World's Growing Population Will Need Crops Engineered to Produce More and Tolerate Climate Change

Stephen Long delivering the 2013 Charles Valentine Riley Memorial Lecture [AAAS/Robert Beets]

Despite technological advances that have allowed U.S. farmers to roughly triple corn and soybean production in the past five decades, the world is facing an impending food shortage. Its almost 7 billion people, coupled with growing middle classes in countries like China, are increasing the demand for soy, rice, wheat, corn and other food staples not just to feed a growing human population, but to also feed an increasing demand for meat and animal products. By 2050, there will be about 30 percent more people, so farmers will need to produce 70 percent more than they currently do, an agricultural expert told a AAAS audience.

More than 80 percent of that increased food production will have to come from an additional increase in the amount of food grown on each acre. In most areas of the world, there isn't additional suitable, undeveloped land available for growing food crops, said Stephen Long, professor of plant biology and crop sciences at the University of Illinois. At the same time that food demand increases, the world will also be facing rising temperatures, increased drought, and increases in atmospheric carbon dioxide and surface ozone concentrations. A larger demand for renewable energy, including ethanol produced from corn or biomass, as well as increasing crop losses to pest insects will make it even harder for food growers.

Long gave the AAAS Charles Valentine Riley Memorial Lecture on 25 June, which was followed by a panel discussion. The lecture — which is organized by the Charles Valentine Riley Memorial Foundation and the World Food Prize Foundation — was created in 2010 to promote a broader understanding of agriculture and of the efforts to improve agriculture through scientific knowledge.

Between the 1940s and the 1970s, the "Green Revolution" improved yields both by improved agronomy, such as use of fertilizer and pest controls, and using improved crop varieties with greater potential yields. But increasing the amount of seed produced by these plants by another 70 percent using the approaches that proved so effective earlier may not be possible, Long said, since some of these plants, like wheat, rice and soybeans, are now close to their biological limits. The best crop varieties can now capture close to 90 percent of the sunlight available in the growing season and partition 60 percent of their mass into the seed or grain. "So what's left to improve?" Long asked.

One answer, he says, is to make plants more efficient by getting them to convert more of the sunlight energy that their leaves capture into food. Currently, the best varieties only achieve about one-third of their theoretical efficiency in photosynthesis. Specifically, researchers have known since the 1970s that photorespiration, a process that consumes oxygen and carbohydrates formed in photosynthesis, can be inhibited by increasing carbon dioxide concentrations within leaves. Some plants such as corn have a biochemical pathway that does this naturally. Introducing the ability to inhibit photorespiration into crops that lack it could increase their productivity by 30 percent or even more in hot climates, Long said.

Long and his colleagues have already begun to work on taking a gene from blue-green algae that diminishes photorespiration and inserting it into soybean plants. The technology could eventually benefit wheat, rice, soy, cotton and some trees.

Researchers are also using computer models to find other ways to improve plant yields, Long said. The models analyze a plant's physical structure as well as its chemical processes to predict its optimal form for maximum productivity. Often, features that evolved to help a plant compete and survive in the wild lower productivity and efficiency in a domesticated crop, Long said. For example, having extra leaves or a leaf pattern that would shade out competitors lowers the yield of a crop.

Panelists Richard Bonanno, President, Mass. Farm Bureau Federation (top), Pam Johnson (middle) and Sonny Ramaswamy (bottom) with Stephen Long (at left). [AAAS/Robert Beets]

Such computer models have already guided researchers to proteins that could increase photosynthesis and yield. More of those ideas will soon be put to the test: the Gates Foundation is giving a consortium of institutions (of which the University of Illinois is a part) $25 million to see if other improvements suggested by the computational models will improve crop plant yields.

While these potential advances make Long optimistic about the ability of science to provide for the increasing food and energy demands on agriculture, he said he's concerned about political opposition that often prevents farmers from ever using these advances. "We have governments that are creating many regulatory hurdles to implementing new technologies," he said. These include proposed laws to require labeling of genetically modified organisms or to limit growing plants for ethanol instead of food, as well as broad restrictions on GMO crops in the European Union. Long is also concerned about the lack of funding for agricultural research that will be necessary to develop these needed technologies.

Participants in the panel discussion following Long's talk echoed his concerns about lack of funding by both private and public entities as well as opposition to some technologies. Pam Johnson, president of the Corn Board within the National Corn Growers Association, attributed the fact that corn yields have increased so much since her grandparents were farming to corn growers who pushed for more research and funding for agricultural technology testing. Without more public and private investment in research, she and the other panelists agreed, U.S. agricultural production will stall.

While he agreed with the need to address food insecurity through increased production, panelist Sonny Ramaswamy, director of the U.S. Department of Agriculture's Institute of Food and Agriculture, said the most "wicked problem" is population growth. Despite being the fundamental cause of food insecurity and climate change, "we can't really deal with [population growth] because of superstition, religious connotations," or political reasons, he said.