Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Induced early flowering : A new plant breeding technique
Schaart, J.G. ; Wiel, C.C.M. van de - \ 2017
Wageningen : Wageningen University
cultivation - plants - flowers
Video about induced early flowering
MADS evolution : insights into evolutionary changes in transcription factors and their binding sites
Bruijn, Suze-Annigje de - \ 2017
University. Promotor(en): Gerco Angenent. - Wageningen : Wageningen University - ISBN 9789463436700 - 195
plants - evolution - mads-box proteins - transcription factors - flowers - molecular biology - planten - evolutie - mads-box eiwitten - transcriptiefactoren - bloemen - moleculaire biologie

Although most flowers follow a conserved 'bauplan' consisting of sepals, petals, stamens and carpels, there is a remarkable amount of morphological diversity. Interestingly, all flowers are specified by the conserved (A)BCE-model. Most of the transcription factors in this model belong to the MADS-domain family. We examined how these transcription factors and their binding sites in the genome evolved, as a first step to elucidate how diversity in flower morphology has been created.

We analyzed the evolution of transcription factor binding sites by comparing binding sites of the major floral regulator SEPALLATA3 between two closely related Arabidopsis species, as well as between A. thaliana ecotypes. We found substantial overlap in transcription factor binding profiles between ecotypes, but limited overlap between the related species.

We also assessed how transcription factors themselves can change in their properties by analyzing the divergence between paralogs. We examined how the PISTILLATA paralogs in Tarenaya hassleriana diverged, as this species occupies an interesting position in the eudicot phylogeny. We also studied whether divergence of the APETALA3 paralogs in Aquilegia could explain the specification of an additional floral organ in this genus. In both cases, we conclude that the paralogs diverged from each other in their biochemical properties.

In the future, it would be interesting to assess how these changes in transcription factors and their binding sites affect floral regulatory networks and ultimately floral shape.

Comparative genomics and trait evolution in Cleomaceae, a model family for ancient polyploidy
Bergh, Erik van den - \ 2017
University. Promotor(en): Eric Schranz; Y. van de Peer. - Wageningen : Wageningen University - ISBN 9789463431705 - 106
capparaceae - genomics - polyploidy - evolution - genomes - reproductive traits - flowers - colour - glucosinolates - genetic variation - biosystematics - taxonomy - identification - genomica - polyploïdie - evolutie - genomen - voortplantingskenmerken - bloemen - kleur - glucosinolaten - genetische variatie - biosystematiek - taxonomie - identificatie

As more and more species have been sequenced, evidence has been piling up for a fascinating phenomenon that seems to occur in all plant lineages: paleopolyploidy. Polyploidy has historically been a much observed and studied trait, but until recently it was assumed that polyploids were evolutionary dead-ends due to their sterility. However, many studies since the 1990’s have challenged this notion by finding evidence for ancient genome duplications in many genomes of current species. This lead to the observation that all seed plants share at least one ancestral polyploidy event. Another polyploidy event has been proven to lie at the base of all angiosperms, further signifying the notion that ancient polyploidy is widespread and common. These findings have led to questions regarding the apparent disadvantages that can be observed in a first generation polyploid. If these disadvantages can be overcome however, duplication of a genome also presents an enormous potential for evolutionary novelty. Duplicated copies of genes are able to acquire changes that can lead to specialization of the duplicated pair into two functions (subfunctionalization) or the development of one copy towards an entirely new function (neofunctionalization).

Currently, most research towards polyploidy has focused on the economically and scientifically important Brassicaceae family containing the model plant Arabidopsis thaliana and many crops such as cabbage, rapeseed, broccoli and turnip. In this thesis, I lay the foundations for the expansion of this scope to the Cleomaceae, a widespread cosmopolitan plant family and a sister family of Brassicaceae. The species within Cleomaceae are diverse and exhibit many scientifically interesting traits. They are also in a perfect position phylogenetically to draw comparisons with the much more studied Brassicaceae. I describe the Cleomaceae and their relevance to polyploid research in more detail in the Introduction. I then describe the important first step towards setting up the genetic framework of this family with the sequencing of Tarenaya hassleriana in Chapter 1.

