Why leaves turn yellow explanation for children. Research work on the topic: Why leaves turn yellow in autumn, but indoor plants do not

DID YOU KNOW...

WHY DO THE LEAVES TURN YELLOW? The green color of the leaves is given by a special substance - chlorophyll. Chlorophyll in a living leaf is constantly destroyed and re-formed. But this only happens in the light.

In summer the sun shines for a long time. Chlorophyll is destroyed and immediately restored. Therefore, the leaf remains green all the time.

Yellow paint is always in the leaves. Only in summer yellow unnoticed. It becomes clogged with a stronger one - green.

Autumn is coming, the nights are lengthening. Plants receive less light. Chlorophyll is destroyed and does not have time to recover. The green color in the leaf decreases, and yellow becomes noticeable - the leaf turns yellow.

The foliage falls green from the alder and lilac trees. In their leaves, in addition to other chlorophyll coloring matter No.

According to G. Graubin

WHY ARE THE LEAVES ON ONE ASPEN YELLOW, AND ON THE OTHER ARE RED?

It turns out that the substance that gives the leaves their red color is formed in those plants that have stored more sugar. Plants that failed to do this have yellow leaves.

WHY DO THE LEAVES FLIP FROM THE PLANTS?

In the winter cold, plant roots are almost unable to get water from the ground.

In autumn there is a lot of water, but it is cold. Therefore, plant roots cannot absorb it.

Leaves continuously evaporate water. So the plants have to shed them so as not to dry out in winter.

In winter, the leaves would only damage the plant. Piles of snow falling on them would break branches and twigs. In addition, harmful substances accumulate in the leaves during spring and summer. By shedding leaves, the plant is cleared of them.

How does spruce get rid of unnecessary substances?

It turns out that spruce leaves are also falling. But its leaves do not fall all at once, but little by little and constantly. New ones grow in their place. Some fall, others grow. This happens unnoticed by our eyes, and it seems to us that the spruce always has the same leaves-needles.

WHY DOESN'T THE SPRUCE LOSE LEAVES FOR THE WINTER?

The needle leaves of the spruce were small, hard, and resinous. They evaporate less water than ordinary leaves. Winter drought is not scary for spruce.

Why don't tree branches break off under the weight of snow? Because they grow obliquely downwards and spring. Snow easily slides off the branches from the slightest push, blowing wind, or from the excessive weight of wet snow. In addition, due to the waxy coating of the needles, the snow does not stick to them firmly.

WHY ARE THERE NO WOUNDS ON THE BRANCHES FROM FALLEN LEAVES?

The thing is that the leaves do not break off the branches, but fall in a strictly defined place - where the petiole is attached.

In summer, the petioles of the leaves are firmly connected to the branches. In autumn, amazing changes occur in the petioles.

In the place where the petiole is attached to the branch, a special cork layer gradually grows. It, like a partition, separates the petiole from the branch.

Now the leaf and branch are connected by several thin fibers. The weight of the leaf itself, the impact of a drop of rain, or a blow of wind is enough for the leaf to easily separate from the plant.

LEAF FALL

The earliest trees to lose their leaves are linden, birch and elm.

In linden and poplar, the leaves of the large lower branches fall off first, then the middle is exposed, and the top of the tree flies last. But in elm, hazel, and ash, leaf fall begins from the upper branches. The foliage gradually melts, revealing the dark trunk of the tree.

With the first frosts, aspen leaves fall off, then maple leaves. Only the alder and willow trees along the river banks stand thick and green until the first snow. And then the frozen, blackened, crispy leaves fall off.

According to V. Korabelnikov

The leaves on the fruit trees in the garden turn yellow at the height of summer. The gardener understands that this is certainly an abnormal phenomenon, so he tries to find ways to restore fruit trees. In today's article we will look at why the leaves on trees turn yellow in the summer and what to do to restore them.

A detailed description of yellowing or symptoms of disorders and diseases will help to determine the reason why leaves on trees turn yellow in summer:

Imbalance nutrients

The main nutrients needed for tree development are:

• Magnesium;
• Potassium;
• Phosphorus;

Magnesium may not be enough on sandy loam and sandy soils. Often its imbalance manifests itself in humid weather, with frequent watering - magnesium is quickly washed out.

Potassium The leaves are missing if, in addition to yellowness, a red rim is noticeable on the leaf plate. A lack of potassium is accompanied by a simultaneous lack of phosphorus.

Phosphorus fasting manifests itself in the appearance of a bronze tint and the leaves dry out, covering the entire surface of the leaf.

