Nodule bacteria living in the roots of leguminous plants. How nodule bacteria live and reproduce

A. A. Imshenetsky.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what "Nodule bacteria" is in other dictionaries:

- (Rhizobium), a genus of nitrogen-fixing bacteria that form nodules on the roots of many others. legume plants. Inside nodules K. b. assimilate they say. nitrogen, converting it into compounds absorbed by plants, which, in turn, provide bacteria with nutrition ... Biological encyclopedic dictionary

A genus of nitrogen-fixing bacteria that form nodules on the roots of many legumes. Absorb atmospheric molecular nitrogen and convert it into nitrogen compounds absorbed by plants, which, in turn, provide other plants ... ... Ecological dictionary

A genus of bacteria that form nodules on the roots of many leguminous plants and fix molecular nitrogen in the air under conditions of symbiosis with the plant. They do not form spores, they are aerobes. Enrich the soil with nitrogen. See also Nitrogen fixation… Big Encyclopedic Dictionary

Nodule bacteria. See rhizobia. (Source: "English Russian dictionary genetic terms. Arefiev V.A., Lisovenko L.A., Moscow: VNIRO Publishing House, 1995) ... Molecular biology and genetics. Dictionary.

nodule bacteria- rhizobia An extensive, genetically heterogeneous (in connection with this, the genus Rhyzobium is now subdivided into 3 4 independent genera) group of soil gram-negative microorganisms capable of entering into intracellular symbiosis with leguminous plants and ... ... Technical Translator's Handbook

Cross section of a soybean root nodule. Bacteria, lat. Bradyrhizobium japonicum, seed the roots and enter into a nitrogen-fixing symbiosis. Nodule bacteria ... Wikipedia

A genus of bacteria that form nodules on the roots of many leguminous plants and fix molecular nitrogen in the air under conditions of symbiosis with the plant. They do not form spores, they are aerobes. Enrich the soil with nitrogen. See also nitrogen fixation. * * * Nodule Bacteria… … encyclopedic Dictionary

nodule bacteria- symbiont bacteria that develop on the tissues of the roots of legumes and some other plants, capable of binding free nitrogen from the air and making it available to higher plants ... Glossary of botanical terms

nodule bacteria- (Rhizobium), a genus of aerobic bacteria that settle in nodules on the roots of legumes and have the ability to absorb atm. nitrogen and enrich the soil with it. They live in symbiosis with plants, providing them with nitrogen and receiving carbon products from early ... Agricultural Encyclopedic Dictionary

nodule bacteria- (Rhizobium), a genus of aerobic bacteria that settle in nodules on the roots of leguminous plants and have the ability to absorb atmospheric nitrogen and enrich the soil with it. They live in symbiosis with plants, providing them with nitrogen and receiving from plants ... ... Agriculture. Big encyclopedic dictionary

Nodule bacteria, capable of living and multiplying on the roots of symbiont plants, have long become a classic example of mutually beneficial cooperation between higher and lower living organisms on Earth.

Despite the fact that even ancient scientists paid attention to the ability of leguminous plants to improve soil quality, the study of nodule microorganisms began only in 1838. At this time, the Frenchman Jean Baptiste Boussingault suggested that the leaves of leguminous plants could fix nitrogen. The experiments he conducted in support of this hypothesis were distinguished by their accuracy and balance. After 15 years, he abandoned his hypothesis when he found out that plants grown on water (without soil) lose their ability to fix nitrogen. Then he failed to find an answer to the question of which organs of legumes are responsible for nitrogen fixation.

This is not surprising - it was not the leaves that turned out to be the factories for the production of nitrates, but nodule bacteria - the favorite symbionts of leguminous plants that live on their roots. Without knowing anything about the mechanism of nitrogen fixation, agronomists began to introduce legumes into multi-field crop rotation systems. The alternation of cereals and clover made it possible to increase their productivity by two and a half times. Among the leguminous plants, the most productive species were identified - alfalfa, clover, lupine, sweet clover. It turned out that they leave 2-5 times more nitrogen in the soil than grain legumes.

The work of scientists to identify symbionts with which nodule bacteria cooperate has made it possible to identify more than 200 species of non-legume plants, on the roots of which nitrogen-fixing bacteria live and multiply.

