Corn, wheat and soybean futures rose early this week on speculation that Japan will step up grain purchases once ports and milling operations reopen following last week’s deadly earthquake.

The powerful quake and subsequent tsunami killed thousands of people and left millions without water or electricity. Japan, the largest importer of U.S. corn and second-biggest buyer of wheat, may need to purchase more to guarantee food supplies, said Standard Chartered PLC. The government asked the Tokyo-based Feed Supply Stabilization Organization, an industry group, to release grain reserves.

Japan is “going to need more food, more meat and probably more grains eventually, if some of theirs got wiped out,” said Tomm Pfitzenmaier, a partner at Summit Commodity Brokerage in Urbandale.

Corn for May delivery rose 9.25 cents, or 1.4 percent, to $6.735 a bushel Monday morning on the Chicago Board of Trade. Soybean futures for May delivery rose 6.5 cents, or 0.5 percent, to $13.41 a bushel.

Only two of Japan’s 12 major ports for receiving grain shipments were damaged by the earthquake, “so trade will not be that negatively affected,” said Roy Huckabay, an executive vice president for the Linn Group in Chicago.

The tsunami disrupted as much as 20 percent of Japan’s livestock-feed output, and operations unloading imported grain from vessels to storage facilities have been suspended at four ports in the north, the country’s agriculture ministry said.