M.S. Swaminathan, architect of the Indian "green revolution" in the late 1960s that doubled crop yields in just four years, painted a confident picture on Friday of sustained rises in agricultural output in the developing world, fueled by genetically-modified foods and other new technologies.

The green revolution introduced superior plant breeds and increased rice and wheat farmers' productivity. It has been widely credited with having prevented famine in Swaminathan's home country.

In a lecture at the Science Center sponsored by the University Committee on Environment, Swaminathan outlined what he called an "ever-green revolution" that would produce continued productivity gains but prevent farmers from exhausting the soil and water supply.

"There is no complacency. There is no time to relax," he said. "One must defend the gains that have already been made....We must make new gains in farming systems."

Environmentalists and others have objected to a key element of Swaminathan's plan--genetically-modified foods--saying the ecological impact is uncertain. Already, Britain, Germany, Switzerland, Brazil and other countries have curbed farmers' use of these modified crops.

Though he said no such crops have been approved for planting in India, Swaminathan predicted genetically-engineered crops would gain approval there within the next five or six years. He said they would cause crop yields to climb consistently over the next 50 years.

Genetically-modified foods could also have nutritional benefits, he said. For example, he said that "golden rice," which is enriched in beta-carotene, could help to combat vitamin-A deficiency, which kills a million children worldwide every year.

But Swaminathan cautioned that genetically-modified products are not cure-alls that will eradicate health problems, such as children's blindness.