In Chapter 2, I have studied the effects of polyploidy on the development of C4 photosynthesis by comparing the transcriptome of C3 photosynthesis based species Tarenaya hassleriana with the C4 based Gynandropsis gynandra. C4 photosynthesis is an elaboration of the more common C3 form of photosynthesis that concentrates CO2 in specific cells leading to decreased photorespiration by the RuBisCO and higher photosynthetic efficieny in low CO2 environments. I find that polyploidy has not led to sub- or neofunctionalization towards the development of this trait, but instead find evidence for another important phenomenon in postpolyploid evolution: the dosage balance hypothesis. This hypothesis states that genes which are dependent on specific dosage levels of their products will be maintained in duplicate; any change in their function would lead to dosage imbalance which would have deleterious effects on their pathway. We show that most genes involved in photosynthesis have returned to single copy in G. gynandra and that the changes leading to C4 have mostly taken place at the expression level confirming current assumptions on the development of this trait.

In Chapter 3, I have studied the effects of polyploidy on an important class of plant defence compounds: glucosinolates. These compounds, sometimes referred to as ‘mustard oils’, play an important role in the defence against herbivores and have radiated widely in Brassicaceae to form many different ‘flavors’ to deter specific herbivores. I show that in Cleomaceae many genes responsible for these compounds have benefited from the three rounds of polyploidy that T. hassleriana has undergone and that many duplicated genes have been retained. We also show that more than 75% is actively expressed in the plant, proving that the majority of these duplications has an active function in the plant.

Finally, in Chapter 4 I investigate a simple observation made during experiments with T. hassleriana in the greenhouse regarding the variation in flower colour between different individuals: some had pink flowers and some purple. Using LC-PDA mass spectrometry we find that the two colours are caused by different levels of two anthocyanin pigments, with cyanidin dominating in the purple flowers and pelargonidin being more abundant in pink flowers. Through sequence comparison and synteny analysis between A. thaliana and T. hassleriana we find the orthologs of the genes involved in this pathway. Using a Genotyping by Sequencing method on a cross between these two flower colours, we produce a collection of SNP markers on the reference genome. With these SNPs, we find two significant binary trait loci, one of which corresponds to the location of the F3’H ortholog which performs the conversion of a pelargonidin precursor to a cyanidin precursor.

In the General Conclusion, I combine all findings of the previous chapters and explain how they establish part of a larger species framework to study ancient polyploidy in angiosperms. I then put forth what these findings can mean for possible future research and the directions that are worth to be explored further.

Fighting over water values : diverse framings of flower and food production with communal irrigation in the Ecuadorian Andes
Mena-Vásconez, Patricio ; Vincent, Linden ; Vos, Jeroen ; Boelens, Rutgerd - \ 2017
Water International 42 (2017)4. - ISSN 0250-8060 - p. 443 - 461.
communal water resource management - Community irrigation - Ecuador - flowers - framing - values

Water management studies often overlook community diversity, different stakeholders’ values, and frames to claim water rights. Using a political-ecology approach, this article examines an irrigation system in Ecuador’s highlands via Fraser’s principles of justice (recognition, representation, redistribution). Large flower companies and indigenous smallholders frame their arguments differently to legitimize water allocation claims. Framing is effective when it resonates with other stakeholders’ values. Some unexpected findings are explained: most of the water is still used by large companies since communities took control; rules regarding water use differ greatly among sectors in the system; and small flower producers have been appearing recently.

