https://www.nytimes.com/1984/08/14/science/new-varieties-of-hardy-rice-hold-promise.html

The new varieties promise to give high yields without the costly irrigation required by the earlier ''miracle'' rice strains developed at the International Rice Research Institute here. The new strains have not yet been tested in farmers' fields, but one particularly promising variety has produced test yields more than twice as large as those from traditional varieties.

So in the 1970's the mission of rice scientists became to develop high-yielding strains that were also resistant to disease and insect pests. That second frontier, too, was crossed, and once again the institute led the way. A strain called IR-36, the progeny of 13 different varieties from six countries, is the best example of that effort. First planted by farmers in the Philippines in 1976, IR-36 is now grown on more than 24.7 million acres of rice lands throughout the world.

Progress is likely to proceed gradually for two main reasons. First, breakthroughs inevitably become harder to come by as the work advances. Second, while the irrigated environments for earlier high-yielding varieties tend to be uniform, the adverse conditions of rain-fed areas vary tremendously. Some areas are drought-prone, but others are frequently flooded.