Sooner or later, any gardener faces a problem... slow growth indoor plants. If there is a pause in development during the resting phase or after transplantation, then this is a natural process. But any signs of dwarfism or slow growth during "normal" times are signs of problems with the plant's care or health. Improper watering, lack of nutrients and even individual trace elements can lead to serious growth problems. And the sooner you can diagnose the cause and take appropriate measures, the more likely it is that your plant will soon return to normal.

Calathea in the room. ©Verity Welstead Content:

Causes of stunting and dwarfism

Plant growth that is natural or indicates a problem is always noticeable. It is usually noticeable in spring and summer, when any normal plant produces at least a couple of leaves, or even a dozen, young shoots develop and there is a visible change in their development. But if natural causes do not require any measures, they simply correspond to the stage of development or adaptation, then all other possible causes of unexpected and atypical growth arrest require much more serious actions.

To understand why development is delayed in indoor crops, you should first analyze all possible natural causes and factors. These include:

1. acclimatization to new conditions;
2. rest period;
3. root growth and development of the substrate (many crops develop slowly in the first years of life until they have built up a sufficient mass of roots);
4. natural characteristics of the species or variety - very slow, almost imperceptible development;
5. the first month after transplantation (for shrubs and trees - up to 3 months);
6. division or other vegetative propagation methods that require very long adaptation.

Only by excluding everything from possible reasons natural in nature, you should start to worry. Besides natural factors Factors that require you to take active measures can also lead to stunted growth and dwarfism. The main problems causing growth to stop or slow down include:

1. Too small a container, complete absorption of the substrate by the roots.
2. Low nutritional value of the soil or incorrect, insufficient fertilizing and the resulting lack of nutrients (minor or serious).
3. Improper watering with complete drying of the substrate.
4. Lack of calcium in the soil.
5. Substrate salinity.
6. Contamination of the substrate with toxins and heavy metals.
7. Leaf spotting.
8. Infectious dwarfism due to infection of the substrate by nematodes.

In indoor plants different problems, manifested in slow growth, are most often associated with care. But there are also specific diseases or pests, which are not so easy to combat than to compensate for the lack of certain substances. Depending on what exactly caused the growth to stop, control methods are used. If the approach to watering or fertilizing is incorrect, which can be compensated for quickly enough, then the fight against serious lesions requires some patience and endurance.

It should always be remembered that improper care increases the likelihood of problems with the growth and development of the plant. Thus, the use of incorrectly selected fertilizers without systematic approach threatens leaf spotting and dwarfism, and overwatering or the use of random soil mixtures threatens nematodes. If you comply with all plant requirements and carefully study their characteristics, then the risk that your plant will suffer from growth retardation will be minimal.

Replacing soil for a plant with slow growth. © Felder Rushing

Lack of nutrients or need for replanting

Usually, the simplest of all symptoms of growth retardation are associated with insufficient fertilizing or depleted soil, incorrectly selected fertilizers and cramped containers. This slowdown manifests itself independently, without accompanying signs and problems: there is no damage to the leaves, no loss of decorativeness, no drying out, but normal growth simply slows down or stops. Solving these problems is very simple:

1. If the roots come out of the drainage holes, this clearly means that the entire substrate has been developed and has not been changed for a long time. The plant needs to be replanted.
2. If there is enough free soil in the containers, you need to fertilize with complex fertilizers, check your fertilizing schedule with the recommendations for of this plant, and if necessary, change the fertilizer to a more suitable mixture, carefully studying the description of the plant.

In plants, you can often observe signs of a lack of a certain macro- or micronutrient. But most of them manifest themselves in changes in leaf color, and not in stunted growth. With one exception: a lack of calcium (including) can manifest itself in dwarfism, stunted growth, and a clear discrepancy between the size of the bushes and those declared for this type of indoor plant. The symptoms of calcium deficiency can be recognized only by the problems accompanying dwarfism - the death of the upper buds on the shoots, thickening, shortening of the roots, and the appearance of mucus on them.

Problems with irrigation and water quality

If slow growth or stunted growth is due to improper watering, then identifying the problem is also quite simple. In plants that suffer from drying out of the substrate, insufficient, irregular watering and lack of moisture, in addition to stunted growth, the leaves also droop, they begin to turn yellow, their tips dry out, individual leaves wrinkle and dry out, most often from the bottom of the crown or the oldest leaves. Flowering also stops, flowers and buds fall off.

