It has long been proven that plants are living beings. They, like animals, eat, breathe, reproduce. Thousands of biochemical reactions take place in them, useful nutrients are formed, and decay products are removed from them as a result of metabolism. That is, all the processes that characterize the manifestation of life are also present in plants that make our planet unimaginably beautiful, clean and diverse.
Biological rhythms
How do plants breathe? Why do their leaves turn yellow? What do they eat? How do they grow? Many questions arise for those who see these amazing creatures, so diverse, beautiful, bright and colorful.
All plants are characterized by certain biological rhythms, just like other living organisms. These include:
- opening and closing of buds under the influence of the length of daylight hours and the chemical composition of the environment;
- intensive growth of shoot mass;
- shrinkage and opening of stomata on leaves;
- strengthening or weakening of respiration, photosynthesis;
- falling leaves and others.
Thus, the answer to the question of whetherwhy the leaves of plants turn yellow lies in the mechanisms of biological rhythms. It is these processes that allow them to adapt to environmental conditions, survive in them, carry out their life activities as efficiently as possible, grow and develop, respond to chemical and physical influences from nature, humans, animals, and so on.
Why do leaves turn yellow on trees, for example? This is also one of the manifestations of the biological rhythm aimed at maintaining the viability of the individual in conditions of low temperatures and reducing the amount of sunlight and moisture. The color of the leaf blade is determined by special substances in its composition.
Pigments of plants contained in leaves
Why do leaves turn yellow and fall off? Yes, because there is a restructuring of chemical reactions inside the plant organism. Each representative of the flora contains in its composition a number of pigments - substances that determine the color of organs (leaves, corollas of flowers, stems, and so on). In total, four main groups of such compounds can be distinguished:
- Chlorophyll. A pigment containing in its structure a magnesium cation and several porphyrin rings. It gives the plants and its parts a rich green color, takes an active part in the processes of photosynthesis. It is under its influence that plants in the light convert solar energy into the energy of chemical bonds. This forms a reserve nutrient - starch. Under favorable conditions in evergreens, chlorophyll is in the vast majority,therefore other pigments do not appear.
- Xanthophyll. This compound is contained in the composition of all individuals, but does not appear under favorable conditions, since it is suppressed by chlorophyll. In many algae, in the corollas of flowers, in the stems, this pigment manifests itself, forming a yellow color.
- Carotenoid. The orange color of the leaves, parts of the shoot, corollas of flowers is determined precisely by this compound. It is often suppressed by chlorophyll and manifests itself only at the onset of low temperatures, adverse environmental conditions.
- Anthocyanins are pigments that produce beautiful red hues in parts of plants. Just like the previous two, it appears in its natural form only in corollas of flowers or algae (red algae). Changing conditions and destruction of the porphyrin rings of chlorophyll causes a stronger effect of anthocyanins.
All of the listed pigments primarily give an external reaction to a change in the state of individuals. Why do plants turn yellow leaves, which causes such manifestations, we will consider in more detail.
Causes of leaf fall in trees
The phenomenon of leaf fall is one of the most beautiful in nature. That is why autumn is the favorite season of many poets. After all, the surrounding beauty simply cannot but become a source of inspiration for creative people. Multicolor around, yellow, green, red, orange and even brown-violet hues just dizzy, and the smell of fallen leaves pleasantly pleases the sense of smell.
What caused such changes and is it always normal? Consider the causes of leaf fall in trees. They can be divided into two groups: natural and forced. Each includes a number of points and explanations for them.
Natural
These reasons include seasonal changes in weather conditions, as well as changes in the length of daylight hours. All summer the green giants prepare for these rhythmic changes. Accumulate nutrients and store them in the stems and trunk, actively carry out the processes of photosynthesis and respiration, consume the maximum possible amount of moisture.
With the onset of cold weather, shortened daylight hours, transformations begin inside the leaf plates.
- The chlorophyll pigment begins to act less and less, the color turns pale. This allows other pigments to show up. As a result, the leaves turn yellow, redden and so on. What will be the color of the falling leaves depends on the genetic characteristics of the tree species. Moreover, an interesting fact is that the brighter the sun in the autumn, the faster the chlorophyll is destroyed, and the leaves turn yellow. During prolonged rains, the trees delight with greenery longer.
- During the summer period, a lot of metabolic products, s alts, minerals accumulate in the plates of the sheets. This makes the leaf heavy, and it gradually begins to flake off the petiole from the stem.
- At the base of the petiole, between it and the trunk, the processes of formation of a special tissue layer begin, gradually rejecting the leaf.
- Under the influence of mechanical factors (rain, wind, thunderstorm, etc.)further), of their own gravity, all the leaves begin to fall one by one.
Forced
There is another answer to the question of why the leaves turn yellow. This happens for forced reasons, such as:
- sudden fluctuations in temperature;
- lack of mineral nutrition;
- lack of sufficient or excess moisture;
- hard exposure to direct sunlight;
- life activity of parasites.
The above reasons lead to a decrease in the viability of trees. That's why the leaves turn yellow on them.
Indoor plants
Many flower growers also have the question: "Why do flowers turn yellow leaves?" Often you can see drooping parts of plants, their unhe althy, faded appearance, and this applies not only to flowering species, but also to ferns, rare flowering plants and succulents. What is the reason, let's try to figure it out.
Causes of yellowing
Why does a flower turn yellow leaves?
- Overwatering or underwatering.
- Too much or too little sun.
- Lack of potassium, magnesium and other minerals.
- Infection of parts of shoots or roots by pests.
- Excess dust, fungus and bacteria.
These are the most common causes of yellowing leaves in plants.
Methods to eliminate the phenomenon
Before taking action, you need to determine the specific reason whyleaves turn yellow. To do this, you should study the materials for the care of each specific plant, because any of them requires an individual approach.
Next, it is necessary to limit the limiting factor of development: if it is insufficient watering - increase it, if it is excessive - reduce it, protect it from the sun or add it, feed it with mineral fertilizers, but do not overdo it. The main thing to remember is that flowers love cleanliness. Therefore, they must be protected from dust, debris and pollution.