The ubiquitous prokaryotes

At the beginning of the last century, the first nodule microorganisms were discovered that can assimilate atmospheric nitrogen. Interestingly, anaerobic Clostridium pasterianum (S.N. Vinogradsky) and aerobic Azotobacter (M. Beyerink) were discovered almost simultaneously. Over time, other nitrogen-fixing bacteria were identified, both free-living and symbionts, which live and reproduce on the roots of cereals, legumes, and Asteraceae (the most famous are timothy, sorghum, and potatoes). Growing nodule bacteria on nutrient media, scientists found that in addition to nitrogen fixation, they live and multiply, performing the synthesis of growth and root formation stimulants, some vitamins, and antibiotics.

Nodule bacteria are highly specific towards symbiont plants. The study of their specificity made it possible to find an answer to the question of why bacterial preparations have varying effectiveness depending on the crops they are treated with. The first bacterial preparation Nitragin, intended for the treatment of seeds of leguminous plants, was proposed in 1897 by F. Nobbe and L. Giltner. It started industrial production bacterial fertilizers, research on the specificity of nitrogen fixers, as well as the search for the most convenient forms of bacterial preparations for transportation and storage, which are able to live and multiply in the future.

Differences

Distinguish microorganisms of broad and narrow specificity. Looking for an answer to the question of its causes, scientists have identified the genetic transfer of specificity using plasmids at a time when bacteria multiply.

1. Highly specific. Capable of symbiosis with a limited number of species, and sometimes even varieties or forms. A striking example is lupine symbionts, which can only live on its alkaloid-free varieties.
2. Broadly specific. Able to infect plants of the same family or similar chemical composition.

Among the nitrogen-fixing symbiont bacteria, representatives of all taxonomic units of prokaryotes were identified - eubacteria, cyanobacteria (or blue-green algae), archaebacteria. Agronomists divided them into three groups depending on productivity:

• active or effective,
• ineffective or inactive,
• ineffective.

They also differ in virulence - this is the name of their ability to penetrate the roots of symbiont plants. The most productive are highly virulent active strains that combine a high rate of infection and production of nitrogen compounds.

A new development was rhizotorfin, a drug that contains finely dispersed peat and nodule bacteria. Its production is a kind of response to foreign manufacturers. By maintaining the necessary acidity and humidity in the briquette, it is possible to maintain the activity of bacteria, their ability to live and multiply for a long time.

Favorable conditions and life of bacteria inside the nodule

Nodule bacteria demonstrate different efficiency of nitrogen fixation depending on the conditions in which they live and reproduce. This is the acidity of the soil, its moisture, as well as the presence of organic substances (carbohydrates), potassium, phosphorus. Relatively recently, a positive effect on nodule bacteria of molybdenum was discovered. Its preparations, together with liming, lead to a significant increase in the amount of protein in the grains of legumes. The action of boron and molybdenum is due to the fact that they take part in the work of dehydrogenase enzymes.

There are nodule bacteria with different efficiency of nitrogen fixation. Sensitivity to habitat conditions largely depends on host plants and their requirements for soil quality. Thus, nodule microorganisms of clover are more resistant to high soil acidity than their relatives cooperating with alfalfa.

The optimum temperature for these microorganisms is 24-26°C. Their preparations can be stored in an inactive state at a temperature of -2 to -4°C.

Their appearance in root cells begins with penetration through the root hairs. First, a strand is formed inside the hair, then the bacteria penetrate the roots of plants, stimulating their growth and the formation of nodules. According to modern data, nodule bacteria are able to live only in polyploid (carrying an increased number of chromosome sets) cells of plant roots.

Interestingly, nodule bacteria exhibit a high degree of polymorphism. The answer to the question about the reasons for such a variety of forms was not found soon. Free-living nodule microorganisms or young cells found in cultures most often have the form of rods (bacilli). Sometimes these are cocci, L-forms with varying degrees of mobility. They are divided by lacing, and with age they acquire characteristic belts. All nitrogen-fixing bacteria are Gram-negative. Fat deposits accumulate in their cells over time - this is precisely what causes the formation of belted forms.

Nodules are formed only in representatives of the legume family (Fabaceae). AT various plants nodules differ only in shape and size. They are formed after penetration into the root system of nodule bacteria.

Numerous studies have shown that nodule bacteria differ from each other, and therefore the genus Rhizobium should be considered as a group of related microorganisms. AT young age these bacteria are motile, rod-shaped, 1.2 to 3 μm in length, the placement of flagella in some species is peritrichous, in others - subpolar. Nodule bacteria are Gram-negative, non-spore-bearing aerobic organisms.

Aging, nodule bacteria lose their flagella, cease to be mobile and take on the appearance of girdled rods, since with age the bacterial cell is filled with fatty inclusions and does not stain. With aging, thickened, branched, spherical and other forms of formation often appear in the nodules of the Rhizobium culture, much larger than ordinary cells. These polymorphic formations are called bacteroids.

