143,819 research outputs found
Flower development of Begonia franconis Liebm.
No full textChapter 1The effects of growth-regulating substances and environmental conditions on the composition of Begonia franconis Liebm. inflorescences were analysed. The inflorescences are generally composed of two male flowers and one terminal female flower.Auxins, gibberellins, and cytokinins, added to the branch apices, as well as low light intensity, promoted male flowering by increasing the number of male flowers. Removal of branches as well as application of cytokinins induced ramification of the inflorescences by outgrowth of the normally dormant axillary bud in the bract of male flowers. A transition of male flowers into female flowers was not observed.A model of the sex-regulating mechanism in relation to hormones and environmental conditions is put forward. On the principle that female development requires a high nutritional level it is suggested that the level of assimilates is important in regulating sex expression, hormones influencing the sex of flower buds through their regulation of the flow of assimilates.Chapter 2The development of flower buds of Begonia franconis Liebm. was studied in vitro . Inflorescences with two male and one female bud primordium were inoculated on chemically defined media to analyse the requirements for optimum growth.Omission of agar increased growth of the buds, on a liquid medium the buds reached a normal and complete development. Growth required both nitrate and ammonium. A cytokinin was also necessary for bud growth, the optimum cytokinin concentration for the female bud being 10 to 30 times higher than that for the male buds.IAA and ethephon had no effect on bud size, but ABA decreased growth if applied together with cytokinin. Although GA 3 had no effect, GA 4+7 promoted the length of the male perianth.Chapter 3The regulation of sex expression in Begonia franconis Liebm. was studied by analyzing the effects of growth-regulating substances on the initiation of floral organs in inflorescence primordia in vitro.In the absence of growth-regulating substances or with IAA ABA, and Ethephon, no differentiation of flower buds occurred. With 10 -6M BA all floral organs were initiated and the flower buds reached anthesis. Gibberellins promoted organ initiation in the buds. However, removal of the first bud of the inflorescence primordium strongly reduced organ initiation in the remaining buds by gibberellins. The growth-regulating substances did not change the sex of the buds as determined by their position in the inflorescence. However, female differentiation was inhibited at low sucrose levels that increased the number of male flowers.It is suggested that sexual differentiation is regulated endogenously by the central region of the inflorescence primordium, the carbohydrate level being a limiting factor for female differentiation.Chapter 4On stem segments of Begonia franconis Liebm. in vitro, only vegetative buds could be induced. On inflorescence pedicels, on the contrary, the formation of adventitious flower buds was abundant. Both cytokinin and auxin were required, the latter during the first 10 days. After the promotion of callus formation, the auxin became inhibitory to flower bud formation. Gibberellin strongly repressed flower bud development.None of the growth regulators tested affected the ratio of male to female flower buds. Pistillate buds never differentiated directly on the callus, but originated at the bracts on the pedicels of the staminate ones. A high sucrose level was required for female differentiation, particularly.It is concluded that the sex of Begonia franconis Liebm. flower buds is determined by the nutritional state of the tissue as a limiting factor for female differentiation.</p
Flowers through insect eyes: the contribution of pollinator vision to the evolution of flower colour
No full textPhDFlowers’ colours are an essential element of their ability to attract visits from
pollinators. However, the colours as they appear to human observers can differ
substantially from their appearance to insect pollinators, and so it is essential to consider
pollinator vision in any study of the ecology of flower colour.
In this thesis I describe how I have overseen the development of an online database to
provide accurate information on floral spectral reflectance measured without human
observational bias. This resource allows a more accurate consideration of flower colours
in future studies, and permits investigations of flower colours within and across
habitats. Using the records in this database, I analysed flowers from two European
habitats for spatial or temporal changes, modelling the colours according to insect visual
perception. I discovered that the insect-colour composition of the plant communities
does not change either along an altitudinal gradient or throughout the year. These novel
and ecologically-relevant analyses contradict previous observational studies, but support
the theory of a pollination “market” in which flowers compete for pollinator visitation.
I then describe my experimental investigations into the visual capabilities of two
pollinators and how this may relate to what colours of flowers they visit. Firstly I study
the foraging behaviour of bees under spatially inconsistent illumination and how this
impacts on their choice behaviour. I revealed patchy light can have measurable effects
on bee foraging behaviour: they intentionally choose familiar over unfamiliar
illumination, which may impact on the flowers they visit in complex natural
environments. Secondly, I detail the new evidence for a red-sensitive photoreceptor in
South African monkey beetles, a major pollinator in a habitat containing many longwavelength-
reflecting flowers, which are not classically “attractive” to bees.
Throughout this thesis, I explore how pollinator vision has shaped the evolution of
flower colours in different contexts.Biotechnology and Biological Science Research Council.
