53,045 research outputs found
Postharvest investigations into chlorophyll fluorescence and low temperature injury in cut roses (Rosa hybrida L.)
No full textThis is one of the first studies on the relationship between pre-harvest
environmental conditions found in the Mediterranean and postharvest characteristics
of cut roses (Rosa hybrida L. ). Effects of storage temperature on vase life parameters
were also studied for roses grown all year round. The postharvest storage of roses at
low temperature is a useful practice, in terms of market flow regulation. However, a
reduction in vase life and loss of flower quality has been recorded after storage due to
Low Temperature Injury (LTI). LTI of roses is difficult to assess by visual
observation. Relative chlorophyll fluorescence (F'IFR, ), which is a non-invasive
technique that provides an index of stress effects on photosystem II (PS II) activity,
was used to investigate LTI in roses. The plant growth regulator abscisic acid (ABA)
can cause physiological responses that protect plants against CI or LTI. The overall
objectives of this study were firstly to evaluate the pre-harvest environmental
conditions affecting vase life and secondly to evaluate novel potential ABA
treatments to protect cut roses against LTI.
Vase life durations and Fv. /Fm ratios measured after low temperature storage
for `First Red' and `Akito' roses were seasonally dependant. Vase lives of roses
grown during winter were significantly (P
_<
0.001) shorter compared to roses grown
during the rest of the year. In autumn and winter experiments F.. IF.. ratios were
generally reduced following storage at 1°C, suggesting LTI of roses. Thus, the fall of
F,. /Fm was due to an interaction of growing season and storage at I. T. However, in
second year experiments, growing temperature and PFD were relatively higher and, as
a result, Fý/Fm did not decline for `Akito' roses after low temperature storage,
indicating a strong influence of environmental conditions. Higher PFD and
temperature glasshouse during the year were positively and significantly correlated
with maintenance of post-storage Fv. /Fm ratios and longer vase life. It is suggested
that shorter vase lives and lower post-storage FV/Fm values after storage at 1°C are
consequences of reduced photosynthesis and smaller carbohydrate pools in winter-
harvested roses. Because of the lack of correlation between Fv. /Fm and post-storage
vase life, it is concluded that the CF parameter F,. /Fm is not a practical index for
assessing LTI in cold-stored roses. Growing roses in autumn and winter months increased flower blueing in red petals of `First Red' roses and prevented flower
opening for both cultivars.
ABA applied as pulse treatment before storage or as vase solution during vase
life generally improved vase life parameters. Pulsing `Akito' roses with 10-1 M ABA
before storage increased vase life and inhibited bent neck incidence. Also, the
presence of ABA in vase solution increased vase life after storage at 1°C, reducing
vase solution usage during vase life. Similarly, the synthetic ABA analogue PBI-365,
as vase solution ingredient, was effective in extending vase life and reducing
transpiration rates in roses after low temperature storage. Increased ABA levels were
detected in leaves and petals using HPLC when roses were treated with exogenous
ABA before storage and during vase life. Thus, it was assumed that ABA or PBI-365
acted on guard cells by causing stomatal closure. Electrolyte leakage and lipid
peroxidation, measured after storage at 1°C, were markedly reduced by application of
ABA. Both pulse ABA treatment and vase solutions containing ABA helped to
recover F,, /Fm during vase life. Moreover, addition of PBI-365 in vase solution
reduced the degree of lipid peroxidation in leaves and petals after storage at 1°C.
These observations indicated a protection role of ABA against LTI for roses, which
has also been observed in other crops.
Further research at the cellular and/or molecular level may help in better
understanding the physiological responses of roses to seasonal variation during the
year and LTI. In addition, work is also required to look at the ABA and PBI-365
mode of action in roses. Additional research using a wide range of ABA
concentrations and assays using exogenous radio-labelled ABA may help to better
understand the nature of ABA efficacy
Did Plant Patents Create the American Rose?