Nodule bacteria can assimilate various carbohydrates, organic acids, and polyhydric alcohols. Amino acids are available to them as a source of nitrogen. For most Rhizobium crops optimal value The pH of the medium is 6.5-7.5, and the optimum temperature is 24-26 ° C.

It has been established that nodule bacteria can infect only a certain group of leguminous plants. The selective ability of these bacteria with respect to plants is called specificity. This property has become the main feature for the development of the taxonomy of nodule bacteria.

In some cases, not only species, but also varietal specificity of nodule bacteria is observed. In addition to specificity, these bacteria are characterized by virulence - the ability to penetrate the root tissue, multiply there and cause the formation of bubbles. Under certain conditions, these bacteria can reduce or even lose their activity.

An essential property of nodule bacteria is also their activity, that is, the ability to assimilate molecular nitrogen in symbiosis with plants. Strains of active and inactive nodule bacteria occur in the soil. Infection of leguminous plants with an active race of bacteria leads to the formation of a large number of bubbles on the main root and causes a vigorous process of atmospheric nitrogen fixation. Inactive races of these bacteria cause bubbles to form, but nitrogen is not fixed.

Nodules, which are formed by active races of bacteria, are pink in color. The pigment that gives them that color chemical composition close to blood hemoglobin and is called leghemoglobin (phytoglobin). It is believed that this pigment contributes to the process of nitrogen assimilation, maintaining the redox potential at a certain level. Nodules that form inactive races of bacteria are greenish in color.

The first soil bacteria that humanity noticed were nodule bacteria. Of the 13 thousand plants, about 1300 form a nodule, and 200 are used in agriculture. All of them have the function of fixing atmospheric nitrogen. In the soil on the nodule, microorganisms settle and multiply - symbionts that replace fertilizers.

What is nodule bacteria

More than 2 thousand years ago, farmers noticed that poor, exhausted soil resources yield crops after cultivation on them legumes. The next attempts to reveal the secret were in 1838: J.-B. Boussengo decided that the leaves of legumes fix nitrogen, but experiments with an unfavorable aquatic environment didn't confirm it. In 1901, Azotobacter chroococcum (6 species from the genus Azotobacter) was discovered. The first drug based on "earthen" bacteria Nitragin was created in 1897.

All nodule bacteria are microaerophiles. They have a rod-shaped/oval shape. Rhizobium (Rhizobiales) belong to those capable of converting the gaseous form of nitrogen into a plant-assimilable - soluble. Facts:

1. By the extent to which microorganisms affect the crop, they are divided into active (effectively enrich the soil), inactive and inactive (inefficient).
2. When there is no moisture, they do not reproduce, therefore, in a dry climate, specially infected plants are introduced deeper into the soil.
3. Optimum temperature for the reproduction of all representatives of nitrogen-fixing - 20-30°C, but growth continues at 0-35°C. The best environment (pH) is neutral, about 6.5-7.1, but acidic causes the death of colonies.
4. Thanks to the experiments of the Moscow Agricultural Academy, it turned out that even in the absence of "donors", the bacterial material does not leave the soil for up to 50 years.
5. Microorganisms are able to survive even the conditions after an atomic explosion, withstand gamma radiation and ultraviolet, solar radiation, but cannot live in high temperature.
6. Microorganisms are of maximum importance for root development.

The role of nodule bacteria in nature

In addition to the fixation of atmospheric nitrogen, the role of nodule bacteria in nature is very large. In the process of reproduction, they "engage" in the synthesis of vitamins, natural antibiotics, and contribute to the development of the root first, and then the tops. The benefit lies in the fact that soil bacteria of the nitrogen-fixing type due to symbiosis with plants:

• are part of the cycle of matter - nitrogen;
• synthesize phytohormones, stimulating plant growth;
• can be used as a way of self-purification of soils contaminated with heavy metals under mineralizing factors (natural / enterprises);
• decompose some chlorine-containing compounds.

Legumes and nodule bacteria

• through tissue damage
• penetration through the root hairs;
• penetration through young root tips;
• thanks to companion bacteria.

Symbiotic bacteria of the genus Rhizobium, having penetrated into the root, move into its tissues, easily overcoming the intercellular space in groups or single cells (like in lupine). More often, during reproduction, the cell forms infectious threads (strands, colonies). Their number varies by plant type. Often there are common threads of infection, forming a single nodule.

