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1 .This is Scientific American 60-Second Earth. I'm Cynthia Graber. Got a minute?
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2 .Over the past decades, farmers have been getting bigger harvests from the same size plot of land.
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3 .That story's particularly true in the American Midwest, the world's corn basket.
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4 .The U.S.now grows more than 36 percent of the world's corn.
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5 .One key is that breeders developed corn plants that can grow very close together.
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6 .Newer varieties can better withstand stress and grow roots deeper to access water.
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7 .So stalks are planted more densely and yields per acre are up.
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8 .But a study in the journal Science finds that as corn plants get closer together, they become more sensitive to drought.
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9 ."What we did see for corn is that progress has been much greater for what we consider good weather conditions, so cooler, wetter conditions."
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10 .Study leader David Lobell of Stanford University, on Science's podcast.
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11 ."And when you get to the hottest conditions we see actually very little progress…
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12 .the simple observation was that the sensitivity to those hot conditions seems to be growing over time."
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13 .So in the hotter, drier climate predicted for the coming decades, the varieties of corn that currently produce bumper crops could be in trouble.
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14 ."The impacts of drought are actually growing, at least in the case of maize."
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15 .Thanks for the minute, for Scientific American 60-Second Earth. I'm Cynthia Graber.
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