SEEDS OF REVOLUTION

WHITE-COATED Lois Muriithi carefully holds up a test-tube to show a tiny curl of green plant growing in a clear compound. Outside, cheerful Ruth Mathu patrols 40 small, silver-painted greeenhouses containing potted plants with names like Kerr's Pink, Dutch Robijn, and Desiree.

In brown rubber boots, brown trousers, sportshirt and white coat, Dr. Sylvester Nganga oversees them, striding up and down the long slope from the lab to what look like four long Nissan huts made from black wire mesh.

Here on green and undulating farmland outside Nairobi, all three are trying to follow Asian and Latin American examples and lift food production on an African continent ravaged by drought and caught in a maze of different climates, customs, and controls.

It is too soon to speak of an African Green Revolution - new seeds, fertilizers, and methods achieving dramatic results. No major research progress has been made on rain-fed millet and sorghum, which cover 80 percent of cultivated land in the Sahel and other dry areas, according to the World Bank and United States officials.

A mere $170 million was spent on basic research for Africa in 1980, says the World Bank, which advocates at least twice this sum per year by 1990, aimed at improving entire systems of land use as well as hybrid seeds and weed control.

The world's headlines today tell about emergency aid being rushed to Ethiopia , Kenya, Mozambique, and the Sahel. But long-term hopes lie in places like this quiet corner of Kenya.

Without publicity or fanfare, researchers, lab workers and agronomists are working to produce new varieties of food crops resistant to disease, able to withstand drought, higher yielding than ever before, and that appeal to African tastes.

It is a long process. It can take 10-15 years to experiment, isolate, define, and grow in bulk new strains of tuber or seed. No one expects instant solutions. Yet. . .starting with tiny tissue-cultures sent in test tubes from international research organizations abroad, workers are finding, growing, and sending to more than 20 other African countries new kinds of potatoes, pinto beans, wheat, and maize (corn).

Some seeds are suitable for African highlands (the Kerr's Pink potato), some for lowlands and some for medium altitudes (the potato called Desiree.)

There are only two other establishments like this one in Africa. One is in Ibadan, Nigeria, the other is in Cameroon.

The Kenyan work is done in a corner of the 4,000-acre National Plant Quarantine Station, where all imported plants must come to be tested for disease before being released. Dr. Nganga and his team specialize in potatoes.

''In a year, we're producing about 20 tons of disease-free potato tubers, from about 500 different clones,'' says Dr. Nganga. ''Some of the yields have been spectacular.''

African farmers generally raise five to seven tons of potatoes per hectare (2 .47 acres). On experimental plots, Dr. Nganga has obtained 45 tons per hectare. A Kenyan farmer came into the Muguga station recently to fill a bag with new varieties which he sells as seed to suddenly eager neighbors.

''When African farmers realize that new varieties really work with a minimum of tending,'' Nganga explains, ''they are very keen. The new varieties take off. We're at that point now with potatoes.''

The work begins when Lois Muriithi gets new tissue-cultures from the International Potato Institute in Lima, Peru.

Kenyan agronomists also work with such other groups as the International Maize and Wheat Improvement Center in Mexico, home of much of the Asian and Latin American Green Revolution.

One test tube goes into storage. The other is kept for a week under fluorescent light, then potted into a mixture of sterile sand, peat, and soil and covered with glass jars for another week. Then they are moved to bigger pots and to the greenhouses.

There Ruth Mathu and Jane Muturi test the fledgling plants for the commonest African potato diseases such as late blight, bacteria wilt, and leaf roll virus. If the plants are ''clean,'' they go up the hill to the screened-in plots to be grown to full maturity. Tubers then are sent to farmers around the country and abroad.

If the plants are diseased, then Lois Muriithi ''cleans'' them. She treats some of the stored test-tube tissue with heat or chemotherapy to kill the disease. Then the growing process begins again. Mrs. Muriithi also works at ''cleaning'' cuttings of existing plants long used by Kenyan farmers and whose seeds have developed weaknesses and diseases.

The next big step at the center, which is supported by the US Agency for International Development (AID), is to cross-pollinate the new varieties of grown plants and develop ''true seeds'' that will grow to specification every time.

AID agronomist Bob McColaugh hands me a small glass jar containing what looks like pale sand.

''You're holding half a million different seeds there,'' he says. ''Every gram of weight equals 2,500 seeds. To hold the same number of actual tubers you'd need a line of trucks from here to Nairobi.''

An African farmer needs two tons per hectare as seed. If he produces five tons per acre, he can eat or sell only half.

''It would be better all around if we could simply give him a few ounces of seeds,'' McColaugh says. ''But it takes time to develop the parent cuttings, to grow and test them, and produce seeds.''

Multiply this potato research by the other crops being developed here and progress, while slow, is considerable. The quarantine station as a whole now has seed banks of more than 10,000 acquisitions. Some 150 varieties of plants are ready for distribution in Africa.

Tomorrow: Food is not the only answer.