Nitrogen fixation by bacteria

The value that nitrogen fixation by bacteria represents is enormous: it not only restores the soil, but also allows you to get richer crops than on humus or chemical fertilizers. There is an interaction between the substance and the nitrogen fixer:

• in Azotobacter (“autonomous”, not requiring the presence of a plant) - by enzymes, due to oxygen in the cell;
• in Rhizobium (nodule bacteria) - only in the presence of magnesium, sulfur, iron.

Nodule bacteria are specific - certain types or their races are able to form nodules on the roots of only certain legumes. So, some of them develop only on the roots of clover, but cannot infect the roots of peas, alfalfa, lupine and other legumes. Groups of bacteria that form nodules on the roots of lupine and seradella do not infect the roots of clover and peas, etc. Sometimes the specificity of nodule bacteria is so pronounced that various varieties one but G? and the same culture (or even plant varieties) have different attitudes towards one or another strain of bacteria. For example, the roots of yellow fodder lupins are not always well infected with nodule bacteria from the roots of annual bitter lupins. Groups of nodule bacteria according to their specificity are indicated on page 382.[ ...]

Nodule bacteria develop most intensively when the soil reaction is close to neutral. Therefore, when sowing legumes on acidic soils ah, along with the inoculation of seeds, liming of the soil is necessary. Inoculation without liming has very little effect on yield and protein content. According to K. Fillers, when soybeans were grown on acidic soil without inoculation and without lime, the protein content in the seeds was 32.8%; increased by 11.2%.[ ...]

Nodule bacteria of various leguminous plants die in acidic soils.[ ...]

Nodule bacteria need a sufficient supply of carbohydrates, phosphorus and calcium to them. AT last years It has been established that a number of microelements (especially molybdenum) play an important role in the vital activity of nodule bacteria. Liming and the use of molybdenum for legumes on acidic soils regulate the reaction of the soil; sufficient supply of legumes with phosphorus is needed on all soils.[ ...]

Prokaryotes (bacteria, archaebacteria, cyanobacteria) - unicellular organisms, do not have a nucleus. Due to this diverse metabolism, bacteria can exist in the most various conditions environments: in water, air, soil, living organisms. The role of bacteria in the formation of oil is great, hard coal, peat, natural gas, in soil formation, in the cycles of nitrogen, phosphorus, sulfur and other elements in nature. Saprotrophic bacteria participate in the decomposition of the organic remains of plants and animals and in their mineralization to CO2, H20, H2S, ICHH3 and other inorganic substances. Together with fungi, they are decomposers. Nodule bacteria (nitrogen-fixing) form a symbiosis with leguminous plants and are involved in the fixation of atmospheric nitrogen into mineral compounds available to plants. Plants themselves do not have this ability.[ ...]

In the absence of nodule bacteria on the roots of legumes, they become the same consumers of nitrogen from the soil as other plants.[ ...]

An important property root nodule bacteria is their activity (efficiency), i.e., the ability to assimilate molecular nitrogen in symbiosis with leguminous plants and satisfy the needs of the host plant in it. Depending on the extent to which nodule bacteria contribute to an increase in the yield of legumes (Fig. 146), they are usually divided into active (effective), inactive (ineffective) and inactive (ineffective).[ ...]

Among nitrogen-fixing bacteria, free-living in the soil and nodule bacteria living on the roots of leguminous plants are distinguished (Fig. 9, h). The most important representatives of free-living nitrogen-fixing bacteria are Azotobacter and Clostridium, which fix several tens of kilograms of nitrogen per 1 ha of soil per year. The activity of nodule bacteria, which infect the cells of the roots of legumes, is much more effective. As a result, microbiological accumulation of nitrogen available to plants occurs under legumes. Under an area of ​​1 ha, sown with clover, as a result of the action of these bacteria, 100 times more nitrogen can be accumulated than free-living fixatives of this element.[ ...]

Since nodule bacteria do not reproduce in the absence of moisture, in the event of a dry spring, inoculated (artificially infected) seeds must be applied deeper into the soil. For example, in Australia, seeds coated with nodule bacteria are buried deep into the soil. Interestingly, root nodule bacteria in soils of arid climates are more resistant to drought than bacteria in soils of humid climates. This shows their ecological adaptability.[ ...]

