Drought-plagued countries of Africa have undergone a "spectacular" transformation during the past year as good rains have produced record harvests across much of the continent, according to a statement released here today by the head of the United Nations Food and Agriculture Organization.

FAO Secretary General Edouard Saouma warned, however, that the bumper crop, combined with expected deliveries of millions more tons of outside relief food, could flood grain markets in Africa and sharply reduce prices paid to farmers.

Saouma has appealed to donor countries to help prop up prices by buying some of Africa's record grain surpluses. The FAO proposes, for example, that donor governments buy some of Zimbabwe's 1.2 million metric ton surplus and distribute it in Mozambique, where drought and war are expected to create a need for 400,000 metric tons of food.

A senior economist for the FAO said today that the United States, which accounts for more than half of the relief food pledged for Africa next year, has shown little interest in giving financial aid to redistribute the food Africa produces.

"The United States has responded very generously with food in 1985 and 1986," said Peter Newhouse, editor of the FAO's special report on the food situation in Africa. But he said that the U.S. government is "not so willing" to give money as it is to give surplus grain.

Echoing the concern of many specialists in African agriculture, Saouma's statement today argued that one year's plentiful rain does not spell the end of the continent's food crisis.

"While donors have generously supplied food and emergency aid, they have been rather less interested in providing agricultural inputs. Emphasis still remains on feeding the person, not on recovery," Saouma said. "We have to build a bridge from emergency to sustained development. Without rehabilitation assistance, Africa risks becoming irreversibly dependent on food aid."

In Ethiopia, which again next year will need more relief food than any country in Africa, U.N. officials complained in recent weeks that their development funds were cut proportionately to increases in emergency aid.

"They tell us we have spent the money feeding people, and there is none left over to make sure a famine doesn't happen again," Alan Court, program planning officer in Ethiopia for the U.N. Children's Fund, said recently.

Of the 21 countries in sub-Saharan Africa that were on the FAO's "danger list" last year, only six remain for next year: Ethiopia, Sudan, Angola, Botswana, Mozambique and Cape Verde. Sudan, although hit with severe crop failure in the western regions of Darfur and Kordofan, produced 4.6 million metric tons of cereal grain, a record, and more than three times last year's harvest, the FAO said.

Six West African countries that last year were affected by drought produced a record 6.7 million metric tons of grain this year, a 50 percent increase, FAO said. They are Burkina Faso, Chad, Mali, Mauritania, Niger and Senegal.

This year's harvest reversed a disturbing four-year-old trend in Africa in which growth in the continent's population had outstripped growth in food production. Between 1980 and 1984, according to the World Bank, per capita food production fell at a rate of 1.9 percent a year.

According to the FAO, food and agricultural production increased 4 percent this year, well ahead of Africa's 3.01 percent annual population growth rate.

Besides plentiful rain, Saouma said that the bumper crop was helped by $250 million in seeds, fertilizers and other nonfood aid that donors have supplied since 1984 to African farmers.

Africa still will need to import about 6.2 million tons of food next year, 3.4 million of which will need to come in food assistance, the FAO said. That food-aid requirement is less than half of the 1985 need, and two-thirds of it has been promised by donor governments, the FAO said.

Saouma said that one of the main lessons learned in the past year's massive international relief effort is that there is about 10 months between the time a famine is detected and the time it begins to threaten life.

He called on donor governments to create a 2 million metric ton emergency food reserve to be used in future crises.