Prices for top-quality US wheat jumped to a record high on Tuesday, extending their gains over the past two months to 40 per cent as demand from emerging countries was boosted by weakness in the US dollar and sharp declines in freight costs.

High quality spring and winter hard red wheat is in demand from importers because of its high protein content. The recent price rally for hard red wheat has also spilled over into lower quality soft wheat, which is traded in Chicago.