What is the reason why the leaves turn yellow in autumn?

The main reason why the leaves on the tree turn yellow in autumn is that the leaves contain substances such as chlorophyll, lutein and carotene. In spring and summer, chlorophyll is much more abundant in the leaves than other pigments, so the leaves show the green color of chlorophyll and the color of other pigments is not visible. ‍‍

Autumn is still relatively warm, and this is the season when the sun is at its most intense, and the winds are stronger, so the leaves will turn yellow.

When autumn arrives, trees no longer produce as much chlorophyll as they do in spring and summer, and existing pigments, such as chlorophyll, gradually break down. In this way, as the chlorophyll content gradually decreases, the colors of other pigments will gradually appear on the leaf surface, so that the leaves will show yellow, red and other colors. This is also the case with the formation of maple leaves that are all over the mountain. ‍‍

Because there is no chlorophyll in it, the tree will enter the state of wintering and will not provide nutrients to the leaves.

When the temperature drops in autumn, the light time is shortened, which affects the absorption capacity of the root system and the photosynthesis of leaves, so it cannot meet the growth and development of trees. When the temperature drops and the air is dry, the water in the leaves evaporates quickly, but the ability of the roots to absorb water has been greatly reduced, and the water and nutrients are insufficient. In order to survive, the tree generates an isolation layer at the junction of the petiole and the leaf stem, and the leaves are cut off from the water **, coupled with the low temperature, the chlorophyll is destroyed, so the lutein begins to be active, which is the reason why the leaves of the tree will turn yellow in autumn.

When I was young, my mother asked me what season I liked the most, at that time I liked summer, because I could eat ice cream and go swimming, but as I grew up, I found that I liked autumn more and more, and when I liked the leaves, I thought it was the most beautiful, when I questioned the reason why the leaves turned yellow in autumn, it turned out that it was because the temperature was low, it stopped producing chlorophyll, and the leaves no longer photosynthesize, so slowly the green pigment was consumed, and other colors would appear, and the leaves were not simply green. It also includes several other colors, because other colors can not be photosynthesized, usually covered by green, and when the green pigment stops working, it will show other colors, and in autumn, red leaves, yellow leaves, these colors can not photosynthesize, so after a while it will drift away, let me understand it. ‍‍

Autumn is coming. When the autumn breeze blows, the trees are keenly aware of the changes in the weather. Deciduous trees begin to stop growing, and only a small amount of nutrients are needed to survive this season.

Because autumn and winter are dry, they choose to shed their leaves in order to save water volatilization. Before the leaves fall, the chlorophyll in the leaves is broken down, and the resulting material is transported from the leaves to the roots of the tree as nutrients for the winter. When chlorophyll is broken down, there are many pigments such as carotenoids and lutein left in the leaves, and the leaves are mainly yellow.

The reason why the leaves turn yellow is because it contains chlorophyll and lutein. In summer, when the weather is hot, chlorophyll can work normally, and in autumn, when the weather is cool, chlorophyll does not adapt to the environment, and only lutein can work normally, so when autumn comes, the leaves gradually turn yellow.

Autumn comes, the temperature drops, the synthesis of chlorophyll is hindered, and the destruction of chlorophyll is increasing day by day. Chlorophyll disappears quickly in the leaves, which creates the conditions for other pigments to reveal color in the leaves. Therefore, leaves containing more lutein and carotene appear yellow.

Since I had a child, I have become the answer to 100,000 whys, my baby has to ask me 100,000 questions every day, which makes me suddenly remember when I was a child pestering my mother, I still remember asking her why the leaves turn yellow in autumn, and my mother told me that this is the law of nature. When people get old, their hair turns gray until they die, and the reason is the same, except that the trees are only fallen leaves, and they are still maintaining nutrients, and the trees themselves do not die. In autumn, the weather gradually cools and becomes colder, due to the weakening of photosynthesis, the trees stop chlorophyll synthesis and sustenance, and the leaves turn yellow and fall off, and in winter, the temperature is lower, and the green leaves also fall off with the freezing.

At that time, I thought that my mother was really very knowledgeable.

I read in a book that the leaves and other plants turn yellow in autumn due to changes in temperature, and the chlorophyll is lost, so the leaves turn yellow. Autumn has arrived, the weather is cooler, and leaves are falling from the trees. ‍‍

Leaves contain chlorophyll and lutein, and in summer the color of chlorophyll will mask lutein, and in autumn the problem will be low and the chlorophyll will be destroyed, and the color of lutein will be revealed.

