seed barley irradiation laser

The most important and effective part of the treatment is chemical, or seed dressing.

Even 4 thousand years ago, in Ancient Egypt and Greece, seeds were soaked in onion juice or stored with cypress needles.

In the Middle Ages, with the development of alchemy and, thanks to it, chemists began to soak seeds in rock and potassium salt, copper sulfate, arsenic salts. In Germany, the simplest methods were popular - keeping seeds in hot water or in a manure solution.

At the beginning of the 16th century, it was noticed that seeds that had been in sea water during a shipwreck produced crops that were less affected by smut. Much later, 300 years ago, the effectiveness of pre-sowing chemical seed treatment was scientifically proven during the experiments of the French scientist Thiele, who studied the effect of treating seeds with salt and lime on the spread of smut through seeds.

At the beginning of the 19th century, the use of preparations with arsenic as dangerous to human life was prohibited, but at the beginning of the 20th century they began to use mercury-containing substances, which were banned for use only in 1982, and only in Western Europe.

And only in the 60s of the last century were developed systemic fungicides for pre-treatment of seeds, and industrial countries began to actively use them. Since the 90s, complexes of modern, highly effective and relatively safe insecticides and fungicides have been used.

Depending on the seed treatment technology, there are three types: simple dressing, panning and encrusting.

Standard dressing is the most common and traditional method of seed treatment. Most often used in gardens and farms, as well as in seed production. Increases seed weight by no more than 2%. If the film-forming composition completely covers the seeds, their weight can increase by up to 20%

Encrusting - seeds are coated with sticky substances to ensure that chemicals adhere to their surface. Treated seeds may become 5 times heavier, but the shape does not change.

Pelleting - substances cover the seeds with a thick layer, increasing their weight up to 25 times and changing their shape to spherical or elliptical. The most “powerful” panning (pelletizing) makes seeds up to 100 times heavier.

The most widely used preparations for treating grain seeds are Raxil, Premix, Vincit, Divident, and Colfugo Super Color. These are systemic fungicides that kill spores of stone, dusty and hard smut, nematodes, effectively fighting fusarium, septoria and root rot. They are produced in the form of liquids, powders or concentrated suspensions and are used for processing seeds in special devices at the rate of 0.5-2 kg per 1 ton of seeds.

In private households and farms, the use of strong chemicals is not always justified. Relatively small quantities of small seeds of vegetable or ornamental crops, such as marigolds, carrots or tomatoes, can be treated with less toxic substances. It is important not only and not so much to initially destroy the entire infection on the seeds, but also to form in the plant, even at the stage of the seed embryo, resistance to diseases, that is, lasting immunity.

At the beginning of germination, the influence of growth stimulants is also useful, which will promote the development of a large number of lateral roots in plants, creating a strong root system. Plant growth stimulants that enter the embryo before germination begin cause active transport of nutrients to the above-ground parts of the plant. Seeds treated with such preparations germinate faster and their germination rate increases. Seedlings become more resistant not only to diseases, but also to temperature changes, lack of moisture and other stressful conditions. More long-term consequences of proper pre-treatment with pre-sowing preparations are considered to be an increase in yield and a reduction in ripening time.

Many preparations for pre-sowing seed treatment are created on a humic basis. They are a concentrated (up to 75%) aqueous solution of humic acids and humates, potassium and sodium, saturated with a complex of mineral substances necessary for the plant, which can also be used as a fertilizer. Such preparations are produced on the basis of peat, being its aqueous extract.