Growth retardation caused by soil drying out must be combated comprehensively. Before returning the plant to the optimal watering schedule, the soil is saturated with water using several methods:

1. Immerse the container with the roots in water for irrigation, saturating the earthen lump with water, and after air bubbles stop appearing, carefully remove it and allow all of it to drain. excess water. This option is not suitable for plants that are sensitive to waterlogging, prone to rot, or succulents with succulent stems, tubers and bulbs.
2. Slow bottom feeding of the soil with moisture, when water is poured into the pan in small portions at intervals to uniformly and gradually moisten the earthen clod from below.
3. Dividing the usual amount of water for irrigation into several waterings with an interval of 4-5 hours - a series of light but frequent waterings, which gradually restores comfortable humidity to the plant.

After any water-recharging irrigation, the substrate is allowed to dry only in the top layer - 2-3 cm - of the substrate. After this, a schedule of procedures is selected again that will maintain the soil moisture that a particular plant needs.

If you use regular water for watering plants tap water, do not settle it, or even use settled, but not soft water for those plants that are afraid of alkalization, then quite quickly the substrate will become salted and change the soil reaction, accumulating microelements that will cause problems with the development of plants. Salinity is determined by white deposits on the walls of the container and the surface of the substrate. In this case, there is only one way to help - transplantation into a fresh substrate and correction of care.

Only if you notice signs of alkalization in the initial stages, you can acidify the water for irrigation and start using soft water in time. But such measures do not save the situation and are temporary, helping to reduce damage until replanting and changing the soil.

Poor watering can lead to dwarfism and slow growth of indoor plants. © Gardenerdy

Diseases, pests and substrate poisoning

Leaf spotting is a disease that is always associated with a stop or severe retardation of growth. Of course, it is determined by completely different signs: spots of brown, gray, black colors that appear on the surface, as well as yellowing and dying of foliage, loss of decorativeness. But growth arrest is a companion, without which spotting never appears.

To save the plant, you will have to use fungicides. You can use both copper-containing preparations and systemic pesticides. But if the disease was noticed in the early stages and growth did not slow down critically, then you can try to cope with the problem with infusions of marigolds, ash, and horsetail decoction.

Infectious dwarfism in houseplants is diagnosed only after excluding any other possible causes. Most often it is associated with contamination of the soil by nematodes, but sometimes it manifests itself independently. It is impossible to fight it; the plant must be isolated, carefully cared for, and systematically treated with fungicides and insecticides. But the chance of success is low. If dwarfism is the result of the activity of nematodes, then they are combated not only by emergency transplantation, but also by special insecticides for soil pests, lowering the level of substrate moisture, and correcting care. When transplanting, the roots are additionally disinfected, as is fresh soil and containers.

Substrate contamination with heavy metals and toxins is not that uncommon. If there are no other possible reasons, and the environmental situation is far from optimal, the apartment or house is located near highways and large industrial production, plants are taken out for the summer open air where toxins can leach into the soil, or where untreated water containing high levels of heavy metals is used, stunting may well be toxic in nature. Usually, drainage from expanded clay and vermiculite helps combat the inevitable partial accumulation of toxins, but it is better to take measures to protect plants from polluted air and water, including the use of special filters, refusal to remove Fresh air and ventilation restrictions.

In the life of plants, there are always periods of intense growth, slower growth and a period of no growth. They usually coincide with changing conditions environment. Thus, increased growth in the spring slows down by summer, and completely stops by autumn. Rhythmicity is also observed in places with rhythmic alternation of periods of rain and drought. This allows us to conclude that rhythmic growth is an adaptation of plants to tolerate favorable conditions.

Everyone knows that seeds that have fallen in the fall, even under normal conditions of moisture and temperature, do not germinate, but will only germinate in the spring. In autumn they are dormant and are not capable of germination. This phenomenon or state of a plant, when there is no growth under certain environmental conditions, is called plant dormancy.

There is a distinction between rest associated with exposure to unfavorable conditions, called forced rest. It is associated with a lack of favorable temperature and humidity (delayed bud break and seed germination).

Peace associated with internal biochemical and physiological processes called organic rest. This is the inability to open buds in the summer, the inability to germinate seeds, tubers, and root crops during ontogenesis in the fall or post-harvest.

It turned out that the dormant period as a state of the plant organism is a necessary condition in the life of a plant and not associated with unfavorable environmental factors, which it is forced to overcome when moving to dormancy. This rhythmic alternation of active growth and dormancy is also observed in evergreen plants in a fairly stable tropical climate. Therefore, peace is not only an adaptation to endure unfavorable conditions external environment, but also necessary stage

It is necessary to distinguish between the dormant state of annual and perennial plants. Annual plants have a pronounced dormant state in the form of seeds. Perennial plants go dormant as their entire vegetative mass, and their dormancy is determined by the state of the buds, vegetative organs, and seeds. This necessary biological phenomenon is characterized in plants by: 1.) slowing down and stopping all growth; 2) slowing everyone down biochemical processes; 3) changes in the composition and activity of biopolymers and biologically active substances (BAS).

