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Why does maple leaf turn red in autumn? The reason why maple leaves turn red in autumn

Autumn is the best season to watch maple leaves. At this time of the year, Xiangshan red leaves in Beijing attract tourists from home and abroad to visit Beijing. Is there a different style of red leaves? Then why do you know that maple leaves turn red?

In fact, maple leaves turn red in autumn. There are internal and external factors. First, let's look at the internal conditions:

There are two kinds of substances that make the leaves red, one is carotene, which is the orange red pigment in chloroplast, the other is anthocyanin, which is in the cell fluid of vacuole.

When the cell fluid is alkaline, the anthocyanin is blue purple. When the cell fluid is acidic, the anthocyanin is red. After autumn, the anthocyanins in maple leaves increased, and the decrease of temperature made the destruction of chlorophyll disappear, so the green leaves became red leaves.

The external factor of discoloration is the climate condition: when the temperature drops rapidly to a certain extent, and the temperature at night drops much lower than that in the day, the leaves have not yet withered, and most of the chlorophyll has been destroyed. At the same time, the increase of the temperature difference between day and night is also conducive to the formation of anthocyanin, so the leaves quickly turn red.

If the temperature drops very slowly, and the temperature difference between day and night is not big, the chlorophyll has not been destroyed and the tree has withered, then it will not become a beautiful red leaf.

In addition, the sugar in the maple leaves also played a great role. Someone did a small experiment. First, he picked a few green maple leaves and soaked them in sugar and sugar free cups for five days. Five days later, the maple leaf in the cup with sugar water turned red, only the maple leaf in the cup with water was still green. Experiments show that: the sugar content of maple has a lot to do with the reddening of maple leaves!