Erratic rains test staying power of Asia's green revolution. Century's worst drought spurs search for new ways to protect and increase farm production

Agriculture scientists are taking a second look at the ``green revolution'' in light of a drought that threatens farmers in parts of Asia. From China to India, erratic rains this year are testing the limits of innovative grain-growing methods that have made Asia nearly self-sufficent in food during the past two decades.

The drought is expected to reduce Asia's total harvest of cereals to below last year's, the United Nations Food and Agriculture Organization estimates, as well as decrease important export crops. ``But the world now has nearly 500 million tons of grains in stock - that's the big difference,'' said Monkombu Swaminathan, director of the Philippines-based International Rice Research Institute (IRRI).

If normal rain resumes in coming days, however, production could pick up again in most countries. In India, heavy rains over the weekend appear to have ended the drought. However, unusual flooding in a few areas, such as Bangladesh and Burma, are also hurting crops.

A range of agricultural ideas are being offered to countries hit by the drought.

In India, for instance, Prime Minister Rajiv Gandhi created an emergency committee of agricultural experts this month to suggest ways of reducing harm from the drought. In dry areas, use of more fertilizer and quick-maturing rice seed can make a difference, says Dr. Swaminathan, a member of the committee. Villages still not affected by drought can be asked to set aside underground water reserves for later use.

In Indonesia, officials plan to seed clouds in hopes of bringing rain to dry areas. An estimated 100,000 acres of crops have been destroyed by the drought already, says the government.

In Vietnam, only half the normal rain fell from March to July. Officials have requested people to change their diet to include more foods not affected by the drought. One helpful aspect is that Vietnam has increased its use of a technique called dry-seeding. Developed at IRRI in the late 1970s, it enables a rice plant to last longer during long dry spells.

These tactics, known as ``adverse-monsoon management,'' build on progress already made in growing so-called ``miracle rice'' on newly-irrigated paddies, which rely on chemical pesticides and fertilizers.

The drought points up the fact that Asia's ``green revolution'' may be a victim of its own success.

``The lesson is that we must harness more resources for irrigation,'' says IRRI's head of plant breeding, Gurdev Khush, who led the team in the 1960s that developed the most famous hybrid rice variety, known as IR-36. ``The price of cereals has gone down so much as a result of increased production that governments have not invested much in irrigation. But for the sake of food security, they must,'' he said.

In southern and southeast Asia, about 30 percent of rice is grown in irrigated paddies. About 55 percent of rice grown in poor countries is planted with the new high-yielding varieties.

``Certain high-yielding varieties can tolerate mild droughts,'' says IRRI spokesman Thomas Hargrove. ``But in a bad drought, no rice seed can survive.''

Average rice yields in Asia have risen about 50 percent in the last 20 years, while production has gone up about 82 percent, Dr. Hargrove says. In India and Indonesia, the world's second and fifth most populated nations, rice production has nearly tripled since 1965.

``This drought may force more countries to create rice-seed reserves and to develop seeds for nonirrigated areas,'' said Swaminathan. Most countries have developed a public system of emergency food distribution as well as food-for-work programs, he says.

Two countries particularly hard hit by the drought - and among the least advanced in modern rice technology - are Cambodia and Laos. This month, officials in both counties sent out pleas for international help.

Cambodian agricultural officials say rice is growing scarce in the markets. The communist-led government reports the country is experiencing ``the most severe drought in a decade.'' The UN estimates Cambodia has lost about 10 percent or more of its rice crop.

Western donor countries have been asked to send rice seed in order to avoid a repeat of the near-famine conditions that occurred in the early 1980s. Many seed nurseries have dried up, threatening planting for the rest of the year. ``It's not alarming yet - it depends on rains in September,'' says a UN official.

Laos, however, ``is desperate,'' says Greg Wells, an Australian rice expert who visited both Cambodia and Laos in August. He estimates one-third of the rice crop in Laos has been lost to dry weather. He has recommended to both Cambodia and Laos that they plant maize and legumes in dry rice paddies. Cambodia, he estimates, may lose more than half its harvest.

In Thailand, which traditionally has been the ``rice bowl'' of Asia, harvests are down 7 percent, which could cut the nation's rice export by as much as half. The government is sending water pumps to the hardest-hit areas in the northeast. In June, construction workers began building two dams to submerge some of the battle zones on the Thai-Cambodian border. Besides forming natural barriers against Vietnamese military incursions, the reservoirs will help relieve future droughts.