Rice production faces the threat of a growing worldwide water scarcity. Approximately, 75 percent of the world’s rice is grown in flooded, lowland conditions. Lowland rice crops either rely on irrigation or rainwater to provide adequate growing conditions. The food security of millions of people depends on the availability of water.

Scientists at the International Rice Research Institute (IRRI) have developed a rice crop that is not only drought tolerant but high yielding despite the lack of water. These genotypes have been dispersed to other Asian countries including Bangladesh, Cambodia, India, Laos, Nepal, Pakistan, and the Philippines.

The study was funded by the Asian Development Bank and the Bill and Melinda Gates Foundation and can be found in the November – December 2010 issue of Crop Science.

Originally, researchers planted different rice genotypes on two separate plots at IRRI headquarters in Los Baños. The field plots were of similar soil fertility and the crops were equally managed apart from receiving different amounts of water. Initial analysis found rice crops grown in drought like conditions show a decrease in plant height, harvest index, and grain yield.

Nevertheless, upon repeating the experiment, IRRI scientists were able to identify 26 second-generation aerobic rice genotypes that produced significant yields compared to the first generation crops. The rice crops subjected to less water yielded 50 percent more than the previous generation and further gains are expected as the cycle is repeated.

The use aerobic rice is a relatively new, but necessary trend. Aerobic rice crops eliminate the need for flooding, instead using long root systems to extract moisture from the soil. Water is still necessary to maintain the crop, however not at the volume used in lowland rice before.

Dr. Dule Zhao, one of the authors of the study, says, “Aerobic rice is a good strategy for coping with the increasing water shortage and ensuring rice food security in tropical regions. A breeding protocol is key to the success of a breeding program in developing new aerobic rice varieties.”

Aerobic rice breeding studies are continuing at IRRI. Researchers are attempting to develop rice crops that are drought tolerant and also weed competitive and high quality.