Peace has important in plant life. It allows the plant to adapt to seasonal changes environment. Thus, the shedding of leaves and cessation of growth in the fall ensures that plants are prepared for winter; weed seeds have adapted to germinate in plowed soil, etc. As a rule, the plant has a pronounced dormant period in the form of seeds and buds. Let us consider the state of rest of the vegetative organs. Their state of dormancy also has a mechanism similar to the state of dormancy of buds and seeds.

In perennial woody plants of temperate climates, growth slows down during a certain part of the growing season, followed by a period of dormancy. It was found that the signal for the suspension of growth, and then the fall of leaves, is a shortening of the duration of daylight hours. This process is based on the photoperiodic response of the leaves. The leaves contain the pigment phytochrome, which is sensitive to the spectral composition of light and the duration of its action. By changing, it gives a signal to change metabolism in cells. In the leaves, valuable nutrients flow into the shoot, growth inhibitors are synthesized and accumulated, a separating cork layer is formed at the base of the petiole, the leaves fall off, and leaf fall occurs.

The reverse process, lengthening the photoperiod in spring, promotes the emergence of buds from dormancy and blossoming. Why is the length of the day the signal for plants to go dormant? The length of daylight hours is the most stable factor throughout plant phylogenesis, preceding the unfavorable factors of winter. Therefore, it is not a decrease in temperature, but rather a reduction in daylight hours, even under still favorable temperature conditions, that turns on the mechanism of plant transition to dormancy. Therefore, temperature could not gain a foothold in phylogeny as a signaling factor.

29 06.18

Reasons for slow tomato growth. How to improve the harvest?

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Often, gardeners who grow tomatoes are faced with the problem of slow plant growth and a meager harvest. There may be several reasons why this happens.

Insufficiently favorable ambient temperature

Tomatoes are a heat-loving plant that does not tolerate sudden changes in temperature, especially low temperatures. For this reason, in the northern regions, tomatoes are grown exclusively in greenhouse conditions.

The most suitable temperature for growth and formation of ovaries:

• in cloudless weather from +23 to +27;
• on cloudy days from +19 to +23;
• at night from +17 to +19.

In hot weather, when the temperature exceeds 31 degrees Celsius, plant pollen becomes unable to fertilize. On cold days, when the temperature is below 14 degrees Celsius, the pollen will not be able to ripen. Under unfavorable temperature conditions, pollination does not occur, barren flowers fall off without forming ovaries. All the strength of the plant goes into growth.

Insufficient watering

It is necessary to water tomatoes, but not as abundantly and often as, for example, peppers or eggplants. It is necessary to regularly and moderately moisten the soil during the formation of ovaries so that the plant does not drop the nascent fruits. The water must be warm, as cold water may cause shock to the plant. Watering should only be done in the evening, when the sun is not so active.

Not everyone has the opportunity to water every day, and some gardeners try to water their tomatoes as abundantly as possible on their infrequent visits. With such watering, the fruits may crack. To prevent this from happening, you need to water in small volumes in several applications, for example, in the morning, during the day (but not in the sun) and in the evening.

Excessive air humidity

Tomatoes love moist soil and moderately dry air. In the open ground middle zone In Russia, the air can rarely be humid, unlike greenhouses and greenhouses. The microclimate in such structures must be regulated through regular ventilation. If the greenhouse is too hot and humid, then you can’t expect fruit, since the wet and sticky pollen will lose its flowability, gather in lumps without getting on the pistils, and the ovaries will not form.

To protect leaves from direct sunlight, most sunny side glass greenhouse is treated with a chalk solution.

If ventilation does not help, and it is still hot and humid inside the greenhouse or greenhouse, you can use ovary stimulants, which are available in an assortment at any specialized store.

Diseases and pests

Slow tomato growth may be the result of plant damage from pests or diseases.

If the temperature and humidity are optimal, but the tomato is slowing down and not producing fruit, you should carefully examine the leaves. If on back side small whitish threads appeared on the leaf, which means the plant was infected by a tomato mite. This pest drinks all the juices from the plant, ovaries appear on the tomatoes, but they fall off and the plant slowly dies. Karbofos, Fitoverm and Actellik are very effective drugs in the fight against tomato mites.

Viral diseases can also cause slow growth and lack of fruit in tomatoes. Clear signs Such diseases are: deformed leaves, regrowth of stepsons, formation of small fruits that do not fill with juice and do not grow.

