This is a feature of the site that will change every month or so. Forthcoming essays will feature topics such as 'The Future of Genetically Modified Crops' and 'Learning a New Language by Total Immersion in the Culture'. Something for everyone, I hope.

Nearly all modern potato varieties have either a white, creamy or pale yellow flesh. But what if other, more vibrant colours where available? Orange, for example, or even purple. Would consumers be interested?

Dr. Charles Brown, a scientist working for the USDA's Agricultural Research Service in Prosser, Washington, believes so. In fact, he has a number of breeding lines which he thinks would make ideal crops. One of them will be commercialised later this year.

Whereas the cultivated European potato, Solanum tuberosum, produces mainly whitish tubers, various relatives are capable of producing tubers with elevated levels of plant pigments. In taste tests, products made from these traditional South American varieties often do better than conventional S. tuberosum-derived products.

"We have discovered potatoes with an exceptionally high level of the yellow pigment, zeaxanthin, and levels of carotenoids in these tubers are five times greater than in normal potatoes," says Dr. Brown. "These potatoes also have a pleasant, nutty flavour and a very favourable golden appearance when processed in hash browns, French fries etc."

Not only that, but pigments such as carotenoids (yellow) and anthocyanins (purple) also have anti-oxidant properties. Anti-oxidants are believed to aid in the prevention of certain cancers, as well as improving cardiovascular health. In other words, as well as tasting better, these pigments also provide health benefits. In one laboratory test to measure the level of anti-oxidant activity, Dr. Brown's coloured potatoes achieved levels as good as or better than those obtained by well-known health-enhancing vegetables such as Brussels sprouts and spinach.

"We also have evidence that at least part of the dietary intake of the potato anthocyanins is stable to the point of excretion, so it is likely that these pigments have a genuine anti-oxidant role that can play in overall health," adds Dr. Brown.

"The development of new varieties containing various combinations of these 'phytonutrients' is a high priority for new product development and commodity differentiation in the market place," he confirms.

Dr. Brown selected his materials from mainstream US potato breeding programmes. Tubers with orange coloration, with high levels of carotenoids, were developed from selections derived from two of the seven cultivated forms of Solanum tuberosum grown in South America, namely S. tuberosum group phureja and S. tubersoum group stenotomum. The main problem now is that there are only small amounts of seed available for most of his breeding lines, often just 25 to 30 kg.

"This is a barrier to commercialisation," he says. A private company would need to invest $100 thousand to rapidly multiply the variety by tissue culture in order to bring it to commercialisation within a year or two. Otherwise it would take three to five years to multiply the seed."

Even so, one variety has been taken on commercially in the US. The actual product is currently under wraps, but will shortly be on the market.

At the Scottish Crop Research Institute near Dundee, scientists have also been developing new varieties from S. tuberosum group phureja.

Initially, there were problems with shape as phureja tubers are typically very irregular. Also, coming from Ecuador and Peru where days are short, breeding lines had to be selected for more northerly, long-day growing conditions.

Then, as with Dr. Brown's work in America, once the best lines had been selected, taste tests were performed. Again, the phureja-derived products won through, with people preferring their nutty flavour and more yellow flesh. Now, two phureja varieties bred at SCRI (Mayan Gold and Inca Sun) have been placed on the UK National List.

"One has been selected for a consortium which includes a supermarket, and the other for a company that retails to the garden trade," confirms SCRI's George Mackay.

Yukon Gold, a yellow-fleshed variety released in Canada in 1981, also contains phureja in its pedigree.

If the growth of the UK's salad potato market is anything to go by, there is an increasing awareness that unusual, value-added products can succeed in niche markets, and the success of SCRI's two new phureja varieties should be assured.

In the US, too, Dr. Brown's new coloured varieties are being seen as a radically new type of potato for a previously untapped market.

"Americans love their potatoes," confirms Dr. Brown. "Giving them additional reasons to include potatoes in their diet is a plan that's likely to succeed. There is tremendous interest from growers."

Not only that, but there is the possibility that these, or other similar varieties, could also serve as the raw product for a whole new industry - the extraction of natural colorants from potato.

For the moment, it seems that the potato varieties based on different forms of Solanum tuberosum now being released in the UK and the US will be the first of many unusual varieties, each of which offers growers new and diverse opportunities.

The original tetraploid potato from the Andean region of South America is known as Solanum tuberosum 'group' andigena. The conventional European potato, S. tuberosum group tuberosum was derived from this and is believed to have evolved after its introduction into Europe. It, too, has a tetraploid genome.

There are five other tuber-bearing groups of S. tuberosum traditionally grown in South America. The phureja and stenotomum groups used in Dr. Brown's breeding programme fall into this category. In fact, after S. tuberosum group tuberosum, the phureja types are the second most widely grown potato varieties in South America.

There are also several hundred wild Solanum species, about 200 of which bear tubers. These have often been used as sources of useful genes in potato breeding programmes, providing desired traits such as disease resistance. Unlike varieties derived from phureja or other edible types, after the first hybridisation with a commercial variety, breeding lines which include wild Solanum species in their genetic make-up must be repeatedly back-crossed to remove unwanted genetic material.

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English Raspberries Under Threat. The Grower. 21 August 1997.

Herbs Could Keep Slugs Off The Scent. Farmers Weekly. 29 August 1997.

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Aphid Alert as Bugs Survive Mild Winter. Farmers’ Weekly. 6 March 1998.

Good Times for Organic Producers. The Grower. 26 March 1998.

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Better Bens on the Way. The Grower. 9 April 1998.

