Why do leaves turn yellow?

Yellowing of leaves is a natural phenomenon.

Generally, after the temperature drops in autumn, the leaves will turn yellow, some will turn red, and slowly dry up and fall off. This is because in spring and summer, the chlorophyll content in leaves is richer than other pigments, and leaves will appear green.

When the temperature drops in autumn, the chlorophyll color in the leaves will gradually decrease, and yellow and red pigments will be exposed, so the leaves will turn yellow or red.

When plants enter dormancy, the nutrients supplied to leaves will be less and less, so besides chlorophyll, other pigments that can reflect the color of leaves will slowly decompose. At this time, the leaves will turn yellow or red, gradually turn brown, and then dry up and fall to the ground. These are the reasons for the seasonal natural changes of leaves turning yellow.

The role of leaves

1, breathe

Plants, like animals and humans, need to breathe. The leaves of plants breathe through the stomata on the leaves. Air can enter and exit from the pores, and the inhaled gas can be diffused to all parts of the trees to meet the growth needs.

2. Photosynthesis

The function of leaves also includes photosynthesis. There are small green particles called chloroplasts in the leaves of plants. Chloroplasts can carry out photosynthesis and strive for oxygen for their own growth, which is also the difference between plants and animals.

3. Nutritional transformation

Plants can absorb carbon dioxide from the air through the pores on the leaves, or absorb water from the soil through the roots and transport it to the leaves. Carbon dioxide and water meet in chloroplasts of leaves, and sunlight converts them into nutrients such as starch, thus making trees grow more vigorously.