To prevent the plant from getting sick, before sowing seedlings, its seeds must be soaked in a solution of potassium permanganate. If the plant does become sick, it should be dug up and destroyed so that the disease does not affect healthy plants.

Landing distance too close

When planting tomatoes, the feeding area of ​​the plants should be taken into account. Tomatoes planted too densely will grow more slowly and produce a meager harvest, as they do not have enough useful elements. The root of the plant will not be able to develop fully due to the fact that the neighboring plant will interfere with it.

Planting rates for tomato varieties:

1. Superdeterminate 7-8 plants per 1 sq.m.
2. Determinate 4-5 plants per 1 sq.m.
3. Indeterminate 1-2 plants per 1 sq.m.

If these standards are followed, the plant will produce the most big harvest. But it should be taken into account that very rare plantings can cause slow growth and lack of ovaries.

Lack or excess of fertilizers in the soil

Tomatoes require abundant nutrition at all stages of growth and fruiting. Poor soil and insufficient fertilizer can cause poor growth and lack of fruit. If you overfeed a tomato nitrogen fertilizer, which many gardeners often do, this will not affect in the best possible way on the plant: strong growth and many large and bright colors with short stamens - barren flowers.

When feeding tomatoes moderately with nitrogen, the plant required quantity microelements such as potassium, calcium, copper, zinc, iron and manganese are also absorbed.

What happens if certain microelements are lacking in the soil:

1. The leaves are ugly, thin and dull, new shoots do not grow - lack of fluoride.
2. Thin and hard stem - the plant lacks sulfur.
3. The growing points die off, which means the plant lacks calcium.
4. The leaves become “marbled” - the tomato lacks magnesium
5. The leaves become yellow color– the plant lacks iron.
6. The core of the stem is black, and cracks appear on the fruits - boron deficiency.
7. Lack of new shoots, leaves become smaller, which means the plant lacks zinc

Proper feeding will help avoid problems with the growth and fruiting of tomatoes. It is best to fertilize tomatoes for the first time two weeks after planting the seedlings in the ground. Use a solution of cow manure or chicken droppings as fertilizer. Then, every two weeks, feed nitrophoska or azofoska, as well as microelements, 2-3 times.

Tomatoes are bred incorrectly

Self-collection of seeds for several years in a row from one variety of tomatoes can lead to deterioration of varietal characteristics and susceptibility to diseases and pests. Every year the plants become weaker, grow more slowly and produce less yield. Therefore, the seed fund should be updated at least once every 3-4 years, purchasing seeds from trusted specialized stores.

Plant growth occurs due to divisions And sprains cells various organs. Growth processes are localized in meristems. Distinguish apical, intercalary and lateral meristems.

Apical , or apical, meristems are located at the ends growing shoots and tips roots all orders ( apexes, or growth points). Taper shoot apex called growth cone. Due to these meristems, the growth of axial organs is carried out in length, education organ primordium and its initial division into fabrics. By activating or suppressing the activity of the apical meristem, it is possible to influence the productivity and stability of plants. According to V.V. Polevoy (1989), the apical meristems of the shoot and root are the main coordinating (dominant) centers plants that determine its morphogenesis.

Due to intercalary (intercalary) meristem located at the base of young internodes grows monocot stem and leaves plants.

Lateral (lateral) meristems provide thickening stem and root: primary - procambium and pericycle And secondary - cambium and phellogen. The constant growth of the plant at all stages of ontogenesis allows it to satisfy the needs for energy, water and mineral nutrients.

The activity of meristems depends on the influence of external conditions, complex relationships within the plant organism (polarity, correlation, symmetry, etc.). In agriculture practice with the help watering, fertilizing, thinning and other measures can influence the number of metameric organs formed in the growth cones, on their subsequent growth, reduction and, ultimately, on plant productivity.

1. Features of plant organ growth

Stem growth. The apex of the stem measures 0.1-0.2 mm V diameter and protected by leaves. Stem elongation occurs due to the growth of internodes. The upper internodes grow first. The next internode begins intensive growth while its rate of the previous one decreases. Each individual internode is characterized by slow initial growth(cell division), subsequent rapid growth (stretching cells) and finally growth retardation at mature internode.

At growing internodes external fabrics are tested tension(stretching), and internal- compression ( compression), which, along with cell turgor pressure, provides strength stems of herbaceous plants.

IN favorable conditions the longest internodes are formed in middle part escape.

Lateral branching occurs due to growth axillary or germination subordinate clauses(adventive) kidneys.

Thickening - result of activity lateral meristem - cambium. U annuals plant cambium division ends with flowering. U woody cambium forms from autumn to spring ( in winter) is in a state peace(determines the presence tree rings).

