The search for crops that can survive the increasingly salty soils of some developing countries has taken a step forward.

A researcher has produced a highly nutritious plant that can live in 50 per cent sea water and should cope with the Yellow River delta in north-east China, where saline soils are expanding by several kilometres a year.

The plant, amaranth, has been produced at Coventry University by a Chinese PhD student, Zhang Li-Yong.

Salty soil is a big problem in areas such as north-east China, Pakistan and north-west India. Poor irrigation has caused an environment which most crops and trees cannot survive. The problem is acute in China's Yellow River where white deserts of salt prevent growth.

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Amaranth is a non-cereal grain crop that is exciting because it produces a balance of protein almost as good as that of milk, and its green leaves can be eaten as well as its grains. By working with a store of amaranth varieties, culturing their cells again and again and selecting those that survive saline solutions, Mr Zhang has doubled the salt tolerance of the plant.

Field tests will start in China in November. Phil Harris, principal research fellow in the division of biological sciences at Coventry, who supervised Mr Zhang, said: "Potentially this is quite important. Not only is it bringing land into cultivation that is currently useless but also it is working with a crop which is nutritionally very beneficial."

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The researchers are also developing acacia trees that can tolerate salt and could be a source of fuel, fodder and food for subsistence farmers; and salt-resistant vegetables from the cabbage family that could survive in South Korea, where vegetables are increasingly expensive because fertile land is in short supply.

The work is beingdone with the Henry Doubleday Research Association, also in Coventry.