Z.F. Rakhmankulova and co-authors studied the effect of pre-sowing treatment of wheat (Triticum aestivum L.) seeds with 0.05 mm salicylic acid (SA) on its endogenous content and the ratio of free and bound forms in the shoots and roots of seedlings. During the two-week growth of seedlings, a gradual decrease in the total SA content in the shoots was observed; no changes were detected in the roots. At the same time, there was a redistribution of SA forms in the shoots - an increase in the level of the conjugated form and a decrease in the free form. Pre-sowing treatment of seeds with salicylate led to a decrease in the total content of endogenous SA in both shoots and roots of seedlings. The content of free SA decreased most intensively in the shoots, and slightly less in the roots. It was assumed that this decrease was caused by a violation of SA biosynthesis. This was accompanied by an increase in the mass and length of shoots and especially roots, stimulation of total dark respiration and a change in the ratio of the respiratory tract. An increase in the proportion of the cytochrome respiration pathway was observed in the roots, and an alternative cyanide-resistant one was observed in the shoots. Changes in the antioxidant system of plants are shown. The degree of lipid peroxidation was more pronounced in the shoots. Under the influence of SA pretreatment, the MDA content in the shoots increased by 2.5 times, while in the roots it decreased by 1.7 times. From the presented data it follows that the nature and intensity of the effect of exogenous SA on growth, energy balance and antioxidant status of plants may be associated with changes in its content in cells and with redistribution between free and conjugated forms of SA.

E.K. In production experiments, Eskov studied the effect of pre-sowing treatment of corn seeds with iron nanoparticles on the intensification of growth and development, increasing the yield of green mass and grain of this crop. As a result, photosynthetic processes intensified. The content of Fe, Cu, Mn, Cd and Pb in the ontogenesis of corn varied widely, but the adsorption of Fe nanoparticles at the initial stages of plant development influenced the decrease in the content of these chemical elements in the ripening grain, which was accompanied by a change in its biochemical properties.

Thus, pre-sowing treatment of seeds with chemicals is associated with high labor costs and low technological efficiency of the process. In addition, the use of pesticides to disinfect seeds causes great harm to the environment.

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

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Posted on http://www.allbest.ru/

MINISTRY OF EDUCATION OF THE REPUBLIC OF BELARUS

Educational institution

"MOZYR STATE

PEDAGOGICAL UNIVERSITY named after. I.P. SHAMYAKIN"

DEPARTMENT OF BIOLOGY

DEPARTMENT OF NATURE MANAGEMENT AND NATURE CONSERVATION

Coursework in the discipline

"plant physiology"

The influence of minerals on plant growth and development

Executor:

Bogdanovich Vladimir Grigorievich

MOZYR 2011

INTRODUCTION

CHAPTER 1. LITERATURE REVIEW

1.3 Phosphorus

1.6 Calcium

1.7 Magnesium

3.4 Nitrogen deficiency

3.5 Phosphorus deficiency

3.6 Sulfur deficiency

3.7 Potassium deficiency

3.8 Calcium deficiency

3.9 Magnesium deficiency

CONCLUSION

BIBLIOGRAPHICAL LIST

INTRODUCTION

mineral substance plant

Mineral nutrition of plants is a set of processes of absorption, movement and assimilation by plants of chemical elements obtained from the soil in the form of ions of mineral salts.

Each chemical element plays a special role in the life of a plant.

Nitrogen is a component of amino acids, the building blocks that make up proteins. Nitrogen is also found in many other compounds: purines, alkaloids, enzymes, growth regulators, chlorophyll and cell membranes

Phosphorus is absorbed by the plant in the form of salts of phosphoric acid (phosphates) and is found in it in a free state or together with proteins and other organic substances that make up the plasma and nucleus.

Sulfur is absorbed by the plant in the form of sulfuric acid salts and is part of proteins and essential oils.

Potassium is concentrated in young organs rich in plasma, as well as in organs storing reserve substances - seeds, tubers; it probably plays the role of a neutralizer of the acidic reaction of cell sap and is involved in turgor.

Magnesium is found in the plant in the same place as potassium, and, in addition, is part of chlorophyll.

Calcium accumulates in adult organs, especially in leaves, serves as a neutralizer of oxalic acid, which is harmful to the plant, and protects it from toxic effects. various salts, participates in the formation of mechanical shells.

In addition to the indicated vital elements, sodium chloride, manganese, iron, fluorine, iodine, bromine, zinc, cobalt, which stimulate plant growth, etc., are of particular importance.

Purpose: To study the effect of minerals on the growth and development of plants.

