Wheat prices rose the most in a week on speculation that a weaker dollar will boost demand for supplies from the US, the world's biggest exporter.

The greenback fell as much as 0.6% on Thursday (April 29) against a basket of six major currencies, the first decline this week. A drop in the dollar gives buyers using other currencies more purchasing power. Before Thursday, the dollar gained 5.8% this year as wheat fell 9.9%.

"The grain markets are looking to the outside markets," including the dollar, said Jon Marcus, president of Lakefront Futures and Options LLC in Chicago. A weaker dollar should improve overseas demand, he said.

Wheat futures for July delivery rose 19 cents, or 3.9%, to US$5.07 a bushel on Thursday at 10:14 a.m. on the Chicago Board of Trade. A close at that price would be the biggest decline since April 20. The most-active contract has fallen this year because of reduced demand for US grain and rising global stockpiles.