The rate of shoot stem elongation is regulated by incoming auxins And gibberellins. It is typical for intensively growing internodes increased content of gibberellins and auxins.

Plant height determined by their genome, and to a large extent by growing conditions.

Laying of generative organs associated with photoperiodic sensitivity, vernalization and other factors. U cereals ear differentiation begins in the tillering phase.

Leaf growth. Several leaf primordia are present in the embryonic bud, but most of them are formed after germination. Rudimentary leaves appear on the shoot growth cone (from ridges or tubercles - primordia). The interval between the initiation of two leaf primordia at different plants ranges from several hours to several days and is called plastochron . For the formation of primordia and leaf tissues, cytokinin and auxin. Auxin affects the formation of vascular bundles, and gibberellin affects the elongation of the leaf blade.

U dicotyledons the leaf blade enlarges by uniform cell growth(mostly by stretching) throughout the entire area leaf. Availability several growth points defines education teeth, lobes, leaves.

U monocots the sheet is lengthened due to basal And intercalary growth.

Thickening leaf growth is carried out due to the division and elongation of palisade parenchyma cells and mesophyll cells.

Leaf growth is greatly influenced by light intensity and quality. In the dark leaf growth is inhibited. Light stimulates division but inhibits elongation cells. Leaves become larger and thinner when shaded . Intense light causes thickening leaf blades due to the formation additional layers of columnar parenchyma.

At lack of water Small leaves with a xeromorphic structure are formed, which is associated with an increase in ABA and ethylene.

At nitrogen deficiency the number of cell divisions during the period of leaf growth decreases, its surface decreases.

Low temperature slows down leaf growth in length And stimulates thickening. Wherein in frost-resistant varieties In winter wheat, the duration of the cell elongation phase is reduced to a greater extent than in non-resistant ones.

Height sheet stops when the intense starts export products of photosynthesis.

Root growth. The rate of cell division and growth in the roots is much higher than in other plant organs. Primary the root is formed in embryo seed, and its growth before exiting the seed occurs by sprains basal cells of the germinal root meristem. U dicotyledons plant embryonic root becomes main(tap), forms lateral roots. U monocots of plants, the primary root is supplemented by adventitious roots formed at the base of the shoot, and is formed fibrous root system.

During germination seeds appear embryonic a root that is very fast growing, then its growth rate are decreasing while accelerating the growth of aboveground organs. Subsequently, root growth again resumes. These features ensure rooting at the first stage and harmonious development of the heterotrophic and autotrophic parts of the plant in the subsequent period.

Apical meristem root forms root cap , which performs very important functions (protects the meristem as the root moves in the soil; secretes polysaccharide mucus and constantly exfoliates from its surface; mucus protects against pathogens and drying out; is sensory zone, perceiving the effects of gravity, light, soil pressure, chemical substances and determines the direction and speed of root growth; ABA is synthesized in it).

At the border with the cap in the meristem there are resting center cells , which includes initials cells of different tissues ( 500-1000 cells). Center at rest restores the number of meristem cells when they are naturally worn out or damaged.

In roots of all types there are 4 zones : divisions , sprains , root hairs And carrying out (branching).

At the roots corn, peas, oats, wheat etc. the growing part is short - less than 1 cm. The thinner the root, the shorter its meristem. Fundamentally short stretch zone, which is important for overcoming soil resistance (develop pressure before 8-16 atm by 1 cm). Branching and high speed of root growth ensure constant absorption of water and ions.

For stretch zones the roots are characteristic increased ID, row activation enzymes(auxin oxidase, polyphenol oxidase, cytochrome oxidase, etc.). As a result of growth by extension, the initial volume of the meristematic cell increases by 10-30 times due to the formation and enlargement of vacuoles, in which the content of osmotically active substances increases - ions, OCs, sugars, etc.

Some root epidermal cells form root hairs length 0.15-8 mm. The number of root hairs in corn reaches 420 by 1 cm 2 root surface. They function on average 2-3 days and die. In the absence of calcium in nutrient solution, aeration does not produce root hairs.

Lateral roots are laid in pericycle maternal root in the zone takeovers or higher. Its meristematic cells secrete hydrolytic enzymes that dissolve the membranes of the cells of the cortex and rhizoderm, ensuring its release to the outside.

Adventitious roots are laid down in meristematic or potentially meristematic tissues (cambium, phellogen, medullary rays) of various plant organs (old sections of the root, stems, leaves, etc.).