1. Study material about the main types of minerals and their effect on the growth and development of plants.

2. Familiarize yourself with methods for determining minerals in plant tissues.

3. Identify symptoms of insufficient and excessive mineral content in plants

CHAPTER 1. LITERATURE REVIEW

Plants are capable of absorbing almost all elements from the environment in larger or smaller quantities. periodic table. Meanwhile for normal life cycle A plant organism requires only a certain group of basic nutrients, the functions of which in the plant cannot be replaced by other chemical elements. This group includes the following 19 elements:

Among these basic nutritional elements, only 16 are actually mineral, since C, H and O enter plants mainly in the form of CO 2, O 2 and H 2 O. The elements Na, Si and Co are given in parentheses, since they are necessary for all higher plants not yet installed. Sodium is absorbed in relatively high quantities by some species of the family. Chenopodiaceae (chenopodiaceae), in particular beets, as well as species adapted to salinity conditions, is also necessary in this case. The same is true for silicon, which is found in especially large quantities in the straw of cereals; for rice it is an essential element.

The first four elements - C, H, O, N - are called organogens. Carbon on average makes up 45% of the dry mass of tissues, oxygen - 42, hydrogen - 6.5 and nitrogen - 1.5, and all together - 95%. The remaining 5% comes from ash substances: P, S, K, Ca, Mg, Fe, Al, Si, Na, etc. The mineral composition of plants is usually judged by analyzing the ash remaining after burning the organic matter of plants. The content of mineral elements (or their oxides) in a plant is expressed, as a rule, as a percentage of the dry matter mass or as a percentage of the ash mass. The ash substances listed above are classified as macroelements.

Elements that are present in tissues in concentrations of 0.001% or less of the dry mass of tissues are called microelements. Some of them play an important role in metabolism (Mn, Cu, Zn, Co, Mo, B, C1).

The content of one or another element in plant tissues is not constant and can vary greatly under the influence of environmental factors. For example, Al, Ni, F and others can accumulate in plants to toxic levels. Among higher plants there are species that sharply differ in the content in the tissues of such elements as Na, as already mentioned, and Ca, and therefore the groups of plants are natriephiles, calciumphiles (most legumes, including beans, legumes, clover), calciumphobes (lupine, whiteweed, sorrel, etc.). These species characteristics are determined by the nature of the soils in the places of origin and habitat of the species, a certain genetically fixed role that these elements play in plant metabolism.

The leaves are richest in mineral elements, in which ash can range from 2 to 15% of the dry matter weight. The minimum ash content (0.4-1%) was found in tree trunks.

Nitrogen was discovered in 1772 by the Scottish chemist, botanist and physician D. Rutherford as a gas that does not support respiration and combustion. That’s why it was called nitrogen, which means “non-life.” However, nitrogen is part of proteins, nucleic acids and many vital organic substances. Eliminating the deficiency of some essential nitrogen-containing compounds - amino acids, vitamins, etc. - is the most acute problem of humankind's food programs.

Nitrogen is one of the most widely distributed elements in nature. Its main forms on Earth are bound nitrogen of the lithosphere and gaseous molecular nitrogen (N 2) of the atmosphere, which makes up 75.6% of air by mass. According to calculations, the reserves of N 2 in the atmosphere are estimated at 4 * 10 15 tons. An air column above 1 m 2 of the earth's surface contains 8 tons of nitrogen. However, molecular nitrogen as such is not absorbed by higher plants and can be converted into a form accessible to them only due to the activity of nitrogen-fixing microorganisms.

The reserves of fixed nitrogen in the lithosphere are also significant and are estimated at 18 * 10 15 tons. However, only a minimal part of the Earth's lithospheric nitrogen is concentrated in the soil, and only 0.5 - 2% of the total reserve in the soil is directly available to plants. On average, 1 hectare of arable chernozem contains no more than 200 kg of nitrogen available to plants, and on podzols its amount is 3-4 times less. This nitrogen is presented mainly in the form of NH 4 + - and NO 3 -ions.

Nitrogen-fixing microorganisms. Microorganisms that carry out biological nitrogen fixation can be divided into two main groups: a) free-living nitrogen fixers and b) microorganisms living in symbiosis with higher plants.

Free-living nitrogen fixers are heterotrophs, require a carbohydrate source of nutrition and are therefore often associated with microorganisms capable of decomposing cellulose and other polysaccharides. Bacteria of the genera Azotobacter and Beijerinckia, as a rule, settle on the surface of the roots of higher plants. Such associations are explained by the fact that bacteria use products released by roots into the rhizosphere as a carbon source.

