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The problem of improper watering is one of the most common misfortunes faced by flower growers, especially beginners. The bad news is that different plants have different sensitivity to over-or under-watering. The harm caused to the plant from systematic waterlogging is primarily associated with a violation of the oxygen regime in the root system. Oxygen access to plant roots is hampered, causing hypoxia, or completely stopped, causing anoxia.
As we remember from the course of botany, plant roots absorb oxygen necessary for plant respiration directly from the soil. And this is possible only if the soil is loose enough, structured, consisting of lumps, the space between which is filled with oxygen. According to scientists, for the growth and development of various plants, a certain minimum of oxygen in the soil is required - above 10%, and the lower permissible limit is 5%.
Respiration of the roots is accompanied by the absorption of oxygen and the release of CO2. The main material for plant respiration is glucose. The glucose molecule is split into two triose molecules, which are further oxidized to pyruvic acid, and then completely oxidized to CO2 and H2O in the tricarboxylic acid cycle - this is aerobic respiration.
The Brazilian swamps are no different from the Russians …
Plaunas are true hygrophytes, sometimes grown in pots as ornamental plants.
If the plant is watered too often, when the earth does not have time to dry out, then the space between the grains of earth is filled with water. Anaerobic processes develop in the soil: pyruvic acid is converted into alcohol and lactic acid (fermentation). Carbon dioxide, methane, organic acids and other compounds accumulate, most of which poison the root system of plants, these are the so-called bog toxins. In the cells of the roots, the transport of electrons and oxidative phosphorylation (the stage of cellular respiration, leading to the production of energy in the form of ATP) is stopped. The reactions of the tricarboxylic acid cycle (Krebs cycle) do not occur - after all, this is an aerobic process, and the result is free hydrogen, which participates in tissue respiration and ATP synthesis. ATP production decreasesand with such a deficit of energy, metabolic processes slow down. There is a deterioration in the assimilation of ions from the soil, a gradual death of roots, and in the aboveground parts of the plants a lack of nutrients, primarily chlorosis, is observed, and growth retardation is observed.
This issue of soil moisture has been studied especially carefully by agronomists and foresters. For example, it is known that some species of willow Salix atrocinerea and Salix aurita can stay in water for a long time, completely devoid of dissolved oxygen, but the growth of roots is halved. It is assumed that willows can conduct air trapped in leaves to the roots in order to carry out root respiration. But willows are rather an exception, there are only a few plants that can withstand prolonged flooding.
More precisely, many plants are able to withstand a short-term bay, because in nature there are often heavy rains, rivers overflow, flooding the banks. But there is one very important point - these waters are renewing (riverine groundwater is constantly in motion) and they are saturated with oxygen! Stagnant water is dangerous - there is almost no oxygen in them. Please note: single plant species can grow in swamps, only those who are able to tolerate root anaerobiosis: fluffy birch, some types of willow, alder buckthorn.
Calla lilies, aroid family, grow at the edge of the reservoir (Golden Gate Park, San Francisco)
Many carnivorous plants are inhabitants of swamps.
The need for plants in water
Among the indoor plants that are collected on our windowsills from different parts of the world, there are completely different families, genus and species, their attitude to soil moisture and soil structure is different. Plants that are capable of synthesizing ATP during waterlogging (prolonged drying of the substrate) due to the anaerobic metabolism of a unit, and even the most adapted ones usually withstand no more than 3-5 days of strong moisture. But the trouble is that in addition to the root system of plants, useful soil microorganisms need oxygen, which is sorely lacking in waterlogged soil. Under anaerobic conditions, they die, but pathogenic microflora begins to multiply intensively - pathogens of many plant diseases, root and stem rot appear, the plant no longer dies from anoxia and poisonous gases in the soil,and from bacterial and fungal rot.
In some cases, when flower growers realize that they have watered the plant unnecessarily, and it is depressed due to irrigation errors, they manage to correct the situation - they loosen the soil or transplant flowers, but the process has already started and wet brown spots of necrotic tissues appear on the plants. In such cases, the usual measures to resuscitate flooded plants are not enough; treatment with fungicides that can kill pathogenic microflora is required.
But back to the relationship of various plants to the aquatic environment and survival in high humidity conditions. To do this, we turn to the well-known classification of plants into ecological groups in relation to various environmental factors. In addition to their habitat, different groups of plants have or do not have aerenchyme - airborne tissue, which has very large intercellular spaces filled with air. Moreover, the intercellular spaces and air cavities in the roots, stems and leaf petioles communicate with each other, and not only serve as a reservoir for oxygen, but also help tissues that find themselves in conditions of lack of oxygen not to suffer from hypoxia.
