“It’s the best example in agriculture,” said Julia Bailey-Serres, a researcher at the University of California, Riverside, who has done genetic work on the rice variety that Mr. Singh used. “The submergence-tolerant rice essentially sits and waits out the flood.”

In the heyday of the Green Revolution, the 1960s, leaders like Dr. Borlaug founded an international network of research centers to focus on the world’s major crops. The corn and wheat center in Mexico is one. The new rice variety that is exciting farmers in India is the product of another, the International Rice Research Institute in the Philippines.

Leading researchers say it is possible to create crop varieties that are more resistant to drought and flooding and that respond especially well to rising carbon dioxide. The scientists are less certain that crops can be made to withstand withering heat, though genetic engineering may eventually do the trick.

The flood-tolerant rice was created from an old strain grown in a small area of India, but decades of work were required to improve it. Money was so tight that even after the rice had been proven to survive floods for twice as long as previous varieties, distribution to farmers was not assured. Then an American charity, the Bill & Melinda Gates Foundation, stepped in with a $20 million grant to finance final development and distribution of the rice in India and other countries. It may get into a million farmers’ hands this year.

The Gateses, widely known for their work in public health, have also become leading backers of agricultural projects in recent years. “I’m an optimist,” Mr. Gates said in an interview. “I think we can get crops that will mitigate many of our problems.”

The Gates Foundation has awarded $1.7 billion for agricultural projects since 2006, but even a charity as large as it is cannot solve humanity’s food problems on its own. Governments have recognized that far more effort is needed on their part, but they have been slow to deliver.

In 2008 and 2009, in the midst of the political crises set off by food prices, the world’s governments outbid one another to offer support. At a conference in L’Aquila, Italy, they pledged about $22 billion for agricultural development.