Wheat advanced on speculation rains in Australia will hurt the harvest in the fourth-largest exporter of the grain and dry weather in the U.S. will curb output.

A "moderate drought" is harming plants in Kansas, the biggest U.S. producer of winter wheat, according to data from the University of Nebraska in Lincoln.

Rice, the staple food of more than three billion people, may as much as triple in 18 months as supplies tighten after flooding in exporters including Thailand and demand climbs.

The forecast would put rice at more than the peak during the 2008 food crisis. Wheat and corn also surged that year, while record oil prices boosted fertilizer costs.

For more see these wheat and rice articles in the San Francisco Chronicle.