Reactions to adverse environmental factors only under certain conditions are detachious for living organisms, and in most cases they have an adaptive value. Therefore, these responses were named Selle "General Adaptation Syndrome". In later works, the terms "Stress" and "Common Adaptation Syndrome" he used as synonyms.

Adaptation - This is a genetically deterministic process for the formation of protective systems that ensure an increase in the stability and the flow of ontogenesis into unfavorable conditions for it.

Adaptation is one of the most important mechanisms that increases the stability of the biological system, including vegetable organism, in the changed conditions of existence. The better the body is adapted to some factor, the more stable to its oscillations.

The genotypically determined ability of the body to change metabolism within certain limits, depending on the action of the external environment is called round reaction. It is controlled by genotype and is peculiar to all living organisms. Most modifications that occur within the reaction rate are adaptive. They correspond to changes in habitat and provide better plant survival with fluctuations in environmental condition. In this regard, such modifications have evolutionary importance. The term "reaction rate" was introduced by V.L. Johansen (1909).

The greater the ability of the type or variety to be modified in accordance with the environment, the wider its reaction rate and the above ability to adapt. This property is distinguished by stable agricultural crops. As a rule, non-core and short-term changes in the factors of the external environment do not lead to essential violations of physiological functions of plants. This is due to their ability to maintain a relative dynamic equilibrium of the inner medium and the stability of the main physiological functions in the conditions of a changing external environment. At the same time, sharp and long exposure leads to a violation of many plants functions, and often to his death.

Adaptation includes all processes and devices (anatomical, morphological, physiological, behavioral, etc.), which contribute to increasing stability and contribute to the survival of the species.

1. Anatomo morphological devices. In some representatives of xerophytes, the length of the root system reaches several tens of meters, which allows the plant to use groundwater and not to test the lack of moisture under conditions of soil and atmospheric drought. In other xerophytes, the presence of thick cuticle, the pubescence of the leaves, the conversion of leaves in the spins reduce the loss of water, which is very important in conditions of lack of moisture.

Burning hairs and spines protect plants from eating animals.

Trees in the tundra or at large mountain altitudes have the kind of squat steering shrubs, in the winter they fall asleep with snow, which protects them from severe frosts.

In mountainous areas with large daily fluctuations in the temperature of the plant often have the form of splashing pillows with tightly located numerous stems. This allows you to maintain inside the pillows moisture and relatively uniform temperatures during the day.

Bolotnaya I. water plants A special air-capable parenchyma (aerenhima) is formed, which is the air tank and facilitates the breath of parts of the plant, immersed in water.

2. Physiology-biochemical devices. Succulent adaptation for growing in the conditions of deserts and semi-desert is the assimilation of CO 2 during the photosynthesis by the CAM path. These plants are closed in these plants. Thus, the plant retains the internal reserves of water from evaporation. In the deserts, water is the main factor limiting the growth of plants. Stitza open at night, and at this time there is an admission of CO 2 into photosynthetic fabrics. The subsequent involvement of CO 2 to the photosynthetic cycle occurs during the day with closed dusts.

Physiological and biochemical devices include the ability of alloys to open and close, depending on external conditions. Synthesis in the cells of abscise acid, proline, protective proteins, phytoo-altercins, phytoncides, increasing the activity of enzymes, opposing oxidative decay organic substances, accumulation of sugars cells and a number of other changes in the metabolism contributes to increasing plant resistance to adverse environmental conditions.

The same biochemical reaction can be carried out by several molecular forms of the same enzyme (isoenzymes), while each isoform exhibits catalytic activity in a relatively narrow range of some environmental parameter, such as temperature. The presence of a number of isoenzymes allows the plant to react to a significantly wider range of temperatures, compared with each individual isoenzyme. This makes it possible to plant successfully perform life functions in changing temperature conditions.

3. Behavioral devices, or avoiding the action of an adverse factor. An example is epfemeers and ephemeroids (poppy, star, crocuses, tulips, snowdrops). They pass the whole cycle of their development in the spring for 1.5-2 months, even before the onset of heat and drought. Thus, they seek, or avoid entering the influence of the stressor. Similarly, the early-weighted varieties of crops form a harvest before the occurrence of adverse seasonal phenomena: August fogs, rains, frosts. Therefore, the selection of many crops is aimed at creating early varieties. Perennial plants winter in the form of rhizomes and bulbs in the soil under snow protecting them from freezing.

Adaptation of plants to adverse factors is carried out simultaneously at many levels of regulation - from a separate cell to phytocenosis. The higher the level of the organization (cell organism, population). The greater the number of mechanisms simultaneously participates in the adaptation of plants to stress.

Regulation of metabolic and adaptation processes inside the cell is carried out using systems: metabolic (enzymatic); genetic; Membrane. These systems are closely related to each other. Thus, the properties of membranes depend on gene activity, and the differential activity of the genes themselves is under the control of membranes. Enzyme synthesis and their activity are controlled at the genetic level, at the same time enzymes regulate nucleic exchange in the cell.

On the organize level New, reflecting the interaction of organs is added to the cellular mechanisms of adaptation. In adverse conditions, plants create and preserve such a number of fruit elements, which in sufficient quantities are provided with the necessary substances to form full-fledged seeds. For example, in inflorescences cultural Zlatkov And in the crowns of fruit trees in adverse conditions, more than half of the laid barbells may fall. Such changes are based on competitive relations between organs for physiologically active and nutrients.

In conditions of stress, the processes of aging and the fear of the lower leaves are sharply accelerated. Wherein related plants Substances move from them into young organs, responding to the body survival strategy. Thanks to the reutence nutrients From the lower leaves are preserved viable younger - upper leaves.

There are mechanisms for regeneration of lost bodies. For example, the surface of the injury is covered by a secondary coating cloth (wounded periderma), the wound on the trunk or branch is frozen (calls). With the loss of the top shooting, the plants are awakening sleeping kidneys and lateral shoots are developing. Spring restoration of leaves instead of fallen autumn is also an example of natural regeneration of organs. Regeneration as a biological device, providing vegetative reproduction of plants with sections of the root, rhizomes, layers, stroke and sheet cuttings, isolated cells, individual protoplasts, is of great practical importance for crop production, fruit growing, forestry, decorative gardening, etc.