Much attention has recently been paid to cyanobacteria, in particular Tolypothrix tenius. Enriching rice fields with them increases the rice yield by an average of 20%. In general, the agricultural importance of free-living nitrogen fixers is not so great. In temperate climates, their annual nitrogen fixation is, as a rule, several kilograms of nitrogen per 1 ha, but if there are favorable conditions in the soil (for example, a large amount of organic residues), it can reach 20 - 40 kg N/ha.

The group of symbiotic nitrogen fixers primarily includes bacteria of the genus Rhizobium, which form nodules on the roots of legumes, as well as some actinomycetes and cyanobacteria. Currently, there are about 190 species of plants of different families that are capable of symbiotically assimilating nitrogen. These include some trees and shrubs: alder, waxwort, oleaster, sea buckthorn, etc. The nodules growing on the roots of alder and some other non-legume plants are inhabited by actinomycetes of the genus Frankia.

Of greatest interest to Agriculture represent nodule bacteria of the genus Rhizobium, living in symbiosis with leguminous plants and fixing on average from 100 to 400 kg N/ha per year. Among leguminous crops, alfalfa can accumulate up to 500 - 600 kg N/ha per year, clover - 250 - 300, lupine - 150, broad beans, peas, beans - 50 - 60 kg N/ha. Due to crop residues and green manure, these plants significantly enrich the soil with nitrogen.

Nitrogen reserves in the soil can be replenished in different ways. When cultivating agricultural crops, much attention is paid to the application of mineral fertilizers. Under natural conditions, the main role belongs to specialized groups of microorganisms. These are nitrogen fixers, as well as soil bacteria, capable of mineralizing and converting into the form NH 4 + or NO 3 - organic nitrogen of plant and animal residues and humus nitrogen, which account for the bulk of soil nitrogen, which is not available to plants.

The content of nitrogen available to plants in the soil is determined not only by the microbiological processes of mineralization of organic nitrogen and nitrogen fixation, as well as the rate of nitrogen absorption by plants and its leaching from the soil, but also by the loss of nitrogen in the process of denitrification, carried out by anaerobic microorganisms capable of reducing the NO 3 ion to gaseous N 2. This process occurs especially intensively in wet, flooded, weakly aerated soils, in particular in rice fields.

Thus, nitrogen is a very labile element that circulates between the atmosphere, soil and living organisms.

1.3 Phosphorus

Phosphorus, like nitrogen, - essential element plant nutrition. It is absorbed by them in the form of the higher oxide PO 4 3- and does not change, being included in organic compounds. In plant tissues, the concentration of phosphorus is 0.2-1.3% of the dry mass of the plant.

Forms of phosphorus compounds available to plants

Phosphorus reserves in the arable soil layer are relatively small, about 2.3 - 4.4 t/ha (in terms of P 2 O 5). Of this amount, 2/3 comes from mineral salts of orthophosphoric acid (H 3 PO 4), and 1/3 from organic compounds containing phosphorus (organic residues, humus, phytate, etc.). Phytates make up up to half of soil organic phosphorus. Most phosphorus compounds are slightly soluble in soil solution. This, on the one hand, reduces the loss of phosphorus from the soil due to leaching, but, on the other hand, limits the possibilities of using it by plants.

The main natural source of phosphorus entering the arable layer is weathering of the soil-forming rock, where it is contained mainly in the form of apatites 3Ca 3 (P0 4) 2 * CaF 2, etc. Trisubstituted phosphorus salts of calcium and magnesium and salts of sesquioxides of iron and aluminum (FeP0 4, AIPO 4 in acidic soils) are slightly soluble and inaccessible to plants. Dibasic and especially monosubstituted calcium and magnesium salts, especially salts of monovalent cations and free orthophosphoric acid, are soluble in water and are used by plants as main source phosphorus in soil solution. Plants are also able to absorb some organic forms of phosphorus (sugar phosphates, phytin). The concentration of phosphorus in the soil solution is low (0.1 - 1 mg/l). Phosphorus from organic residues and humus is mineralized by soil microorganisms and most of it is converted into poorly soluble salts. Plants obtain phosphorus from them, making it more mobile. This is achieved due to the secretion of organic acids by the roots, which chelate divalent cations and acidify the rhizosphere, promoting the transition HPO 4 3-> HPO 4 2-> HP0 4 -. Some agricultural crops absorb sparingly soluble phosphates well (lupine, buckwheat, peas). This ability in plants increases with age.