- Hydatophytes are aquatic plants that are completely submerged in water and absorb nutrients over the entire available surface (aquarium plants). These plants die in a matter of minutes if they are taken out of the water - they have no stomata, no cuticles, they are not adapted for life outside the water. But they have a very well developed aerenchyma.
- Hydrophytes - plants, partially submerged in water, live along the banks of reservoirs, in swamps (arrowhead, lotus). But this group of plants has better developed conductive and mechanical tissues than hydatophytes. Aerenchyma is also well expressed. The epidermis has stomata, and the intensity of transpiration (evaporation of water by the plant) is very high.
- Hygrophytes are plants from places with high air humidity. Among them, there are two categories: shadow and light. Shadow hygrophytes are plants of the lower tiers of damp forests (circe). Light hygrophytes grow in open places, but also on constantly moist soils and in humid air - the most famous representatives are rice, sundew, shieldwort, and garden neptunia.
- Hygrophytes are moisture-loving plants, they have low drought resistance. They have rather large thin leaves, and a few stomata on both sides of the leaf, and they are always open. The transpiration process is poorly regulated. Overdrying for such plants is destructive. The peculiarity of plants is dense, but weakly branched roots with a very limited number of sucking roots. In some hygrophytes aerenchyma is quite developed, in others it develops vigorously in conditions of high soil moisture.
Bromeliads grow on trees, their roots breathe air freely. From constant dampness during the period of prolonged rains, spots are formed on the leaves, for plants in nature this is a natural look.
Ficus pumila is a moisture-loving plant that absolutely does not tolerate drying out of the earth, in contrast to ficus benjamin and elastica, which must be dried. But if the earth is dense, clayey, it will die from waterlogging.
Mesophytes are plants growing in habitats with sufficient, but non-excessive moisture, they are able to tolerate a slight drying out of the soil and dry air for a short time. The stomata on the leaves are located on the underside and have a good mechanism for regulating stomatal transpiration. These plants are the most convenient for flower growers, they are quite plastic, they are the easiest to adapt to the moisture of the soil and air. They are characterized by a well-developed root system with a dense network of sucking roots. In a normal state, mesophytic plants do not have aerenchyma. But when exposed to conditions of high humidity, under conditions of hypoxia, the formation of ethylene in the roots of mesophytes is sharply increased, which triggers such a phenomenon as cell apoptosis
Apoptosis is programmed cell death. In fact, in a plant, the cells of the primary cortex of the root and stem die, but they do not disappear without a trace, but form the basis for the formation of aerenchyma, which stores oxygen. Therefore, a short, abundant waterlogging of the soil causes damage to the roots and a delay in plant growth, but if the process of drying out the soil is delayed, the mesophyte plant is not able to turn into a hygrophyte and build up a full-fledged "ventilation" system, it simply dies. By the way, for mesophytic plants, an excess of water in the soil can be as destructive as its lack.
Xerophytes are plants growing in places with insufficient moisture (deserts, steppes, sand dunes and rigid-leaved evergreen forests), for us they are cacti and succulents. They have devices that allow you to extract water when it is scarce, limit the evaporation of water, or store it during a drought. These plants lack aerenchem and are unable to develop it. In conditions of waterlogging, these plants die very quickly
The vast majority of common houseplants are mesophytes. The division according to this classification is somewhat arbitrary. Many plants behave not as one hundred percent mesophytes, but as mesohygrophytes (they tend to regulate their water exchange as hygrophytes) or as mesoxerophytes (they tend to more drought-resistant forms) - such plasticity allows plants to survive in a variety of unfavorable conditions.
Among indoor plants, hygrophytes and mesohygrophytes are natives of tropical forests. Hygrophytes, and there are few of them, are tropical herbs, for example, selaginella, saltyrolia, lyre (some are grown as ornamental), fittonias, balsams, and some types of begonias. Those that grow on the forest floor and in the period of prolonged rains are "knee-deep" in water. Mesohygrophytes: tradescantia (and other commeline), ferns, philodendrons, some types of palms. But not all plants living in the lower tier of the rain forest are hygrophytes or mesohygrophytes, a lot of epiphytes (bromeliads and orchids) grow there, their roots never end up in puddles of water, because they cling to tree trunks or grow on the forks of fallen branches, they catch water either with funnels of leaves (bromeliads),or spreading wide to the sides fleshy roots covered with root hairs (orchids).
