Researchers have successfully obtained the hybrid species of rice-maize, wheat-maize, and pea-maize. Tolerant of drought, salt and alkaline, these species are high yielding, and consume less water and energy. They can also improve soil condition.

These hybrid species get the best from each mother species. For instance, the pea-maize hybrid is as high yielding as maize and as rich in protein as peas. Wheat is rich in protein, but has a low yield and is picky about soil, while maize is high yielding and easy to grow; the wheat-maize hybrid has inherited the best from both sides, and can thrive in poor soil.

"The desirable traits in the new species created through chromosome hybridization can be passed on to their offspring," said Liu Shide, a professor in the College of Life Sciences, Shenzhen University.

Zhu agreed with Liu, taking the wheat-maize hybrid as an example. "Now we have gotten the 13th generation of the wheat-maize hybrid. It still has those traits. Usually, if a trait is kept through the seventh generation, then it is judged by scientists to be stable."

Some scientists are skeptical of chromosome hybridization. "As there is insufficient empirical molecule biology data, it is too early to conclude certain biotechnology can hybridize any plants," said Zhang Chuxiong, Dean of the College of Life Sciences, South China Agricultural University.

Meanwhile, consumers wonder how the new crop species will change the taste of foods. "It depends," Zhu said. "For instance, the wheat-maize hybrid may have a pleasant taste, while the sorghum-rice hybrid might not taste as good as regular rice. It could well be used to brew alcohol."

Zhu revealed that scientists have successfully hybridized rice and reed, which makes it possible to treat rice sheath blight disease. Each year, a large amount of pesticide is sprayed to treat the disease, raising questions about food safety. Zhu also said that the soybean-maize hybrid could improve soil condition and make food safer by eliminating the need for chemical fertilizer.

Distant hybridization

Li Zhensheng, an academician in the Chinese Academy of Sciences, has spent half a century on distant hybridization. Using this technology he has developed fine strains of wheat that contributed to China's food security. In 2006, he was awarded the State Top Scientific and Technological Award, presented by Chinese President Hu Jintao.

In 1956, Li gave up a promising job and comfortable life in Beijing to respond to the government's call to work in northwest China. He relocated to Yangling, a small town in Shaanxi Province.

In that year, the most serious wheat stripe rust in China's history broke out in northwest China. The disease was cancer for plants. It was widespread and heavily damaging. The disease caused a 20-to-30-percent loss in wheat production, while some fields did not yield any wheat at all. Li was 25 then, and he made up his mind to find a treatment for the disease by breeding new disease-resistant wheat species.

The outbreak of wheat stripe rust was caused by the mutation of germ, which mutated into a new species once every five years on average, while it takes at least eight years to breed a new wheat species. The traditional breeding method is to crossbreed between disease-resistant wheat species, which is called interspecies hybridization.

"Farmers have been cultivating wheat for thousands of years, yet wheat is still vulnerable to diseases. No one takes care of wild grass, but it grows well," Li said. Li started his research career by studying grasses. He has collected or planted over 800 grass species. So naturally, he thought of distant hybridization between grass and wheat to get the disease-resistant gene.

The wheat we eat today is the natural hybrid between wheat and grass. The hybrid has been through numerous natural and human selections and evolved into today's wheat. It has become more productive and easier to grow. Yet an ensuing problem is that after thousands of years of human cultivation, wheat has gradually lost its disease-resistant genes.

Distant hybridization has to overcome three obstacles: non-compatibility, infertility of offspring and "frenzied separation." For the hybrid between quackgrass and wheat, the first two obstacles have been cleared. The most difficult part is the third obstacle. Even if a hybrid has desirable traits, its offspring may lose them, Li said.

When his research went into its eighth year, some people suggested that Li give up because the research had not produced any results. The research team eventually obtained a hybrid that is resistant to drought, heat and disease. Later, they derived 70 desirable species from the hybrid. It took them 23 years in all to breed the wheat strain "Xiaoyan No.6," which greatly boosted crop production.

Before the 1980s, there was a positive correlation between China's food production and the amount of fertilizer used. Yet later, even though more fertilizer was being used, food production did not increase accordingly. Chemical fertilizers not only consume resources, but are also hazardous to the environment. In light of this, Li set up a breeding base in Changping District, Beijing, where he carefully screened for wheat species that can absorb potassium and nitrogen from the soil to obtain wheat species that are high yielding and protein-rich.

"We should thank grasses for donating their good genes to wheat, so that we have wonderful foods," Li said with a smile.