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Research to Reduce Spray Drift. The Fruit Grower. May 1998.

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Muck and magic products evaluated. The Vegetable Farmer. September1998.

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Clydesdales in Clover. Best of British. October 1998.

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Get into the sludge. The Grower. 15 October 1998.

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Bacterial seed disease control offers benefits to all growers. Farmers’ Weekly. 6 November 1998.

Household waste, Compost cash. The Grower. 12 November 1998.

East Anglia too dry for sugar? Farmers’ Weekly. 13 November 1998.

Racing to a Better Raspberry. The Grower. 19 November 1998.

Potato farming faces ‘high-tech’ revolution. The Grower. 26 November 1998.

Scots reap the rewards from precision farming. Farmers’ Weekly. 27 November 1998.

The bionic tomato. The Grower. 3 December 1998.

Can spear rot be blunted. The Grower. 10 December 1998.

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Varroa strikes deep into Scotland. The Grower. 25 February 1999.

GM strawberries shut out weevils. The Grower. 25 February 1999.

Spin off with GM beet. Farmers' Weekly. 26 February 1999.

Walkies! Walkies! Walkies! Dogs Monthly. February 1999.

The gene is out of the bottle. The Grower. 4 March 1999.

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Peat Squeeze. The Grower. 11 March 1999.

What weather station? The Grower 11 March 1999.

GM potato debate hots up. The Vegetable Farmer. March 1999.

Cereal Killers. British Baker. March 1999.

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Genes, Rubus and the SCRI. The Grower. 15 April 1999.

Worm alert, heading south. The Grower. 13 May 1999.

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Feed the soil. The Grower. 27 may 1999.

Honeybee pest marches on. Smallholder. June 1999.

Wheat quality linked to El Nino weather force. British Baker. 11 June 1999.

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No. 1 Seed. Brechin Advertiser. 29 July 1999.

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Bearing Fruit. Scots Magazine. September 1999.

Scientist warns of E. coli in organics. The Grower. 9 September 1999.

Pulling the plug on protected extraction. The Grower. 16 September 1999.

Taking a compass to the web. The Grower. 23 September 1999.

Fingerprinting Blight. The Grower. 2 September 1999.

GM Spuds Resist Danger. Farmers' Weekly. 1 October 1999.

Seed rates and skin set compared in Scotland. The Vegetable Farmer. November 1999.

Battling Blight - Protection and Control. The Grower. 18 November 1999.

Of mites and markers. The Grower. 9 December 1999.

Shadow on the moon. The Courier. 20 January 2000.

All in favour - the future of GM crop research. The Grower. 18 January 2001.

£33M for genome work. The Grower. 8 February 2001.

Study clears GM crops. 15 February 2001.

Another peat-free alternative? The Grower. 5 April 2001.

Dutch scientists speed up pathogen screening. The Grower. 26 April 2001.

SAC urges seed potato growers to act against risk of resistance. The Grower. 17 May 2001.

No clear case for the health benefits of an organic diet. The Grower. 24 May 2001.

Worries over knowledge of organics in Italy. The Grower. 28 June 2001.

Pymetrozine advised or seed potato growers. The Vegetable Farmer. June 2001.

Setting the trap. The Grower. 5 July 2001.

Setting the trap [for potato cyst nematodes]. The Grower. 5 July 2001.

After hours harvesting to test lettuce's preference. The Grower. 5 July 2001.

Vegetable growing north of the border. The Vegetable Farmer. July 2001.

Spore counters will make blight sprays more precise. The Grower. 2 August 2001.

Australia and New Zealand sign wheat improvement agreement. Farmers' Weekly. 9 August 2001.

Getting the measure of Miscanthus. The Grower. 30 August 2001.

Kenyans go for the Gold Standard. New Agriculturalist. September 2001.

Laboratory aid for Columbian floriculture. New Agriculturalist. September 2001.

Last stand for papaya? New Agriculturalist. September 2001.

The lure of success. New Agriculturalist. September 2001.

Exposure from outer space. New Agriculturalist. September 2001.

DREAM project targets root knot species. Potato Review. September 2001.

Codling caught by kairomone. The Grower. 11 October 2001.

Time short to cash in on Defra's R&D offer. The Grower. 18 October 2001.

Treasures under threat. The Countryman. October 2001.

Banned GM imports found in Japanese potato snacks. The Vegetable Farmer. October 2001.

Raised fields raise yields. New Agriculturalist. November 2001.

The magic of mucuna bean. New Agriculturalist. November 2001.

Fatal attaction for termites. New Agriculturalist. November 2001.

Vaccine project for Vietnamese pigs. New Agriculturalist. November 2001.

Purple potato could be blight beater. The Vegetable Farmer. November 2001.

Healthier lettuce could have longer shelf life. The Vegetable Farmer. November 2001.

Italian authorities clamp down on organic 'irregularities'. The Grower. 15 November 2001.

Prepare for more floods says expert. The Grower. 29 November 2001.

Italian golds at Flora 2001, Naples. The Grower. 29 November 2001.

Italians seek to improve on imported seed. Potato Review. November 2001.

Thrips breakthrough by Dutch scientists. The Grower. 20 December 2001.

Vernalisation gene discovered. The Vegetable Farmer. December 2001.

Hatching factors fool potato cyst nematodes. The Vegetable Farmer. December 2001.

Vanilla Viruses. New Agriculturalist. January 2002.

Coffee - less for more? New Agriculturalist. January 2002.

Colourful spuds. The Grower. 10 January 2002.

Time to look again at GM technology? Potato Review. January 2002.

Peter McGrath, March 2001