In the processes of protection and adaptation at the plant level, the hormonal system is also involved. For example, under the action of unfavorable conditions in the plant, the content of growth inhibitors: ethylene and abscissa acid increases. They reduce metabolism, inhibit growth processes, accelerate aging, exhausting organs, transition of plants into rest state. The inhibition of functional activity in stress conditions under the influence of growth inhibitors is a reaction characteristic of plants. At the same time, the content of growth stimulants is reduced in the tissues: cytokinin, auxin and gibbersellin.

On the population level The selection is joined, which leads to the appearance of more adapted organisms. The possibility of selection is determined by the existence of intrapopulation variability of plant resistance to various factors of the external environment. An example of inspirational variability in stability can be the non-departure of the emergence of seractions on saline soil and an increase in varying germination time when the stressor is increased.

The view in the modern presentation consists of a large number of biotypes - smaller environmental units, genetically identical, but manifesting different resistance to the factors of the external environment. IN different conditions Not all biotypes are equally vitality, and as a result of competition, only those that are most consistent with these conditions remain. That is, the stability of the population (varieties) to one or another factor is determined by the stability of the components of the population of organisms. Sustainable varieties are in their composition a set of biotypes that provide good productivity even in adverse conditions.

At the same time, in the process of many years of cultivation in varieties, the composition and the ratio of biotypes in the population is changed, which is reflected on productivity and quality of the variety, often not for the better.

So, adaptation includes all processes and devices that increase the stability of plants to adverse environmental conditions (anatomical, morphological, physiological, biochemical, behavioral, population, etc.)

But to select the most effective way to adapt the main time during which the body should adapt to new conditions.

In case of a sudden action of an extreme factor, the answer cannot be postponed, it must follow immediately to eliminate irreversible damage to the plant. With prolonged exposure to a small force, adaptive restructuring occurs gradually, while the choice of possible strategies increases.

In this regard, three main adaptation strategies are distinguished: evolutionary, ontogenetic and urgered. Task Strategy - effective use resources to achieve the main goal - the survival of the body under stress conditions. The adaptation strategy is aimed at maintaining the structural integrity of vital macromolecules and the functional activity of cellular structures, the preservation of system regulation systems, providing plants with energy.

Evolutionary, or phylogenetic adaptation (Phylogenesis - the development of biological species in time) is adaptations arising during the evolutionary process based on genetic mutations, selection and inherited. They are most reliable to survive plants.

Each type of plants in the process of evolution developed certain needs for the conditions of existence and the adaptation to the ecological niche occupied by it, the resistant adaptation of the body to the habitat. Moistlability and shadowness, heat resistance, cold resistance and other environmental features of specific plant species were formed as a result of a long action of the relevant conditions. Thus, the thermal loving and short-lasting plants are characteristic of southern latitudes, less demanding to heat and the long-term plants - for the northern. Numerous evolutionary adaptations for drought-xerophyte plants are well known: economical water spending, a deeply occurring root system, dropping the leaves and the transition to the rest state and other devices.

In this regard, agricultural plant varieties are sustainable precisely to the factors of the external environment, against the background of which the selection and selection of productive forms is carried out. If the selection passes in a number of consecutive generations against the background of the constant influence of any adverse factor, then the stability of the grade to it can be significantly increased. It is natural that the breeding varieties of the southeast agriculture (Saratov), \u200b\u200bmore resistant to drought than grades created in the selection centers of the Moscow region. In the same way, in ecological zones with unfavorable short-lumility conditions, sustainable local varieties of plants were formed, and endemic plants are stable precisely to the stressor, which is expressed in the arale of their habitat.

Characteristics of the stability of varieties of spring wheat from the collection of the All-Russian Planting Institute (Semenov et al., 2005)

In the natural environment, the environment conditions usually change very quickly, and the time during which the stressful factor reaches the damaging level, is not enough to form evolutionary devices. In these cases, plants are not constant, and the protective mechanisms induced by stressor, the formation of which is genetically predetermined (deterministic).

Ontogenetic (phenotypic) adaptation Not related to genetic mutations and are not inherited. The formation of this kind of adaptation requires a relatively long time, so they are called long-term adaptation. One such mechanisms is the ability of a row of plants to form the water-saving path of the Cam-type photosynthesis in a water deficit caused by drought, salinization, the action of low temperatures and other stressors.

This adaptation is associated with the induction of the expression of "inactive" under normal conditions of phosphoenolpiruvataukarboxylase genes and genes of other CAM-path enzymes of CO 2, with the osmolite biosynthesis (proline), with activation of antioxidant systems and the change in the daily rhythms of alloying movements. All this leads to very economical water spending.

In field crops, for example, in corn, Aerrenakhim is absent under normal conditions. But in the conditions of flooding and disadvantage in oxygen tissues in the roots, it occurs the death of a part of the cells of the primary root and stem cell (apoptosis, or programmable cell death). In their place, cavities formed by which oxygen from the above-ground part of the plant is transported in root system. The signal for cell death is ethylene synthesis.

Urgent adaptation It occurs at fast and intensive changes in habitat. It is based on the formation and functioning of shock protective systems. The shock protective systems include, for example, a heat shock protein system, which is formed in response to a rapid increase in temperature. These mechanisms provide short-term survival conditions under the action of a damaging factor and thereby create prerequisites for the formation of more reliable long-term specialized adaptation mechanisms. An example of specialized adaptation mechanisms is the neoplasm of antifreeze proteins at low temperatures or synthesis of sugars in the process of overwrieving winter crops. At the same time, if the damaging effect of the factor exceeds the protective and reparation capabilities of the body, then death comes inevitably. In this case, the body dies at the stage of urgent or at the stage of specialized adaptation depending on the intensity and duration of the extreme factor.

Distinguish specific and nonspecific (general) Response reactions of plants on stressor.

