How long does it take for maple leaves to turn red?
Maple leaves turn red in autumn. In autumn, the green pigment of maple leaves turns red due to the drop in temperature. In northern China, autumn is from August to October. Autumn usually does not enter until September. After the month is over, the maple leaves usually don’t turn red until September or October. In southern China, it gets colder later, so the maple leaves turn red relatively later.
Reasons why maple leaves turn red:
1. Stress response: The redness of maple leaves is actually the result of the maple tree’s response to stress in nature. The redness actually acts as a sunscreen. , making the leaves stay on the tree longer, allowing the tree to absorb more nutrients. Research has found that nutritional pressure, especially the pressure of nitrogen deficiency, makes maple leaves red earlier and more transparently.
2. Intrinsic factors: There are two main substances that make leaves appear red. One is carotene, an 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, the anthocyanin is blue-violet. When the cell fluid is acidic, the anthocyanin is red. After autumn, the anthocyanin in the cotinus leaves increases, and the drop in temperature destroys the chlorophyll, so the green leaves turn red.
3. External factors: When the temperature drops rapidly to a certain level, and the temperature at night is much lower than during the day, the leaves have not yet fallen, but the chlorophyll has been mostly destroyed, and the temperature difference between day and night increases. , also contributes to the formation of anthocyanins, so the leaves turn red quickly. If the temperature drops very slowly, and the temperature difference between day and night is not large, and the chlorophyll has not been destroyed but the tree has withered, it will not turn into beautiful red leaves.
When do maple leaves turn red?
There are already red ones in early September of the lunar calendar. There is no specific time for this. The temperature and humidity will turn red when the temperature and humidity reach a certain level.
Every year from the end of October to mid-November, thousands of Thousands of people will go to Xiangshan to see the red leaves, and the red leaves in Xiangshan have become a famous scene in Beijing. So, why do mountains of red leaves appear all over Xiangshan in late autumn?
It turns out that the leaves of plants contain different pigments. In spring and summer. The leaves of maple leaves, cotinus and other trees appear green due to strong photosynthesis and chlorophyll covering up anthocyanins. It's late autumn. The leaves are attacked by cold waves and frosts, the chlorophyll is destroyed, and the water in the leaves is also reduced. The starch that cannot be transported in time turns into glucose, and the sugar gradually converts into anthocyanins, so the green leaves turn into red leaves.
You might as well do a little experiment: In early autumn, cut a maple leaf and place it in a dry place at home. After a few days, the water evaporates and it turns into a red leaf. If you dip a cut green leaf directly into sugar water, it will turn red faster.
What is the reason why maple leaves change from green to red?
Citing the latest research results, American scientists believe that the main reason why leaves turn red is because trees need to absorb and store as many nutrients as possible from leaves and soil before winter. The reason why leaves turn red in autumn is due to anthocyanins. But the scientific literature has many different explanations for why trees produce anthocyanins in the fall. According to a new study, Bill Hedge of the University of Wisconsin-Madison believes that this kind of anthocyanins exists in maples, oaks, etc. The red pigment in plants called "anthocyanins" plays the role of "sunscreen oil". In autumn, when trees can no longer absorb nutrients from their leaves, they can shield sensitive photosynthetic tissues, allowing trees to stay as healthy as possible before their leaves fall off. Storage of nutrients. Photosynthetic tissues are particularly unstable in autumn when the trees are destroyed and can no longer absorb important nutrients from the leaves. They are easily damaged by too strong light or other plant survival stress, such as low temperatures near freezing point, drought, low nutrient levels, etc. damaged; and once this process begins, the leaves will produce a large amount of anthocyanins near the leaf surface. Hedge believes that the pigments can protect the leaves' decreasing nutrient production capacity during this period. According to this theory, the more In a climate with dry air, plenty of sunshine during the day, and low temperatures at night, the better the autumn colors develop. It is also not difficult to understand why the outer leaves are more colorful than the inner leaves in the shade and the north. In addition, this theory also explains The reason why most native maples and oaks in the American Midwest and New England turn red, but European exotic species such as Norway maples do not. Researchers believe that the reason why these European tree species growing in North America do not The large amount of anthocyanins is due to the fact that the autumn climate in the native areas of these tree species has more clouds and warmer temperatures, and does not require the protection of these pigments.
Composition on why maple leaves turn red
Ye Qing is a "botanist" that I admire very much. He is really talented.
If nothing else, just talk about his "leaf book", it will make you stick out your tongue in surprise. His book collects leaves of various shapes, including needle-shaped, sword-shaped, belt-shaped, heart-shaped, triangular, pentagram-shaped, toothed, and non-toothed. I'm dazzled! He could tell me the names of these leaves, and also told me that there is a plant called Sagittarius, which has three kinds of leaves growing on the same plant; the leaves on the water are arrow-shaped, and the leaves on the water are heart-shaped. Underwater leaves are band-shaped.
What’s even more amazing is that Ye Qing knows why the leaves change color.
