Reporter 458, 6 November 2000

Isotope study holds hope for rice crops

People living in some of the world’s most flood-prone regions stand to gain from spectroscopic studies of iron isotopes in the School of Physics and Astronomy.

Dr Sue Kilcoyne of the School’s Condensed Matter group works in Mössbauer spectroscopy, a means of identifying metals in materials by measuring radiation. One of her projects uses it to investigate how iron toxicity can lead to rice crop failures.

In recent years the technique has become a powerful and almost routine tool for probing the chemical and magnetic states of condensed matter but hitherto it has seldom been used to study living matter.

It is based on measuring gamma rays emitted by a radioactive isotope and absorbed by nuclei of the same isotope in a sample. The effect has been observed in over 40 elements, but the iron isotope 57Fe is the most studied and the most appropriate for bio- and geo-physical research.

Dr Kilcoyne said: "Iron is one of the most common elements on the planet. It occurs in minerals, sands and soils, is metabolised by plants and animals and is vital to our own health. Yet the role of iron in governing the physical, chemical and biological properties of materials is not well understood."

The absorption of iron by rice plants can cause catastrophic crop failures. In the developing world, rice is often the only crop than can be cultivated on marginal land that is vulnerable to flooding. More than 100 million people living in such areas depend on the harvest for survival.

Flooding generates anaerobic conditions around a plant and causes many severe problems due to the accumulation of toxic substances, including iron. This stimulates the formation of highly reactive radicals, which can kill a plant within days. Through Mössbauer spectroscopy, Dr Kilcoyne has obtained information on the form of the iron taken up and translocated within the plant, which will help explain its role in crop failure and suggest ways of tackling the problem.

In addition to her work in magnetism and superconductivity, Dr Kilcoyne has also used Mössbauer spectroscopy to analyse the agricultural potential of soils in North Africa.

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