Non-specific reactions Do not depend on the nature of the acting factor. They are the same under the action of high and low temperatures, lack or excess moisture, high saline concentration in soil or harmful gases in the air. In all cases, membranes permeability increases in plant cells, breathing is disturbed, the hydrolytic decay of substances increases, the synthesis of ethylene and abscisic acid increases, the division and stretching of the cells is inhibited.

The table presents a complex of non-specific changes that occur in plants under the influence of various factors of the external environment.

Changes in physiological parameters in plants under the action of stressful conditions (according to GV, Udovenko, 1995)

Based on the data of the table, it can be seen that the stability of plants to several factors is accompanied by unidirectional physiological changes. This gives reason to believe that increasing the stability of plants to one factor may be accompanied by an increase in resistance to another. This is confirmed by experiments.

Experience at the Institute of Plant Physiology RAS (VL. V. Kuznetsov et al.) It is shown that short-term thermal treatment of cotton plants is accompanied by an increase in their resistance to subsequent salinization. And the adaptation of plants to salinity leads to an increase in their resistance to high temperature. The heat shock increases the ability of plants to adapt to the subsequent drought and, on the contrary, in the process of drought, the body's resistance to high temperature increases. A short-term exposure to high temperatures increases heavy metals and UV radiation resistance. The preceding drought contributes to the survival of plants in saline or cold conditions.

The process of increasing the sustainability of the body to this environmental factor as a result of adaptation to the factory of other nature is called cross adaptation.

To study the general (non-specific) stability mechanisms. Of great interest is the answer of plants on factors causing water deficiency in plants: for salinization, drought, low and high temperatures and some others. At the level of a whole body, all plants react to water deficit equally. It is characterized by the oppression of the growth of shoots, enhancing the growth of the root system, the synthesis of abscicoic acid, the decrease in the nutritional conductivity. After some time, the lower leaves are rapidly aging, and their death is observed. All these reactions are aimed at reducing water spending due to the reduction of evaporating surface, as well as by increasing the absorption activity of the root.

Specific reactions - This is a reaction to the action of a single stress factor. Thus, phytoaecxins (substances with antibiotic properties) are synthesized in plants in response to contact with pathogens of microorganisms (pathogens).

The specificity or not specificity of response reactions implies, on the one hand, the attitude of the plant to different stressors and, on the other hand, the nature of the reactions of plants of various types and varieties on the same stressor.

The manifestation of specific and nonspecific responses of plants depends on the strength of stress and the rate of its development. Specific responses occur more often if stress develops slowly, and the body has time to restructure and adapt to it. Nonspecific reactions usually occur with a shorter and strong action of the stressor. The functioning of non-specific (general) stability mechanisms allows the plant to avoid high energy costs for the formation of specialized (specific) adaptation mechanisms in response to any deviation from the norm of their habitat conditions.

The stability of plants to stressful exposure depends on the phase of ontogenesis. The most resistant plants and plant organs in a resting state: in the form of seeds, bulbs; Wood perennials - in a state of deep rest after leaffall. The most sensitive plants are in young age, since in the conditions of stress, the growth processes are damaged primarily. The second critical period is the period of formation of weights and fertilization. The action of stress in this period leads to a decrease in the reproductive function of plants and a decrease in the crop.

If stressful conditions are repeated and have a slight intensity, they contribute to the hardening of plants. This basis methods of increasing resistance to low temperatures, heat, salinization, increased maintenance of harmful gas in the air.

Reliability The vegetable organism is determined by its ability to prevent or eliminate failures at different levels of the biological organization: molecular, subcellular, cellular, tissue, organ, organized and population.

To prevent failures in the vital activity of plants under the influence of adverse factors, principles are used redundancy, heterogeneity of functionally equivalent components, reparation systems lost structures.

The redundancy of structures and functionality is one of the main ways to ensure the reliability of systems. Redundancy and reservation has diverse manifestations. At the sub-cell level, the redundancy and duplication of genetic material contribute to improving the reliability of the plant organism. This is ensured, for example, a double DNA spiral, an increase in the fluid. The reliability of the functioning of the plant organism in the changing conditions is also maintained due to the presence of various molecules of information RNA and the formation of heterogeneous polypeptides. These include and isoenzymes that catalyzize the same reaction, but differ in their physicochemical properties and the stability of the structure of molecules in the changing conditions of the medium.

At the cell level, an example of redundancy is an excess of cellular organelle. So, it was established that in order to provide a plant with photosynthesis products, there are enough parts of the existing chloroplasts. The remaining chloroplasts as it were in the reserve. The same applies to the total content of chlorophyll. Redundancy is also manifested in a large accumulation of precursors for biosynthesis of many compounds.

At the organizational level, the principle of redundancy is expressed in education and in the time-based bookmark more than it is required to change generations, the number of shoots, flowers, spikelets, in a huge amount of pollen, segments, seeds.

In the population level, the principle of redundancy is manifested in a large number of individuals differing in sustainability to one or another stress factor.

Reparation systems are also operating at different levels - molecular, cellular, organized, population and biosotic. Reparative processes go with the cost of energy and plastic substances, so reparation is possible only while maintaining sufficient metabolic intensity. If the metabolism is terminated, reparation stops. In extreme conditions of the external environment, respiratory preservation is especially important, since it is breathing that provides energy reparation processes.

The reduction capacity of cells of adapted organisms is determined by the resistance of their proteins to denaturation, namely the stability of the relationship, which determine the secondary, tertiary and quaternary structure of the protein. For example, the stability of mature seeds to high temperatures is, as a rule, is due to the fact that after dehydration, their proteins acquire resistance to denaturation.

The main source of energy material as a respiratory substrate is photosynthesis, therefore, the stability and ability of the photosynthetic apparatus is restored after damage depends the cell power supply and related reparation processes. To maintain photosynthesis in extreme conditions in plants, the synthesis of the tilacoid membranes components is activated, the lipid oxidation is braked, the ultrastructure of the plastic is restored.

At the organizational level, an example of regeneration can serve the development of replacing shoots, the awakening of sleeping kidneys during damage to growth points.

