Autumn is the best time to watch red leaves. Do you know why maple leaves turn red? The literati and poets of all ages are fond of maple leaves and recite various ancient poems. For example, Du Mu, a poet of the Tang Dynasty, likes to park in the maple forest late, and the frost leaves turn red in February. 'wait, the beauty of maple has been recognized by people of all ages. Maple trees planted in gardens and landscapes are also common. Let's take a look at why maple leaves turn red!
When do maple leaves turn red
Maple leaves turn red in autumn. Maple leaf is in autumn, because the temperature drops, leading to the maple leaf green color red. In northern China, autumn is from August to October. It usually comes after September when autumn really starts, so maple leaves usually don't turn red until September 10. In southern China, when it gets cold later, the maple leaves will turn red later.
When do maples lose their leaves
Maple leaves fall in autumn. When autumn comes, the day shortens and the night lengthens, the weather becomes cold, the soil temperature reduces, the rain reduces, the root system water absorption capacity greatly weakens, but the transpiration intensity does not weaken, the water shortage causes the fallen leaves. At the same time, after a certain period of physiological activities, a large number of metabolites, such as mineral substances, accumulated in the cells, leading to the decline of physiological function and death (chlorophyll destruction).
Why do maple leaves turn red
1. Pressure response: Maple Leaf reddening is actually the result of maple's response to natural pressure. Reddening actually acts as a sunscreen, making leaves stay on the tree for longer, so that the tree can absorb more nutrition. It was found that the pressure of nutrition, especially nitrogen deficiency, made maple leaves red earlier and more transparent.
2. Internal factors: there are two main substances that make the leaves red. One is carotene, the orange red pigment commonly found in chloroplasts. The other is anthocyanin, which exists in the cell fluid in the vacuole. When the cell fluid is alkaline, anthocyanin is blue purple. When the cell fluid is acidic, anthocyanin is red. After autumn, the anthocyanins in the leaves of Cotoneaster increased, and the decrease of temperature made the chlorophyll destroyed and disappeared, so the green leaves became red leaves.
3. External factors: when the temperature drops rapidly to a certain extent, and the temperature at night is much lower than that during the day, the leaves have not 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 anthocyanins, 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.