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Developer of super rice honored

It's not often that one person can be said to be responsible for feeding 60 million people. But then Yuan Longping has never been an ordinary person.

Yuan, 74, a Chinese agricultural scientist, is widely acknowledged as having discovered the genetic basis of heterosis in rice — a breakthrough that helped lead to the development of hybrid rice.

In the three decades that followed the discovery, hybrid rice has spread so that it is now planted on about half of China's rice area, resulting in a 20 percent higher yield over previously grown varieties.

That 20 percent increase translates into enough food to feed an additional 60 million people per year in China, according to scientists with the Hunan Academy of Agricultural Sciences where Yuan serves as a research professor and mentor to a number of other agricultural scientists.

For that and other accomplishments, including helping establish the hybrid rice seed production industry in China, Yuan was recently named recipient of the 2004 World Food Prize.

Despite his age, Yuan is currently in the middle of a three-phase program aimed at further increasing rice yields in China. His team of scientists at the China National Hybrid Rice Research and Development Center in Changsha met its first goal of 10.5 metric tons of rice per hectare (9,352 pounds of rice per acre) in 2000.

“We achieved the first plan by the year 2000, and we believe we are making good progress on the second goal of 12 metric tons per hectare (10,688 pounds per acre),” said Yuan, speaking to a group of U.S. rice researchers at a meeting sponsored by RiceTec, Inc., in Houston.

“After this, in the third phase, the target is 13.5 tons per hectare (12,024 pounds per acre) by 2010.”

Photos of Yuan's new lines, called Super Pioneer Rice, created a stir during the RiceTec meeting, which was attended by university and Extension specialists and crop consultants from across the Rice Belt.

Because of the cascading effect of the heads on the rice, some have compared it to a waterfall in appearance. “This is our vision and our dream,” said Yuan. “It's the kind of rice we need if we are to feed our population.”

Yuan said demonstration plots of the Hunan Center's new P885/0293 hybrid produced more than 12 metric tons per hectare in four locations in 2003.

The “super hybrids” developed by Yuan and his associates are tall, erect types with lower panicle positions. The lines are characterized by bigger panicles — what one U.S. researcher at the meeting called “grapefruit-sized rice.”

“Having long, erect and narrow leaves means the leaves can intercept solar radiation on both sides,” says Yuan. “Because they're narrow, they occupy less space. The tip of the panicle is 60 to 70 centimeters (24 to 28 inches) above ground, which results in faster ripening. These plants are also highly resistant to lodging.”

The China National Hybrid Rice Research and Development Center, which Yuan serves as director-general, was created in the early 1970s to help China become more self-sufficient in rice production.

In developing his “three-line system” of hybrid rice, Professor Yuan and his team soon produced a commercial hybrid rice variety called Nan-you No. 2, which was released in 1974. With yields 20 percent higher than previous varieties, the new rice immediately began to improve food availability in China.

With China's population now estimated to be about 1.3 billion, increasing food production will continue to be a priority.

“Globally, rice production must increase 60 percent in the next 50 years to keep up with population growth,” says Fred Fuller, RiceTec's president. “We can't increase acreage to accomplish that because farmland is actually shrinking worldwide.”

During Yuan's visit to Houston, RiceTec announced he had agreed to extend his long-time consulting relationship with the Alvin, Texas-based rice research and marketing company.

In an interview, Yuan said China's adoption of super hybrid rice is currently limited by differences in the two kinds of rice — Japonica and Indica — that its farmers grow. Japonica is grown mainly in the northern provinces or on about 30 percent of the area and Indica in the southern provinces or 70 percent.

“Heterosis is not as strong in Japonica rice as in Indica,” says Yuan. “Thus the yield advances have only been about 5 percent in Japonica. That's why the area cannot be expanded further.”

Yuan and his fellow researchers are working to improve heterosis, a phenomenon in which the progeny of two distinctly different parents grow faster, yield more and resist stress better than either parent, in Japonica.

He believes that further development of new rice hybrids and varieties must rely on biotechnology.

His team of researchers, for example, is working on improving the seed set rate in rice hybrids by making use of the wide compatibility gene. Another possibility is importing favorable genes from wild rice plants.

One of their more startling avenues of research involves a plant most growers consider a weed in commercial rice fields. The researchers are using genomic DNA from barnyardgrass to create new sources of genetic diversity to increase yield.

Yuan believes new breakthroughs with biotechnology will be needed if China's farmers are to continue progressing toward their goal of feeding the country's population of 1.3-plus billion.

“Rice is the major food in China, and we currently feed half the population of the world with rice — wheat is second,” he notes. “Rice yields can be increased step by step because rice still has great yield potential.”

How great?

Yuan pauses to consider an answer. “Many scholars believe that the conversion of photo-synthesis in rice can be as high as 5 percent; that is 5 percent of the sunlight can be used by the rice plant,” he says.

“Even if we can reach 50 percent of that or 2.5 percent, rice yields could reach 22 to 23 metric tons per hectare (19,595 to 20,485 pounds of rice per acre.”


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