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Ministry of Agriculture of the Russian Federation

FGOU VPO "St. Petersburg Academy of Veterinary Medicine"

Department of General Biology and Histology

Essay on ecology on the topic:

"Adaptation of plants to drought and dry habitats"

perched student Ivanova E.O.

3rd groups of the 1st year

Checked the teacher:

Zhilochka Tatyana Ivanovna

St. Petersburg

Introduction 3.

Impact on the plant lack of moisture. four

Drought resistance. 7.

Adaptation of plants to drought. nine

Conclusion. fourteen

List of used literature. fifteen

Introduction

The adaptability of ontogenesis of plants to the conditions of the medium is the result of their evolutionary development (variability, heredity, selection). Throughout the philogenesis of each type of plants in the process of evolution, certain needs of the individual were developed to the conditions of existence and the adaptation to the environmental niche occupied. Moisture resistance, cold resistance and other environmental features of specific plant species were formed during evolution as a result of a long action of relevant conditions. Thus, the thermal-loving plants and plants of a short day are characteristic of southern latitudes, less demanding to heat and a long day plant - for the northern.

In nature, in the same geographic region, each type of plants occupies an ecological niche corresponding to its biological characteristics: moisture-loving - closer to the water bodies, trees-beyond - under the field of forest, etc. The heredity of plants is formed under the influence of certain conditions of the external environment. External conditions of plant ontogenesis are important.

In most cases, plant and crops (landings) of crops, experiencing the effect of certain adverse factors, are shown to be resistant to them as a result of adaptation to the conditions of the existence that has developed historically, which also noted K. A. Timiryazev.

Impact on the plant lack of moisture.

The lack of water in plant tissues occurs as a result of exceeding its flow rate on transpiration before entering the soil. It is often observed in hot sunny weather by the middle of the day. At the same time, the water content in the leaves is reduced by 25-28% compared with the morning, the plants are lost by the turgor and bind. As a result, the water potential of the leaves is reduced, which activates the flow of water from the soil into the plant.

There are two types of convictions: temporary and deep. The cause of temporary planting plants is usually atmospheric drought, when, if there is an affordable water in the soil, it does not have time to enter the plant and compensate for its consumption. With temporary plotting, Turgor Leaves is restored in the evening and night hours. Temporary building reduces plant productivity, since with the loss of the turgora, the Ustian closes

and photosynthesis slows down sharply. It is observed, as noted by A. G. Lorch, "simple" plants in the accumulation of the crop.

Deep planting plants occurs when in the soil there is practically no available for water roots. There is a partial, and with a long drought and general drainage and even the death of the plant organism. A characteristic sign of a sustainable water deficit is to preserve it in the tissues in the morning. Temporary and even deep tying can be considered as one of the ways to protect the plant from lethal dehydration, allowing for some time to maintain the water necessary to maintain the viability of the plant. The establishment can occur with different water loss by plants: in the tepelubil - at 3-5%, in more persistent - with water deficiency in 20 and even 30%.

Water deficit and planting in different extent affect the physiological activity of the plant depending on the duration of dehydration and the type of plant. The consequences of water deficit during drought are diverse. The cells of the free water decrease in cells, the concentration increases and the pH of the vacuolar juice is reduced, which affects the hydration of proteins of cytoplasm and the activity of enzymes. The degree of dispersion and the adsorbing capacity of the cytoplasm, its viscosity changes. The permeability of membranes and the output of ions from cells, including from leaves and roots (exo-vos), increases dramatically; These cells lose the ability to absorb nutrients.

With long-term entry, the activity of enzymes catalyzing the synthesis processes is reduced, and enhances enzymes catalyzing hydrolytic processes, in particular the decay (proteolysis) of proteins on amino acids and further to ammonia, poly-saccharides (starch on sugar, etc.), as well as other biopolymers. Many products formed, accumulating, poison the organism of the plant. A device of protein synthesis is broken. With an increase in the water deficit, a long drought is disturbed by a nucleic exchange, synthesis is suspended and the disintegration of DNA is enhanced. In the leaves, the synthesis is reduced and the disintegration of all types of RNA increases, the polisoms are disintegrated by ribosomes and subunits. Termination of mitosis, strengthening the decay of proteins with progressive dehydration lead to the death of the plant.

Of course, the changes that occur to a certain stage in conditions of dehydration also play a protective role, lead to an increase in the concentration of cell juice, a decrease in osmotic potential, and therefore, increase the water-holding plant's ability. With a lack of moisture, total photosynthesis decreases, which is a consequence of the main disadvantage of CO2 in the leaves; disorders of synthesis and decay of chlorophylls and other photosynthesis pigments; disunity of transport of electrons and photophosphorylation; disorders of the normal movement of photochemical reactions and reactions of enzymatic

formation CO2; disorders of the structure of chloroplasts; Delays of outflow of assimilates from leaves. According to V. A. Brilliant (1925), a decrease in the height of the leaf in sugar beets by 3-4% leads to a decrease in photosynthesis by 76%.

With increasing dehydration in unnecessary plants, in the first period of the initiation, the respiratory intensity increases due to the large number of simple products (hexosis) of polysaccharides hydrolysis, mainly starch, and then gradually decreases. However, the energy released during respiration is not accumulated in ATP, and is dissipated in the form of heat (idle breathing). Under action on high temperature plants (45 ° C) and Sukhov, deep structural changes mitochondria, damage or inhibiting the enzymes of the phosphorylation mechanism occur. All this indicates a violation of the energy exchanging of plants. The root and PASK increase the content of amides. As a result, the growth of the plant, especially the leaves and stalks, is reduced, harvest is reduced. In more drought-resistant plants, all these changes are less pronounced.

Of the physiological processes, the process of growth is the most sensitive to the lack of moisture, the pace of which at the increasing disadvantage of moisture is reduced significantly earlier photosynthesis and respiration. Growth processes are delayed even after water recovery. With progressive dehydration, a certain sequence in the action of drought is observed into separate parts of the plant.