Some orchids (Losnyak Lösel) grow on marshy soil.
Others (Airangis) lead an exclusively epiphytic lifestyle.
It must be said that the need for substrate moisture is very variable within the same family. Take, for example, orchids - a vast variety of species, among which most are mesophytes, but there are also hygrophytes, for example, Losnyak Losel, in Russia it is found in the forest and forest-steppe zones of the European part and in Western Siberia. It lives on sphagnum bogs, peat floats, marshy meadows, swampy shores of lakes, it grows among reeds like marsh grass. Or, for example, the ficus family. Their attitude to water is also different: the ficuses of benjamin and rubbery are pronounced mesophytes, they do not tolerate waterlogging, they tolerate overdrying well. But the ficus pumila is a hygrophyte that dies as soon as the soil dries up completely and grows well with regular abundant watering.
Outwardly, moisture-loving plants that do not tolerate overdrying can be distinguished only in general terms: the main difference is thin, not leathery leaves, for example, like hibiscus, fittonia. When the substrate dries up, their leaves quickly lose turgor and wither deplorably. But we cannot say that they are resistant to overflow, let's say, they need a more moisture-consuming substrate. But, as I already mentioned at the beginning of the article, they are not able to put up with too wet soil, since their roots will inevitably be in a state of hypoxia. Those. we can only talk about an increased need for water, but not about immunity to bays.
What is abundant watering
We turn to what is considered abundant watering, moderate and what will be considered overflow. As you can imagine, the correct amount of water for irrigation cannot be measured either with tablespoons or liters, just as the frequency of watering cannot be measured in days. The only indicator that dictates to us the rate and volume of irrigation is the state of the substrate.
And he, in turn, develops and depends on many factors, here are the main ones:
- looseness and structuredness of the substrate,
- the degree of filling it with roots,
- soil moisture,
- the presence of drainage holes at the bottom of the pot,
- ambient temperature and humidity.
The looser and lighter the substrate, the faster it dries. Say, leafy or peaty soil dries out twice (approximately!) Faster than clay or garden soil (with a large dose of sand, clay and humus). The soil in the pot dries out much faster if almost all the space is filled with roots, and much longer if the pot is large, there is a lot of free soil. The drainage holes at the bottom of the pot also play a role - excess water drains into them. But if the soil is heavy, clayey, then no drainage holes will speed up its drying! The higher the temperature in the room and the lower the humidity, the faster the potted soil dries out.
The two dracaenas (left and center) look exactly the same, as if the same plant, but no, the picture of the bay is just too typical. And on the right is a yucca, indistinguishable from dracaena - according to the hostess: "the top of the head is soft, the earth is moist, but there was no bay!" Unfortunately, it only seems that there were no bays, in fact, systematic abundant watering leads to a similar state.
Thus, it turns out that two identical plants planted, say, by Masha and Vanya in pots of the same diameter, need a different watering regime, because, for example, Masha bought peat soil, and Vanya dug it up in his garden. Masha's room temperature is + 22 degrees and humidity is 50%, and Vanya's is + 26 degrees with humidity of 20%. And to check if it's time to water, you can only feel the ground. Not slightly picking the top 2 cm with your finger, but plunging your finger into the ground. And depending on how wet the soil inside the pot is, water or wait.
Abundant watering is considered when the soil has time to dry out in the upper third of the pot for the next watering. It is to dry completely - it is dry at the top, slightly damp closer to the middle of the pot. Not wet, not wet, but not dry either. Of course, it is difficult to explain these feelings, otherwise everything would have been clear to everyone, and so many bays are unlikely to have happened.
Moderate watering - when the soil has time to dry out about half of the pot or in the top 2/3 of the pot. Of course, your finger may not be long enough to touch the soil so deeply, and you shouldn't. If the pot is deep, large, then I do this: in the morning I check (touch) the ground at the top of the pot. If it's still a bit damp, don't water it, wait until evening. If it is dry in the evening, I water it in the morning, if not yet, I check it again in the morning. Those. I water it not when it dries out in the upper part of the pot, but after waiting another 6-8 hours.
Philodendrons are moisture-loving plants, but they also turn yellow from irrigation, and then the tips of the leaves dry out.