Top dressing soil mixture the missing ingredients will solve the problem.

Soil waterlogging

Close occurrence groundwater and waterlogging of the soil due to frequent watering will affect water stagnation and oxygen decomposition. The fruit trees in the garden will begin not only to turn yellow, but also to dry out and wither, it is possible that root system will rot. The problem will be solved by soil drainage, increasing the planting level, and normalizing care.

Chlorosis of fruit trees

With the development of chlorosis, the leaves of fruit trees become dull, pale, and turn yellow, as if there is no sun in the garden. Chlorosis can appear for many reasons:

• Exceeding the level of lime in the soil;
• Excessive amounts of fresh manure;
• Lack of iron salts (chlorophyll is not formed);
• Freezing of roots;
• Oxygen starvation (due to waterlogging);

If chlorosis has not managed to cover the entire crown of the tree, then it is necessary to restore the gap in care that caused chlorosis, and also feed with a solution iron sulfate (2%).

Pests and diseases of fruit trees

When aphids or mites appear, the leaves of trees in the garden not only turn yellow in the summer, but deformed shoots appear. Similar symptoms may appear with the development of fungal diseases. In order to garden trees were healthy, it is necessary to carry out prevention by spraying with solutions before flowering begins and after it ends.

Damage to the bark of garden trees in summer

In summer, garden trees begin to turn yellow if their bark or root system was previously mechanically damaged. This could happen during replanting, loosening the soil, pruning or tilling. Due to disruption of the vital functions of tree tissue, general withering occurs. Identify the problem in in this case difficult. Restore fruit tree in the garden in the summer, either fertilizing or using biological drugs for covering wounds.

Greetings, my dear researchers!

Today on discussion new project, the material on which may be useful to you for your next presentation in class “ The world" Why do leaves turn yellow in autumn? This question is often interesting for children, especially when they are walking along a park path, raking fallen leaves with their feet. But really, why?

Lesson plan:

What artist paints leaves?

In the summer, the green canopy of trees lives through a process called photosynthesis. Have you heard of this one?

I think it’s no secret even for preschoolers that leaves absorb carbon and process it with the help of solar energy into organic substances that they feed on, releasing oxygen back. This magic inside a tree leaf only happens when comfortable conditions: Warmth and sunlight are important to him. What is responsible for paints?

How do pigment neighbors live in leaves?

I see the question in my eyes: “Why, if all the pigments live together, there are no yellow and orange leaves in the summer, and green ones in the fall?

The thing is that active chlorophyll big amount in warm weather it masks other dyes, they are simply not visible. With the onset of autumn, when there is little sun and daylight, the green artist begins to be produced less and less, no longer being replenished in such quantities as in the summer. That's when other shades begin to shine through.

That’s why very often, at the very beginning of autumn, the leaves on the tree are not all colored at once, but are painted in a bizarre pattern, when green veins still remain on the yellow or orange background.

Every day closer to winter, the existing chlorophyll is destroyed, new chlorophyll is not replenished due to the lack of conditions for photosynthesis. The veins of the leaves, through which nutrients flow, are closed with a dense plug of cells, reducing the amount of sap in the plant.

Here she is: Golden autumn at it's peak, green leaves can no longer be found on the tree! Moreover, the faster the cold sets in, the sooner the tree “turns off” photosynthesis. A motley carpet appears under your feet, it’s time to curse a couple of times.

Why do trees shed leaves?

Yellow leaves are circling over the city,

With a quiet rustling they fall at our feet...

They really would have stood all winter long, delighted us with their bright beauty. But no! Leaves begin to fall at our feet, heralding the change of season. Why?

With the arrival of cold weather, the soil begins to freeze, the trees no longer have enough moisture and minerals. Life processes gradually fade out, all plants go into hibernation. How can you sleep if you need to feed every leaf? We have to save on food by getting rid of unnecessary consumers, which is why trees shed their leaves before winter.

At the place where the leaf petiole is attached, a special cork layer is formed, which blocks the flow of nutrients from the tree. The leaves are holding on weaker and weaker every day and gradually fall off. As when changing color, they do not all leave the tree at once. Some will linger longer, fluttering in the wind, some will fall among the first, lining golden paths.

Therefore, leaf fall is a condition for the continuation of the life of a tree, necessary so that with the arrival of spring we can once again enjoy young green leaves.

This is how briefly we found the answer to the question posed today. To make the report interesting, I suggest a rebus on autumn theme. Catch it! And I say goodbye to you until we meet again on projects.

