4 Dec 2013
Last month the Professional Horticulture Group South West held its annual Christmas lunch (well you have to start sometime) at Wiltshire College's Lackham campus. The guest speaker was Nick Morgan, Senior Superintendent RHS Garden Wisley, who described the trials and tribulations of constructing and managing the new Wisley Glasshouse. A summary of part of his talk appears below.
After lunch a tree planting ceremony was held in memory of Oliver Menhinick, a former Head of Horticulture at the college and member of the Group who was killed in an accident during one of the Group's meeting earlier in the year. The planting was undertaken by Nicholas Wray, Curator of the University of Bristol Botanic Garden and James Chamberlain, Oliver's step-son (the picture shows James planting the tree while Nick provides support).
Development of the Wisley Glasshouse
Although the RHS was founded in 1804, the early RHS gardens were based in Chiswick and South Kensington. It was not until a century later in 1904 that they acquired the gardens at Wisley. The initial 'greenhouse' range built at that time was a series of the traditional vinery glasshouses widely used in commercial horticulture at that time.
These survived until 1969 but, being wooden structures, by this time they were showing their age. In 1969 a new aluminium glasshouse was opened higher up on the Wisley site. This structure was widespan glass, once again typical of the commercial houses of its time. Such glasshouses were usually reckoned to have a twenty year life so by the turn of the millennium they had outlived their usefulness.
Having decided that a new greenhouse was needed, the RHS needed both a site and a design, not to mention the money to deliver the end product. After examining several possibilities the site chosen was an underused level area in the north-west corner of the gardens flanked by the river Wey. The site was typical local Bagshot sand but suffered from a high water table so a comprehensive drainage system was installed around the site to cope with this.
The project required £7.5million and raising this was a challenge. In the end it was not one large donations but a mix of larger and smaller donations. Hundreds of RHS members can claim to have helped pay for it through their donations and many of these are commemorated on glass panels alongside the approach to the main entrance to the glasshouse.
In choosing the design they were particularly attracted to the possibilities of curved glass demonstrated by Dutch glasshouse manufacturer Smiemans Projecten and, in the fullness of time, they were selected to design and build the structure we see today.
However, before they could start the building the site had to be inspected to ensure there were no bat colonies living in the old oak trees that were scattered across the site and then a team of archaeologists arrived to survey the area to ensure there were no important remains of historical interest. Fortunately neither of these inspections identified anything to hold up progress on the build.
To assist with groundwater control the ground level raised by 0.5 metre. Then, in order to provide a firmer foundation, stone filled piles were drilled into the Bagshot sand and capped by concrete plates. The framework was built on these and then glazed. The glass sheets are up to 7m2 of 4mm toughened glass. Nevertheless they arrive as flat sheets and are flexible enough to be bent into the curves. Only one sheet broke during the whole process and that was while taking it off the lorry. Their faith in curves has been justified as the new glasshouse has proved to have much better winter light quality.
The final structure is 13m high and 3000m2 in area. It is heated by spiral hot water heating coils in the roof with paddle fans pushing the heat down. In addition finned tubes around the sides provide extra heating capacity.
Behind the 'public' glasshouse there is a service glasshouse of standard Venlo design where replacement plants can be propagated to keep the displays updated.
They wanted to divide the tropical and temperate sections of the glasshouse with rocks but these were going to be too heavy. Instead they opted for glass reinforced concrete replicas created by Rock themes International.
When Nick was asked to go and source plants he had visions of trips to far-off places but had to make do with a day at Fachjan Project Plants in Holland which supplied many of the larger specimens that provide the framework planting.
Once the glasshouse was finished and planted, the lake and the plantings around it could be completed in readiness for the final opening by the Queen in June 2007. Since then it has become the most visited part of the garden and has ousted the old laboratory block as the 'icon' of Wisley.
