Seed migration to US heartland marches on . Movement that started in Fertile Crescent is still improving crop strains

Bountiful harvests in the rich Nebraska plains are as American an image as the Stars and Stripes. But the seeds that create those bumper crops fly flags of poor third-world countries. ``The majority of the farmers out here,'' says David Stock, who runs a local seed farm, ``don't realize the importance of foreign germ plasm,'' the genetic material used to breed new varieties of high-yielding disease- and insect-resistant seeds.

Agronomists who develop the improved varieties of seed that Mr. Stock raises are acutely aware of farmers' dependence on germ plasm garnered abroad. And they are deeply concerned about problems that could shrink the supply of valuable new genes -- among them environmental degradation, inadequate financial resources, and, ironically, the process of development itself.

Whatever blessings American farmland reflects today, the prairies started out poor in food crops. The sunflower is native to the United States. But corn originated in Central America, wheat in the Fertile Crescent, potatoes in the South American Andes, sorghum in Africa, and soybeans in North China -- all countries generally classified as third world.

Corn spread naturally to North America. Europeans brought wheat with them. The first wheat planting in the colonies is thought to have been at Buzzards Bay, Mass., in 1620.

The continuing process of importing new germ plasms, and using increasingly sophisticated techniques for crossing them, has paid big dividends to farmers here.

``Every time a new variety comes in, you have a minimum 2 to 3 percent increase in yield for just about any crop,'' says Stock, who sells the seed he grows to about 200 farmers and seed dealers.

Because there is scant new land that can be brought into production, improved varieties are the only avenues to bigger harvests. But it is not just the prospects for still bigger harvests that keeps breeders working.

Just as new varieties produce more food for man, they provide ``banquet tables'' for pests, says Dr. Lee Briggle, who oversees a United States Department of Agriculture (USDA) grain collection facility in Beltsville, Md. To keep ahead of thriving pest populations, farmers must continually introduce varieties with new resistances, sometimes changing crops as often as every four years.

In the search for new germ plasm, says John W. Schmidt, a veteran research agronomist at the University of Nebraska in Lincoln, ``The industrialized countries have been pretty well worked over.''

Dr. Schmidt expects that some of the best new finds will come in the third world where isolated communities have sown the same seed for centuries or where wild species have survived.

Among the contributions of third-world germ plasm was the discovery at the turn of the century of a Chinese spinach that resisted blight and wilt. In the late 1970s, when a new virus attacked Southern US corn crops, researchers developed a resistant variety from a breeding line tracing its ancestry to Cuba.

Breeders use Turkey wheat, a type brought from southern Russia by Mennonites, to produce varieties resistant to stinking bunt, a fungus that attacks crops in the Pacific Northwest and the Great Plains. One additional advantage of Turkey wheat, says Schmidt, is that it has resistance to strip rust, another fungus.

During the 1930s drought, the federal government encouraged the planting of prairie grass in this region to stop erosion. Because native grasses had problems germinating, conservationists used varieties from Central Europe, says Stock, whose great-great-grandparents, German immigrants, homesteaded the land he farms today.

That farmers are not generally aware of the importance of foreign germ plasm is not surprising: It can take decades before seed collected on a Turkish hillside or in a village market finds its way into a new variety that is released to farmers.

Schmidt and his colleague of 31 years, Virgil Johnson, spent more than a decade developing Souixland wheat, which Stock began to raise last year. This new variety incorporates germ plasm originating in a region between the Caspian and Black Seas.

Because researchers cannot be sure which germ plasm will be useful someday and which won't, they need to collect and preserve every exotic variety possible. ``We may not know for 50 years what a plant has, but it may have something,'' Dr. Johnson says.

Finding out a seed variety's precise properties is costly, involving trial plantings in a variety of settings. But without classification, says Johnson, ``The situation is like a drugstore with every shelf full but no labels on the bottles.``

Unfortunately, Johnson and Schmidt say, the drugstore is not yet full. In wooden file boxes behind his desk, Johnson has cards for 35,000 varieties of wheat, not quite the total stored in gene banks. Although estimates are sketchy and can differ widely, conservative figures suggest that 10 percent of the cultivated varieties of wheat and 40 percent of the wild varieties have yet to be collected.

Estimates for other crops run much higher, Dr. Judith M. Lyman, a plant scientist at Rutgers University, estimates that gene banks do not have 90 percent of the world varieties of potatoes, sorghum, runner bean, and cassava.

``There is not a single crop which experts feel we have explored sufficiently,'' says Johnson.

Collection of additional germ plasm has become a race against environmental degradation. Overgrazing by livestock threatens wild wheat species in the Middle East and North Africa. Deforestation has brought on climatic change which has brought on drought, a process that can kill off species.

The loss of germ plasm has environmental implications for the industrialized world, too. Because wild species grow without the help of man, they are especially resistant to insects and disease. Those resistant traits are helpful in breeding varieties that do not require pesticides.

``The loss of genetic diversity, particularly in crop gene pools, may well be the single most serious environmental problem facing mankind,'' according to Donald L. Plucknett, a World Bank agronomist.

Ironically, economic development improving the lives of farmers in the third world can add an additional threat to the gene pool. Flooding created behind the Aswan Dam in Egypt is believed to have drowned out unique crop varieties.

``The greatest losses have come when new varieties are introduced,'' says Johnson of a regular feature of helping farmers raise incomes.

As a Peace Corps volunteer, Stock urged Colombian farmers to use new high-protein corn, for instance. Although he says many wisely resisted, farmers elsewhere have abandoned traditional varieties before they were preserved.

Italian, Greek, and Cypriot farmers switched too quickly to new wheats after World War II. The release of high-yielding Texas hybrids of sorghum has replaced most indigenous varieties in South Africa.

``Once lost, it's lost,'' Johnson says. ``You can't go back and get it again.''

USDA and the State of Nebraska fund the work done by Johnson and Schmidt at the university, an international center for breeding red winter wheat. Thirteen internationally funded research centers carry out similar activities in third-world countries, many of which have national programs of their own.

According to a widespread and mounting number of critics, germplasm collection, classification, and preservation suffer because of lack of financial resources. The $55 million spent in 1982 -- slightly below the level today -- is roughly the cost of a single twin-engine Boeing 767, says Dr. Plucknett. Much more is spent on breeding, some of which is done by private grain companies such as Cargill.

USDA now spends $14.5 million annually on its germplasm program.

``We say to other countries that they should collect the plasm,'' says Schmidt. ``But it is very expensive.''

Schmidt and Johnson visited a Turkish experimental agricultural station several years ago where the electricity was turned off a couple of days each week because of budgetary problems. Seed preservation requires constant refrigeration.

Third-world countries have little problem acquiring seed developed by international centers of the USDA. But they must pay for privately developed seed, which has provoked North-South acrimony.

Contending that it is ``genetic imperialism'' for companies to collect germ plasm freely in their countries and sell the improved varieties back to them, some developing nations say the entire international seed system should be revamped. Third-world leaders raised these proposals most recently at a Food and Agriculture Organization meeting in Rome.

One bright spot in North-South cooperation is improved US-Chinese relations, which has given breeders access to new soybean germ plasm. The payoff in higher yields could come at the end of the century, says Stock, an official with the American Soybean Association.

Researchers are meanwhile considering ways of introducing new third-world crops into the US. If they succeed, amaranth, grown by the Aztecs, and quinoa, raised by the Incas, may someday flourish in the fields around Murdock.

Third in a monthly series tracing US business and economic ties to the developing world.