In what season do maple leaves fall?

Maple leaves fall in autumn. When autumn comes, the days get shorter, the nights get longer, the weather gets colder, the soil temperature decreases, the rainfall decreases, and the water absorption capacity of roots is greatly weakened, but the transpiration intensity is not weakened, resulting in water shortage and defoliation. At the same time, after a certain period of physiological activities, a large number of metabolites such as minerals accumulate in cells, causing physiological function decline and death (chlorophyll destruction).

Maple leaves turn red in autumn. Maple leaves in autumn, because the temperature drops, the green pigment of maple leaves turns red. In northern China, autumn comes from August to 10, and the real autumn usually comes after September, so the maple leaves generally don't turn red until September 10. In the south of China, when it is cold later, the maple leaves will turn red later.

Extended data:

In fact, the red maple leaves are the result of maple trees' response to natural pressure, which is actually a sunscreen, which makes the leaves stay on the trees for a longer time and allows the trees to absorb more nutrients. There are two main substances that make leaves appear red:

One is carotene, which is an orange-red pigment ubiquitous in chloroplasts;

The other is anthocyanin, which exists in the cytosol of vacuoles. When the cytosol is alkaline, anthocyanins are blue-purple, and when the cytosol is acidic, anthocyanins are red.

After autumn, anthocyanins in maple leaves increased, and the destruction of chlorophyll disappeared with the decrease of temperature, so the green leaves became red leaves.

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