In addition to specificity, nodule bacteria races differ in virulence and activity. Virulence - the ability of them to penetrate through the root hairs into the root of a leguminous plant and form nodules. The activity of nodule bacteria is called their ability to assimilate atmospheric nitrogen. Only active strains of these bacteria supply legumes with nitrogen. When the roots are infected with virulent but inactive nodule bacteria, nodules are formed, but nitrogen fixation does not occur. Nodule bacteria used for the preparation of nitragin must have high virulence and high activity. If the virulence of nitragin nodule bacteria is higher than the virulence of less active bacteria already in the soil, then this allows nitragin nodule bacteria to penetrate into the root faster and in large numbers.[ ...]

Of all these examples, the symbiosis of nodule bacteria with legumes has been studied most carefully, since these plants are of great importance for humans.[ ...]

Big influence the soil reaction affects the vital activity of nodule bacteria and the formation of nodules. For different types and even strains of nodule bacteria, the pH value of the habitat is somewhat different. For example, clover nodule bacteria are more resistant to low pH values ​​than alfalfa nodule bacteria. Obviously, the adaptation of microorganisms to the environment also affects here. Clover grows in more acidic soils than alfalfa. Soil reaction as an ecological factor affects the activity and virulence of nodule bacteria. The most active strains tend to be easier to isolate from soils with neutral pH values. In acidic soils, inactive and weakly virulent strains are more common. Acidic environment (pH 4.0-4.5) direct influence and on plants, in particular by disrupting the synthetic processes of plant metabolism and the normal development of root hairs.[ ...]

Exist a large number of species and races of nodule bacteria, each of which has adapted to the infection of one or more species of leguminous plants. The root systems of leguminous plants have specific root secretions. Due to this, nodule bacteria accumulate around the root hairs, which are twisted during the atom. Through the root hair, bacteria in the form of a continuous strand, consisting of countless bacteria connected by mucus, penetrate into the root parenchyma. Vovmozhpo, bacteria secrete the hormone auxin in the ato is the cause of tissue growth, swellings are formed - nodules. Nodule cells are filled with rapidly reproducing bacteria, but remain alive and retain large nuclei. Nodule bacteria infect only polyploid root cells.[ ...]

Alfalfa as a leguminous plant is capable of accumulating a large amount of nitrogen in the soil with the help of nodule bacteria on the roots, not yielding in this respect to clover. Its root system develops better in the 1st year of use, and by the 3rd year it accumulates nitrogen in the soil 120 ... 200 kg / ha. By increasing soil fertility and improving its structure, alfalfa is a good predecessor in crop rotation.[ ...]

When lupins are cultivated, nitragin is used to increase the activity of lupine nodule bacteria, boric and molybdenum microfertilizers are also useful (the seeds are treated with a solution of ammonium molybdate simultaneously with their nitraginization).[ ...]

Anaerobic decomposition of cellulose is carried out only by bacteria (for example, Omelyansky's bacillus), and aerobic - by many types of bacteria, fungi, actinomycetes.[ ...]

This indicates that the fixed labeled nitrogen enters the bacterial bodies from the tissues of the higher plant, which is the source of nitrogen nutrition for the bacteria. Thus, the fixation of atmospheric nitrogen is localized not in the body of nodule bacteria, but in the nodule tissue of the higher plant. Important role nodule bacteria lies in the fact that they induce the formation of this specific nodule tissue. Further studies showed that the maximum content of labeled nitrogen in individual nitrogenous fractions of nodule cell sap always falls on the amide group of asparagine and glutamine. Since this group can be considered as transformed ammonia, it is ammonia that is the final inorganic product of biological nitrogen fixation.[ ...]

In the biosphere, nitrogen fixation is carried out by several groups of anaerobic bacteria and cyanobacteria. normal temperature and pressure, due to the high efficiency of biocatalysis. It is believed that bacteria convert approximately 1 billion tons of nitrogen per year into a bound form (the world volume of industrial fixation is about 100 million tons). In nodule bacteria of leguminous plants, nitrogen fixation is carried out with the help of a complex enzyme complex protected from excess oxygen by special plant hemoglobin.[ ...]

One of the reasons for the positive effect of molybdenum on the fixation of molecular nitrogen by nodule bacteria is the increase under its action of the activity of dehydrogenases, which provide a continuous influx of activated hydrogen necessary for the reduction of atmospheric nitrogen.[ ...]

The value of the new nitragin preparation lies in the long-term preservation of the viability of root nodule bacteria and the possibility of early preparation of preparations by a mechanized method. In terms of efficiency, dry nitragin is close to soil. It can be applied as a dust, dusting the seeds without soaking them.[ ...]

