KUNMING, China (AP) - Zeng Yawen's outdoor laboratory in the terraced hills of southern China is a trove of genetic potential - rice that thrives in unusually cool temperatures, high altitudes or in dry soil; rice rich in calcium, vitamins or iron.

"See these plants? They can tolerate the cold," Zeng says as he walks through a checkerboard of test fields sown with different rice varieties on the outskirts of Kunming, capital of southwestern China's Yunnan province.

"We can extract the cold-tolerant gene from this plant and use it in a genetically manipulated variety to improve its cold tolerance," Zeng says.

In a mountainous place like Yunnan, and in many other parts of the developing world, such advantages can tip the balance between hunger and a decent living. And China is now ready to tip that scale in favor of genetically modified crops.

Surging costs, population growth, and drought and other setbacks linked to global climate change are pressuring world food supplies, while soaring prices on the street have triggered riots and raised the number of people going hungry to more than 923 million, according to U.N. estimates.

With food demand forecast to increase by half by 2030, the incentive to use genetic engineering to boost harvests and protect precious crops from insects and other damage has never been greater.

In Europe, Africa and Asia, governments that have resisted imports of genetically modified foods and banned growing such crops are loosening those restrictions. Meanwhile, they are pushing ahead faster with their own research, despite lingering questions over the safety of such technology.

"Influential voices around the world are calling for a re-examination of the GM debate," says C.S. Prakash, a professor of plant molecular genetics at Alabama's Tuskegee University. "Biotechnology provides such tools to help address food sustainability issues."

Genetic manipulation to insert desirable genes or accelerate changes traditionally achieved through crossbreeding can help make crops resistant to insects and disease or enable them to tolerate herbicides. Livestock similarly can be altered by inserting a gene from one animal into the DNA of another.

Many researchers believe such methods are essential for a second "green revolution," now that the gains from the first, in the mid-20th century, are tapering off.

Bioengineered crops are widely grown in Canada, Argentina and the U.S., where nearly all soybeans, most cotton and a growing proportion of corn are designed for tolerance to herbicides or resistance to insects. A virus-resistant GM variety of papaya is commercially grown in Hawaii and China.

Biotechnology is bound to play an important role in the agriculture of the future, Robert Zeigler, director of the International Rice Research Institute, said in an interview with The Associated Press at IRRI's headquarters south of Manila in the Philippines.

Such crops "bring tremendous power and advantages to producers and consumers," Zeigler said, noting the potential savings from reduced use of farm chemicals and of fuel for the tractors to spread them.

After delaying the long-expected commercialization of GM grains for years, China's leaders in July endorsed a 13-year, $2.9 billion program to promote use of genetically altered crops and livestock. Beijing is on the verge of releasing an insect-resistant rice variety, Zeigler said.

Chinese Premier Wen Jiabao is a champion of the new agriculture.

"I strongly advocate making great efforts to pursue transgenic engineering. The recent food shortages around the world have further strengthened that belief," Wen recently told Science magazine.

He praised the benefits - higher farm incomes and reduced use of pesticides - from widespread use of so-called Bt cotton engineered to prevent bollworm infestations.

The trend extends beyond China: Worldwide cultivation of bioengineered crops has expanded by over 10 percent a year for a decade, although by 2007 it still had reached only 282 million acres, an area about the size of Cuba, in 22 countries.

Vietnam is pushing ahead with an ambitious program to develop commercial GM crops to reduce reliance on imports. In May, South Korea, which already imports GM soybeans, began importing bioengineered corn to help bridge shortfalls of conventional corn after China began limiting its exports.

Last month, Brazil's National Biosafety Commission approved two new varieties of genetically modified corn seeds, after giving the green light two years ago for GM varieties of soybeans. India has followed China's example, tripling acreage of GM cotton, the only bioengineered crop it allows.

In Africa, where governments have sometimes rejected food aid shipments containing GM grains, South African scientists have completed field tests of a potato developed to fend off tuber moths. They also recently approved trials of sorghum genetically enhanced to improve the digestibility and nutritional content of the coarse grain, which thrives in arid soils.

European countries face growing pressure, under World Trade Organization rules, to open their markets to GM products. Many among the EU's 27 member nations remain wary and, backed by consumers opposed to what some call "Franken-foods," are fighting to keep genetically altered crops out of their fields and supermarkets.

"Why should we change what nature has given us, when it is everything we need?" asked Filippo De Angelis, selling newspapers at a kiosk in Rome. "I don't think we can solve the problem of world hunger through genetics."

Even in China, despite its hefty investments in the research, few are familiar with genetic modification. Some who have heard of it remain cautious.

"It's impossible to know if it's harmful to the body," said Zheng Wencai, a retired architect in Kunming shopping for soybeans in a downtown market. "There is still a global debate on this. So basically, I don't use it."

Besides papayas, China allows farmers to grow GM varieties of green peppers and tomatoes, along with several nonfood crops. But genetically modified rice and wheat are still in field tests.

Those test facilities are kept under high security, both to prevent contamination of non-GM crops and to protect the country's own GM technology. Beijing seems determined not to cede its potentially huge local markets to big agribusinesses like the U.S. company Monsanto and Switzerland's Sygenta AG.

"In general, the government has a very positive view toward GM technology and its products," says Lu Baorong, a member of the National Biosafety Committee, whose desk at Shanghai's prestigious Fudan University was piled with GM rice seed samples to be tested on Hainan, a tropical southern island.

"Since China is a big country and we have so many people to feed, to have our own technology and guarantee food security is very important," Lu said.

He wouldn't speculate on a timeline for commercial approvals of GM rice.

Ultimately, widespread cultivation of such crops will depend on work done at IRRI and by researchers like Zeng, who have spent years painstakingly searching for traits that might unlock the secrets to future abundance.

Zeng views genetic engineering as just one of many strategies, including irrigation and soil improvements and better farm management, needed to increase productivity to ensure future generations will have enough to eat.

"Without all these, it will be very hard to boost output further. There will be breakthroughs, but it will be very hard," he said.

Associated Press writer Paul Alexander in Manila and AP researcher Ji Chen in Shanghai contributed to this report.