One of the criticisms of genetically modified crops is that they haven’t done much to increase yields—the amount of corn or wheat a farmer can grow on an acre of land.

But now scientists tinkering with the process of photosynthesis in tobacco plants say they’ve done exactly that. They’ve created breeds that grow up to 20 percent larger, ending up taller, with bigger leaves and thicker roots.

The study is the first to show a big boost in the basic efficiency of photosynthesis, according to the Guardian, which predicts plants altered in this way could help meet what the UN projects will be a 70 percent increase in food demand over the next 30 years.

Researchers used genetic engineering to increase the yield of tobacco plants.

Plants use photosynthesis to turn sunlight and carbon dioxide into energy and carbohydrates. However, under bright sunlight, they have a way of shedding extra photons they don’t need.

If the weather turns cloudy, they do ramp up photosynthesis again, but only slowly. That’s the process the scientists sought to make more efficient. They did it by adding extra copies of the gene that regulates the switchover. That shortened the process known as “photosynthetic recovery time,” so the plants took advantage of more sunlight.

The team has already incorporated the genes into rice and corn, according to Science, and might find ways to make plants’ response to changing light conditions even faster.

“We don’t know for certain this approach will work in other crops, but because we’re targeting a universal process that is the same in all crops, we’re pretty sure it will,” Stephen Long, a researcher at the University of Illinois who led the project, told the Guardian.

The fast-growing plants were 14 to 20 percent larger after growing for three weeks in Illinois test plots. That’s a huge gain in yield in a single step. By comparison, farmers in the U.S. have succeeded in increasing corn yields steadily, using a variety of methods, but at only about 2 percent a year.

Long told the New York Times he thinks that “production gains of 50 percent or more may ultimately be achievable” with genetic engineering and that the technology could create a second “Green Revolution,” a reference to gains in productivity that modern agricultural methods brought to the developing world during the last century.

The research was carried out along with Krishna Niyogi at the University of California, Berkeley, and was funded by the Bill & Melinda Gates Foundation.

Another research team, called the C4 Rice Consortium, has also been seeking to alter photosynthesis in an effort to increase yields of rice and wheat by 50 percent while using less water and fertilizer (see “Supercharged Photosynthesis”).