Particularly significant in the nitrogen cycle is the role of symbiotic (from the Greek. symbiosis - cohabitation) nodule bacteria, localized on the roots of plants, mainly of the legume family. Bacteria of the genera Azotobacter or Rhizobium are capable of fixing atmospheric nitrogen by enzymatic cleavage of N3 molecules and making it available to plant root systems.[ ...]

Biological fixation of atmospheric molecular nitrogen in the soil is carried out by two groups of bacteria: free-living aerobic and anaerobic and nodule bacteria living in symbiosis with leguminous plants. The most important representative of the first group of aerobes is Azotobacter, and of the anaerobic - Clostridium pasteurianum. A favorable environment for the vigorous activity of nodule bacteria is well-aerated soils with a slightly acidic and neutral reaction. The activity of nitrogen-fixing bacteria importance in the overall balance of nitrogen in agriculturally used soils. Therefore, for the activity of nodule bacteria, it is important to cultivate soils. To increase the number of root nodule bacteria, the bacterial preparation nitragin, which contains active races of nodule bacteria, is introduced into the soil.[ ...]

According to the Research Institute of Agricultural Microbiology, in a number of soils nodule bacteria corresponding to one or another legume culture may be absent, and those that are present have an unproductive system of nitrogen fixation. In this regard, microbiologists carried out selection work. As a result, every three years, up to ten new strains of nodule bacteria are transferred to plants, the nitrogen-fixing capacity of which is 10-20% higher than the previous reference strains. The drug rhizotorfin has been created and mass-produced - a convenient and practical form of delivery of nodule bacteria to seeds and growing roots of legumes.[ ...]

Organic and mineral fertilizers (phosphorus-potassium) introduced into the soil significantly improve the ability of nodule bacteria to assimilate atmospheric nitrogen. To activate the activity of nodule bacteria, acidic soils must be limed, and soils in arid regions must be provided with moisture.[ ...]

Mutualism is an interaction between two organisms of different species that is beneficial to each of them. For example, nitrogen-fixing nodule bacteria live on the roots of leguminous plants, converting atmospheric nitrogen into a form available for uptake by these plants. Therefore, bacteria provide plants with nitrogen. In turn, plants provide nodule bacteria with all the necessary nutrients. Mutualism can also be considered the interaction between microorganisms living in the human large intestine and the person himself. For microorganisms, the benefit is determined by the fact that they provide their nutritional needs at the expense of the contents of the intestine, and for humans, the benefit lies in the fact that microorganisms carry out additional digestion of food and also synthesize vitamin K, which is essential for it. In the world of flowering plants, pollination by insects of plants is mutualism. and nutrition of insects with plant nectar. Mutualism is also significant in the "recycling" of organic substances. For example, the digestion of cellulose in the stomach (rumen) of cattle is provided by the bacteria contained in it.[ ...]

The peculiarity of the nutrition of legumes is that they do not need the presence of mineral nitrogen compounds in the soil. In symbiosis with nodule bacteria, leguminous plants use the free nitrogen of the atmosphere. Therefore, these crops are a source of biological nitrogen for Agriculture.[ ...]

In this regard, the practice of agriculture has firmly entered the method of inoculation - pre-sowing treatment of seeds of leguminous plants with a preparation of nodule bacteria of the corresponding species. AT different countries a technical preparation for the inoculation of leguminous plants has received different names. In the USSR, the GDR, the FRG and Poland, it is called nitragin. Hence, the reception of inoculation of the respective cultures in these countries is called nitragynization. Nitragin increases the yield of leguminous plants by 10-15%, and in new areas of cultivation - by 50% or more.[ ...]

As noted above, clover grows poorly on acidic soils, often thins out, and sometimes falls out completely and even in the 1st year of use. The vital activity of nodule bacteria on such soils is suppressed. Soil acidity, especially in the northwestern regions of the Non-Chernozem Zone (here more than half of the arable land has hyperacidity), in the presence of mobile forms of aluminum in them, is one of the reasons for the decrease in the yield of grasses.[ ...]

Atmospheric nitrogen fixation. none green plant cannot feed directly on atmospheric nitrogen. Since, as a result of the activity of denitrifying bacteria, there is a continuous decrease in the reserves of bound nitrogen in nature and its conversion into atmospheric nitrogen, life on the earth would be threatened with inevitable death due to nitrogen starvation. However, there is a group of microorganisms capable of fixing atmospheric nitrogen, making it available to plants. These microorganisms are called nitrogen-fixing bacteria, they are divided into nodule bacteria that develop on the roots of leguminous plants, and free-living in the soil.[ ...]

