We all know that plants use photosynthesis to convert sunlight into food, but here's a question for you: how do plants get energy and keep growing at night?

Now we have an answer: according to new research out of the John Innes Centre in the U.K., plants perform a complex calculation to figure out how much of stored energy to use during the night. The plants actually ration that energy from the day and burn it off bit by bit through the evening.

"The calculations are precise so that plants prevent starvation but also make the most efficient use of their food," biologist Alison Smith, one of the new study's authors, said in press release. The plants use sunlight to convert carbon dioxide into sugar and starch during the day, and then adjust how quickly they burn that starch to last through the night. "If the starch store is used too fast, plants will starve and stop growing during the night. If the store is used too slowly, some of it will be wasted."

The research team from the John Innes Centre — which specializes in plant science and microbiology — studied a type of flowering plant called Arabidopsis. They adjusted the amount of daylight the plants were exposed to and then calculated starch levels in their leaves. They found that the plants automatically adjusted the rates at which they burned their starch based on how long the nights would last. No matter how long the nights were, the plants ended up using about 95 percent of their stored starch.

The research, published today in the journal eLife, not only improves our general understanding of plants but it could also have specific implications for agriculture. "The capacity to perform arithmetic calculation is vital for plant growth and productivity," Smith said. "Understanding how plants continue to grow in the dark could help unlock new ways to boost crop yield."

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