Root growth depends on the age and type of plant, environmental conditions. Environmental conditions favorable for photosynthesis promote root growth, and vice versa. Shading plants or mowing the above-ground parts inhibits growth and reduces root mass. Optimal temperature several for root growth lower than for escape. The relationship of roots to temperature changes during ontogenesis. So, the roots of young plants tomatoes grow better at 30°C than at 20 °C, and adults on the contrary. At drying out of the soil before wilting moisture root growth stops. With moderate irrigation, wheat roots are located in upper layers soil, and without watering they penetrate deeper. Optimal soil density for root growth of corn and other crops 1.1...1.3 g/cm 3 . IN dense soil, the length of cells and the size of the elongation zone decrease due to the formation ethylene, breathing costs increase. Critical content ABOUT 2 in soil air - about 3-5 % volume. The higher the soil temperature, the greater the need for oxygen by roots. Minimum oxygen requirements differ rice and buckwheat, A maximum - tomato, peas, corn. Roots rice have aerenchyma. In winter rye and wheat plants in crops flooded with melt water in the spring, the leaves, while in the air, can also supply the roots with oxygen for a short time. For root growth of most plants, optimal pH 5-6.

Hormonal regulation of root growth . Root growth requires low (10 -11 ...10 -10 M) auxin concentrations. An increase in the flow of auxin from the shoot inhibits root growth in length, which is also explained by the induction of ethylene synthesis. Gibberellins do not affect root growth, but cytokinins in elevated concentrations they inhibit it. ABK, formed by the root cap, slows down the growth of the root in length. The root apex inhibits the formation of lateral roots, so its removal stimulates their formation. Apparently, this is the result of the action of cytokinins, which slow down rhizogenesis, formed in the root apex.

The initiation of lateral roots begins at a distance from the root apex where a certain ratio of cytokinin and auxin (an activator of rhizogenesis) coming from the stem is ensured. Ethylene promotes the formation of lateral roots closer to the root apex, and treating plants with it causes massive formation of adventitious roots. On dense soils, the mechanical resistance of the environment leads to the synthesis of “stress” ethylene in the roots. In this case, in the zone of cell elongation, instead of elongation, thickening occurs, which facilitates the moving apart of soil particles and subsequent elongation of the root. A decrease in root growth may also be associated with the accumulation of phenolic inhibitors in cells and further lignification of cell walls.

Growth and development are integral properties of any living organism. These are integral processes. A plant organism absorbs water and nutrients, accumulates energy, and countless metabolic reactions occur in it, as a result of which it grows and develops. The processes of growth and development are closely interrelated, since usually the body both grows and develops. However, the pace of growth and development may be different; rapid growth may be accompanied by slow development or rapid development by slow growth. For example, a chrysanthemum plant grows quickly at the beginning of summer (long days), but does not bloom, and therefore develops slowly. A similar thing happens with winter plants sown in spring: they grow quickly, but do not go into reproduction. From these examples it is clear that the criteria that determine the rate of growth and development are different. The criterion for the pace of development is the transition of plants to reproduction, to reproduction. For flowering plants, this is the formation of flower buds and flowering. Growth rate criteria are usually determined by the rate of increase in mass, volume, and size of the plant. The above emphasizes the non-identity of these concepts and allows us to consider the processes of growth and development sequentially.

The plant grows both in length and thickness. Growth in length usually occurs at the tips of shoots and roots where the cells of the educational tissue are located. They form the so-called growth cones. Young cells of educational tissue are constantly dividing, their number and size increase, as a result of which the root or shoot grows in length. In cereals, the educational tissue is located at the base of the internode, and the stem grows in this place. The growth zone at the root does not exceed 1 cm, at the shoot it reaches 10 cm or more.

The growth rate of shoots and roots varies from plant to plant. The record holder for the speed of shoot growth is bamboo, whose shoot can grow up to 80 cm in a day.

The rate of root growth depends on humidity, temperature, and oxygen content in the soil. There is a greater need for oxygen in tomatoes, peas, and corn, and less in rice and buckwheat. Roots grow best in loose, moist soil.
Root growth depends on the intensity of photosynthesis. Conditions favorable for photosynthesis also have a positive effect on root growth. Mowing the above-ground parts of plants inhibits the growth of roots and leads to a decrease in their mass. A heavy fruit harvest also retards the tree's root growth, and removing the inflorescences promotes root growth.

Photo: MarkKoeber

The growth of plants in thickness occurs due to the division of cells of the educational tissue - the cambium, located between the phloem and the wood. In annual plants, cambium cells stop dividing by the time of flowering, and in trees and shrubs they stop dividing from mid-autumn until spring, when the plant enters the dormant stage. The periodicity of cambium cell division leads to the formation of annual rings in the tree trunk. The tree ring is the growth of wood per year. The number of annual rings on a stump determines the age of the cut tree, as well as the climatic conditions in which it grew. Wide growth rings indicate favorable climatic conditions for plant growth, while narrow growth rings indicate less favorable conditions.