If the growth of shoots and leaves at the beginning of the drought slows down, the roots even accelerates and decreases only with a long lack of water in the soil. At the same time, the young top on a stalk of the leaves pull the water from older the lower, as well as from the fruit elements and the root system. The roots of high orders and root hairs die out, the processing and suberinization processes are increasing. All this leads to a reduction in the absorption roots of water from the soil. After long-term installations, the plants are sent slowly and their functions are not completely restored. The prolonged building during drought leads to a sharp reduction in crop crops or even their death. In the sudden and strong voltage of all meteorological factors, the plant can quickly die as a result of drying (capture) or high temperatures (fused). The drought resistance of various organs of plants is non-etinakov. Thus, young growing leaves due to the influx of assimiles longer retain the ability to synthesis, relatively more resistant than the leaves that ended in growth, or old, which when drought are prior to the first place.

In the conditions of a protracted drought, the outflow of water and substances in young leaves can also occur from the generative organs.

Drought in early development periods leads to the death of floral adventures, their sterility (bellarge), and in later - to the formation of prize grain (capture). In this case, the capture will be more likely with a well-developed leaf surface drought. Therefore, with a combination of wet spring and starting summer with a very dry second half (or even individual strong sukhovyev), the risk of reducing the harvest is most likely.

Drought resistance.

The term "drought resistance" in a literal understanding denotes the ability of the plant to carry drought. In this sense, the term "drought resistance" is similar to the term "frost resistance", which denotes the ability of the plant to carry low temperatures. Usually, however, drought resistance is understood in broader content. Drought-resistant plants, naturally living in arid areas, although many of them are not at all such if the term "drought resistance" is literally understood. Such plants include, for example, ephemers developing in a wet and non-jarous period of spring or in the fall with the onset of rains. Drought-resistant is also called relatively more productive varieties of plants cultivated in arid areas, although in many cases the high productivity of the variety is not directly in direct connection with greater drought-resistance in a literal understanding.

Based on the above, it is necessary to distinguish between the three concepts of drought resistance:

1. Physiological (or literal) concept. Drought resistance - the ability of the plant to transfer drought.

2. Biological concept. Drought resistance - biological fitness of the plant for life in conditions of a dry area. The drought resistance in a literal understanding enters the biological concept as an integral part.

3. Aggonomic concept. The plant can be drought-resistant in biological concept, but by nature its inability to accumulate a large mass of dry matter. Drought resistance in agronomic concept is associated with the productivity of the plant drought resistance in a literal understanding - as the ability of the plant to transfer drought - is complex ability and is expressed in a number of properties. This is determined by the complexity and variety of drought action on plants. The main, defining drought, condition, is the lack of water in ambient plant Medium: Soil and air. In accordance with this, the soil and atmospheric drought differ. The lack of water causes dehydration of the plant cells. This in turn leads to a decrease in the performance of the plant and in extreme cases to death. But the lack of water is not the only reason for the suffering and death of the plants in the time of drought. In the process of drought growth, on a row with a decrease in the amount of water in the environment of the plant, new, additional, reasons that limit the vital activity of the plant and often decisive his fate. Such reasons include: 1) an increase in the temperature of the green organs of the plant as a result of a decrease in transpiration and 2) the toxic effect of individual salts for the concentration of the soil solution known.

Each drought-resistant plant is always a combination of three properties: 1) cell stability to dehydration, 2) resistance of green organs to high temperature and 3) resistance to soil salts. But the ratio of these individual properties and the proportion of each of them in the resistance of the plant to drought is very volatile depending on the type of plant and the conditions of its habitat. In arid, but not hot areas and on unexpected soil, as well as during Sukhovyev, the plants will suffer mainly from dehydration, and drought resistance will be determined mainly by the property of the plant cells to transfer far-reaching water loss. In hot arid areas, especially in plants, economically spending water, for example. At the succulents of the type of cacti, the first place is the heating factor of green organs, and drought resistance will be determined largely resistant to high temperature.

Plant fixtures for drought.

In most areas of Central Asia, agriculture is impossible without irrigation. Agricultural plants here suffer from drought, i.e., from lack of water in the soil and from too dry and hot air.

At the same time, there are many plants in the deserts that have adapted to these harsh conditions, grow well and develop. It helps to carry cruel drought and successfully combat it a number of adaptive properties. These properties in the desert plants did not occur immediately. Many thousand generations were changed, many of the species died. Only those species that under the influence of the surrounding conditions in the process of natural selection are influenced and the features that helped them struggle with drought were entered.

Plants, well-carrying drought, is not only in the deserts, but also in the steppes. In the steppes of precipitation more (300-350 mm per year), but in the summer almost always, at least for a short time, the drought is. Plants, well-carrying drought, got the name of xerophytes (from the Greek words "xeros" - dry and "phyton" - a plant).

The most famous xerophytes are cacti, residents of the deserts of North and Central America. Cacti binds hotel lovers. Academician N. A. Maximov successfully called Cacti Plants-Skopidomas. Indeed, in the period of rains, cacti spare water in the stems, absorbing it strongly branched, but in the soil a shallow root system. The leaves have changed and become spiny. Cacti covered with thick cuticle and water spent very economically. At the same time, they are resistant to the action of high temperatures. Many cactis without much harm are heated to 62 ° and even slightly higher. This is the most ferrous-resistant flowering plants on the ground.

In addition to cacti, stocking water in stems, there are plants, stocking water in the leaves. These include the aloe indoor plant. In a wild form, it grows in South African deserts. In the middle lane of our country on sandy soil grows a small blooming golden yellow flowers. The leaves of the sucker is fleshy, with water reserves, which plant spends when there is no rain.

Many shrubs and small trees in the deserts of Central Asia produce water with a deep root system in the soil. Among the mourned vegetation, bright green bushes with very small leaves and a mass of barbles are highlighted among the ridiculous herds. This is camel spin. There are a lot of sugar in the fabrics of the camel barrels, but only an unpretentious camel feeds it. Why does the camel-Kullet feel good when most other plants are deserted from drought? The fact is that the long root of the barbs comes to groundwater - to a depth of 10-20 m. When the Suez Canal was sworn, then in one place they found the root of camel spines at a depth of 33 m. Therefore, the barley and does not lack the water. Evicious water, it cools its fabrics and can move high air temperature.

