no major effect on product quality and shelf life. The research also indicates that adoption is affected by seven TAM constructs, namely perceived ease of use, usefulness, attitudes, behavioural intentions, trust, social influence, and costs.
The study contributes to the Information System literature by presenting an integrated TAM model that can be utilised to understand adoption in horticulture supply chains. It supports and strengthens the TAM by providing evidence of its applicability to real-life horticulture industry supply chains around a fundamental and pivotally important adoption problem in the industry. The practical implications for ICT developers, industry peak bodies, and governments are that inter-firm interactions must be considered when designing and implementing cold chain improvement programs. This dissertation provides government, industry, and businesses with detailed insights into supply chain participant’s interactions can be applied to improve cold chain practices across the whole chain.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Dept Bus Strategy & InnovationGriffith Business SchoolFull Tex
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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