Plant growth occurs at a certain temperature, humidity, and light. During the growth period, organic substances and the energy contained in them are intensively consumed. Organic matter enter growing organs from photosynthetic and storage tissues. Water and minerals are also necessary for growth.
However, water and nutrients alone are not enough for growth. We need special substances - hormones - internal growth factors. The plant needs them in small quantities. Increasing the dose of the hormone causes the opposite effect - growth inhibition.
The growth hormone heteroauxin is widespread in the plant world. If you cut off the top of the stem, its growth slows down and then stops. This indicates that heteroauxin is formed in the growing zones of the stem, from where it enters the elongation zone and affects the cytoplasm of cells, increases the plasticity and extensibility of their membranes.
The hormone gibberellin also stimulates plant growth. This hormone is produced by a special type of lower fungi. In small doses, it causes elongation of the stem, peduncle, and accelerated flowering of plants. Dwarf forms peas and corn after treatment with gibberellin reach normal height. Growth hormones bring seeds and buds, tubers and bulbs out of dormancy.

Many plants have special substances - inhibitors that inhibit growth. They are found in the pulp of apple, pear, tomato, honeysuckle fruits, in the shells of chestnut and wheat seeds, in sunflower germs, in onion and garlic bulbs, in the roots of carrots and radishes.
The content of inhibitors increases in autumn, due to which fruits, seeds, roots, bulbs, tubers are well stored and do not germinate in autumn and early winter. However, closer to spring, if conditions are favorable, they begin to germinate, since the inhibitors are destroyed during the winter.

Plant growth is a fickle process: the period of active growth in spring and summer is replaced by the attenuation of growth processes in autumn. In winter, trees, shrubs and grasses are dormant.
During the dormant period, growth stops and the vital processes of plants slow down greatly. For example, in winter their breathing is 100-400 times weaker than in summer. However, one should not think that plants in a state of dormancy completely cease their vital activity. In resting organs (in the buds of trees and shrubs, in tubers, bulbs and rhizomes of perennial grasses), the most important life processes continue, but growth completely stops, even if all the conditions for this are present. During periods of deep dormancy, plants are difficult to “awaken.” For example, potato tubers just harvested from the field will not germinate even in warm and wet sand. But within a few months the tubers will begin to sprout and this process will be difficult to delay.

Rest is the body's response to changing environmental conditions.
Changing environmental conditions can lengthen or shorten the dormant period. So, if you artificially lengthen the day, you can delay the transition of plants to a dormant state.
Thus, plant dormancy is an important adaptation to surviving unfavorable conditions that arose during evolution.
Growth processes underlie plant movement. The movements of plants are different. Tropisms are widespread in nature - bending of plant organs under the influence of a factor acting in one direction. For example, when a plant is illuminated from one side, it bends towards the light. This is phototropism. The plant bends because its organs on the illuminated side grow more slowly than on the non-illuminated side, since light slows down cell division.
The response of plants to gravity is called geotropism. The stem and root react differently to gravity. The stem grows upward, in the opposite direction to the action of gravity (negative geotropism), and the root grows downward, in the direction of the action of this force (positive geotropism). Turn the germinating seed over with the root facing up and the stem facing down. After a while you will see that the root will bend downwards and the stem upwards, i.e. they will take their usual position.

Plants also respond to the presence of chemicals in the environment by movement. This reaction is called chemotropism. It plays an important role in mineral nutrition, as well as in plant fertilization. So, in the soil, roots grow towards nutrients. But they bend in the opposite direction from pesticides and herbicides.
Pollen grains, as a rule, germinate only on the stigma of plants of their own species, and sperm (male reproductive cells) move towards the ovule, the egg cell and the central nucleus located in it. If a pollen grain lands on the stigma of a flower of another species, it first germinates and then bends in the direction opposite to the ovule. This indicates that the pistil secretes substances that stimulate the growth of “its” pollen grain, but suppress the growth of foreign pollen.
Plants respond with tropisms to the effects of temperature, water, and organ damage.
Plants are also characterized by another type of movement - nastia. Nasty is also based on plant growth, which is caused by various irritants acting on the plant as a whole. There are photonasties caused by changes in lighting and thermonasties associated with changes in temperature. Many flowers open in the morning and close in the evening, i.e. react to changes in lighting. For example, in the morning, in bright sunlight, dandelion baskets open, and in the evening, as the light decreases, they close. Flowers of fragrant tobacco, on the contrary, open in the evening, with a decrease in illumination.
Nastia, like tropisms, is also based on uneven growth: if the upper side of the petals grows more strongly, the flower opens, if the lower side closes. Consequently, the movement of plant organs is based on their uneven growth.
Tropisms and nasties play a big role in the life of plants; this is one of the signs of plant adaptation to the environment, to an active response to the influence of its various factors.