Medicinal Plant of the Month
Taxus baccata, English Yew, Taxaceae
The 25 July 2021 will mark the 400th anniversary of the founding of the Botanic Garden in Oxford. This also marks the beginning of botanical research and teaching at the University. In order to celebrate this anniversary, the Department of Plant Sciences, the University Herbaria and the Botanic Garden and Harcourt Arboretum are working together to 'countdown' the 400 weeks to the 400th anniversary by celebrating 400 culturally and scientifically important plants.
The countdown began on 24 November with Plant No 1, the English or European Yew.
A familiar, if somewhat gloomy sight in most churchyards, the European yew tree can live for thousands of years. Still a youngster, the largest yew tree growing in the Oxford Botanic Garden is also the oldest tree, planted in 1645 by the first Curator, Jacob Bobart (see catalogue, right). Although herbalists at the time said that this tree 'had no place among medicinal plants,' Bobart still planted an avenue of these trees in the UK's very first physic (medicinal) garden. More likely to be used in the 17th century for making longbows or knife handles, almost four centuries later, we know now that this tree does indeed have a place among medicinal plants.
In 1962 a sample of Taxus brevifolia, the Pacific yew was collected, from which a potent anti-cancer substance was subsequently isolated. This substance was found in such small amounts that six fully mature trees were required to provide enough drug substance to treat a single patient. The removal of the bark necessitated killing the trees - clearly not a sustainable supply.
However, the mode of action of paclitaxel was unravelled and found to be novel. Paclitaxel binds to a protein called tubulin which plays a key role in cell division (mitosis). The microtubules it binds to are prevented from disassembling, thereby stopping cell division. A new mode of action is appealing to the pharmaceutical industry as the drug should have a different (and one hopes, improved) profile to existing drugs. So the hunt began for an alternative supply.
The chemical structure of paclitaxel is complex and whilst several academic groups have achieved a chemical synthesis in the laboratory it is not feasible to produce commercial quantities in this manner. Different species in the same genus often contain similar molecules and so other species of yew from across the world were tested to see if they contained paclitaxel.
Eventually they found that a similar molecule can be isolated from the leaves of Taxus baccata, the English yew. With a small amount of modification in the laboratory this molecule could be converted to paclitaxel. Today paclitaxel (Taxol) has been joined on the market by docetaxel (Taxotere), a slightly more water-soluble analogue.
Paclitaxel is used to treat ovarian cancer and both drugs are used to treat breast cancer and non-small cell lung cancer. Commercial supplies of paclitaxel now come from a plant cell culture technique initially developed by scientists in the United States Department of Agriculture and then licensed to a commercial company.
Picture right: The familiar flowers and fruits of the Yew Tree (pictures courtesy of Oxford Botanic Garden).
The story of Taxol , Nature and politics in the pursuit of an anti-cancer drug by Jordan Goodman and Vivien Walsh. Cambridge University Press, ISBN: 0-521-56123-X
Oxford Botanic Garden
Horticulture Industry News
It's the microbes that count
Terroir is a concept at the heart of French winemaking. It denotes the holistic combination of soil, geology, climate and local grape-growing practices that make each region's wine unique. There must be something to terroir, given that expert wine tasters can often identify the region from which a wine comes.
Now American researchers may have penetrated the veil that hides the landscape of terroir from clear view, at least in part. They have seized on a plausible aspect of terroir that can be scientifically measured - the fungi and bacteria that grow on the surface of the wine grape. They found, for instance, that one set of microbes is associated with chardonnay musts from the Napa Valley, another set with those of a must in Central Valley and a third grouping with musts from Sonoma.
They noticed a similarly distinctive pattern of microbes in cabernet sauvignon musts from the north San Joaquin Valley, the Central Coast, Sonoma and Napa. The discovery of stable but differing patterns of microbial communities from one region's vineyards to another means that microbes could explain, at least in part, why one region's zinfandel, say, tastes different from another's. The links between microbes and wine-growing regions 'provide compelling support for the role of grape-surface microbial communities in regional wine characteristics,' the researchers conclude. More
Salt bladders deter insect herbivores
Trichomes on the leaves and stems of certain members of the Chenopodiaceae are modified with a greatly enlarged apical cell (a salt bladder), containing a huge central vacuole. These structures may aid in the extreme salt tolerance of many species by concentrating salts in the vacuole. Bladders eventually burst, covering the leaf in a residue of bladder membranes and solid precipitates. The presence of this system in non-halophytic species suggests additional functions. The novel hypothesis that these bladders have a defensive function against insect herbivores were tested using choice, no choice, and field tests.