De groene compacte stad : Een verkennende studie naar de kwantitatieve resultaten van het wegnemen van verharding in stedelijke gebieden.
Vries, E.A. de; Boone, P. ; Rooij, L.L. de; Keip, Linde - \ 2017
Wageningen : Wageningen Environmental Research - 72 p.
health - urban areas - greening - plantations - plants - flowers - citizens - social participation
Optimale assimilatie eerste vereiste voor goede bloemkleuren : kleur afhankelijk van pigmenten en celstructuur
Heuvelink, E. ; Kierkels, T. - \ 2016
Onder Glas 13 (2016)11. - p. 14 - 15.
bloemen - bloementeelt - glastuinbouw - plantkunde - kleur - pigmenten - flowers - floriculture - greenhouse horticulture - botany - colour - pigments
Oorspronkelijk zijn bloemkleuren vooral van belang om bestuivers te lokken, maar in de bloemisterij is dat juist niet gewenst. Daar staat de aantrekkelijkheid voor de koper voorop. Er is voortdurend behoefte aan nieuwe spannende kleuren. Bloemkleur is daarmee een economische factor van belang. Veredelaar maar ook teler kunnen het verschil maken.
Milieufactoren en beschikbaarheid nectar en stuifmeel in graslanden
Ozinga, W.A. ; Geerts, R.H.E.M. ; Hennekens, S.M. ; Schaminee, J.H.J. - \ 2016
Landschap : tijdschrift voor Landschapsecologie en Milieukunde 33 (2016)1. - ISSN 0169-6300 - p. 45 - 47.
functionele biodiversiteit - graslanden - milieufactoren - nectar - stuifmeel - ecosysteemdiensten - bloemen - plantengemeenschappen - functional biodiversity - grasslands - environmental factors - pollen - ecosystem services - flowers - plant communities
Plantengemeenschappen spelen bij veel ecosysteemfuncties en -diensten een cruciale rol. De bijdrage van plantensoorten hangt af van functionele eigenschappen als het aanbod van nectar en stuifmeel in bloemen. Lokale plantengemeenschappen verschillen sterk in het spectrum aan eigenschappen van de soorten en inzicht in deze variatie kan helpen bij duurzaam beheer en gebruik van deze functionele diversiteit. Stilgestaan wordt bij factoren die de variatie in het aanbod van nectar en stuifmeel in graslanden beïnvloeden.
Meer bloemen, meer bijen in agrarische landschappen?
Bukovinszki, T. ; Biesmeijer, J.C. ; Wäckers, F.L. ; Prins, H.H.T. ; Kleijn, D. - \ 2016
Landschap : tijdschrift voor Landschapsecologie en Milieukunde 33 (2016)1. - ISSN 0169-6300 - p. 37 - 40.
cultuurlandschap - functionele biodiversiteit - wilde bijenvolken - apidae - bombus - bloemen - bijenstanden - bestuiving - veldproeven - cultural landscape - functional biodiversity - wild honey bee colonies - flowers - apiaries - pollination - field tests
In moderne cultuurlandschappen wordt het voor wilde bijen steeds moeilijker om de benodigde hulpbronnen, zoals bloemen en nestgelegenheid te bemachtigen. Wij willen nagaan of de aanleg van meerjarige bloemenvelden de achteruitgang van wilde bijen in deze landschappen kan tegengaan. De resultaten laten zien dat het verhogen van het aanbod van bloemen kan leiden tot een soortenrijkere gemeenschap van wilde bestuivers, niet alleen in de bloemenvelden zelf maar ook in het omliggende landschap.
Bees and bumblebees useful for crop protection as well as pollinating : handy 'air quality detectors' pick up bacteria and fungal spores
Steen, Sjef van der - \ 2016
horticulture - greenhouse horticulture - apidae - bombus - pollination - plant protection - plant health - antagonism - air quality - agricultural research - flowers

Bees and bumblebees are, thanks to their build and behaviour, good pollinators. But they have additional potential. They are also useful for disease control by transferring antagonistic microorganisms and for retrieving information about diseases in the fields. An important aspect for all these tasks is: How do we keep them working under the ‘new’ growing conditions in the greenhouse?