In plants there are other ways to fight drought. In the sandy deserts of Central Asia, there are ripped bushes of Juzgun (Calliore). Its leaves have grown with stems. The leaf surface of the Juzgun is less than that of other plants, and therefore the evaporation of the water is relatively small.

The Little Sizay Plant is drawn in the West Siberian Step Step Step. The stem and leaves were published by hairs. The hairs are quickly dying and filled with air. The air does not miss the heat well, because Veronica is sisaya not so much heated by sunlight. In addition, Veronica relatively easily tolerate drying. It can lose up to 60% of the water contained in it and still survive drought. The same properties are distinguished and wormwood is sisaya.

In the steppes during and after the rain, you can see small dark green lumps of cinema algae of the Nostok on the surface of the soil. When there is no rain, the nostok dries, it becomes a small dry brown-gray crust, which is difficult to notice. In this form, the Nostok transfers drought, and it grows and develops after dropping rain and autumn.

In the clay deserts of Central Asia in early spring, the soil is almost completely covered with ephemers, (from the Greek word "ephemeros" -od farms) - plants from various families: cereal, cruciferous, poppies, etc. These plants are struggling with drought, as if overtaking it: they have Very rapid development. In the spring in the soil of the desert there is moisture and air temperature moderate. Efemers use it and quickly finish their growth and development. For 5-6 weeks, they manage to bloom and bring seeds that will lay in dry soil until next spring.

In addition to annual ephemers in the desert there are perennial ephemeroids. Efemeroids include tulips, sandy and a number of other plants in the steppes and deserts of the tulips. They are experiencing drought, forming rhizomes, tubers and bulbs. All these parts of the plants are in the soil and are protected from water loss with special seals. Efemeroids, like Efemers, have time to bring offspring (seeds) in the spring. When drought comes, she is no longer scary.

Xerophytes are found not only in the steppes and deserts. There are them in middle lane, and even in the northern part of our country. For example, a lichen Yagel, like almost all lichens, tolerates dryness well, and after the rain again begins to grow.

No less interesting group of gallophyte plants (from the Greek word "galks" - salt). They grow on saline soil: on the shores of the seas or in a arid climate (in the steppes zone, semi-desert and desert). In the arid climate from the soil surface, water is strongly evaporated, and the salts dissolved in it (soda, sulphate sodium, soda, etc.) rise with water upstairs and remain in the soil. So the salt marshes are formed, on which only alone halofitis can grow. Usually in the very center of Solonchak, where the salinization is most strongly, there are no plants, but only whites "fades" of salts. Around the deprived vegetation spots, where the salts are already less, the plant is settled in the light of the plant - Soleeros. The view of Salteros is unusual. This is a small, from 10 to 30 cm high, one-year herbate plant. It consists of individual segments, thick and fleshy. Each such a segment represents a surrounding stalk with a sheet. Inside its fabrics, salteros accumulates salt. When there are too many salts in the tissue, separate segments disappear. So salteros is protected from excess salts inside its body. Side by side with Soleeros grows with skews, having stem and thick fleshy leaves. It is worse than Salker, withstands the soil salinization. A somewhat otherwise struggles with the salinization of Kermek, having a root rosette of the leaves. On a hot sunny day, Kermek leaves covers a flour white flag. Try to lease this falling tongue, and you will feel salty-bitter taste. Through the special riversion of Kermek, it allocates excess salts to the surface of the sheet, and it rains them from here. Also allocates salts and Central Asian shrubs Tamarix.

At the very edge of Solonchak, a special kind of wormwood is growing - slayd salt. It can grow on saline soil, but differs from, salterros and kermec in that it absorbs very few salts from the soil.

Galophytes undoubtedly occurred in the distant past from glucophytes, i.e., plants growing on the unexpected soil (from the Greek word "glucos" - sweet). In the process of natural selection among glucophytes, which have been settled on saline soil, they survived those that were able to transfer salinization. Now many halophytes can no longer live in any other place and better develop with a relatively high content of salts in the soil. Their origin from glucophytes is confirmed by the fact that the seeds of many halophytes are better germinate on a low-fat soil. Usually in the fall, in the winter and early spring, the salt marsh is washed away from salts, or rather salt leave with rainwater in deeper soil layers. Solloris seeds germinate when there are almost no salts in the soil. Then, the salt is then rising with evaporating water upwards, where they are absorbed by the roots of a sprouted plant.

Peculiarly adapted to the salinization of mangall vegetation. Mangrove plants grow on the coasts of the tropical seas - in the bays, straits or in the mouths of the rivers, where the sea surf does not reach. Very often, mangroves are covered with the inner coast of coral atolls. In the tropical part of China, on the island of Hainan, Mangrove are shrubs significantly higher than human growth. In Indonesia, some mangroves reach 20 or more height meters (see Fig. On page 158).

Most mangrove plants are trees with smooth leaf leaves, they resemble indoor ficuses, but they stand on huge backups. These are wounded roots, they help mangrove plants to end the crown above the tide level. From the surface of the soil rise upwards the curved breathing roots. With their help, many mangroves absorb oxygen from the atmosphere. In the soil Mangrove lacks it, as it flooded with a tide.

Many mangroves are most amazing that these are niphelistic plants: their seeds germinate on the parent plant. Fruits with sprouted seeds are fused from trees in the form of long formations reaching in some breeds 30 cm. On the surface of the soil, where mangroves grow, usually lies a large number of such seedlings that have left the parent plant. Many of the seedlings at the lower end can be noted the roots going to the ground. All researchers who studied the life of mangrove plants argue that the roots on these seedlings are formed very quickly (in a few hours), and the seedlings are easily rooted in or the sandy soil. If the seed of mangrove rocks fell into the sea water by the unkind, it would quickly choose the salts. However, this does not happen, because the seed germinates on the parent plant. Getting nutrients and salts from it, it adapts to salinization. A seedlings that cut off from the parent plant is no longer scary to sleep.