No full textThe Plant Patent Act of 1930 was the first step towards creating property rights for biological innovation: it introduced patent rights for asexually-propagated plants. This paper uses data on plant patents and registrations of new varieties to examine whether the Act encouraged innovation. Nearly half of all plant patents between 1931 and 1970 were for roses. Large commercial nurseries, which began to build mass hybridization programs in the 1940s, accounted for most of these patents, suggesting that the new intellectual property rights may have helped to encourage the development of a commercial rose breeding industry. Data on registrations of newly-created roses, however, yield no evidence of an increase in innovation: less than 20 percent of new roses were patented, European breeders continued to create most new roses, and there was no increase in the number of new varieties per year after 1931.
Roses bring dreams of you.
No full textGift of Dr. Mary Jane Esplen.Piano vocal [instrumentation]Alone I sit this summer morn the roses all in bloom [first line]Roses roses roses bring mem'ries of you dear [first line of chorus]C major [key]Andante [tempo]Popular song [form/genre]Roses; photograph: Frankie Campbell [illustration]Starmer [engraver]S. H. Knox & Co., Detroit [dealer stamp]Publisher's advertisement on front inside cover & back cover [note
Domestication of wild roses for fruit production
No full textThe utilization of rose hips has a long tradition in Sweden, where they are used for the manufacturing of a popular dessert soup rich in vitamin C. In the mid 1980s a project was initiated at Balsgård, situated in the south of Sweden, with the aim to develop rose cultivars as a field crop for rose hip production. In the present thesis, some aspects of the domestication process in wild roses for fruit production are reported and discussed. Most of the papers concern species within section Caninae. All of these species are polyploid and characterized by their unique meiosis with unequal distribution of chromosomes from the parents to the offspring. The plant breeding program was divided into three steps. In the first step, plant material was acquired from different sources. The second step involved intraspecific and interspecific crosses in section Caninae and the third step concerned intersectional crosses between sections Caninae and Cinnamomeae. Seed germination was studied with different temperature treatments, and differences in amount of germination among the species were noted. Morphological diversity within and between three species, belonging to section Caninae, R. dumalis, R. rubiginosa and R. villosa was investigated. Rosa dumalis demonstrated the most pronounced intraspecific variation, whereas R. rubiginosa was very homogenous. Similar results were obtained when offspring plants were screened for fruit traits, such as fruit weight, % fruit flesh, % dry matter and vitamin C. Matroclinal inheritance was demonstrated with molecular markers (RAPD) in a pair of reciprocal crosses between R. dumalis and R. rubiginosa. The development of colour and some other fruit characteristics during ripening was studied for 6 weeks in R. dumalis, R. rubiginosa and R. spinosissima. For R. dumalis and R. rubiginosa it is possible to use colour as an indicator of optimum harvesting time. In R. spinosissima the fruits should be harvested in the middle of September, when most of the fruit traits have reached an optimum. Seedlings from 11 intersectional crosses (Caninae and Cinnamomeae) were screened for blackspot, leaf spot, powdery mildew and rust. Blackspot was the most severe disease followed by leaf spot, whereas symptoms of powdery mildew and rust were rare
Violence, Political Instability, and International Trade: Evidence from Kenya’s Cut Flower Sector
No full textAbstract: We assess whether and how violence and political instability affect trade between developed and developing countries considering the special case of EU imports of Kenyan roses after the 2007/08 post-election violence and political instability in Kenya. Using the Rotterdam model to estimate EU demand for roses from Kenya and other global competitors, we find evidence of a structural change in the import growth rate for Kenya, approximately equivalent to an 18.6% tariff. These results highlight the importance of non-tariff barriers to trade and contribute to the growing literature on the role of insecurity and instability in hindering international trade.Kenya, Africa, EU, election violence, cut flowers, roses, imports, international trade, Demand and Price Analysis, International Development, International Relations/Trade, Political Economy, F14, F23, F59, O13, Q17,
Experimental investigation of plasma impedance in Linac4 source