Nederlandse handelsbalans bloemen
Benninga, J. ; Jukema, G.D. - \ 2016
LEI Wageningen UR (Factsheet / LEI Wageningen UR 2016-012f) - 2 p.
handelsbalans - export - bloemen - nederland - balance of trade - exports - flowers - netherlands
De handelsbalans voor bloemen daalt al enkele jaren op rij. In 2014 is daar geen verandering in gekomen. Nederland is een belangrijk land voor de afzet van bloemen uit andere landen. Meer import bij een lagere eigen productie zorgt voor een nagenoeg gelijkblijvende export. Nederland exporteert vooral bloemen naar Duitsland, het VK en Frankrijk. De import van bloemen in Duitsland is vooral afkomstig uit Nederland. Kenia is op gepaste afstand tweede herkomstland op deze markt. De verwachting is dat de export van Nederland in 2015 toeneemt.
Visual and odours cues: plant responses to pollination and herbivory affect the behaviour of flower visitors
Lucas-Barbosa, D. ; Sun, P. ; Hakman, A. ; Beek, T.A. van; Loon, J.J.A. van; Dicke, M. - \ 2015
flowers - florivory - herbivore-induced plant volatiles - phenolics - pollination
Plants evolved strategies to attract pollinators that are essential for reproduction. However, plant defence against herbivores may trade off with pollinator attraction. Here, we investigated the role of inducible plant secondary metabolites in such a trade-off. Our objective was to reveal the mechanisms underlying the effects of induced plant responses to pollination and herbivory. We assessed how responses of plants to pollination and insect herbivory affect the behaviour of flower visitors. Subsequently, we investigated how the production of volatile and non-volatile compounds changes after pollination and herbivory. Both herbivores and pollinators induced important phenotypic changes in flowers. Brassica nigra plants respond to pollination and herbivory with changes in the profile of volatiles and non-volatiles of their flowers. Our results show that butterflies use different cues when searching for an oviposition site or a nectar source. Pollination status influenced the behaviour of butterflies, but not that of syrphid flies. We discuss the results in the context of the trade-off between defence and reproduction in plants and suggest that systemic responses to herbivores can interfere with local responses to pollination. Therefore, these responses must be addressed in an integrated way because, in nature, plants are simultaneously exposed to herbivores and pollinators.
Agrofood-trein naar China
Guiking, K. ; Zhang XiaoYong, Xiaoyong - \ 2015
Resource: weekblad voor Wageningen UR 10 (2015)6. - ISSN 1874-3625 - p. 4 - 4.
china - voedingsmiddelen - bloemen - transport - railtransport - agro-industriële sector - nederland - foods - flowers - rail transport - agroindustrial sector - netherlands
Transport van voedingsmiddelen en bloemen van Nederland naar China kan goed via het spoor, zegt LEI-onderzoeker Xiaoyong Zhang. Ze presenteerde haar bevindingen op 28 oktober aan een handelsdelegatie in China, met toehoorders als de Rotterdamse burgemeester Ahmed Aboutaleb en koning Willem-Alexander.
MADS dynamics : gene regulation in flower development by changes in chromatin structure and MADS-domain protein binding
Pajoro, A. - \ 2015
University. Promotor(en): Gerco Angenent, co-promotor(en): Kerstin Kaufmann. - Wageningen : Wageningen University - ISBN 9789462572669 - 219
bloemen - plantenontwikkeling - genregulatie - chromatine - apicale meristemen - arabidopsis - moleculaire biologie - flowers - plant development - gene regulation - chromatin - apical meristems - molecular biology

Abstract

During the life cycle, a plant undergoes a series of developmental phase changes. The first phase change is the transition from the initial juvenile vegetative stage into the adult vegetative phase. During the juvenile phase plants produce leaves and axillary buds, whereas during the adult phase the initiation of reproductive structures occurs. The next developmental change is the switch from vegetative to reproductive growth, when the shoot apical meristem acquires the identity of an inflorescence meristem that will then produce floral meristems. Arabidopsis floral meristems produce four concentric whorls of floral organs: sepals, petals, stamens and carpels. Each developmental change is controlled by coordinated network of regulators, known as gene regulatory networks (GRNs), which determine the transcription of a specific set of genes. The aim of the study presented in this thesis was to understand the dynamics of GRNs during floral organ development in Arabidopsis and correlate the binding of key regulatory MADS domain transcription factors with the accessibility of the chromatin in a genome-wide context.

In chapter 1 and 2 we reviewed the current knowledge on the regulation of transcription in the model plant Arabidopsis thaliana. In chapter 1 we mainly focus on how the view of the GRN underling flower development has changed during the last decades, while in chapter 2 we more broadly revised the mechanisms that control developmental switches in plants. The recent introduction of next-generation sequencing and genome-wide approaches has changed our view on gene regulation and GRNs. We moved from linear genetic interactions towards global highly connected gene networks. The high numbers of interactions that were detected in protein-DNA binding profiles revealed a much higher network complexity than previously anticipated and demonstrated that master regulators of development not only control another layer of regulators, but also genes encoding structural proteins, enzymes and signalling proteins. Moreover, most transcription factors bind to their own locus, highlighting that auto-regulatory loops are a common mechanism of regulation.

The discovery of interactions between transcriptional master regulators with epigenetic factors provides new insights into general transcriptional regulatory mechanisms. Switches of developmental programmes and cell fates in complex organisms are controlled at the level of gene expression by the combined action of chromatin regulators and transcription factors.

