Sen. Bob Dole (R-Kan.) charged yesterday that Agriculture Secreatry Bob Bergland's proposal for a joint American-Canadian floor under wheat prices could reduce prices and might ropedo a Soviet commitment to buy American grain.

Bergland had described his proposal as an effort to prevent Canadian-American wheat price wars and to stablize the currently low world wheat market.

Dole, however, told a wheat seminar meeting here that the plan is "fundamentally just another form of export control."

"Kansas farmers recognize that stable prices usually mean low prices, and this proposal to 'stabilize' the wheat market is no exception. Prices dropped 10 to 14 cents per bushel when talk of an agreement began," he said.

Also, Dole said, there is "serious question" whether such an agreement would lead Soviet authorities to back out their current five-year agreement for purchase of American wheat and corn. Under that agreement, teh Soviets are committed to buy at least 6 million metric tons of American grain annually.

"One article of that agreement was a pledge not to engage in export control. I would not like to see a guaranteed market of such a volume go down the governmental drain," Dole said.

Dole said he was renewing his recommendation to President Carter to name an agricultural trade expert to a top post in his White House special trade representatives office. The Kansas, ranking GOP member of the Senate Agriculture Committee, said he would support Carter's nomination of former Democratic National Chairman Robert S. Strauss to head the trade office.