President Reagan, seeking to quell the incipient rebellion of hard-pressed farmers against his economic program, told their representatives yesterday that his recovery plan ultimately will bring prosperity and profits.

In his first speech devoted to agriculture, Reagan partly blamed the sagging farm economy on the decision by former President Jimmy Carter in January 1980 to ban grain exports to the Soviet Union in retaliation for their invasion of Afghanistan. Calling the embargo the "first body blow" to agriculture, Reagan pledged not to use farm exports as an instrument of foreign policy "except in extreme situations and as part of a broader embargo."

American farmers--buffeted by high interest rates, inflation and the lowest net income since the Depression era--have sought direct federal intervention for temporary relief until the national economy begins to turn around.

But Reagan, saying there is "no quick fix" for the economy or farmers, has resisted those pressures. Reagan said the government can aid the farmer by promoting basic agricultural research, seeking out new markets, countering unfair trade practices of U.S. trading partners, providing protection from erratic weather conditions and creating the proper environment to encourage the forces of supply and demand.

Reagan met with congressional agricultural leaders yesterday morning and spoke later to editors of agricultural publications, but absent were the leaders of more than 40 House Republicans and Democrats who have announced formation of a Farm Crisis Group. That group has attempted unsuccessfully since January to meet with the president.

Rep. Kent Hance (D-Tex.), one of the leaders of the Farm Crisis Group, said that while members are "disappointed" that Reagan will not meet with them, they still intend to seek action by the Department of Agriculture. If that fails, they intend to promote legislation requiring higher price support loans.