Although many master regulators of meristem and organ identities have been identified, it is still not well understood how they act at the molecular level and how they can switch an entire developmental program in which thousands of genes are involved. Using flower development as a model system, in chapters 3 and 4 we investigated general concepts of transcription regulation by analysing the dynamics of protein-DNA binding, chromatin accessibility and gene expression.

Using an inducible system for synchronised flower formation, we characterised DNA-binding profiles of two MADS-domain transcription factors, APETALA1 (AP1) and SEPALLATA3 (SEP3), at three stages of flower development. Our study revealed that these MADS-domain proteins, select their binding sites, and thereby their target genes, in a partly stage-specific fashion. By combining the information from DNA-binding and gene expression data, we proposed models of stage-specific GRNs in flower development. Since developmental control of gene expression is tightly linked with dynamic changes in chromatin accessibility, we identified DNase I hypersensitive sites (DHSs, chapter 3) and we characterised nucleosome occupancy (chapter 4) at different stages of flower development. We observed dynamics in chromatin landscape manifested in increasing and decreasing DHSs as well as in changes in nucleosome occupancy and position.

Next, we addressed the question how MADS-domain protein stage-specific binding is achieved at the molecular level in a chromatin context. In the nucleus the DNA is wrapped around histone octamers to form nucleosomes, which are then packed into highly dense structures, and hence transcription factor binding sites may not be easily accessible. A result of the combined analysis of MADS-domain binding and chromatin dynamics is that MADS-domain proteins bind prevalently to nucleosome depleted regions, and that binding of AP1 and SEP3 to DNA precedes opening of the chromatin, which suggests that these MADS-domain transcription factors may act as so-called “pioneer factors”.

The isolation and analysis of developing flowers of specific stages increased the specificity of our genome-wide experiments, enabling the identification of novel actors in the GRN that regulates flower development. In this thesis we characterised the role of some novel regulators in more detail: in chapter 3 we focussed on the GROWTH REGULATING FACTOR (GRF) family genes; in chapter 5 we investigated the action of STERILE APETALA (SAP); and in chapter 6 we elucidated the regulation and the role of a member of the WUSCHEL-related homeobox (WOX) family, WOX12. GRF family genes are dynamically bound by AP1 and SEP3 at the different stages of flower development. All family members are bound by SEP3, while only a subset of the genes is bound by AP1. The defects in floral organs observed upon down-regulation of these genes highlight their role down-stream of MADS-domain transcription factors. In addition to AP1 and SEP3, SAP is also a target of other MADS-domain proteins, such as APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG). SAP is strongly expressed in meristems and loss of function of SAP causes strong aberrations in flowers, such as a reduction in petal and stamen numbers. We found that SAP interacts with proteins of the SCF ubiquitin ligase complex, suggesting that SAP could act in the ubiquitination pathway.

WOX12 down-regulation leads to defects in floral organ identity specification with the formation of stamenoid-petals, while ectopic expression of WOX12 leads to an opposite effect: it causes the formation of petaloid-stamens in the third whorl. WOX12 acts downstream of AP1. Ectopic expression of WOX12 leads to reduction of AG expression, suggesting a role for WOX12 in the antagonistic interplay between the homeotic genes AP1 and AG.

In chapter 7 we discuss the findings of this thesis. Taken together, the work performed in this thesis increased our knowledge on the GRN that regulates flower development and on the mode of action of MADS-domain transcription factors. We hypothesise that MADS-domain proteins may act as pioneer factors, proteins that access and remodel condensed chromatin. However, differently from other pioneer factors, MADS-domain transcription factors do not actively deplete nucleosomes, but instead they interact with chromatin remodelers to shape chromatin landscape. Given the important roles of MADS-domain proteins as master regulators of developmental switches, their pioneer behaviour represents an intriguing mode of action.

