Flood-resistant rice could feed millions

Although rice is normally grown half-submerged in water, it ‘drowns’ if completely submerged for longer periods of time, so that crops are very sensitive to water levels. Because rice is the staple food of 70 million of the world’s poorest people, flood-resistant rice that would greatly reduce losses has been the holy grail of plant geneticists for some time.

“For half a century, researchers have been trying to introduce submergence tolerance into the commonly grown rice varieties through conventional breeding,” said David Mackill, rice geneticist at the International Rice Research Institute, who participated in the study, published in the journal Nature.

“Several traditional rice varieties have exhibited a greater tolerance of submergence, but attempts to breed that tolerance into commercially viable rice failed to generate successful varieties,” he said.

“We’re especially pleased that we have been able to use the latest advances in molecular biology to help improve the lives of the world’s poor,” Mackill said.

Losses in rice crops caused by flooding range from 10% to the entire harvest, depending on environmental factors such as the age of the plants and the time they are submerged, as well as agricultural practices like the amounts of pesticide used. Rice plants submerged under water for too long die by ‘suffocation,’ as the supply of oxygen and carbon dioxide is reduced.

“Globally, rice is the most important food for humans, and each year millions of small farmers in the poorest areas of the world lose their entire crops to flooding,” said Pamela Ronald, a rice geneticist at the University of California who also worked on the research project.

“Our research team anticipates that these newly developed rice varieties will help ensure a more dependable food supply for poor farmers and their families. And, in the long run, our findings may allow rice producers in the United States to reduce the amount of herbicides used to fight weeds.”

Goska Romanowicz