Photo: Sharon

Growth processes are an integral part of individual plant development, or ontogenesis. The entire individual development of an individual is composed of a number of processes, certain periods in the life of an individual, starting from the moment of its appearance until its death. The number of periods of ontogenesis and the complexity of development processes depend on the level of plant organization. Thus, the individual development of unicellular organisms begins with the formation of a new daughter cell (after the division of the mother cell), continues during its growth and ends with its division. Sometimes unicellular organisms have a period of rest - during the formation of spores; the spore then germinates and development continues until cell division. During vegetative reproduction, individual development begins from the moment of separation of part of the maternal organism, continues with the formation of a new individual, its life, and ends with death. U higher plants during sexual reproduction, ontogenesis begins with fertilization of the egg and includes periods of development of the zygote and embryo, formation of the seed (or spore), its germination and formation of the young plant, its maturity, reproduction, withering and death.

If in unicellular organisms all processes of their development and vital activity occur in one cell, then in multicellular organisms the processes of ontogenesis are much more complex and consist of a number of transformations. During the development of a new individual, as a result of cell division, various tissues are formed (integumentary, educational, photosynthetic, conductive, etc.) and organs that perform various functions, the reproductive apparatus is formed, the body enters the time of reproduction, produces offspring (some plants - once in a lifetime , others - annually for many years). In the process of individual development, irreversible changes accumulate in the body, it ages and dies.
Duration of ontogenesis, i.e. the life of an individual also depends on the level of plant organization. Single-celled organisms live for several days, multicellular organisms live from several days to several hundred years.

The duration of development of plant organisms also depends on environmental factors: light, temperature, humidity, etc. Scientists have found that at temperatures of 25°C and above, the development of flowering plants accelerates, they bloom earlier, form fruits and seeds. Abundant moisture accelerates plant growth, but retards their development.
Light has a complex effect on plant development: plants respond to day length. In progress historical development Some plants develop normally if the daylight hours do not exceed 12 hours. These are short-day plants (soybeans, millet, watermelon). Other plants flower and produce seeds when grown under longer day conditions. These are long-day plants (radishes, potatoes, wheat, barley).

Knowledge about the patterns of growth and individual development of plants is used by humans in practice when growing them. Thus, the property of plants to form lateral roots when the tip of the main root is removed is used when growing vegetables and ornamental plants. In seedlings of cabbage, tomatoes, asters and other cultivated plants when transplanted into open ground pinch the tip of the root, i.e. pick. As a result, the growth of the main root in length stops, the growth of lateral roots increases and their distribution in the upper, fertile layer of soil. As a result, plant nutrition improves and their yield increases. Picking is widely used when planting cabbage seedlings. The development of a powerful root system is facilitated by hilling - loosening and rolling the soil to the lower parts of the plants. In this way, the flow of air into the soil is improved and thus normal conditions are created for breathing and root growth, for the development of the root system. This, in turn, improves leaf growth, resulting in increased photosynthesis and the formation of more organic matter.

Trimming the tops of young shoots, such as apple trees, raspberries, and cucumbers, leads to a cessation of their growth in length and increased growth of side shoots.
Currently, growth stimulants are used to accelerate the growth and development of plants. They are usually used when cuttings and transplanting plants to accelerate the formation of roots.
For economic purposes, it is sometimes necessary to inhibit the growth of plants, for example, the germination of potatoes in winter and especially in spring. The appearance of sprouts is accompanied by a deterioration in the quality of tubers, loss of valuable substances, a decrease in starch content, and accumulation of the toxic substance solanine. Therefore, to delay the germination of tubers before storing them, they are treated with inhibitors. As a result, the tubers do not germinate until spring and remain fresh.

The general pattern of development of each organism is programmed in its hereditary basis. Plants vary dramatically in life expectancy. Plants are known that complete their ontogenesis within 10-14 days (ephemera). At the same time, there are plants whose lifespan is estimated at thousands of years (sequoias). Regardless of life expectancy, all plants can be divided into two groups: monocarpic, or bearing fruit once, and polycarpic, or bearing fruit many times. All are considered monocarpic annual plants, most are biennial, and some are perennial. Perennial monocarpic plants (for example, bamboo, agave) begin to bear fruit after several years of life and die after a single fruiting. Most perennial plants are classified as polycarpic.