He said that because leaves contain something called "chlorophyll", this chlorophyll absorbs more red and blue light in the sun, does not absorb green light, and reflects green light, so the leaves turn green.
"So why did it turn yellow again?" I asked. "That's because chlorophyll is afraid of cold. When the temperature drops, it becomes sluggish, but the lutein in the leaves is not afraid of cold. In this way, lutein is formed quickly and the leaves are mainly yellow."
Oh, that’s it! Chlorophyll knows so much! "Then why do maple leaves turn red?" I asked him quickly. "It's the effect of sugar!" Ye Qing replied without thinking.
"What?" I don't understand. Are people giving Maple Leaf sugar water? I saw Ye Qing bring a small cup, add a spoonful of sugar into it, stir it up, find a green maple leaf from the "leaf book", put it into the sugar water, and said: "Let's take a look tomorrow!" I Ye Qing stared at the cup intently, what the hell was he doing? The next day, I hurried to Ye Qing's house to see if the green maple leaves soaked in sugar water had turned red. Ye Qing held the small cup in front of me. ha! It’s turned red, it’s really turned red! "Look!" Ye Qing pointed to an open "Science Illustrated" and I read it carefully. It turned out that maple trees were ready for the winter before the cold came. It turned some substances in the body into Sugar, if there is too much sugar, it will be able to withstand the cold, and it will produce something called anthocyanin, which is what works when maple leaves turn red! .
How long does it take for maple leaves to turn red?
In areas with distinct four seasons, nature is like a magician, performing scenes of beautiful scenery and making the entire space extraordinarily vivid and beautiful.
Every year in March and April, flowers bloom and tender pink buds sprout from the treetops, telling people that spring has arrived. In summer, the earth is covered with green leaves, a thriving scene.
When autumn comes, the earth is like a canvas again. Let nature sway, the leaves suddenly turn from green to yellow, to golden, to red, and the mountains and fields are colorful, forming a beautiful autumn scenery. After entering winter, deciduous trees open their bare trunks, and cold zone plants also carry verdant green branches, topped with white snow, accompanying the arrival of Christmas and New Year festivals.
The magician behind these colorful color changes is the abundant natural pigments in nature. At the same time, these natural pigments are also the catalysts required for photosynthesis to maintain plant growth.
Plants contain many pigments, each with different functions. The main plant pigments include chlorophyll, lutein, carotene and anthocyanins. The pigment of leaves exists in colored granules in the cytoplasm, which are divided into three types: green granules, which appear green or yellow; colorless granules, which do not show color; and variegated granules, which appear red or yellow.
As cells grow, the chromatic granules will divide and increase, or differentiate and change color. In autumn, you can see many plants that change color. The leaves of five-pointed maple, ginkgo and other plants turn golden yellow in late autumn. The leaves that turn red include wild sumac, ebony mortar, maple, wall-creeper, terminalia tree, etc. Autumn maple viewing has become a national tourism trend.
Anyone with maple viewing experience knows that to enjoy the scenery of red maple mountains, detailed and careful itinerary planning is required in advance, including choosing maple viewing spots and arranging the appropriate time. Even so, it also requires The cooperation of temperature also requires a little bit of luck. Only with the cooperation of weather and location can a perfect maple viewing itinerary be performed. The reason why it is so difficult to perfectly appreciate maple leaves is because the turning of maple leaves into red is a precise chemical reaction.
To appreciate maple trees, you first need to understand maple trees. Most of the maple trees we see in major maple viewing resorts are green maples. Another kind of liquidambar tree looks very similar to the green maple. Most of the leaves are yellow or green, not as beautiful as the green maple. We can distinguish them by some characteristics.
"Green maple" is also called "maple tree". Most maple trees grow in temperate areas and belong to the genus Acer in the family Aceraceae. "Liquidambar" is a subtropical deciduous tree belonging to the genus Liquidambar of the Hamamelidaceae family. It grows in Taiwan at low altitudes to an altitude of 1,500 meters.
As far as the leaves are concerned, the liquidambar leaves are arranged alternately, and the leaves are in the shape of a three-lobed palm, just like bending the thumb and little finger to make a "three" gesture, and the leaf edges are smooth. Maple leaves grow in pairs, with a five-lobed palm shape, like an open palm, and a serrated edge.
As far as fruits are concerned, the fruits of the liquidambar tree are like round thorny capsules; the fruits of the maple tree are like splayed wings. As we marvel at the beauty of nature as maple leaves turn red, let’s explore the interesting chemistry of color.
The main pigments in plants are chlorophyll, lutein, carotene and anthocyanins. The discoloration of leaves is mainly dominated by changes in pigments in plants. When the sunshine is long in spring and summer, photosynthesis is particularly active. In addition to synthesizing sugars, photosynthesis of leaves also accelerates the decomposition of chlorophyll. At night, chlorophyll begins to be synthesized again.
Because chlorophyll is continuously decomposed and regenerated, leaves are rich in chlorophyll. When the leaves contain both chlorophyll and carotene, the leaves will absorb red light, blue light, and blue-green light, and the remaining light will be reflected, making the leaves appear green.