Darkening of the base of the leaves in echmea is caused by waterlogging.
Limited watering is when watering is carried out only after the soil is completely dry in the pot, and then not immediately, but after 2-3 days. Those. for a while, the plant should stand with dry roots. In the upper part of the pot, the soil may already be dried into dust, but in the lower part of the pot it is somewhat wetter. If the plant stands longer without watering, then all the earth in the pot dries up to dust. The pot seems almost weightless. Why do I say "to dust", because just touch such a dry earth - it crumbles like dust, and dust particles fly into the air. If all the soil in the pot dries up in such a state, then only xerophytes (cacti and succulents) can withstand this. In other plants, the roots dry out and die off.
When keeping plants in rooms, the most common watering recommendation is: abundant in the spring in the summer, moderate in the winter. This applies only to mesophytes, the most common flowers in the house: ficuses, crotons, ivy, dieffenbachia, aglaonem, palms, cissus, nephrolepis, shefflers, hoyas, etc. Those. during the growing season (growth), the next watering after the top layer of the earth dries out, about 1/3 of the height of the pot. In winter, watering is more moderate for two reasons: in winter, the temperature is often several degrees lower than in summer, and in winter, when there is a lack of light, the plants do not grow, or grow very slowly, i.e. energy costs are much lower.
Danger of waterlogging
Oddly enough, the watering regime is more stable in winter than at any other time. This is due to the fact that during the heating season the temperature in the apartment usually fluctuates by no more than 2-3 degrees. Of course, if you have old wooden frames that need to be plugged, glued or a private house where heating can be turned down or added, then the temperature drops are quite significant. But most people now have plastic windows, reliable front doors with insulation, and the temperature in the apartment changes little depending on the weather. I specially measured the temperature in the apartment from November to February several times a week, my temperature is stable at 26-27 degrees, and only when there is a strong wind through the windows, the wind found its way in the ceiling, and the temperature dropped to 24 degrees. Alas, the air humidity is no more than 20%.
But in those periods when the heating is turned off, the microclimate in the apartment changes radically - it depends on the weather much more strongly. First, the air humidity increases - up to 50% on average, and on rainy days in autumn and summer up to 70%. Second, the difference between nighttime and daytime temperatures increases. It may be 26 during the day, and 22 at night. We ventilate much more often during the warm season.
Carmona died from waterlogging, bonsai is very easy to fill. The leaves appear dry, but there is a characteristic darkening. The leaves do not crumble, and hang on the branches for a long time.
Signs of a bay in citrus - the edges of the leaves darken, gradually brown and dry. The stains can be wet or dry.
The most dangerous time for flowers in terms of watering is in late summer and autumn, before the heating season, i.e. the time when the difference in daily temperatures is greatest. Here drying the soil in a pot directly depends on the weather. And the weather is unpredictable. It's hot for one week, we water abundantly, and then the rains are charging. It seems to be warm, but at a humidity of 70-80%, the soil in pots dries for a very long time. At this time, the only way not to flood is to check the ground before watering by touching it with your finger, and not counting the days by eye.
Also, the danger is the opening and closing (so to speak) of the growing season. Simply put, the beginning of growth is a rapid start of young growth and a sharp inhibition of growth with a decrease in daylight hours in autumn. In the first case, the plants vigorously increase the mass of leaves - the evaporating surface increases. Some gardeners, in joy, try to water the plants more, sometimes they overdo it. In autumn, the growth of plants is also suddenly inhibited, plus it gets colder, it would be necessary to water less, but by inertia we can continue to water in the same mode.
Thus, I would like to advise flower growers to think, remember and mark such dangerous moments for themselves. You know your house better, whether it is warm or cold, blowing through the windows or not, loose earth in pots or not, whether there is a lot of drainage at the bottom of the pot or not at all, etc. moments. Notice changes in the weather - anything related to cold snaps and rains should alert you.
Another dangerous point in watering is associated with overdrying. A very common situation when the plant turns out to be very dry and they immediately try to give it plenty of water. And this is wrong. After a strong overdrying of the earth, part of the roots dries up and dies off. Those. the suction surface of the roots decreases, sometimes very strongly, but here we are with abundant watering, which there is nothing to suck in - as a result, the remaining roots rot. This is the same as trying to feed a starving patient at once a lot and abundantly, and he gets indigestion.
Reanimation of flooded plants
Watering indoor plants