Why do the leaves start to turn yellow and fall down in autumn?

Most of the vigorous leaves are green, and the senescent leaves turn yellow. The green leaves of cochines and maples turn scarlet in autumn, while the leaves of purple duck plantar grass are purple red all year round. They are all leaves, so why are there so many color variations?

It turns out that in addition to green chlorophyll, the leaves also contain orange-yellow carotene and yellow lutein. Typically, chlorophyll is the most abundant, other pigments are less, and the other colors are completely masked by the green color. As a result, the leaves appear green.

However, chlorophyll also has a weakness, that is, it is easy to destroy. In autumn, chlorophyll can't stand the effects of factors such as the temperature dropping day by day. Chlorophyll breaks down and disappears quickly in the leaves, while carotene and lutein are more stable, and they finally "see the light of day" in the fall.

This is the reason why the leaves turn yellow in autumn.

The leaves of cochines and maple trees have another unique ability: when the temperature drops and the chlorophyll decomposes and disappears, the sugar in the leaves is converted into a large number of red anthocyanins, so the leaves turn red. In late autumn, the red leaves all over the mountains are very beautiful.

Ancient poems even praised it as "frost leaves red in February".

As for plants such as purple duck plant, the anthocyanins in the leaves are always dominant, completely covering the color of other pigments, so they are purple-red all year round.

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 Why do trees lose their leaves in autumn?

Because autumn means the advent of winter, trees need to be dormant for self-protection, and overwintering dormant trees themselves also need nutrients, in order to regulate their own homeostasis, many trees need to lose leaves, reduce the loss of water's nutrients, and save energy until the conditions are suitable before germinating from scratch.

Because the leaves are aging in autumn, and the cold air blows, the leaves turn yellow and fall.

In autumn and winter, the leaves lack sunlight, and the amount of chlorophyll synthesis in the leaves is not as good as the amount of decomposition, which reveals the color of other pigments in the plant, so it shows yellow, red and other colors.

As the leaves gradually age, the chlorophyll in the leaves is decomposed and reduced, the chlorophyll is decomposed, 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, making it invisible to the user.

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.

Precautions for the care of plant leaves.

When germinating new leaves, control light and water to slow down the growth rate of new leaves as much as possible, so that the stem germinates more leaves, and the more closely the new leaves are arranged, the more their growth will bend downward, which helps to produce natural and beautiful adult leaves.

Watering appropriately to prevent water accumulation in the pot, otherwise the new branches will grow and the old leaves will wither, resulting in a significant imbalance in the number and shape of the new and old leaves. Therefore, the amount of water should be controlled, and the foliage plants with strong drought resistance should wait until 2 3 cm under the potting soil to dry out and then replenish the appropriate amount of water, the watering time is 10 o'clock in the morning, and then resume normal management after the new leaves are set.

The above content refers to Encyclopedia-Leaves.

Hello, the reason why the leaves turn yellow in autumn is because in autumn, the roots and stems of the trees no longer deliver nutrients and water to the leaves, and will decompose the chlorophyll in the leaves, and transport nutrients to the roots of the tree as nutrients for the winter. The leaves also contain lutein, lutein, etc., and the leaves have no chlorophyll and nutrients, so only chlorophyll and lutein are left, so the leaves will show a yellow or red state.

It turns out that plants do not excrete the waste products of their own metabolism like animals. They usually accumulate sediment in the leaves during the metabolic process, and at the same time return nutrients to the trunk or roots of the tree for future use, so the process of defoliation is the process of processing metabolites.

The newborn leaves are usually green, which is due to the chlorophyll. The new leaves mainly contain chlorophyll (green) and carotene (yellow), and the chlorophyll content is 8 times that of other pigments. In spring and summer, plants produce a large amount of chlorophyll for photosynthesis in order to grow, so the leaves are mostly green at this time.

The yellowing of the leaves is due to the decomposition of the various pigments in the leaves during the fall season. The nutrients from the leaves are redistributed to the trunk and roots for winter.