As a result of these studies, it was found that the labeled gaseous nitrogen of the atmosphere fixed by legumes initially in large quantities is contained only in the cell sap of the nodule tissue, which is a hypertrophied root tissue of legumes, from where it then gradually passes into other plant organs. In nodule bacteria, labeled nitrogen is completely absent during plant exposure from 6 to 48 hours or is contained in extremely small amounts, usually not exceeding possible error experiment (Table 4).[ ...]

In addition, P. S. Kossovich belongs to the studies of the circulation of sulfur and chlorine in nature and economy, which have not lost their importance to this day, as well as the proof of the position that nodule bacteria bind atmospheric nitrogen, which came through the roots, and not through the leaves of leguminous plants. He successfully studied the root secretions of crops, especially the isolation carbon dioxide, linking it with the assimilative ability of the roots.[ ...]

A community of organisms based on mutual benefit, when two species create a favorable environment for each other to develop, is called symbiosis. An example is the relationship between nodule bacteria and leguminous plants. Nodule bacteria receive nitrogen-free organic substances and mineral salts from a leguminous plant, and in return provide it with nitrogenous substances synthesized by them from atmospheric nitrogen.[ ...]

Aminoautotrophs include microorganisms that use nitrogen from ammonia salts, nitrate salts and urea. Aminoautotrophs, when using nitrogen from mineral compounds, first convert it into ammonia nitrogen, and then consume it to build amino acids, from which proteins are synthesized. The preliminary conversion of nitrogen into ammonia is explained by the fact that nitrogen in the microbial cell is in a reduced state in the form of amino (NH2) and imino groups (NH). The role of nitrogen in the protein substances of bacterial protoplasm is that it imparts reactivity to the proteins. Nitrogen is difficult to enter into compounds due to inertness, but easily leaves them.[ ...]

The influence of the predecessor affects primarily the supply of fertilized crops with nitrogen. Plants sown after legumes, which leave some nitrogen assimilated by nodule bacteria from the atmosphere, respond better to phosphorus than those following other predecessors. S. P. Kulzhinsky (1935) illustrated this situation with data from Ukrainian experimental stations (Table 72).[ ...]

Behind recent times more and more data are accumulating that many lysogenic cultures contain 2, 3, 4 or more temperate phages, that is, they are polylysogenic. For example, many actinomycetes, proactinomycetes, nodule bacteria and some spore-bearing bacteria contain 4 or more phages. The phages contained in polylysogenic cultures often differ sharply from each other in particle shape, antigenic properties, and spectrum of lytic activity. Polylysogenic cultures can be experimentally obtained by exposing them simultaneously or sequentially to various temperate phages. Cultures obtained in this way do not differ from those isolated from natural sources.[ ...]

These changes can be both positive for fertility and negative. An example of positive changes is the elimination of excess acidity as a result of liming, the accumulation of nitrogen due to the activity of nodule bacteria during legume crops, the removal of harmful salts in irrigated soils after their washing, the improvement of the water-air regime due to the loosening of the subsurface layer, etc. [ .. .]

Green manure First of all, it enriches the soil with organic matter and nitrogen. Often, depending on the conditions of its use, 35-45 tons of organic matter containing 150-200 kg of nitrogen fixed from the air by nodule bacteria are plowed per hectare of arable land (when sowing bean green manure).[ ...]

Mutualism (symbiosis): each of the species can live, grow and reproduce only in the presence of the other. Symbionts can be only plants, or plants and animals, or only animals. Typical examples of food-conditioned symbionts are nodule bacteria and legumes, mycorrhiza of some fungi and tree roots, lichens and termites.[ ...]

However, in nature and economy there are significant differences in the cycle of nitrogen and phosphorus. As you know, almost 4D of air consists of molecular nitrogen. And although it is not available to higher plants, it is absorbed by some microorganisms, in particular nodule bacteria that live on the roots of legumes. These bacteria supply nitrogenous food not only legumes. When crop residues are plowed into the soil and the roots decompose, a sufficient amount of nitrogen remains for a crop sown after legumes, especially after clover and alfalfa.[ ...]

Peas only enrich the soil with nitrogen when nodules develop on its roots, while the larger and more powerful, the better soil enriched with nitrogen. For this purpose, pea seeds must be treated on the day of sowing with nitragin under a canopy, protecting nitrogen-fixing bacteria from the harmful effects of sunlight. The contents of one bottle of nitragin dissolved in 2 liters of water are moistened with seeds, shoveling them. Dried seeds are sown without delay. Nitraginization causes early nodule formation and promotes better development plants. The use of nitragin is effective in early sowing peas in moist soil. On uncalcified acidic soils, nodule bacteria develop poorly and the effect of nitragin sharply decreases.[ ...]

