Autumn is characterized by brilliantly colored foliage, which slowly falls from trees and shrubs to the ground. This happens all over the world, have you ever wondered why the leaves fall before winter and why they are so wonderful colors?
Leaves of trees and the reason for their fall in the fall
Why do leaves fall off?
Add to your information: The main compound in tree wood and plants is Lignin
The relationship of photosynthesis to defoliation
When autumn arrives, we all know that the day is greatly shortened, and thus the process of photosynthesis decreases, while the leaves continue to need the same nutrients found in the sap, those substances that are largely produced from photosynthesis.
For leaves that enter the aging stage, the photosynthesis process becomes more expensive for them, and with the decrease in the photosynthesis process in light of the need for these leaves to mineral substances, this will lead to leaf fall.
This process is carried out by the phytochromes, which are very important proteins in the leaves and have the property of photoreception, this property that makes the leaves able to cross the nights quickly.
The cells in the leaves of plants secrete two hormones, Abscissic Acid and Ethylene, and then these two hormones destroy the pigments, which enable the leaves to absorb light rays in the process of photosynthesis.
Falling leaves is a benefit
It has become clear to botanists, that falling leaves in the fall is a very important form of self-protection. In cold climates, plants are evergreen and fresh. At that time, they contain wax and thick resin to protect their leaves from freezing and damage. Types of trees whose leaves are consistent are thin leaf susceptible to cold temperatures. Since water expands greatly upon freezing, the thinner leaves will be torn in winter, making them useless in the process of representation, and without the process of dropping leaves that tree will be full of many unproductive branches and appendages, if this is not reason enough. To indicate that leaf fall is a benefit, so allow me to inform you that the surface of these extra leaves causes a threat to plants and trees and the quality of their products.
In winter, the air and wind are much greater than at any other time. If the fragile leaves have not fallen yet, the strong winds will cause a major break in the tree or plants due to their weakness.
At the end of the summer, the leaves have weakened and eaten by insects or were infected with disease. Their fall gives a new beginning to the tree or plant in the spring. After the leaves fall, nutrients emerge from them after decomposition that help the growth of the next generation of leaves and plants.
Is the paper cut and fall off?
One of the interesting things is that the autumn leaves when they fall are not cut, but they are uprooted from the trees, not only that, but they are completely separated from the plants in a precise and organized process.
When the temperatures increase and the length of the day shortens, certain hormones are activated within the plant to start the process of separating the garage, and thus the production of chlorophyll stops and the pigment begins to decompose, often revealing the red and yellow color that has been hidden in green.
The vessels that work in nature to transfer water to the leaf are closed, and a layer of separation begins to grow between the leaf stem and the branch that carries it. These cells work to slowly cut the leaf from the plants without an open wound. After the leaves fall, the plant enters a state of dormancy, and this works to provide its energy for the explosion of buds in the spring.
After the secretion of ethylene and acid for the drop leads to the formation of a large weak area on the thin part of the leaf that connects it to the stem, this leads to the formation of deeper cracks, then the formation of what is known as a "plug" consisting of suberin, which ends the fusion of the stalk with the branch of the tree . The phenomenon of defoliation mentioned does not include trees with perennial leaves that produce chlorophyll permanently.
Suberin: It is a component of cork
Why do fallen leaves change color?
Chlorophyll, the substance that covers plants in green and outperforms other pigments such as carotene, which gives the red-orange color, and xanthophyll, which gives the yellow color.
It is known that chlorophyll is one of the most sensitive substances, and therefore it was the first to disappear, leaving a place for other pigments, and thus the paper goes through several stages. .
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