No full textCERN ’s new particle accelerator Linac4 is part of the upgrade of the LHC accelerator chain. Linac4 is required to deliver 160 MeV H− beam to improve the beam brightness and luminosity in the Large Hadron Collider (LHC). The Linac4 H− source must deliver 40-50 mA, 45 keV H− beam in the RFQ acceptance. Since the RF power coupled to the H− source plasma is one of the important parameters that determines the quality of the H− beam, the experimental investigation of the dependence of the load impedance on the operational parameters is mandatory. In this study, we have measured the impedance of the H− source plasma varying the RF power coupled to the plasma and the condition of the hydrogen gas. Also, optical emission spectroscopy (OES) measurements have been carried out simultaneously with the impedance measurement in order to determine the plasma parameters. The determination of the plasma parameters allows us to compare the experimental results with the analytic model of the plasma parameters, which is useful to discuss the results from a physical point of view
Influence of the cusp field on the plasma parameters of the Linac4 H− ion source
No full textWhen the H ion source of CERN’s Linac4 is operated in volume mode, a maximum of the extracted current is obtained at varying RF power. The power required for this maximum and its absolute value is strongly influenced by the cusp magnets installed at the source for electron confinement: without magnets, 15−20 mA are typically obtained at 20 kW whereas with magnets a factor of two more power is needed and 25−30 mA are achieved. In order to access the reasons behind the peaked performance with varying RF power and for determining the influence of the cusp field on the discharge, optical emission spectroscopy (OES) measurements of the atomic Balmer series and of the molecular Fulcher transition have been carried out. In all investigated cases, the gas temperature of the discharge has been virtually equal to the ambient temperature as the short discharge pulse length of 500 s is not long enough for considerable heavy particle heating. When no cusp magnets are installed, the plasma parameters evaluated with the collisional radiative models Yacora H and Yacora H show a minimum in the electron temperature of 3.25 eV and a maximum in the electron density of and also in the vibrational excitation of the hydrogen molecule at 20 kW. Assessing the relevant production and destruction processes demonstrates that the H yield is maximal at this point thereby explaining the optimum ion source performance. When the cusp magnets are applied, the same general trends are observed but the required RF power is a factor of two higher. The OES results indicate an optimum performance around 30 kW whereas the highest H current is actually achieved around 40 kW. Furthermore, a higher H yield is indicated without cusp magnets but a better ion source performance is observed with magnets. These differences can most likely be attributed to changing gradients in the plasma parameters which are not accessible by OES. Nevertheless, the obtained plasma parameters can be used as benchmark for RF coupling codes simulating the Linac4 ion source
A molecular dynamics study of N-A-S-H gel with various Si/Al ratios
No full textThe understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the polymerization of Si and Al monomers by molecular dynamics. The simulated polymerization process is in good agreement with the experimental results especially in terms of the reaction rate of Si and Al species. The atomic structural features of the N-A-S-H gel were analyzed in terms of bond length and bond angle information, simulated X-ray diffraction (XRD) and Qn distribution. A significant finding is the existence of pentacoordinate Al in all simulated N-A-S-H structures, indicating that pentacoordinate Al in geopolymer does not only come from raw material. Besides, the results show that a smaller Si/Al ratio led to a more crosslinked and compacted structure of N-A-S-H gel
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Effects of the extraction voltage applied by the puller-electrode on the H extraction in the Linac4 negative ion source
No full textIn order to understand the H extraction mechanism and investigate the effect of the extraction voltage applied by the puller-electrode on the H extraction in the Linac4 negative ion source, we are developing a 2D3V-PIC (two dimensions in the real space and three dimensions in the velocity space, Particle in Cell) model with volume produced H ions. It is shown that how to take the magnetic filter field direction is important for the 2D modeling to take into account the important 3D effect of electron drift. It is also shown that the meniscus formation is not symmetric due to the electron drift in the extraction region and the divergence of the H beam is asymmetric. In order to make more quantitative comparison of the extracted H and electron currents with the experiments and 3D modeling, further improvements, especially the electron loss along the magnetic filter field line will be needed
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