Why are some plants hardy? Why are evergreens particularly hardy?

When the severe cold comes, many animals thicken their "skin robes" and live in seclusion, or simply burrow into the warm depths of the earth to "sleep", but many plants are still energetic and immovable, stretching out their green leaves as if nothing happened, as if they did not "feel" the coming of the severe cold.

Are plants really "insensitive" and completely indifferent to the cold? No! Excessive cold can also "freeze to death" plants.

For example, when the water in plant cells forms ice crystals, many of the plant's physiological activities cannot be carried out. What's worse is that the ice crystals will burst the cell wall, causing the plant to suffer a "fatal disaster". Aren't frosted greens and radishes sweet and soft?

Sweet because they convert a part of the starch into sugar, and soft because the cell tissue has been destroyed.

However, it is not easy to freeze the water in the plant. For example, delicate cabbage will not freeze until -15, radishes and so on can withstand -20 without freezing, and many evergreen trees will not freeze even at -45, what is the secret?

If thick trees can be explained by the fact that cold air is not easy to invade, then why are tiny branches and leaves, delicate vegetables not easy to freeze? It is also true that when cabbage, radish, sweet potatoes, etc., are cold, they will convert some of the stored starch into sugar, and when sugar is dissolved in the water in the plant, the water is not easy to freeze. But if we do the math, we know that this is not the main reason why plants are hardy.

It is important to know that the freezing temperature of the water will only drop after 180 grams of glucose is dissolved in 1 kilogram of water, and even if these sugar solutions are concentrated like syrup, they can only reduce the freezing temperature by 7 8. It can be seen that there must be another reason for this.

It turns out that there are two kinds of water in the body of plants, one is ordinary water, and the other is called "bound water". The so-called "bound water", according to its chemical composition, is no different from ordinary water, but the molecular arrangement of ordinary water is relatively messy and can flow everywhere, while the molecules of bound water are arranged around the plant tissue in a very neat "formation", and the plant tissue is intimately "combined" together, and refuses to be easily separated, so it is called bound water. Interestingly, chemists have found that the "temper" of bound water is very different from that of ordinary water, such as ordinary water boiling at 100 and freezing at 0.

In winter, the amount of ordinary water in the plant decreases, and the proportion of bound water increases. Since the bound water freezes at a much lower temperature than 0, the plants are of course more hardy.

The mystery of plant hardinessWhy do these plants have such amazing cold resistance? It turns out that in the howling cold wind, many plants have their own ability to resist cold: the willow trees in the cold land have changed their slim appearance and become close to the ground to spread and grow to resist the attack of the cold wind; Forget-me-nots grass, which grows on the sandy shores of the Arctic Ocean, grows into a compact mattress to retain the precious heat.

However, further research has shown that frost-tolerant plants are dormant, and they mainly use the magic method of "sleeping" to deal with the winter cold. In spring and summer, plants grow vigorously and consume more nutrients than they accumulate, so their frost resistance is weaker at this time. The pear trees in the north can survive the winter at minus 20 to 30 degrees Celsius, but the spring cannot resist the attack of the slight cold.

As the days get shorter and the temperature drops, more abscisic acid (hypnocin) is synthesized in the leaves of the tree, and when this plant hormone is delivered to the tips and side buds of the plant's branches, the metabolism of these parts is inhibited, and it goes into a dormant state, no longer budding. At this point, the consumption for respiration and growth is reduced, and nutrients are stored. Once the low temperature comes in winter, the protein and starch in the plant are hydrolyzed into soluble amino acids and sugars under the action of enzymes, which increases the concentration of cell fluid, makes the cells not easy to freeze, and is conducive to increasing cold resistance.

This is why the greens, turnips and sweet potatoes taste sweet after frosting. In addition, due to the gradual decrease in temperature, the life activities of plant roots are weakened and water absorption is slower, while the transpiration of stems and leaves is still stronger, which reduces the water content in the plant body, correspondingly increases the concentration of cell fluid, and reduces the possibility of freezing.

Plum blossoms, pines, and bamboos are all cold-tolerant plants, and they have been growing in the growth cycle, and the reason why they are cold-tolerant is related to their own structure, growth cycle, and growth characteristics.

It is the result of plant adaptation and evolution, and the survival of the fittest by natural selection.

Hard. There are hardy leaves that are dense and feel like all tropical plants, and it is difficult to survive the winter.

Reasons why evergreens are particularly hardy:

1. Cold resistance of plants.

2. Adaptive physiological and biochemical changes of plants at low temperatures. Before the severe winter cold comes, with the shortening of sunshine and the decrease of temperature, a series of physiological and biochemical changes to adapt to low temperature will occur in the plant, thereby improving the cold resistance of the plant This adaptation process of gradually improving the cold resistance is called cold resistance exercise or low temperature training.

3. After proper cold-resistant exercise, plants gradually complete a series of metabolic changes to adapt to low temperatures and obtain strong cold-resistantness.

Because evergreen plants will form some special substances to protect against the cold in the process of evolution in order to resist the cold. For example, if the oak infiltrates pine and cypress are sold, there will be a layer of waxy leakage ridge on their leaves to prevent water loss, frostbite and so on.

Hello! The reason why evergreen plants are particularly resistant to cold and combustion: the cold resistance and adaptability of the plant.

Before the severe cold of winter, with the shortening of sunshine and the decrease of temperature, a series of physiological and biochemical changes to adapt to low temperature will occur in the plant, thereby improving the cold resistance of the plant.

This process of adaptation to gradually improve cold tolerance is called cold resistance training or low-temperature training. After the appropriate cold-resistant exercise process, the plant gradually completed a series of metabolic changes to adapt to low temperature, and obtained strong cold resistance.