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Horticulture Group Newsletter April 2014

tomato slice

2 Apr 2014

The SCI Board of Trustees has decided to improve its links with Groups by appointing a Trustee to act as a link to each Group. We are therefore delighted to welcome Prof Jenny Mordue from the University of Aberdeen as our link Trustee. Jenny will be joining our Committee meeting to discuss how best she can help the Group.

This month sees the closing date for this year's David Miller Travel Bursary Award on 14 April. We already have a good number of applications submitted but there is always room for more. Judging will begin immediately after the closing date and we hope to announce this year's winners at the beginning of May.

Also on 14 April we will be joining the Professional Horticulture Group South-West for a visit to Forde Abbey Nursery and Gardens. The nursery concentrates on producing a range of herbaceous perennials and grasses while the 30 acre garden was started in the 18th century by a Monsieur Beaumont, who was a pupil of the French garden designer Le Nôtre, best known for the gardens of Versailles.

On 15 May we will be joining the BioResources Group for an event entitled Breeding Plants for the Future. An excellent panel of speakers has been assembled for the meeting, which will look at the numerous innovations that are dramatically changing plant breeding and the potential performance of crop varieties.

Editor

The versatile tomato

Tomato_flower- Ton Rulkens - CC-BY-SAThe tomato arrived in Europe during the 16th century along with many other new plant species from the new world. Surprisingly the first arrivals were not just small but probably yellow.

The cultivated tomato has long been classified as Lycopersicon esculentum. However the relationship between the genus Lycopersicon and its close relative the genus Solanum remains confused so the tomato is also known as Solanum lycopersicum. However, most members of the genus Lycopersicon can still be easily recognised from the rest of the Solanum genus by the flowers.

The majority of Solanum species, in common with the majority of flowering plants, have separated anthers. In contrast, tomato anthers have bands of hairs down their sides which interlock and hold the five anthers together in a cone (picture right). This cone naturally funnels all the pollen to the narrow opening through which the style protrudes. In the wild tomato species the style is long and holds the stigma well clear of this opening allowing cross pollination to occur. This is effected by bumble bees.

In the cultivated tomato the style is shorter so that the stigma sits in the opening, encouraging self-pollination. Tomatoes grown outdoors receive sufficient vibration to shake the pollen onto the stigma but in the stiller air of the glasshouse it has been traditional to 'vibrate' the flowers, initially by hand and then with mechanical 'buzzers'. More recently the natural method of bumble bees has been adopted spawning a new industry to rear large quantities of bees to introduce into the glasshouses.

Most wild tomato species grow at high altitude in the western valleys of the Peruvian Andes. Here their natural spread is inhibited by mountain barriers and the native people were discouraged by their poisonous green fruit. However one species, Solanum pimpinellifolium, grew at lower levels and had red edible fruit. Despite this, there is no evidence that the natives of Peru or Ecuador ate them. Instead they helped the species spread possibly as a weed along the numerous irrigation channels they created. Spread the species did through Central America to Mexico, where the Aztecs seem to have recognised its potential and selected many of the varied forms that we know today.

Despite this variety the UK until recently only grew and ate one type with red-fleshed near spherical fruits of approximately 45-50mm diameter. Although this type still predominates, we now eat a much more diverse range of small-fruited and oval-fruited types.

The larger 'beefsteak' varieties common in many other countries have never caught on, possibly because their large deformed flowers are difficult to pollinate in our northern climate. They are, however, an important crop in many parts of the world and form the basis of the tomato paste industry. This industry wants fleshy fruits with few seeds, not the juicy fruits with many seeds that we tend to eat.

