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August 28, 2010

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Home » Feature » Health and Environment

Nuking crop seeds for higher yields

CHINA is irradiating crop seeds to create new varieties with higher yields. Experts say it's not genetic modification -- it's radiation-induced mutation that accelerates spontaneous genetic changes.

Li Weiguo is eagerly monitoring the sprouts of irradiated soybean and corn this summer, expecting new varieties with higher yields.

It is the first time the 33-year-old farmer in northeast China's Heilongjiang Province has had seeds irradiated with the help of agricultural experts.

"I just want to try it. I hope nuclear technology can help me to raise either the output or quality of crops," Li says.

He sent seeds to the Heilongjiang Academy of Agricultural Sciences (HAAS) for irradiation earlier this year and is waiting to see the outcome on his fields in Shuqing Village of Shuangcheng City.


The Atomic Energy Institute of HAAS began to experiment with irradiation more than 30 years ago.

The process exposed seeds to low doses of gamma rays from cobalt-60, a radioisotope of cobalt, which caused changes in the seeds' genetic makeup, said Xu Dechun, vice director of the institute.

It usually took experts about five years to screen out seeds for new varieties with stable genetic characteristics, said Xu.

Compared with the widely used cross-breeding method, which largely depended on opportunity and usually took about eight years to get a stable variety, seed irradiation intervention was far more effective in bringing out the desired characteristics of a certain crop, he said.

The institute has assisted many local farmers to irradiate seeds and promoted mass production of high-yield or improved varieties of crops in Heilongjiang, China's major grain base.

Xu's team has developed 28 new soybean breeds, almost 20 wheat varieties and a dozen corn varieties. More than 7 million hectares of farmland in Heilongjiang have grown such crops, which raised yields by more than 50 million kilograms.

China is the world's largest grain producer and consumer. The central and local governments have been supporting the application of nuclear technologies in agricultural development.

Huge investments have been made in research programs across the country and almost every province has established atomic energy institutes, an official of the International Atomic Energy Agency (IAEA) and the Food and Agriculture Organization (FAO) of the United Nations said on the sidelines of an agricultural forum.

Liang Qu, director of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, said at the third Global Forum of Leaders for Agricultural Science and Technology that the FAO and IAEA had continuously promoted the application of nuclear technologies in agriculture since 1950.

So far, more than 3,000 new varieties have entered mass production worldwide for commercial purposes.

China, which started such research in 1957, had contributed about 20 percent of the world's new varieties, joining global initiatives in combating food crises caused by creeping hunger and poverty, worsening climate change and deteriorating environmental degradation, said Liang.

China, which is among the world's leading powers in seed irradiation, has also helped Asian and African countries to train staff and improve grain production.

Food preservation

In addition to developing new varieties, irradiation is also used to retard spoilage and increase the shelf life of food.

In China's eastern province of Shandong, exposing garlic to low doses of gamma rays from cobalt-60 could postpone sprouting, which allowed garlic to be preserved in normal temperatures for longer, said Xu.

So far, China has approved the application of the technique for more than 30 types of food, including meet, dried vegetables, shrimp and fruits.

Many countries like the United States and Japan have recognized food irradiation, as the method did not make the food radioactive, and did not change the food any more than canning or freezing, said Xu.

The US Food and Drug Administration has approved the use of irradiation for fruit, vegetables, pork, poultry, red meat and spices.

Food irradiation kills bacteria, insects and parasites that can cause food-borne diseases, such as salmonella, trichinosis and cholera. According to the US Department of Agriculture, food-borne illnesses affect more than 76 million Americans and kill more than 5,000 each year.

The World Health Organization believed the technology was absolutely safe to people and food after a 10-year survey, said Liang, and no problems concerning radiation-induced mutation had been found.

Unlike genetically modified crops, which could introduce new genetic codes from other plants or species into their genetic makeup to create new characteristics, nuclear radiation-induced mutation simply accelerated the process of spontaneous genetic changes, he said.

More functions

In agriculture, radiation could help kill insect pests, develop more disease-resistant crops, improve the nutritional value of some crops, the baking or melting qualities of produce or reduce their cooking time, said Trevor Nicholls, chief executive officer of CAB International Head Office in the United Kingdom.

The not-for-profit science-based organization provides information and applies scientific expertise to solve problems in agriculture and the environment.

The technology could also pinpoint where illnesses strike animals, allowing the breeding of disease-resistant livestock, and show how plants absorb fertilizer, helping researchers to learn when to apply fertilizer, and how much to use. This could prevent overuse, thus reducing a major source of soil and water pollution, says Nicholls.

However, Chinese specialists were still researching many of the functions of irradiation, said Xu. Xu's staff previously launched an irradiation program to kill the sperm of a certain pest insect in a move to curb insect disease.

"The project failed and we are planning to resume the research and experiments once the authorities approve it," said Xu.

He said the future research would focus on combining seed irradiation with trans-gene technology, cross-breeding and chemical breeding means to develop disease-resistant and natural disaster tolerant varieties.

It has been predicted that the world's population will exceed 9 billion by 2050, posing an even greater challenge to food security.

Along with other means, nuclear technology was expected to help ease the gap between food supply and demand by increasing agricultural productivity and food quality, said Tang Huajun, vice president of the Chinese Academy of Agricultural Sciences.


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