Why do peanut leaves close during the day and at night?

As a daily pastime food, peanuts are not only sweet and delicious, but also rich in nutritional value. People praise the value of peanuts, but few people know the interesting phenomenon that happens on peanut leaves. Generally, there are four leaves on the petiole of peanut. When night falls, the leaves will close and the petioles will bend and droop, as if wrapped in clothes to keep warm. When the sun rises in the morning, the leaves will open and be bathed in the sunshine like stretching. This phenomenon of peanut leaves opening and closing day and night is scientifically called "sleep exercise" and "night exercise". Then why do peanut leaves bloom during the day and close at night?

In fact, the "sleep exercise" of peanut leaves is an act of self-protection. "Sleep exercise" is beneficial to reduce the water output of water storage cells. Maintaining a high water storage capacity is helpful for peanut leaves to resist drought and keep their physiological activities in a normal state, which is a good condition for peanuts to adapt to the environment. Peanut has a strong protective mechanism, which can reflect the "sleep movement" very sensitively, and the leaves will contract and gather immediately in the evening. However, if peanuts are in a weak state, or the growth environment is not good, "sleep exercise" will be relatively slow, so we can also judge their health level by observing their sensitivity and closeness.

"Sleep exercise" is not a specific growth performance of peanuts, and the same phenomenon also exists in leguminous plants such as Albizia Albizia, Oxalis, and soybeans. Some flowers also love to sleep, such as autumn peony, tulip and dandelion. The first person who discovered the "sleep movement" was the famous biologist Darwin. He pointed out that the "sleep movement" of plants is to resist the cold at night. However, this view was limited by the scientific research conditions at that time and was not recognized. Then came the "moonlight theory" to explain "sleep movement", pointing out that plants "sleep movement" is to avoid being invaded by moonlight.

But this theory was quickly overturned, because some tropical plants also have "sleep movement". It was not until Enright, an American scientist, studied with a sensitive thermometer that he found that the leaf temperature of "sleeping exercise" was 65438 0℃ lower than that of non-sleeping exercise, which confirmed Darwin's view. In a word, plant sleep, like the sleep of human beings and animals, is a self-protection skill.