While our juicy fruit are still picked by hand, the processing industry has moved to mechanical harvesting. Here the soft skin of the normal tomato becomes a disadvantage, as too many fruit are damaged by the harvesting machine. Modern processing varieties are thus not only large fleshy-fruited with virtually no seeds but they are also thick-skinned.

coloured_tomatoes (top) - Alina Zienowicz - CC-BY-SA,(bottom) - jammmick - CC-BYAs well as coming in different sizes and shapes tomatoes can come in a wide variety of colours. The familiar orange-red colour is down to the fact that the skin of the fruit is actually yellow, as one can readily see on peeling. Fruits with a colourless skin appear pink (picture upper right). Gene mutations have produced varieties with colourless, yellow, orange or tangerine flesh, with striped skin and with red or green cores. Combinations of these characters enable fruit to be almost any colour from near white to dark brown. About the only option not available so far is blue (a few colours are pictured lower right).

Contrary to the story sometimes put around, there is no connection between colour and flavour. Tomato flavour is primarily a balance between sugars and acids and much breeding and cultural work has been done to maximise these flavour components. Sugars however need sunlight to form, and no amount of breeding and culture can compensate for poor light. The more subtle flavours are down to a complex of flavenoids which have so far been elusive to understand and difficult to breed.

Modern breeding techniques may help solve this problem. Genetic modification has been used in the tomato since the 1980s and the slow ripening Flavr Savr tomato was the first crop to certified for commercial use in 1994. Since then a number of 'healthy' options have been created, the latest being the John Innes Institute's purple tomatoes bred to have a high anthocyanin content, which are currently being grown in Canada.

Despite the great variety of tomatoes available, and these advances in tomato genetics, the majority of us in the UK will continue to eat the traditional round red juicy varieties, while relying unconsciously on the fleshy 'beefsteak' types to supply our ketchup and tomato paste.

Plant of the Month

Sequoia sempervirens, coast redwood, Taxodiaceae

sequoia_sempervirens- Allie Caulfield - CC-BYThe tallest plants on earth are the coast redwoods, found growing in a narrow coastal swathe in Northern California and Oregon (picture right). Once vastly more widespread, the populations have been decimated by logging, due to the trees value for timber. The remaining trees are now a major draw of tourists to the area and much work is underway by conservation groups to preserve these natural wonders.

Sequoia sempervirens is the only extant species in this genus, purportedly named for a gentleman called George Gist, son of a German-American merchant and an American Indian girl. He invented the Cherokee alphabet, and was known as Sequoiah, a nickname often given to mixed-race Cherokee children. This plant was first described by botanists in 1824, from a sample collected by the Vancouver expedition in 1794, and named Taxodium sempervirens (evergreen) to distinguish it from all other species of Taxodium, which are deciduous. However, the name was revised in 1847, by the Austrian botanist Stephen Endlicher to the current genus name of Sequoia.

These trees can grow to over 100m tall, with a girth at the base of over 25m around. They often grown in association with other conifers, such as Sitka spruce (Picea sitchensis) and Douglas fir (Pseudotsuga menziesii). There is also a surprisingly rich under-storey of herbaceous and shrubby plants, as the narrow canopies allow enough light to penetrate to the floor to support this diversity.

sequoia_sempervirencs_ghost- Alison Foster - CC-BY-SAThis is one of the very few conifers that will 'sucker' and resprout new trunks from the base of the tree, or from its roots, and this leads to a ghostly phenomenon. In a very few places in a coast redwood forest, a haunting sight can be seen - an entirely white-leaved tree (picture right). A genetic mutation leads to a disruption in the production of chlorophyll, and these 'off-shoots' or suckers are devoid of their green pigment. They obtain all their necessary sugars for growth from the parent plant, which is of course producing chlorophyll and therefore able to photosynthesise.

A more common tourist attraction, though, would have to be the trees that can be driven through, or have been made into houses and rooms. There is even a 'travel-log' - a kind of caravan that has been constructed from the trunk of one of these giant trees. But what better thing to do, than to hike through the old growth forests, marvelling at the size and splendour all around you.

Further reading: Coast redwood - a natural and cultural history. Cachuma Press ISBN 0-9628505-5-1.

