NEW YORK - January 27, 2011 - Wheat rose, capping the longest rally since November 2009, while corn and soybeans climbed as countries increase purchases from the U.S., the world’s biggest exporter, to cut food inflation and quell civil unrest.

Food-exporting countries are “strongly advised” not to restrict shipments to prevent “more uncertainty and disruption” in world markets, the United Nations said. Governments in Egypt, Algeria, Morocco and Yemen have faced protests amid rising costs and high unemployment, and a revolt toppled Tunisia’s leader.

“Sovereign nations are beginning to stockpile food to prevent unrest, and that will help to boost demand for U.S. grains,” said Jim Gerlach, the president of A/C Trading, Inc. in Fowler, Indiana. “You artificially stimulate much higher demand when nations start to increase stockpiles.”