A lifetime of life, a autumn of grass and trees; People add gray hair when they are middle-aged, and the leaves of trees turn yellow after the beginning of autumn; People have been sparse for seventy years, and the leaves of the trees have fallen through the cold dew. The temperature difference between the white night of the beginning of autumn is large, and it is cold and rainy. It is mainly the yellowing of the leaves when the temperature difference between day and night changes greatly.

Why do the leaves turn yellow in autumn?

Every autumn, as the weather gets colder, the leaves turn from green to yellow, have you ever wondered why the leaves turn yellow in autumn? Below.

Why do I have a learning power, let's take you to understand this problem.

When autumn comes, the trees feel the change in climate from the autumn, so that their own large amount of chlorophyll covers the green chlorophyll, and people naturally see the leaves turn red or yellow. In autumn, deciduous trees stop growing and only need a small amount of nutrients to survive. Before the leaves fall, the trunk of the tree decomposes the chlorophyll, and the substances produced by the decomposition are transported from the leaves to the tree as nutrients for the winter.

When chlorophyll is decomposed, chlorophyllin is left in the leaves, so you can see the leaves turn from green to yellow. The leaves are green because of the chlorophyll in the leaves. However, in addition to green pigment, there are many pigments such as red pigment and yellow pigment in the leaves, but the amount is very small.

In autumn, the green pigment slowly fades, and the red pigment and yellow pigment are revealed.

All leaves contain green chlorophyll, which is used by trees to capture light energy and store it in the form of chemicals such as sugar with the help of other substances in the leaves. In addition to chlorophyll, many leaves contain other pigments such as yellow, orange and red. Although these pigments do not photosynthesize in the same way as chlorophyll, some of them are able to transfer captured light energy to chlorophyll.

In spring and summer, chlorophyll is much more abundant in the leaves than other pigments, so the leaves show the green color of chlorophyll, and the color of the other pigments is not visible.

Professor Yuzo Shiota, who specializes in the process of chlorophyll decomposition at the Graduate School of Creation Science and Technology at Shizuoka University in Japan, said, "As leaves age, the chlorophyll in the leaves is decomposed and decreased. "When chlorophyll is broken down, the green of the leaves becomes lighter and lighter, and the green becomes lighter, and the other pigments contained in the leaves are highlighted, among which the pigment that reflects yellow light is called "lutein".

The amount of chlorophyll contained in the new leaves is about 8 times that of lutein. Spring and summer yellow is obscured by green, which we can't see. As the leaves age, all the pigments contained in the leaves are broken down, but the lutein is broken down slowly, so the leaves gradually turn yellow.

1. The leaves of most trees will turn yellow and fall in autumn, because the chlorophyll in the leaves will slowly decrease in autumn, and the original color of the leaves will be slowly revealed. In the spring, the leaves will photosynthesize, resulting in a large amount of chlorophyll, and in the autumn, when the light weakens and the growth of the tree slows down, the carotene in the leaves will emerge.

2. In fact, yellow is the original hidden color of the leaves, the reason why it will appear green is because the leaves contain a lot of chlorophyll, but in addition to chlorophyll, the leaves also contain red pigment, yellow pigment, etc., when the weather turns cool in autumn, the infusion stops working, and the nutrients in the leaves cannot be transmitted to the branches and trunks, so they will slowly precipitate to the leaves and turn yellow.

3. There are many trees whose leaves turn yellow in autumn, such as sycamore, ginkgo, pomegranate, acacia, etc. Generally speaking, the leaves of plants mainly contain leaf green, lutein and carotene, and these three pigments will change due to the change of temperature, so the leaves will also show different colors.

Because the chlorophyll in the leaves will be reduced in autumn, the original color of the leaves will emerge, and the leaves mainly contain chlorophyll, lutein, and carotene, and the leaves will photosynthesize in spring and autumn, and a large amount of chlorophyll will appear in the leaves at this time. In autumn, when the light is weaker and the trees grow at a slower rate, lutein or carotene will emerge in the leaves.