“On a stream, pockmarked and motley,

Poem - “Before the Rain”

Evgenia Klimkovich.

Everything is very simple - the leaves of the trees produce juice (it is called resin or sucrose), which nourishes the tree itself and participates in the ripening of fruits. Resin is produced using the green sticky substance contained in the leaves, chlorophyll.
Leaves produce nutrients only when sunlight, taking from the air carbon dioxide, and water from the ground through the root system of the tree. At the same time, a chemical process (photosynthesis) occurs in the foliage, during which the leaves produce oxygen, which is very necessary for all living on Earth. That is why trees are called “the lungs of the planet.”

Why do leaves turn yellow in autumn?

In addition to green chlorophyll, there are other substances (pigments) in the leaves that are yellow and red, but there are very few of them. In autumn, the formation of chlorophyll stops and only these pigments remain the main “dye” of the leaves. Why do the leaves turn yellow? With the onset of cold weather it is understandable, but why do they fall?

Why do the leaves fall

By autumn they accumulate many useful and harmful substances. Useful tree takes away, and gets rid of harmful ones by dropping leaves.
Another answer to the question " why are the leaves falling?. The fact is that trees give off a lot of moisture through their leaves as a result of evaporation, and in winter the roots of the tree will not be able to replenish it. By getting rid of foliage, the tree saves itself from drying out during the cold season.

When the days become shorter, and the sun no longer generously shares its warmth with the earth, one of the most beautiful times of the year begins - autumn. She, like a mysterious sorceress, changes the world around her and fills it with rich and unusual colors. These miracles occur most noticeably with plants and shrubs. They are one of the first to respond to weather changes and the onset of autumn. They have three whole months ahead to prepare for winter and part with their main decorations - leaves. However, first, the trees will certainly delight everyone around with the play of color and the madness of colors, and the fallen leaves will carefully cover the earth with their blanket and protect its smallest inhabitants from severe frosts.

Autumn changes in trees and shrubs, the reasons for these phenomena

In autumn, one of the most important changes in the life of trees and shrubs occurs: a change in the color of foliage and leaf fall. Each of these phenomena helps them prepare for winter and survive such a harsh time of year.

For deciduous trees and shrubs, one of the main problems in winter time year is a lack of moisture, so in the fall everything useful material begin to accumulate in the roots and core, and the leaves fall off. Leaf fall helps not only to increase moisture reserves, but also to save them. The fact is that leaves evaporate liquid very strongly, which is very wasteful in winter. Coniferous trees, in turn, can afford to show off their needles even in the cold season, since the evaporation of liquid from them occurs very slowly.

Another reason for leaf fall is the high risk for branches to be broken under the pressure of a snow cap. If fluffy snow fell not only on the branches themselves, but also on their leaves, they would not be able to withstand such a heavy load.

In addition, many harmful substances accumulate in the leaves over time, which can only be gotten rid of when the leaves fall.

One of the recently uncovered mysteries is the fact that deciduous trees that are placed in a warm environment, and therefore do not need to prepare for cold weather, also shed their leaves. This suggests that leaf fall is not so much associated with the change of seasons and preparation for winter, but is an important part life cycle trees and shrubs.

Why do leaves change color in autumn?

With the onset of autumn, trees and shrubs decide to change the emerald color of their leaves to brighter and more unusual colors. At the same time, each tree has its own set of pigments - “paints”. These changes occur because the leaves contain a special substance, chlorophyll, which turns light into nutrients and gives the foliage green color. When a tree or shrub begins to store moisture and it no longer reaches the emerald leaves, and the sunny day becomes much shorter, chlorophyll begins to break down into other pigments, which give the autumn world crimson and golden tones.

The brightness of autumn colors depends on weather conditions. If the street is sunny and relatively warm weather, That autumn leaves will be bright and variegated, and if it rains often, then brown or dull yellow.

How the leaves of different trees and shrubs change color in autumn

Autumn owes its riot of colors and their unearthly beauty to the fact that the foliage of all trees different combinations colors and shades. The most common color of the leaves is purplish. Maple and aspen boast a crimson color. These trees are very beautiful in autumn.

The leaves of birch become light yellow, and those of oak, ash, linden, hornbeam and hazel become brownish-yellow.

Hazel (hazel)

The poplar quickly sheds its foliage; it just begins to turn yellow and has already fallen off.

Shrubs also delight with the variety and brightness of colors. Their foliage turns yellow, purple or red. Grape leaves(grapes - shrubs) acquire a unique dark purple color.

