Gu Riliang works long days tending the white and green sprouts growing in petri dishes at Beijing's Center for Plant Transformation. When the sprouts are big enough, Gu moves them to 20-centimeter-tall glass jars filled with a clear, gelatinous nutrient. Because the building's temperature and light are strictly controlled to avoid disturbing the sensitive plants, it's easy to forget whether it's day or night.

The work is tedious, but important. The sprouts are the first growths of corn seeds that Gu's professors at China Agricultural University have genetically engineered. Some of the strains are made to live longer than natural varieties, others to require less fertilizer, resist disease or be more nutritious. Gu, a 26-year-old grad student, doesn't allow himself to speculate whether the sprouts will be sequestered in the greenhouse behind the labs, along with other genetically modified crops, or be planted one day in a farmer's field. "I only test them," he says. "Policy isn't our responsibility."

Beyond the lab's eerie blandness, the work of Gu and his colleagues is causing a fierce debate over the future of the world's agriculture. At issue is whether genetically modified (GM) plants, like Gu's corn, should be used to supply the world with abundant and cheap staple crops. At present, the bulk of GM corn and soybean produced in the United States and other countries is intended for animal feed. Some scientists argue that the health effects of GM foods should be studied at length before the technology is adopted widely. This dispute is at the heart of a trade clash between Europe--which embraces the environmentalists' argument--and the United States, the world's largest producer of GM crops. For the last few years, China, one of the world's biggest agricultural powers, has been the wild card in this dispute. After taking an early lead in GM technology, China backed off in the late 1990s, largely because of Europe's caution. China's scientists have had to keep their seedlings locked away in the labs.

Now China is on the threshold of allowing the commercial planting of one of the world's biggest staple crops: rice. Six strains of GM rice have already passed a gantlet of field trials and studies, setting the stage for final approval by a meeting of ministers, perhaps as early as January. According to scientists advising the Agriculture Ministry, approval will most likely be forthcoming, which means that China could start planting GM rice as soon as spring 2006. Shortly thereafter GM rice could end up on millions of Chinese dinner tables.

This would be the first time that a genetically engineered plant was used widely as a staple food crop. For China, the implications are far-reaching. GM rice could add billions of dollars in annual revenue to the country's agricultural sector, reduce pollution as farmers begin to use fewer toxic pesticides and fertilizers, improve nutrition and produce higher yields to feed the country's huge population. China's influence would be felt throughout Asia as other countries jumped on the GM bandwagon.

Environmentalists have been doing their best to derail the move. Late last week Greenpeace, a longtime opponent of transgenic plants, denounced the ministry's "behind closed doors process" as "scientifically and ethically flawed" and warned that scientists "still know too little about the unintended impacts of genetic modification." China's press jumped on the story, setting off a firestorm of debate on the Internet. "We can use science," one blogger wrote, "but we'd better not damage the natural balance." The campaigning has had an effect. "Now, I cannot say definitely" whether GM rice will be approved, says Chen Zhangliang, president of China Agricultural University and chairman of a biosafety committee on GM crops. Bloggers aside, the environmentalists raise some legitimate points. As China's leaders prepare to take this big step, it's worth asking: How great is the risk? And will the benefits be worth it?

To China's geneticists, the answer is yes. They've been working for years on GM rice, and they've come up with six strains as candidates for commercializing. One contains a gene from Bacillus thuringiensis, or Bt, a soil bacteria that produces a natural pesticide. Another rice strain uses genes from legumes that confer resistance to pests like the pink stem borer, a common Asian moth that eats rice during its larval stage. A third variety produces a protein that fights bacterial blight, and geneticists are working on "green rice" that would require less fertilizer and resist drought. According to one Chinese study, adopting GM rice, along with GM cotton, could result in an annual increased profit to China's agricultural sector of "roughly $5 billion in 2010."

One test plot of Bt rice in Hubei province showed an increased yield of 15 percent over conventional rice, and another required fewer pesticides. Cutting the tonnage of pesticides sprayed on China's crops would save the lives of at least some of the hundreds of farmers who die each year of pesticide poisoning, particularly in the rice fields. "The farmers stand for hours in shin-deep water that is full of chemicals," Huazhong University professor Zhang Qifa says, adding that one Chinese farmer out of 30 is hospitalized at one time or another for poisoning. At the same time fertilizers--often simply human waste applied to the fields--are polluting groundwater and rivers.

Economic and health figures aren't the only numbers Chinese officials are looking at. Across Asia, populations are booming: by 2045, demographers predict that together India and China will be home to 3 billion people. At the same time the amount of cultivated land in China is shrinking due to urbanization and road building. That's a stark contrast to European countries and some Asian ones, such as Japan and South Korea, where population growth is virtually stalled--and GM produce is mostly banned. "They don't feel a need for the future," says Banwari Mishra, a director of rice research for the Indian Council of Agricultural Research. "But in Asia we have to enhance our production." Little wonder then that the developing world increased its acreage of GM crops from one quarter in 2002 to one third last year, according to the International Service for the Acquisition of Agri-Biotech Applications, a nonprofit GM advocacy group.

Poverty is another consideration. According to Mishra some 20,000 children go blind annually in Asia because of poor nutrition, primarily because they don't get enough vitamin A. Now, he says, researchers are working on creating vitamin A-enhanced rice that might help to cure much of the problem. The upshot, the International Rice Research Institute's Cantrell says, is that people in developing countries are willing to accept a higher risk than those in developed countries.

But how high are the risks? What bothers scientists is that nobody knows for sure. Too few tests have been done to gauge what eating unprocessed GM food could do to human consumers, especially to infants and children. For instance, the pesticides that China's Bt rice produces can trigger a response from the human immune system, potentially causing allergic reactions. According to Xue Dayuan, a professor at Nanjing Institute of Environmental Sciences, the most thorough test to date of the Bt gene's toxicity to mammals was a three-month trial on mice that showed no negative impacts. Scientists won't know if it's truly safe until they've done tests on humans. GM critics also argue that transgenic crops could have serious unintended impacts on the environment. Since GM crops have marked advantages over natural varieties, farmers will be keen to plant them. That might drive down the diversity of crop species, making crops more vulnerable to new pests. Studies have also shown that pollen from GM crops can drift for vast distances, which makes it difficult to contain them on farms.

That's a particular worry in China, which doesn't have a good record in managing GM seeds. When Bt cotton was authorized in two Chinese provinces in 1997, peasants began growing it illegally, and it's since spread to more than 10 provinces. In the Yangtze city of Wuhan, where scientists run China's largest GM-rice-test fields, "a local company got some of the GM [rice] seed and began selling it to local farmers," Zhang says. Today, he says, more than 100 hectares of GM rice are being cultivated. "The government shouldn't move too fast," Xue says. "We need to solve many other problems before we can commercialize GM rice."

That's not likely to happen, given China's eagerness to go ahead with GM rice. And if GM seeds deliver high-quality rice cheaper than natural varieties, there's likely to be pressure throughout the region to adopt the technology. "If Chinese rice comes into India and it's cheaper, maybe [India will] switch over more quickly," says S. D. Shikamany, a researcher at the Indian Institute of Agricultural Research. The Philippines and India have already started field tests of GM rice, and India could be ready to commercialize GM rice in as little as three years. Vietnam, Thailand and Indonesia are also testing GM rice varieties in their labs. Thailand is trying to boot-strap a biotech sector, and Prime Minister Thaksin Shinawatra last summer vowed to overturn any ban on commercial production and trade in GM products. "The government," he said, "won't let the country miss the biotechnology train." The engine seems to be pulling out.