Trees whose leaves turn yellow in autumn include ginkgo, metasequoia, pomegranate, plane tree, acacia, sycamore, etc., and the mesophyll of plants mainly contains chlorophyll, lutein and carotene, which change with the change of temperature. Autumn temperatures are much cooler than spring and summer, when the leaves produce a lot of carotene. Trees usually use chlorophyll to capture sunlight and use other substances in the leaves to convert sunlight into sugars and other chemicals for storage.

In autumn, when the light is weaker and the trees grow more slowly, this is when other substances in the leaves will be revealed.

Hello, because in autumn, the plants gradually stop photosynthesis, intending to "accumulate energy" like small animals preparing for winter, the chlorophyll in the plants is also "destroyed", so we see yellow or orange.

Ask why the leaves fall in the fall.

There is not enough moisture, temperature, and sunlight in the fall, so the leaves fall off in the fall. Moreover, the main use of green leaves is to absorb sunlight for photosynthesis to make nutrients, as well as to transpire water.

In autumn and winter, when rain is scarce and the air is dry, the moisture content of the soil also decreases, which cannot meet the needs of tree growth. Coupled with the fact that the sunlight is oblique in the northern hemisphere, the number of hours of daylight is shortening day by day, which indicates that winter is approaching for trees. At this time, a hormone is produced in the leaves of the tree, abscisic acid.

Under the action of abscisic acid, a natural fracture surface is formed around the separation layer. Due to the lack of normal replenishment of water, the leaves will gradually dry up, and the natural fracture surface will become more and more obvious, and the leaves will fall when the autumn wind blows.

Ask why the leaves fall in the fall.

This is the result of plant evolution, deciduous plants are mostly broad-leaved plants, grow relatively fast, consume large nutrients, in order to avoid frostbite in winter, will produce substances that inhibit growth in autumn, and stop growth. And ** leaves are more nutrients to facilitate winter. Branches and leaves that have lost their nutrients will fall under the influence of gravity.

Since the leaves are not exposed to sunlight in autumn, the amount of chlorophyll synthesis in the leaves is less than the amount of decomposition in the process of photosynthesis, so the color of other pigments in the plant will be exposed and turn yellow.

The reason why the leaves turn yellow in autumn is to fight the cold, the chlorophyll in the leaves is broken down into nutrients and sent to the roots, and the leaves contain chlorophyllin and lutein, so the leaves will turn yellow and red. The leaves contain chlorophyll, lutein, carotene, usually contain more chlorophyll, in autumn it will become colder, the old chlorophyll decomposes, and the new chlorophyll cannot be formed due to the cold weather, so it shows the yellow color contained in lutein and carotene, and after autumn, a small amount of nutrients can support the trees to survive the winter, so there is no need to make chlorophyll. And, since there are a lot of red and yellow pigments that appear in the leaves, the leaves turn yellow and red.

Trees with yellow leaves in autumn include ginkgo, fir, pomegranate, plane tree, acacia, sycamore, etc., and the mesophyll of the plant mainly contains chlorophyll, lutein, and carotene, which change with temperature. Autumn temperatures are much cooler than spring and summer, and carotene is produced in large quantities in the leaves. Trees transport nutrients through transpiration, transpiration is mainly carried out through leaves, and plants have high chlorophyll content in spring and summer, and no other pigments appear.

As the temperature drops and precipitation decreases in autumn, plants can only survive the winter safely by reducing the amount of water consumed by transpiration through leaf loss. Autumn maple leaves turn red because anthocyanins are produced in the leaves when the temperature drops below 7 degrees Celsius. Anthocyanins are the main coloring substances of plant petals, such as roses, peonies, etc.

In autumn, most of the leaves will dry out, turn yellow, and then wither and fall.

In autumn, the temperature drops and the light time is shortened, which affects the absorption capacity of the root system and the photosynthesis of leaves, so it cannot meet the growth and development of trees.

When the temperature drops and the air is dry, the water in the leaves evaporates quickly, but the ability of the roots to absorb water has been greatly reduced, and the water and nutrients are insufficient.

In order to survive the tree, the junction of the petiole and the leaf stem generates an isolation layer, the leaves are cut off from the water **, coupled with the low temperature, the chlorophyll is destroyed, and lutein and so on begin to be active, so the leaves will turn from green to yellow and fall off, with the autumn wind back to the embrace of the earth.

In fact, lutein, which turns leaves yellow, and chlorophyll, which turns leaves orange and red, are present in the leaves from the day they grow, but they are masked by the green chlorophyll.