Studying drought-resistant and salinist plants helps a person to expand crops cultural plants Due to deserts and saline soils. Knowing how the wild plant is protected from drought and excess salts, it is possible to increase the stability of plants to drought and high saline content in the soil, i.e., increase their drought resistance and salt resistance. To do this, by selecting the varieties of different cultivated plants, which can resist the harmful effects of drought or soil salinization. Apply agricultural engineering and amelioration (fertilizer, drying of solontsy, etc.). In addition, to a certain extent to the drought and soil salinity, the plant can be made to adapt.

To increase the drought-resistant, the seeds of young plants in a certain, unequal for different plants The amount of water, and then dry them within a few days in the air. During drying, the seeds are experiencing a kind of drought and relatively easily adapted to it. The plants that grew from such seeds differ significant drought resistance and bring an increased crop in dry conditions. For example, in one of the experiments, the vintage of grain 15 c from hectare, while the plants hardened against the drought were given 20 c from hectares on the same area.

In the saline hardening, plant seeds are maintained before sowing several hours in salt solutions. After that, they acquire increased salt resistance and bring greater yields on saline soil, as they absorb less harmful salts from the soil and reduced sensitivity to the poisonous action of salts.

Thus, using the natural ability of the plant organism to adapt to adverse conditions of existence, it is possible to significantly change the properties of cultivated plants and significantly increase their yield.

ConclusionThe breathtaking harmony of wildlife, its perfection is created by nature itself: the struggle for survival. Forms of fixtures in plants and animals are completely diverse. All animal and floral world since their own appearance is improved along the way of expedient devices to habitat: to water, to air, sunlight, gravity, etc. The adaptability of ontogenesis of plants to the conditions of the medium is the result of their evolutionary development (variability, heredity, selection). Throughout the philogenesis of each type of plants in the process of evolution, certain needs of the individual were developed to the conditions of existence and the adaptation to the environmental niche occupied. Moisture resistance, cold resistance and other environmental features of specific plant species were formed during evolution as a result of a long action of relevant conditions. Thus, the thermal-loving plants and plants of a short day are characteristic of southern latitudes, less demanding to heat and a long day plant - for the northern.

In nature, in the same geographic region, each type of plants occupies an ecological niche corresponding to its biological characteristics: moisture-loving - closer to the water bodies, trees-beyond - under the field of forest, etc. The heredity of plants is formed under the influence of certain conditions of the external environment. External conditions of plant ontogenesis are important.

List of used literature.1. Volodhko I.K. "" Microelements and stability of plants to adverse conditions ", Minsk, Science and Technology, 1983. 2. GORYUSHINA T.K. "" Ecology of plants ", uch. Handbook for universities, Moscow, V. School, 1979 3. Prokofiev A.A. "" Problems of drought-resistant plants ", Moscow, science, 1978.

4.Kultiasov I.M. Ecology of plants. - M.: Publishing House of Moscow Un-Ta, 1982

All reviewed environmental components are included in

The biosphere: Earth shell, including part of the atmosphere, hydrosphere and upper part of the lithosphere, which are mutually bound by complex biochemical migration cycles of the substance and energy, the geological shell of the Earth, populated by alive organisms. The upper limit of the biosphere is limited intensive concentration of ultraviolet rays; lower - high temperature of the earth's depths (over100`s). The extreme limits of it reaches only lower organisms - bacteria.

The adaptation (adaptation) of the plant to specific conditions of the medium is ensured by physiological mechanisms (physiological adaptation), and in the population of organisms (species) - thanks to the mechanisms of genetic variability, heredity and selection (genetic adaptation). The factors of the external environment may vary naturally and accidentally. Moderly changing environmental conditions (changing seasons of the year) produce genetic adaptation to these conditions in plants.

In the natural nature of natural conditions or cultivation of the plant in the process of its growth and development, the impact of adverse environmental factors, which include temperature fluctuations, drought, excessive moisturizing, soil salinity, etc. Each plant has the ability to adapt into changing The conditions of the external environment within the limits caused by its genotype. The higher the ability of the plant to change metabolism in accordance with the environment, the broader the reaction rate of this plant and the better ability to adapt. This property is distinguished by stable agricultural crops. As a rule, non-core and short-term changes in the external environmental factors do not lead to significant disorders of the physiological functions of plants, which is due to their ability to maintain a relatively stable state with changing conditions of the external environment, that is, to support homeostasis. However, sharp and long-term exposures lead to a violation of many plants functions, and often to his death.

Under the action of unfavorable conditions, the decrease in physiological processes and functions can achieve critical levels that do not ensure the implementation of the ontogenesis genetic program, the energy exchange, regulation systems, protein metabolism and other vital functions of the plant organism are violated. When exposed to the plant of adverse factors (stressors) in it there is a stressful state, the deviation from the norm is stress. Stress is the general nonspecific adaptation reaction of the organism on the action of any adverse factors. There are three main groups of factors causing stress in plants: physical - insufficient or excessive humidity, illumination, temperature, radioactive radiation, mechanical impact; Chemicals - salts, gases, xenobiotics (herbicides, insecticides, fungicides, industrial waste, etc.); Biological is the defeat by pathogens of diseases or pests, competition E with other plants, the influence of animals, flowering, ripening fruits.

The strength of stress depends on the rate of development unfavorable to the plant situation and the level of the stressing factor. With the slow development of unfavorable conditions, the plant is better adapting to them than in short, but strong action. In the first case, as a rule, specific sustainability mechanisms are more showing, in the second - nonspecific.

In unfavorable natural conditions, the stability and productivity of plants are determined by a number of features, properties and protective-adaptive reactions. Different kinds Plants provide stability and survival in adverse conditions in three basic ways: with the help of mechanisms that allow them to avoid adverse effects (state of rest, ephemera, etc.); through special structural devices; Thanks to the physiological properties, allowing them to overcome the detrimental effect of the environment.

Annual agricultural plants in temperate zones, completing their ontogenesis in comparatively favorable conditions, winter in the form of sustainable seeds (rest condition). Many perennial plants winter in the form of underground basic organs (bulbs or rhizomes) protected from the freezing of the soil and snow layer. Fruit trees And shrubs of moderate zones, protecting from winter cold, reset the leaves.