Generalist insect herbivores preferred to feed on leaves without salt bladders in choice tests. In no choice tests, herbivores consumed less leaf matter with bladders. In a field test, leaves from which the bladders had been removed suffered greater herbivory than adjacent leaves with bladders. Solutions containing bladders added to otherwise preferred leaves deterred herbivores, suggesting a water-soluble chemical component to the defence. This bladder system has a defensive function in at least four genera of chenopods. It may be a structural defence, like spines or domatia, but also have a chemical defence component. More
'Green water' use to increase food security
With estimates of the world population reaching nine billion by 2050, an increase in food production will become vital. There are limited options for expanding crop production, though. Both land available for conversion to fields and freshwater available for irrigation, also called blue water, are dwindling. But another colour of water is an untapped resource that holds promise for agriculture - green water. Green water is the water in soil that is potentially available for plants to take up, use, and release to the atmosphere. To be used by plants, green water must pass through the rhizosphere.
A paper published recently describes how rhizospheres and positive plant-soil feedbacks can lead to more efficient use of green water. Green water is clearly an important resource. But of all the green water potentially available to plants, as much as 70% can be lost through evaporation or subsurface runoff. That leaves as little as 30% for transpiration under some conditions. If, for example, 85% of available green water could be used for transpiration, and therefore become productive, crop yields could as much as triple in some parts of the world. More
Molecular effectiveness of peptides from African medicinal plants decoded
Scientists have described a peptide (cyclotide) in a plant from the coffee plant family, Oldenlandia affinis, that is similar to the human neuropeptide hormone oxytocin, and which binds to its receptors. This may in the future lead to the development of new medicines. Cyclotides were originally discovered as ingredients of herbal medicines that are used in the traditional medicine practiced by people from African nations to induce birth and avoid complications afterwards.
The plants are prepared as tea ('kalata-kalata') and drunk in order to make the birthing process easier and faster. Until now it was not known whether there was a specific receptor for these peptides that caused the uterus to contract. Now they have found a peptide, Kalata B7, that can not only cause isolated uterine muscle cells to contract, but also binds to two receptors - the oxytocin and vasopressin-1a receptors - and controls their function. More
No proof GM maize caused rat tumours
Bowing to scientists' near-universal scorn, the journal Food and Chemical Toxicology has retracted a controversial paper that claimed that a genetically modified (GM) maize causes serious disease in rats. The paper showed 'no evidence of fraud or intentional misrepresentation of the data', said a statement from the publisher, Elsevier. But the small number and type of animals used in the study means that 'no definitive conclusions can be reached'. The known high incidence of tumours in the Sprague-Dawley rat 'cannot be excluded as the cause of the higher mortality and incidence observed in the treated groups', it added. More
Mushrooms make their own weather
Mushrooms have an extraordinary ability to control the weather, scientists have learned. By altering the moisture of the air around them, they are able to whip up winds that blow away their spores and help them disperse. Mushrooms have long been thought of as passive seed spreaders, releasing their spores and then relying on air currents to carry them.
