Why do leaves turn yellow and fall in autumn, and why do many leaves turn yellow and fall in autumn?

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, making the forest a golden yellow or a fiery red, which is very beautiful.

When autumn arrives, the leaves of the trees in the mountains turn into beautiful colors, why is that?

It used to work hard in the summer, but when the weather cooled down, it stopped working. The nutrients produced by the leaves do not reach the branches and trunks, but settle in the leaves. The chlorophyll of the leaves is also destroyed, and it mixes with the nutrients left in the leaves or the withered brown color, which becomes a variety of beautiful colors.

Why do the green leaves change color in autumn?

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.

When autumn arrives, the days are shortened and the nights are lengthened, which causes the trees to begin to lose their leaves. Before the leaves fall, trees no longer produce large amounts of 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.

Habits, not only yellowing but also turning purple are anthocyanins, and the fall is the result of the formation of abscisic acid by low-temperature plants and the ...... of the earth's gravity

The alternation of the seasons is that it turns yellow, and gravity causes it to fall.

Because the leaves and nutrients have to return to the big tree, so that it has enough nutrients to survive the winter!

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 forms 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 earth embrace.

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.