The leaves of barberry and cherry stand out against the general background with a crimson-red hue.

Barberry

Rowan leaves can be yellow to red in autumn.

The viburnum leaves turn red along with the berries.

Euonymus dresses in purple clothes.

The red and purple shades of foliage are determined by the pigment anthocyanin. An interesting fact is that it is completely absent from the leaves and can only be formed under the influence of cold. This means that the colder the days, the more crimson the surrounding leafy world will be.

However, there are plants that not only in autumn, but also in winter, retain their foliage and remain green. Thanks to such trees and shrubs, the winter landscape comes to life, and many animals and birds find their home in them. In the northern regions, such trees include pine, spruce and cedar. To the south the number of such plants is even greater. Among them are trees and shrubs: juniper, myrtle, thuja, barberry, cypress, boxwood, mountain laurel, abelia.

Evergreen tree - spruce

Some deciduous shrubs They also don’t part with their emerald clothes. These include cranberries and lingonberries. On Far East There is interesting plant wild rosemary, the leaves of which do not change color in the fall, but curl up into a tube in the fall and fall off.

Why do the leaves fall but there are no needles?

Leaves play an important role in the life of trees and shrubs. They help create and store nutrients and also accumulate mineral components. However, in winter, when it occurs acute shortage light, and, therefore, nutrition, leaves only increase the consumption of useful components and cause excessive evaporation of moisture.

Coniferous plants, which most often grow in areas with a rather harsh climate, are in great need of nutrition, so they do not shed their needles, which act as leaves. The needles are perfectly adapted to cold weather. The needles contain a lot of chlorophyll pigment, which converts nutrients from light. In addition, they have a small area, which significantly reduces the evaporation of much-needed moisture from their surface in winter. The needles are protected from the cold by special wax coating, and thanks to the substance they contain, they do not freeze even in severe frosts. The air that the needles capture creates a kind of insulating layer around the tree.

The only one coniferous plant The tree that leaves its needles for the winter is larch. It appeared in ancient times, when summers were very hot and winters incredibly frosty. This climate feature led to the fact that the larch began to shed its needles and there was no need to protect them from the cold.

Leaf fall, as a seasonal phenomenon, occurs in each plant at its own specific time. It depends on the type of tree, its age and climate conditions.

Poplar and oak are the first to part with their leaves, then the time comes for rowan. The apple tree is one of the last to shed its leaves, and even in winter, there may still be a few leaves left on it.

Poplar leaf fall begins at the end of September, and by mid-October it completely ends. Young trees retain their foliage longer and turn yellow later.

The oak begins to lose its leaves at the beginning of September and after a month it completely loses its crown. If frosts start earlier, leaf fall occurs much faster. Along with the oak leaves, acorns also begin to fall off.

Rowan begins its leaf fall in early October and continues to delight with its pink leaves until November 1st. It is believed that after the rowan leaves its last leaves, dank, chilly days begin.

The leaves on the apple tree begin to turn golden by September 20th. By the end of this month, leaf fall begins. Last leaves fall off the apple tree in the second half of October.

Evergreen plants and shrubs do not lose their foliage even with the onset of cold weather, as do ordinary deciduous trees. Permanent leaf cover allows them to survive any weather and maintain the maximum supply of nutrients. Of course, such trees and shrubs renew their leaves, but this process occurs gradually and almost imperceptibly.

Evergreens do not shed all their leaves at once for several reasons. Firstly, then they do not have to spend large reserves of nutrients and energy to grow young leaves in the spring, and secondly, their constant presence ensures continuous nutrition of the trunk and roots. Most often, evergreen trees and shrubs grow in areas with mild and warm climates, where the weather is warm even in winter, however, they are also found in harsh climates. climatic conditions. These plants are most common in tropical rainforests.

Evergreen plants such as cypresses, spruce trees, eucalyptus trees, some types of evergreen oaks, and rhodendron can be found over a wide area from harsh Siberia to the forests of South America.

One of the most beautiful evergreens is blue fan palm, which grows in California.

The Mediterranean oleander shrub is distinguished by its unusual appearance and height of more than 3 meters.

One more evergreen shrub is gardenia jasmine. Its homeland is China.

Autumn is one of the most beautiful and vibrant times of the year. Flashes of purple and golden leaves preparing to cover the ground with a colorful carpet, coniferous trees piercing the first snow with their thin needles and evergreens, always pleasing to the eye, make the autumn world even more delightful and unforgettable. Nature is gradually preparing for winter and does not even suspect how fascinating these preparations are to the eye.