New research has shown that they are able to disperse their spores over a wide area even when there is not a breath of wind - by creating their own 'weather'. Scientists used high-speed filming techniques and mathematical modelling to show how oyster and Shitake mushrooms release water vapour to cool the air surrounding them, creating convection currents. This in turn generates miniature winds that lift their spores into the air. The scientists believe the same process may be used by all mushroom fungi, including those that cause diseases in plants, animals and humans. More
Canada Calling Out For British Cider
A call has been issued by the Ontario Liquor Board for traditional and flavoured styles in order to meet to the rising demand for cider and perry in Canada. UK Trade & Industry (UKTI) says British brands are popular in Canada. Companies require an agent to introduce their products to market and obtain approval for sale. However, UKTI can present company details to Ontario agents for review. These agents are actively seeking new cider and perry products and are interested in developing relationships for this call and for future requests. More
How Scavenging Fungi Became a Plant's Best Friend
Glomeromycota is an ancient lineage of fungi that has a symbiotic relationship with roots that goes back nearly 420 million years to the earliest plants. More than two thirds of the world's plants depend on this soil-dwelling symbiotic fungus to survive, including critical agricultural crops such as wheat, cassava, and rice. The analysis of the Rhizophagus irregularis genome has revealed that this asexual fungus doesn't shuffle its genes the way researchers expected.
Moreover, rather than having lost much of its metabolic genes, as observed in many mutualistic organisms, it has expanded its range of cell-to-cell communication genes and phosphorus-capturing genes. This fungus is a member of the Glomeromycota family and frequently colonizes many plants important to agriculture and forestry. Glomeromycota, also called arbuscular mycorrhizal fungi (AMF), play a vital role in how phosphorus and carbon cycles through the atmosphere and land-based ecosystems, but exactly how it does this vital job is poorly understood. More
Strong growth for Peruvian exports
The recovery of the European and North American markets coupled with a rise in asparagus and avocado production are expected to boost Peru's non-traditional agricultural exports by 18-20% in 2013. Export volumes at the end of September reached 650,619 tonnes, 11.3% more than in 2012. A large part of the increase was due to strong demand for asparagus.
By September, asparagus shipments had billed $278.3m, 25.3% more than for the same period of 2012. Avocado shipments, meanwhile, are expected to finish the year up 15.5% at $156.8m. New acreage coupled with favourable growing conditions were expected to lead to a record 17.2% increase in output in 2013. New production areas in the country's mountainous zones now mean it can extend its growing season into February. More
Pest management centre launch helps form research collaborations
Researchers from across Europe came together to form new collaborations at the official launch of the Harper Adams Centre for Integrated Pest Management (CIPM). The networking event was aimed to develop new working relationships in anticipation of Horizon 2020 - the European Union's framework programme for research and Innovation. It also proved an ideal opportunity to launch the CIPM, which strives to address UK and global issues in agricultural, forestry and horticultural crop protection. Research interests of the centre include entomology, chemical ecology, pest monitoring, application technology, nematology, pesticide science, plant pathology and weed science. More
SCI Horticulture Group events are listed here
Other Events of Interest
Positive Plant Microbial Interactions: Their role in maintaining sustainable and natural ecosystems
2 - 3 Dec, Association of Applied Biologists
Plant Genomes & Biotechnology: From Genes to Networks
4 Dec, Cold Spring Harbor Laboratory
Cold Spring Harbor, USA
Quality Management in Postharvest Systems
4 - 7 Dec, International Society for Horticultural Science
Advances in Nematology
10 Dec, Association of Applied Biologists
Innovation and Trends in Bio-inspired Crop Protection
10 Dec, In Crops
Photo-Physiology Phenotyping Workshop
16 - 17 Dec, University of Essex
Rethinking Agricultural Systems in the UK
18 - 19 Dec, Association of Applied Biologists
International Advances in Pesticide Application
8 - 10 Jan, Association of Applied Biologists
8 - 10 Jan, Society of Experimental Biology
Brassica Growers' Conference and Trade Exhibition
21 Jan, Brassica Growers Association
Impact of Pesticides on Bee Health
22 - 24 Jan, SEB, SB, BES.
5 - 7 Feb, Messe Berlin
International Orchid Symposium
19 - 23 Feb, International Society for Horticultural Science
Plant Genomics Congress
24 - 25 Feb, Global Engage
Kuala Lumpur, Malaysia
Environmental Management & Crop Protection
25 - 26 Feb, Association for Crop Protection in Northern Britain
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Horticulture Group Contact Details
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Chairman - Peter Grimbly
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