In the rich agricultural region of Britain's East Anglia, average temperatures have risen by just under one per cent over the past 30 years, and drought stress in crops has increased sharply.

Sugar beet growers on East Anglia's sandy soils are particularly vulnerable to dry summers because scarce irrigation water is reserved primarily for crops of higher value vegetables and flowers.

Research into drought stress is one of the major priorities at Broom's Barn, Europe's largest sugar beet research centre, situated in the centre of Britain's beet growing area.

"Yield loss due to drought has been bigger than the loss due to any pest or disease," said Keith Jaggard, head of crop production at Broom's Barn, part of the Institute of Arable Crops Research which has 700 staff at three sites.

In Britain, sugar beet is generally considered to beresistant to drought but production losses caused by evaporation have been four times greater than any other factor.

Since 1980, the average annual sugar beet yield loss due to drought in Britain was 10.5 per cent, or 141,000 tonnes of sugar worth around 28 million pounds ($47 million).

Drought loss has fluctuated greatly from year to year, exceeding 20 per cent in 1994 and 1995.

Irrigation

Irrigation has had little impact: During the same period, estimated production losses in the Netherlands were trivial while losses were only 25 per cent of the British level in Germany and 75 per cent in northern France.

Drought was less of a danger in these continental beet areas due partly to their silty, water-retentive soils. Summer rainfall was also higher.

In other continental countries where the drought risk was similar to East Anglia's the beet crop was usually irrigated.

"We're looking for drought-tolerant beet varieties," Jaggard told Reuters. He said this was not a target for plantbreeding companies which tend to have an international focus whereas this problem was centred on eastern England.

"It offers the largest single opportunity for yield and profitability improvement of sugar beet in the UK at present," he said.

Broom's Barn researchers are seeking drought resistant varieties both at home and from international seed banks. They are also studying development of varieties with deeper roots able to absorb more ground water.

On its 77-hectare (190-acre) experimental farm, researchers are testing 16 seed varieties on small plots in drought conditions provided by plastic covers that automatically shield the crop whenever it rains.

"Seeds have to be tested in the field in drought conditions," Jaggard said.

Although June was one of the wettest this century there were still drought problems in East Anglia because rainfall was irregular. British beet needs regular rain because the light, sandy soils in East Anglia drain quickly and only about five per cent of the crop isirrigated.

Warmer weather means farmers are now able to drill beet into the ground from early, instead of late March, and this allows beet to grow longer and develop larger roots.

Sugar beet needs to produce a full canopy of leaves early to intercept maximum sunlight and produce bigger yields. But sowing early makes beet more vulnerable to drought, especially between mid-July and end-August.

Harvesting usually starts in late September and is finished by December 20 before the onset of severe frosts.

Cover crops

Researchers are also looking at so-called "cover" crops such as barley, planted in the same fields a few weeks before the sugar beet, to help stop wind erosion of dry soils.

About 25 per cent of the sugar beet area is on light, sandys oil but only one fifth has any barley cover.

If climate change persists one option might be to shift sugar beet production further North where there is higher rainfall and heavier soils.

But this would incur higher transport costs as sugar beetfactories are concentrated in East Anglia and production could become unviable.

"Sugar beet is 75 per cent water," noted Jaggard.