Botrytis species: relentless necrotrophic thugs or endophytes gone rogue?
Kan, J.A.L. van; Shaw, M.W. ; Grant-Downton, R.T. - \ 2014
Molecular Plant Pathology 15 (2014)9. - ISSN 1464-6722 - p. 957 - 961.
sclerotinia-sclerotiorum - disease development - oxalic-acid - gray mold - cinerea - plant - infection - flowers - diversity - fruits
Plant pathology has a long-standing tradition of classifying microbes as pathogens, endophytes or saprophytes. Lifestyles of pathogens are categorized as biotrophic, necrotrophic or hemibiotrophic. Botrytis species are considered by many to be archetypal examples of necrotrophic fungi, with B.¿cinerea being the most extensively studied species because of its broad host range and economic impact. In this review, we discuss recent work which illustrates that B.¿cinerea is capable of colonizing plants internally, presumably as an endophyte, without causing any disease or stress symptoms. The extent of the facultative endophytic behaviour of B.¿cinerea and its relevance in the ecology and disease epidemiology may be vastly underestimated. Moreover, we discuss the recent discovery of a novel Botrytis species, B.¿deweyae, which normally grows as an endophyte in ornamental daylilies (Hemerocallis), but displays facultative pathogenic behaviour, and is increasingly causing economic damage. We propose that the emergence of endophytes ‘gone rogue’ as novel diseases may be related to increased inbreeding of hybrid lines and reduced genetic diversity. These observations lead us to argue that the sometimes inflexible classification of pathogenic microbes by their lifestyles requires serious reconsideration. There is much more variety to the interactions of Botrytis with its hosts than the eye (or the plant pathologist) can see, and this may be true for other microbes interacting with plants.
Biodiversiteit onder glas : voedsel voor luizenbestrijders
Janmaat, L. ; Bloemhard, C.M.J. ; Kleppe, R. - \ 2014
Driebergen : Louis Bolk Instituut - 20
glastuinbouw - glasgroenten - aphididae - biologische landbouw - gewasbescherming - plagenbestrijding - biodiversiteit - organismen ingezet bij biologische bestrijding - nuttige insecten - bloemen - paprika's - nectarplanten - plaagbestrijding met natuurlijke vijanden - greenhouse horticulture - greenhouse vegetables - organic farming - plant protection - pest control - biodiversity - biological control agents - beneficial insects - flowers - sweet peppers - nectar plants - augmentation
In het praktijknetwerk 'Biodiversiteit onder glas' is door glastuinders geëxperimenteerd met bloemen in en rond de kas. Al dan niet in combinatie met bankerplanten zoals granen. Deze brochure is gemaakt om kennis over bloemen en biologische bestrijders te geven en specifiek het nut van biodiversiteit.
Vroege bloemverdroging bij narcis cultivar Bridal Crown
Vink, P. ; Vreeburg, P.J.M. ; Leeuwen, P.J. van - \ 2013
Lisse : Praktijkonderzoek Plant & Omgeving BBF - 9
narcissus - bloembollen - verdroging - bloemen - afwijkingen - diagnostiek - landbouwkundig onderzoek - ornamental bulbs - desiccation - flowers - abnormalities - diagnostics - agricultural research
In de zomer van 2011 bleek dat in een aanzienlijk aantal partijen narcisbollen van cultivar Bridal Crown sprake was van vroege bloemverdroging. Daarbij was na de oogst van de bollen sprake van een ver ontwikkelde spruit met deels of volledig verdroogde bloemknoppen. Uitwendig zagen de bollen er steeds volkomen normaal en gezond uit waardoor het zowel voor de teelt als de handel lastig tot onmogelijk was om de gezondheid en gebruikswaarde van de partijen goed vast te stellen. Als eenmaal vroege bloemverdroging bij de handel was vastgesteld dan werd de partij meestal terug gestuurd naar de teler om als plantgoed te kunnen worden opgeplant. Bij narcissen is vroege bloemverdroging echter een zeer uitzonderlijk fenomeen waarvan de oorzaak tot nu toe onbekend is. Omdat het soms om aanzienlijke percentages vroege bloemverdroging ging is op verzoek van zowel telers als bloembollenhandelaren geprobeerd om de oorzaak te achterhalen. Daartoe zijn van zowel partijen Bridal Crown met en zonder vroege bloemverdroging verschillende partijgegevens verzameld bij diverse bloembollentelers en met elkaar vergeleken. Ook zijn weerkaarten met