After entering autumn, the daylight hours shorten and the nights become longer. In response to the changes in daylight hours, deciduous tree species will produce abscission hormone at the base of the petiole, causing the leaves to fall off, but it also prevents the transportation of nutrients.
At the same time, as the temperature decreases, the rate of chlorophyll synthesis will slow down.
As a result of the reduction of water in the leaves, chlorophyll decomposes at low temperatures, but the rate of chlorophyll synthesis is too late to replenish it, so the chlorophyll pigment content gradually decreases. In addition, carotene is far more stable than chlorophyll. Even if chlorophyll disappears, carotene can still exist in the leaves. The lutein, carotene, etc. in the leaves gradually dominate the color of the leaves, causing the leaves to appear yellow.
As the plant's ability to transport nutrients decreases, glucose is retained in the leaves, and the sweetness becomes higher and higher. Some plants use glucose and lutein in their leaves to gradually produce anthocyanins under the action of sunlight.
In late autumn, the chlorophyll of the leaves continues to decrease, and the green of the leaves fades, while the anthocyanins continue to increase, and the red color becomes stronger, so they turn into bright red and lovely leaves. The stronger the sunlight, the more anthocyanins the plants produce, the greater the temperature difference, the lower the chlorophyll drops, and the redder the leaves become.
Research has found that when maple trees are deficient in nitrogen nutrients, maple leaves will become redder and turn red earlier. Therefore, the degree of redness of maple leaves is related to sunshine, temperature, drought, pollution, and nitrogen elements.
In addition, red maple leaves act as sunscreens, delaying the time of leaf fall, so maple trees can absorb more nutrients. Therefore, the phenomenon of maple leaves turning red can be seen as the maple tree’s response to changes in the natural environment. result. The relative content and production rate of chlorophyll and anthocyanins can also explain why the buds and new leaves of plants appear red.
When the production rate of chlorophyll is higher than that of anthocyanins, the buds and new leaves of the plant will turn green faster. When the production rate of anthocyanins is higher than that of chlorophyll, the buds and new leaves of the plant will appear red.
When the chlorophyll pigment increases, the leaves turn back to green. Most maple viewing spots in Taiwan are distributed in spots or strips. The entire pure maple forest can only be seen in a few areas such as Aowanda in Nantou, Malabang Mountain in Miaoli, and Shimen Reservoir.
Maple viewing must be done during the alternation of autumn and winter, when the climate changes from warm to cold. Three or four days after the first two cold waves hit, the maple leaves turn red. However, it is best to keep the interval between these two cold waves about Within half a month to three weeks, if the interval is too close, the leaves will not have time to turn red; if the interval is too long, the leaves will have fallen and returned to their roots before the second wave of cold wave arrives. The best place to view maple trees is in areas where the north wind blows the trees, such as along the ridges. As for the maple trees located in valleys and low-lying areas such as cliffs and open spaces, the leaves usually fall before they turn red.
The maple leaves on the flat ground cannot turn red because the temperature difference between day and night is too small. However, you can cut a maple leaf and soak it in sugar water at home. After a while, the sugar turns into anthocyanins and the maple leaf turns red.
Therefore, maple leaves do not turn red.
When do maple tree leaves turn red?
The reddening of maple leaves is actually the result of the maple tree’s response to stress in nature. The reddening reaction actually acts as a sunscreen, keeping the leaves on the tree longer, allowing the tree to absorb more nutrients. Research has found that nutritional pressure, especially the pressure of nitrogen deficiency, makes maple leaves red earlier and more transparently.
There are two factors that cause the green leaves to turn red in autumn. What makes leaves appear red mainly depends on two substances: one is carotene, which is an orange-red pigment commonly found in chloroplasts, and the other is anthocyanins, which is present in the cell fluid inside the vacuole. When it is alkaline, anthocyanins appear blue-violet; when the cell fluid is acidic, anthocyanins appear red. After autumn, the anthocyanin in the cotinus leaves increases, and the drop in temperature causes the chlorophyll to be destroyed and disappear, so the green leaves turn into red leaves. The external factor of discoloration is climatic conditions: when the temperature drops rapidly to a certain extent, and the temperature at night is much lower than during the day, the leaves have not yet fallen, and the chlorophyll has been mostly destroyed. At the same time, the increase in temperature difference between day and night also helps the flowers to bloom. The formation of cyanin causes the leaves to turn red quickly. If the temperature drops very slowly, and the temperature difference between day and night is not large, and the chlorophyll has not been destroyed but the tree has withered, it will not turn into beautiful red leaves.
When will the maple leaves turn red?
Maple leaves usually turn red in autumn.
Because the temperature drops in autumn, the green pigment of maple leaves gradually turns red. Although autumn in the north occurs from August to October, autumn usually does not enter until the end of September, so maple leaves usually only turn red from September to October.
In southern China, it gets colder later, and the maple leaves turn red relatively later.