A typical example symbiosis can serve as a close cohabitation between fungi and algae, leading to the formation of a more complex and more adapted to natural conditions plant organism - lichen. Other a prime example symbiotic cohabitation in the soil is the symbiosis of fungi with higher plants, when the fungi form microbiota on the roots of plants. A pronounced symbiosis is observed between nodule bacteria and leguminous plants.[ ...]

D. N. Pryanishnikov argued that for our country, it is not grass fields that are more promising, but intensive crop rotations. It was they who replaced the three-field grain type, which dominated for a thousand years in Western Europe. Under the three fields, a third of the land was empty (late fallow), and two thirds were sown with grain crops. Legumes were not cultivated, which ruled out the possibility of air nitrogen mobilization with the help of nodule bacteria and adversely affected the nitrogen nutrition of plants and the nitrogen cycle in agriculture. In this crop rotation, tilled crops, including potatoes and root crops, were almost absent, which led to weediness of the fields and a constant lack of fodder. For centuries, the peasant economy (with the exception of the kulak elite) could not break out of the vicious circle noted by the famous Russian agronomist of the 18th century. A. T. Bolotov, who wrote: “... without manure, the land does not produce a crop, and there is little manure, since there are few livestock, and there are few livestock, since there is little fodder, and there is little fodder, because without manure the land does not yield "(1779).[ ...]

Difficulties in storage, transportation and use of nitragin agar and broth preparations, as well as their short shelf life, are serious reasons that contribute to the displacement of this preparation from production. Bulk powder preparations of nitragin have undeniable advantages over agar and broth preparations. The technology of their manufacture is simpler and more economical. Peat crops last longer and are easier to transport. They protect nodule bacteria cells from direct contact with fertilizers and keep them viable on seeds, especially when seeds are granulated with lime.[ ...]

The higher plant according to the scheme is a source of carbon-containing compounds. Their transformation provides energy material for the processes of activation and reduction of N2. Activated nitrogen is the final electron acceptor. The products of incomplete oxidation of carbon-containing compounds serve as ICH3 acceptors and form amino acids in the nodules, which become available to the higher plant. Plants act as a store of carbon-containing compounds (products of photosynthesis) and an energy supplier. Nodule bacteria in the stage of bacteroids show the ability to transfer activated hydrogen to nitrogen with the help of nitrogenase. The path from N2 to T Shz is considered as a recovery process.[ ...]

Pea plants have the ability to absorb nitrogen from the air, enriching the soil with it, and therefore the main direction in the fertilizer system should be the use of phosphorus and potash fertilizers. well developed root system peas are highly digestible nutrients, however, for a significant increase in yield, one cannot count on the use of the aftereffect of fertilizers in the crop rotation, and therefore direct application is necessary. mineral fertilizers under the peas It is responsive to the use of phosphate and potash fertilizers. Phosphorus helps accelerate the maturation of plants. With a lack of it in the soil, nodule bacteria develop poorly on the roots, and the yield decreases. With a lack of potassium, the leaves turn yellow, and the beans develop poorly, especially on soils that are light in texture. On acidic soils, peas sharply reduce the yield, the activity of nodule bacteria is weakened. Therefore, liming acidic soils is prerequisite increase in pea yield and higher efficiency of applied mineral fertilizers. The dose of lime depends on the acidity of the soil (3...6 t/ha), it is better to apply lime under the previous crops.[ ...]

One of the most important processes interactions of microorganisms with higher plant is the symbiotic fixation of atmospheric nitrogen - the main element that determines the size and quality of the crop. The total amount of molecular nitrogen involved in the biological cycle by the symbiotic legume-rhizobium system is 3 million tons annually in the USSR alone. Long-term domestic and foreign experience shows that effective legume-rhizobium symbiosis is not only a guarantee of obtaining a high and high-quality crop of legumes , and consequently, the possibility of solving the problem of food protein, but also the most economical source of nitrogen replenishment in the soil. In order to use cheap “biological nitrogen” in agricultural production in many countries, the area under legumes is being increased, and pre-sowing treatment seeds with preparations of nodule bacteria obtained on the basis of active strains of Rhizobium. The nature and efficiency of the symbiotic relationship between a leguminous plant and nodule bacteria depend on the physiological and biochemical state of both partners, and therefore the influence of any factors on one of them will certainly affect the productivity of the system as a whole.