temperatuur- en neerslaggegevens van het KNMI opgevraagd en beoordeeld. Het bleek uit de verzamelde gegevens van diverse telers van Bridal Crown, en uit de weerkaarten van het KNMI, dat bij zowel de partijen met als zonder vroege bloemverdroging sprake was geweest van droge en warme omstandigheden in het voorjaar van 2011. Dus warmte en droogte konden niet de enige oorzaak zijn van de vroege bloemverdroging. Narcisbollen van Bridal Crown worden bovendien normaliter langdurig warm en droog bewaard zonder dat problemen met verdroogde bloemen in de bol ontstaan. Wel werd duidelijk dat sommige telers van partijen met vroege bloemverdroging hun bollen wat minder diep hadden geplant dan gemiddeld, waardoor een zekere invloed van een hogere bodemtemperatuur de ontwikkeling (in de grond) van de bloemknoppen in de bol kan hebben beïnvloed. Bij narcis vindt de bloemaanleg vanaf mei plaats en is bij rooien veelal al voltooid. Ook bleek dat in de maanden juli en augustus 2011 sprake was geweest van uitzonderlijk veel regenval waardoor percelen met bloembollen soms blank moeten hebben gestaan of op zijn zachts gezegd erg nat zijn geweest. Metname in het teeltgebied in Noord Holland, waar de meeste problemen met vroege bloemverdroging waren vastgesteld, is sprake geweest van extreme nattigheid tot wel 116 mm neerslag meer dan normaal, met half juli meer dan 50mm op één dag. Zonder 100% bewijs in handen te hebben bestaat wel een sterk vermoeden dat hoogstwaarschijnlijk onder invloed van droogte en warmte in het voorjaar van 2011 de bloemknopontwikkeling gemiddeld verder is geweest dan normaal. Dit kan helaas niet worden gestaafd aan andere informatie omdat nog nooit systematisch de bloemontwikkeling bij Bridal Crown tijdens het teeltseizoen is gevolgd en vastgelegd. De verschijnselen van vroege bloemverdroging zijn mogelijk daarna ontstaan onder invloed van extreme regelval en uitzonderlijk natte grond in juli en augustus (de periode kort vóór het rooien) waardoor mogelijk een vorm van verstikking is opgetreden en de bloemknoppen vroeg (direct na het rooien) zijn gaan verdrogen. Op basis van dit vermoeden is het advies aan telers van narcissen cv. Bridal Crown om de bollen voldoende diep te planten zodat warmte en droogte minder effect heeft op de bloemknopontwikkeling. Neerslag is helaas niet te sturen, maar een goede structuur van de grond en voldoende afwatering van een perceel kunnen wel helpen om te natte omstandigheden zo veel mogelijk te beperken.
Biosynthesis of Sesquiterpene Lactones in Pyrethrum (Tanacetum cinerariifolium)
Ramirez, A.M. ; Saillard, N. ; Yang, T. ; Franssen, M.C.R. ; Bouwmeester, H.J. ; Jongsma, M.A. - \ 2013
PLoS One 8 (2013)5. - ISSN 1932-6203
cichorium-intybus l. - glandular trichomes - artemisia-annua - chicory - expression - parthenolide - sunflower - flowers - (+)-germacrene - monoterpene
The daisy-like flowers of pyrethrum (Tanacetum cinerariifolium) are used to extract pyrethrins, a botanical insecticide with a long history of safe and effective use. Pyrethrum flowers also contain other potential defense compounds, particularly sesquiterpene lactones (STLs), which represent problematic allergenic residues in the extracts that are removed by the pyrethrum industry. The STLs are stored in glandular trichomes present on the pyrethrum achenes, and have been shown to be active against herbivores, micro-organisms and in the below-ground competition with other plants. Despite these reported bioactivities and industrial significance, the biosynthetic origin of pyrethrum sesquiterpene lactones remains unknown. In the present study, we show that germacratrien-12-oic acid is most likely the central precursor for all sesquiterpene lactones present in pyrethrum. The formation of the lactone ring depends on the regio- (C6 or C8) and stereo-selective (a or ß) hydroxylation of germacratrien-12-oic acid. Candidate genes implicated in three committed steps leading from farnesyl diphosphate to STL and other oxygenated derivatives of germacratrien-12-oic acid were retrieved from a pyrethrum trichome EST library, cloned, and characterized in yeast and in planta. The diversity and distribution of sesquiterpene lactones in different tissues and the correlation with the expression of these genes are shown and discussed.