Alison Foster
Oxford Botanic Garden

Horticulture Industry News

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Instances of extreme temperatures, brought about by a large increase in global mean temperature, can be detrimental to crops at any stage of their development, but in particular around anthesis. At this stage, extreme temperatures can lead to reduced pollen sterility and reduced seed set, greatly reducing the crop yield. The impacts on wheat and soybean are likely to be less profound, primarily because of the fertilisation effects that elevated levels of CO2 can have on these crops. More and More.

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While the region's olive crop will improve overall, some areas will see profits drop substantially. North Africa estimated profits will rise more than 41%, but in the Middle East, along the eastern portions of the Mediterranean, profits will decline an average of 7.2%. How increased warmth affects the olive fruit fly will have the biggest effect on profits, the team notes. Because the olive tree withstands heat better than its major pest does, some areas now infested with the olive fruit fly will become unsuitable for the insect in coming years. More

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Events Calendar

SCI Horticulture Group events are listed here

Other Events of Interest

Pollinators in Agriculture
1 - 3 Apr, Association of Applied Biologists
Brussels, Belgium

The Genus Lilium
1 - 3 Apr, International Society for Horticultural Science
Zhangzhou, China

Trees, People and the Built Environment
2 - 3 Apr, Chartered Institute of Foresters
Birmingham, UK

Global Berry Congress
7 - 9 Apr, Eurofruit
Amsterdam, The Netherlands

Wild Relatives of Subtropical and Temperate Fruit and Nut Crops
7 - 12 Apr, Wild Relatives of Subtropical and Temperate Fruit and Nut Crops
Baku, Azerbaijan

Investment for business growth - the legal side explained
11 Apr, InCrops
Harpenden, UK

Natural & Organic Products Europe
13 - 14 Apr, Diversified Communication
London, UK

Sulfur Metabolism in Plants
14 Apr, Institut für Forstwissenschaften
Freiburg, Germany

Advances in Cider Technology
16 Apr, Association of Applied Biologists
Pershore, UK

FPJ Live
30 Apr, Fresh Produce Journal
Birmingham, UK

Plant Genomics Conference
12 - 13 May, Global Engage
London, UK

Brassica Conference
15 May, UK Brassica Research Community
Wellesbourne, UK

Loquat Symposium
12 - 15 May, International Society for Horticultural Science
Palermo, Italy

Society of Biology AGM
15 May
London, UK

Plant Chemical Biology
16 May, Agrinet
Jealotts Hill, UK

Risk assessment considerations for RNAi-based GM plants
4 Jun, European Food Safety Authority
Brussels, Belgium

London Produce Show
4 Jun
London, UK

CO2 Assimilation in Plants: Genome to Biome
7 - 8 Jun, Gordon Research Conferences
Waterlooville Valley, USA

World Processing Tomato Congress
8 - 11 Jun, International Society for Horticultural Science
Sirmione, Italy

GreenTech
10 - 12 Jun, Amsterdam RAI
Amsterdam, The Netherlands

Postharvest Unlimited
10 - 13 Jun, International Society for Horticultural Science
Cyprus

Breeding Plants to Cope with Future Climate Change
16 - 18 Jun, Association of Applied Biologists
Leeds, UK

Agronomic Decision Making in an Uncertain Climate
19 Jun, Association of Applied Biologists
Leeds, UK

Plant Biology Europe
22 - 26 Jun, EPSO
Dublin, Ireland

If you would like to advertise a forthcoming event please contact. ester.monfort@soci.org

Horticulture Group Contact Details

For submitting ideas or to volunteer to be part of a committee or a group, please contact:

Chairman - Peter Grimbly
Meetings Secretary - Alison Foster
Minutes Secretary - Margaret Waddy
Newsletter co-ordinator - Sue Grimbly scihortigroup@btinternet.com
Group Contact - Ester Monfort Martinez, E: ester.monfort@soci.org T: +44 (0)20 7598 1584

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