Grower research - A bright future

The opening of a facility dedicated to testing the use of LEDs in growing could mark the start of a revolution, Jack Shamash reports.

David Willetts and Dr Martin McPherson at the opening of the new unit at Stockbridge Technology Centre - image: HW
David Willetts and Dr Martin McPherson at the opening of the new unit at Stockbridge Technology Centre - image: HW

A series of trays of plants illuminated by strangely lurid lights sitting in a small shed inside a Yorkshire glasshouse represents the largest experiment in Europe on the use of LEDs to grow plants. It is a venture that could shape the future of growing.

The Stockbridge Technology Centre (STC) has invested £350,000 in the unit, formally opened on 19 July by minister for universities and science David Willetts. He was certainly impressed, telling the assembled growers and scientists: "This could be the future of horticulture. We will be able to grow cucumbers in the horticultural equivalent of a multi-storey car park. The ultimate beneficiary will be the consumer."

The technology has been available for many years, but only now is it becoming cheap enough to become a realistic commercial proposition for the growing industry. Erik Jansen of Philips Lighting, which provided the lamps, explains: "The use of LEDs is growing enormously. In 2008, around eight per cent of lighting - domestic and industrial - was LED. It is currently 14 per cent and by 2020 we expect it to be more than 75 per cent. The technology is getting cheaper all the time."

Big benefits

The technology has numerous advantages for growers. LED bulbs generate almost no heat, which means plants can be placed close to them without fear of burning, and also grown on shelves.

STC science director Dr Martin McPherson is also enthusiastic: "It opens the door to the concept of urban farming. You can grow food in houses or old factories." LEDs will offer growers great flexibility, he adds. "You can schedule the crops. If you want to bring them on, you can do so. If you want to slow them down, you can reduce power."

Proponents of LED also point out that the lamps can run off photovoltaic cells, thus eliminating costly power bills. ADAS head of horticulture Barry Mulholland says LED is particularly suited to plugs or high-value crops. "It would be useful for ornamental, bedding plants or herbs. It could even be used on cucumbers," he explains.

There are other benefits. LEDs can be tailored to give out specific wavelengths of light, which could be an invaluable tool in propagation. According to Lancaster University professor of plant biology Nigel Paul: "Different light could result in different tastes, shapes and speed of propagation."

At present, the main LEDs in use are blues, reds and "far reds". However, Paul is looking at the use of yellows, oranges and UV light, suggesting that scientists will have to work out the best wavelengths for each particular crop. "It's not just trial and error," he says.

And the potential benefits do not stop there. "Colour balance can give pest and disease control. You can use it to trigger the plant's own defences," says Paul. He also raises the possibility that pathogens such as mildews could be adversely affected by different light wavelengths and could thus be targeted by LEDs.

Growers can experiment with the use of lights. McPherson suggests that using the LEDs as a strobe might trigger the receptors that promote growth in a plant, while using only a small portion of the energy that would be required to keep the lights constantly on.

For growers, the prospects are bright, according to STC chief executive Graham Ward. "A normal lettuce grower can produce five crops a year. With this system, we can grow 15."

British Tomato Growers Association technical officer Phil Morley says: "LEDs shows promise. Their use could supplement daylight, especially when the weather is as poor as this year. We could make the intervals between crops shorter or longer."

Growers also feel that LED might answer the Government's demands for food security.

However, some people are a little more cautious. Reaseheath College head of horticulture Ian Clarke says: "Last year, we spent £10,000 growing peppers under LED. They were practically fried, the skin was wrinkled and they were not suitable for eating. But we got good results with strawberries. We mustn't rush into anything."

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