Onderzoek naar de oorzaak van vroege bloemverdroging in tulpen
Dam, M.F.N. van; Haaster, A.J.M. van - \ 2013
Lisse : Praktijkonderzoek Plant en Omgeving BBF - 29
bloembollen - tulipa - verdroging - bloemen - cultuurmethoden - bloembeginsels - proeven - temperatuur - opslag - landbouwkundig onderzoek - ornamental bulbs - desiccation - flowers - cultural methods - flower primordia - trials - temperature - storage - agricultural research
Sinds 2008 treedt er in tulpen vroege bloemverdroging op. Hierbij is de bloemknop in de bol al in augustus geheel verdroogd. Tijdens de uitbloei in de winterperiode wordt in partijen daarnaast ook een aantal onvol-ledige (deels verdroogde) bloemen aangetroffen. In de jaren na 2008 was er niet altijd sprake van bloem-verdroging in de bol, maar werden afwijkende bloemen nog wel vaak gezien. Steeds betrof het wisselende partijen Strong Gold, maar in 2011 was er een uitbraak in veel partijen met symptomen in de bollen. De bloemverdroging werd toen ook in andere cultivars aangetroffen (Yokohama, Cheirosa, Purple Flag, Purple Prince, Escape, Brigitta, Alibi), redenen genoeg om hier onderzoek naar te starten. Dat onderzoek bestond uit een enquête en teeltkundig onderzoek. In de enquête werd onder andere ge-vraagd naar teeltwijze en bewaring vooraf en na het teeltseizoen, om aanwijzingen voor de oorzaak van bloemverdroging te verkrijgen. In een perceel Strong Gold werd bloemaanleg kunstmatig vervroegd door het aanbrengen van grondverwarming. Er werd ook een deel van de bollen geremd in de ontwikkeling door ze af te dekken met een dikke laag stro. Deze bollen en bollen van 2 andere locaties werden na het rooien bij hoge en lage temperatuur bewaard. Tijdens de bewaring en bij de bloementeelt daarna werden bollen en bloemen beoordeeld op het percentage verdroging.
Grenzen aan CO2 voor Gerbera: Teelt in het najaar van 2012
Gelder, A. de; Warmenhoven, M.G. ; Dings, E. ; Grootscholten, M. - \ 2013
Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1230) - 30
glastuinbouw - teelt onder bescherming - cultuurmethoden - gerbera - cultivars - gewasproductie - bloemen - gewassen, groeifasen - ontwikkeling - kooldioxide - dosering - effecten - ventilatie - greenhouse horticulture - protected cultivation - cultural methods - crop production - flowers - crop growth stage - development - carbon dioxide - dosage - effects - ventilation
Bij Wageningen UR Glastuinbouw en het Improvement Centre is een Gerberateelt met de cultivars Suri, Kimsey en Rich uitgevoerd in de periode juli tot en met december 2012. De centrale vraag in het onderzoek is of telen van Gerbera bij een concentratie van maximaal 550 ppm en een maximale dosering van 75 kg/(ha.uur) vergeleken met een concentratie van maximaal 800 ppm en een maximum capaciteit van 150 kg/(ha.uur) gevolgen heeft voor de productie in stuks, het bloemgewicht en de bloemdiameter.
Voorkomen bloemmisvorming en bloemverdroging in Zantedeschia : effect van kasklimaat op bloemmisvorming
Leeuwen, P.J. van; Trompert, J.P.T. - \ 2013
Lisse : Praktijkonderzoek Plant en Omgeving BBF - 21
zantedeschia - calla - afwijkingen, planten - bloemen - temperatuur - misvormingen - gewasproductie - proeven - plant disorders - flowers - temperature - malformations - crop production - trials
Misvormde bloemen zijn een probleem in Zantedeschia. Bloementelers geven aan dat 15% misvormde bloemen regelmatig voorkomt tot soms wel 50% aan toe. Deze bloemen brengen minder of geen geld op en het kost extra tijd om deze bloemen te verwerken (extra sorteerkosten). Op het mom ent dat de bloemen uit de scheut komen is de afwijking al zichtbaar. Omdat de bloemontwikkeling en uitgroei grotendeels plaatsvind na het planten was de verwachting dat verschillen in kasklimaat (temperatuur en RV) van invloed zou den zijn op het ontstaan van misvormde bloemen. Daarom zijn gedurende twee jaren proeven uitgevoerd in vier kasafdeling met verschillende klimaatinstellingen met hogere en lagere temperaturen en een hogere (80%) en lager e (60%) RV. In deze afdelingen zijn vijf (2011) of drie (201 2) cultivars geplant op twee tijdstippen (maart en mei/juli). Voor het planten zijn de knollen eenmaal of tweemaal in gibberelline gedompeld voor bloeibevordering.
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