New Flood-Tolerant Rice Could Help Farmers and Environment

Inside a greenhouse on the University of California, Davis campus, a group of rice plants is defying conventional farming wisdom and thriving in a formerly life-threatening environment -- under water.

DAVIS, Calif. — Inside a greenhouse on the University of California, Davis campus, a group of rice plants is defying conventional farming wisdom and thriving in a formerly life-threatening environment -- under water.

A new variety of flood-tolerant rice soon could make its way from the lab to the field, offering California rice farmers and environmental advocates a potential weapon against both crop-ravaging weeds and water pollution.

The research is the product of a 20-year-old collaboration between UC Davis, UC Riverside and the International Rice Research Institute in the Philippines. The team isolated a gene within certain traditional rice plants that allows them to survive complete submergence. Researchers then cloned the gene and implanted it into commercially viable rice plants.

The result was a new variety that can survive under water for up to two weeks. Rice plants typically will die if completely submerged for more than a few days.

"This gene has actually been known for about 50 years, but researchers were unable to make use of it because it is thought to be quite complex," said Pamela Ronald, a UC Davis-based rice geneticist who has been working on the project for about a decade.

At present, the dominant farming method involves planting pre-germinated seeds in a field flooded with about five inches (13 centimeters) of water, the greatest depth normal rice plants can withstand. Ideally, the plants begin to grow before weeds can catch up to them. Herbicides are applied as an added protective measure.

Those herbicides, while vital to farmers, have caused concern among environmentalists and groups monitoring the safety and purity of the state's drinking water supply. The rice industry has tried to control its use of chemicals in recent years, contributing to a major reduction in the river's herbicide content, said Tim Johnson, president of the California Rice Commission.

"We have very strict environmental regulations here, and California rice is specifically regulated for water quality," he said.

Rice farmers are required to keep the water in their fields contained for about 30 days after applying herbicides to let the chemicals degrade before they enter the water supply. But farmers' methods and their compliance varies.

"Things happen," said Roland Pang, the water quality superintendent for the Department of Utilities in Sacramento.

"If (researchers) are successful in developing a flood-tolerant rice plant, and it reduces herbicide use, then that is a very good thing," he said. "Production would be less expensive, and there would be less exposure to the river."

Greg Massa, a fourth-generation rice farmer, said the new variety also could help organic farms such as his. Most organic farmers use a deep-water planting method as an alternative to herbicides, but the process is risky, he said.

"We have to push the rice to the limits of its ability to survive in order to kill (the weeds)," he said. "Flood-tolerant rice could have huge benefits for both conventional and organic rice growers."

Although the benefits to U.S. rice farmers would be significant, it is in developing nations that flood-tolerant rice could have the most immediate impact, researchers say.

More than a quarter of the global rice crop is grown in lowland areas that are prone to unpredictable seasonal flash floods. Each year, millions of small farmers in the poorest areas of the world lose their entire rice crops to flooding, a loss that has been estimated at more than $1 billion (euro780 million).

Scientists from one arm of the flood-tolerant rice project, the Philippines-based International Rice Research Institute, are testing the strain in southern Asia. Through a variation on traditional breeding, they have successfully developed submergence-tolerant versions of three major local rice varieties, with an additional three on the way in the next few months, said Dave Mackill, one of the institute's lead researchers.

One of the varieties was tested this year in rice fields in India and Bangladesh, but its performance was difficult to rate because there were no major floods in the area, Mackill said.

The UC Davis research team has not yet tested the new plant variety outside the lab but hopes to receive grant money to start working with local growers, Ronald said. For now, the focus is identifying other genes that might contribute to a plant's tolerance for extended submergence.

"We need to start figuring out what these genes do so we can use them for different applications," Ronald said. "Why are some plants more resistant to environmental stresses? The answer to that could help farmers all over the world."

Source: Associated Press

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