Biologists from the John Innes Centre in England discovered that plants have a biological process which divides their amount of stored energy by the length of the night. This solves the problem of how to portion out (分配) energy reserves during the night so that the plant can keep growing, yet not risk burning off all its stored energy.
While the sun shines, plants perform photosynthesis (光合作用). In this process, the plants change sunlight, water and carbon dioxide into stored energy in the form of long chains of sugar, called starch (淀粉). At night, the plants burn this stored starch to fuel continued growth.
"The calculations are precise so that plants prevent starvation but also make the most efficient use of their food," said study co-author Alison Smith. "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 scientists studied the plant Arabidopsis, which is regarded as a model plant for experiments. To give the plants some math tests, the biologists let night arrive unexpectedly early or late for them.
During one of the exams, they shut off the lights early on them that had been grown with twelve-hour days and nights. Putting them into darkness after only an eight-hour day means they didn't have time to store as much starch as usual. And this forced the plants to adjust their normal nightly rhythm.
Amazingly, even after this day length trick, the plants did very well in their exams and ended up with just five percent of starch left over at the end of the night. They had neither starved, nor stored starch that could have been used to fuel more growth.
The authors suggested that similar biological calculators may explain how a migratory bird, the little stint, can make a five-thousand-kilometer journey to their summer habitat in the Arctic and arrive with enough fat reserves to survive only approximately half a day more, on average.
The results of the study were published ine Life.