Protection against adverse environmental factors in plants is provided by structural devices, features anatomical structure (cuticle, crust, mechanical fabrics, etc.), special protection bodies (burning hairs, spines), motor and physiological reactions, the production of protective substances (resins, phytoncides, toxins, protective proteins).

The structural devices include mellularity and even the absence of leaves, the wax cuticle on the surface of the leaves, their thick omission and the immersion of the dust, the presence of juicy leaves and stems, preserving water reserves, erethotoid, or lowering leaves and other plants have different physiological mechanisms that allow adaptation to adversely environmental conditions. This is the type of photosynthesis of succulent plants, minimizing water loss and is extremely important for the survival of plants in the desert, etc.

2. Fixture in plants

Cool resistance of plants

The stability of plants to low temperatures is divided into cold resistance and frost resistance. Under the cold resistance, the ability of plants to transfer positive temperatures is somewhat higher than O. C. The cold resistance is characteristic of plants of a moderate strip (barley, oats, flax, vika, etc.). Tropical and subtropical plants are damaged and dyed at temperatures from 0є to 10 ° C (coffee, cotton, cucumber, etc.). For most agricultural plants, low positive temperatures are smaller. This is due to the fact that when cooled, the enzymatic plant of plants is not frustrated, the resistance to mushroom diseases is not reduced and there is no noticeable damage to the plants.

The degree of cold resistance of different plants are not the same. Many plant southern latitudes are damaged by cold. At a temperature of 3 ° C, cucumber, cotton, beans, corn, eggplant are damaged. Resistance to cold in varieties is different. For the characteristics of the cold resistance of plants, the concept is used by the temperature of the temperature at which the growth of plants is stopped. For a large group of agricultural plants, its value is 4 ° C. However, many plants have a higher value of the temperature minimum and, accordingly, they are less resistant to cold.

Fixture of plants to low positive temperatures.

Resistance to low temperatures is a genetically deterministic feature. The cold resistance of plants is determined by the ability of plants to maintain the normal structure of the cytoplasm, change the metabolism during the cooling period and the subsequent increase in temperature at a sufficiently high level.

How do plants adapt to habitat? Plants grow almost everywhere on earth and the harder and tougher conditions created by nature, the more amazing and ingenious way of the adaptation of these creatures. If we consider the structure of plants growing in the hottest deserts and in the coldest sections of the Far North, the first thing that can be noted is the ability of plants to change the structure of its leaves and wood, in order to survive in its habitat. There is a mass of data on how the plants adapt, but still the mechanism of their amazing adaptation is still not fully studied, although some interesting information is still available. Relying on archaeological finds and information extracted with modern technologies, it becomes clear that in our time appearance Plants their structure and general metabolism are determined exclusively to their natural habitat.

Modern plants growing in a certain natural zone, acquired their own adaptation mechanisms. With the moment the plants appeared in the water and on land, they look for more and more new ways of survival and must be recognized very exceeded in this. Any example of the adaptability of plants are trees growing in the tundra, which, unlike Its more southern relatives are dwarf and low. Dwarf trees tundra can not grow large for many reasons. First, in summer time In these territories, the Earth warms up just 0.5 meters, so the roots cannot develop greatly and maintain a heavy trunk, and secondly, most of the time in the tundra is blowing the strongest winds that can sow high wood. In addition, even the small trees of the tundra are often naught to the ground, it helps them to withstand the impulses of the wind reaching 180km / h. In the hot deserts, the plants have a very long root system and a small ground part. Trees in frequently flooded rainforests acquired "air" roots, which come out over the level of the ground about 3-4 meters.

Everyone knows how a person uses plants, for example wheat, but is it so? If we consider the situation from the point of view of the plant, it found an animal that take care of him, sows and protects against others, and from this point of view it turns out that wheat uses a person, as well as other plants use insects to pollinate. Examples of how animals affect plants are enough, because some plants learned to produce toxins, while other plants began to use animals to transfer seeds, to acquire delicious juicy fruits filled with seeds. An animal after eating a fruit, transfer seeds to a sufficiently long distance, which does not guarantee the wind. Plants adapted to life in almost all environmental niches, found a way to defend themselves from animals and use them for their own purposes.

Fitness of plants and animals to habitat The types of plants and animals are surprisingly adapted to the conditions of the medium in which they live. A huge number of the most diverse features of the structure, providing a high level of fit adaptability to the medium, plant types and animals are surprisingly adapted to the conditions of the medium in which they live. It is known a huge number of the most diverse features of the structure, providing a high level of fitness to the medium

The tidal life of the hearts live under the layer of sand or dirt, where wet. They have a leg to pull out the hole, and two tubes for food. They are torn out of the soil, but during low tide are drawn. The heartsets live under the layer of sand or dirt, where wet. They have a leg to pull out the hole, and two tubes for food. They are torn out of the soil, but during low tide are drawn. Sea salad is a small green algae, with low riding it lies on the rocks, and the mucosa protects it from drying out. Sea salad is a small green algae, with low riding it lies on the rocks, and the mucosa protects it from drying out.

Forest litter The structure of the front limbs allows you to grow ground very quickly. In addition, the skin of the clock is very thick and durable, the fur on it can go to any side, which helps the mole to move in narrow nora, not unfolding. The structure of the anterior limbs allows you to grow ground very quickly. In addition, the skin of the clock is very thick and durable, the fur on it can go to any side, which helps the mole to move in narrow nora, not unfolding.

Survival during drought Australian stupid sciling has a feedback in its tail, which contains water. In addition, it has thick skin, which prevents the loss of water from the inside. Needles of cacti dry and hard, not to lose water. They also protect the plant from animals. Sometimes it is formed on the cacti of dew. Water flows down to the ground and absorbed roots.

Conclusion The whole organization of any kind of living organisms is adaptive to those conditions in which it lives. Adaptations of organisms to the habitat are manifested at all levels of the organization. The whole organization of any kind of living organisms is adaptable to those conditions in which it lives. Adaptations of organisms to the habitat are manifested at all levels of the organization.