Royal Botanical Gardens Kew (BBS/S/L-2005/12155A
ECONOMIC ASPECTS OF THE SOUTH AFRICAN FLOWER INDUSTRY
No full textIn this paper some interesting findings from recent studies regarding the economic aspects of the South African flower industry are highlighted. By looking at South Africa’s competitiveness and doing a comparative advantage study, an international perspective is firstly developed. The contribution of the flower industry in the South African economy is then discussed. This includes a case study on flower growers in the Gauteng Province. The final section notes some challenges for this industry. This network of studies provide a basis from which a conclusion can be drawn that it would be important to structure government initiatives to assist the private sector to expand this industry. A strategic planning exercise where the South African flower industry is positioned within an international perspective as well as to take note of the current transformation stage of the economy will be required.Agribusiness, Crop Production/Industries,
Cognitive deficits of schizophrenia: the flower workshop initiative
No full textAdvancement of research on the neurobiology of the schizophrenic brain has revealed a complex of factors, from genetic tendencies affecting the development of brain structure to functional impairment caused by defective molecular signaling. Recently, the attention of psychiatrists and mental health professionals has been directed to the presence of cognitive deficits, responsible for most of the obstacles to the social insertion of patients.The schizophrenic person has a difficulty to manage the flux of consciousness in social interactions. We address this difficulty with the Flower Arrangement Workshop, a methodology of Psycho-Social Rehabilitation that reduces the vulnerability of the schizophrenic in the social environment. The workshop was offered regularly (18 months) for a group containing 4 schizophrenic subjects.

International Flower Networks: Transparency and Risks in Marketing Channel Choice
No full textTwo thirds of Kenyan cut flowers are marketed through Dutch flower auctions, while the remainder is marketed directly to retailers. Auctions do not restrict the volumes marketed; however price determination is based on a spot market. A Transaction Cost approach is used to investigate the differences in marketing costs between the channels. The results suggest that there are no differences between the channels in terms of uncertainty about prices, finding buyers or transparency of quality standards. Auction growers pay a higher marketing fee but they have significantly fewer office employees and flower varieties compared to growers who market directly.Transaction Costs, Auction, Flowers, Kenya, Netherlands, Agribusiness, International Relations/Trade,
The evolution of flower size and flowering behaviour in plants: The role of pollination and pre-dispersal seed predation
No full textThis thesis describes research into the effects of insect mediated pollination, and pre-dispersal
seed predation, in common species of Asteraceae, varying both between and throughout
growing seasons, and suggests that these exert selective pressures influencing the evolutuion
of both inflorescence size and flowering phenology. Changes in the level of infestation of capitula (by tephritid fly larvae) and in capitulum size
were monitored by twice-weekly collections from populations of common species of
Asteraceae over the course of five years’ flowering, in 2002 to 2006. Seed counts of drying
flower heads were made over the course of the research, identifying levels of seed set in both
uninfested and infested flower heads. A mathematical model was created to investigate the
extended influence of the parameters measured in the field, and predict their influence on
longer term evolution of Asteraceae. Two flower species exhibited both significant levels of infestation, and significant differences
in fecundity. In Leucanthemum vulgare, infestation (by Tephritis neesii) peaked mid-season at
all sites. In Centaurea nigra, infestation (by gall-forming Urophora spp) peaked mid-season,
infestation (by non-gall forming Chaetostomella cylindrica) was lowest in mid-season. In
both species the probability of attack increased with capitulum size, despite a consistent
decline in capitulum size through the season. This suggests that the insects choose larger
capitula from those available at each stage, regardless of absolute size. The presence of
infestation showed a consistent reduction in the level of fecundity in both species. These
findings suggest a selective effect. The mathematical model provides evidence of the long term effects, up to 1000 generations,
of variations in both pollination success, and pre-dispersal seed predation, and suggests that
the values measured in the field are consistent with selective pressures that contribute to the
evolution of both flower size and phenology
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Long-Term Monitoring at East and West Flower Garden Banks National Marine Sanctuary, 2011-2012. Volume I, Technical Report; Vol II, Appendixes.
No full textSummary describing the work completed at NOAA Flower Garden Banks National Marine Sanctuary for 'Long-Term Monitoring at East and West Flower Garden Banks National Marine Sanctuary (2011-2012).' It includes background information on the project funding and sponsorship, goals, methodology, and findings
Recommended from our members
Long-Term Monitoring at East and West Flower Garden Banks National Marine Sanctuary, 2011-2012, Volume 1: Technical Report
No full textThis is a study on the 25 years of continuous monitoring of coral reefs in the East and West Flower Garden Banks in the Gulf of Mexico. The study was based on concerns of the impact of offshore oil and gas impact on these sensitive reefs
Anti-Allergic Cromones Inhibit Histamine and Eicosanoid Release from Activated Human and Murine Mast Cells by Releasing Annexin A1
No full textPMCID: PMC3601088This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
The adaptive significance of sensory bias in a foraging context: floral colour preferences in the bumblebee Bombus terrestris
No full textInnate sensory biases could play an important role in helping naïve animals to find food. As inexperienced bees are known to have strong innate colour biases we investigated whether bumblebee (Bombus terrestris) colonies with stronger biases for the most rewarding flower colour (violet) foraged more successfully in their local flora. To test the adaptive significance of variation in innate colour bias, we compared the performance of colour-naïve bees, from nine bumblebee colonies raised from local wild-caught queens, in a laboratory colour bias paradigm using violet (bee UV-blue) and blue (bee blue) artificial flowers. The foraging performance of the same colonies was assessed under field conditions. Colonies with a stronger innate bias for violet over blue flowers in the laboratory harvested more nectar per unit time under field conditions. In fact, the colony with the strongest bias for violet (over blue) brought in 41% more nectar than the colony with the least strong bias. As violet flowers in the local area produce more nectar than blue flowers (the next most rewarding flower colour), these data are consistent with the hypothesis that local variation in flower traits could drive selection for innate colour biases
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