Participation of phosphorus in metabolism

In plant tissues, phosphorus is present in organic form and in the form of orthophosphoric acid and its salts. It is part of proteins (phosphoproteins), nucleic acids, phospholipids, phosphorus esters of sugars, nucleotides involved in energy metabolism (ATP, NAD +, etc.), vitamins and many other compounds.

Phosphorus plays a particularly important role in the energy of the cell, since it is in the form of high-energy ester bonds of phosphorus (C--O ~ P) or pyrophosphate bonds in nucleoside di-, nucleoside triphosphates and polyphosphates that energy is stored in a living cell. These bonds have a high standard free energy of hydrolysis (for example, 14 kJ/mol for glucose-6-phosphate and AMP, 30.5 for ADP and ATP, and 62 kJ/mol for phosphoenolpyruvate). This is such a universal way of storing and using energy that almost all metabolic pathways involve one or another phosphorus esters and (or) nucleotides, and the state of the adenine nucleotide system (energy charge) is an important mechanism for controlling respiration.

In the form of a stable diester, phosphate is an integral part of the structure of nucleic acids and phospholipids. In nucleic acids, phosphorus forms bridges between nucleosides, uniting them into a giant chain. The phosphate makes the phospholipid hydrophilic, while the rest of the molecule is lipophilic. Therefore, at the phase boundary in membranes, phospholipid molecules are oriented polarly, with their phosphate ends facing outward, and the lipophilic core of the molecule is firmly held in the lipid bilayer, stabilizing the membrane.

Another unique function of phosphorus is its participation in the phosphorylation of cellular proteins using protein kinases. This mechanism controls many metabolic processes, since the inclusion of phosphate in a protein molecule leads to a redistribution of electrical charges in it and, as a result, to a modification of its structure and function. Protein phosphorylation regulates processes such as RNA and protein synthesis, cell division, cell differentiation and many others.

The main reserve form of phosphorus in plants is phytin - a calcium-magnesium salt of inositol phosphoric acid (inositol hexaphosphate):

Significant amounts of phytin (0.5 - 2% by dry weight) accumulate in seeds, accounting for up to 50% of the total phosphorus in them.

The radial movement of phosphorus in the absorption zone of the root to the xylem occurs along the symplast, and its concentration in the root cells is tens to hundreds of times higher than the concentration of phosphate in the soil solution. Transport through the xylem occurs mainly or entirely in the form of inorganic phosphate; in this form it reaches the leaves and growth zones. Phosphorus, like nitrogen, is easily redistributed between organs. From leaf cells it enters sieve tubes and is transported through the phloem to other parts of the plant, especially to growth cones and developing fruits. A similar outflow of phosphorus occurs from aging leaves.

Sulfur is one of the essential nutrients necessary for plant life. It enters them mainly in the form of sulfate. Its content in plant tissues is relatively small and amounts to 0.2-1.0% based on dry weight. The need for sulfur is high in plants rich in proteins, such as legumes (alfalfa, clover), but it is especially pronounced in representatives of the cruciferous family, which synthesize sulfur-containing mustard oils in large quantities.

In soil, sulfur is found in inorganic and organic forms. In most soils, organic sulfur from plant and animal residues predominates, and in peaty soils it can account for up to 100% of all sulfur. The main inorganic form of sulfur in the soil is sulfate, which can be in the form of salts CaSO 4, MgSO 4, Na 2 SO 4 in the soil solution in ionic form or adsorbed on soil colloids. In Na 2 SO 4 saline soils, the sulfate content can reach 60% of the soil mass. In flooded soils, sulfur is in reduced form in the form of FeS, FeS 2 or H 2 S. The total sulfur content in temperate soils climatic zones averages 0.005 - 0.040%.

Plants absorb sulfur mainly in the form of sulfate. Transmembrane transfer of sulfate occurs in cotransport with H + or in exchange for HCO 3 - ions. Less oxidized (SO 2) or more reduced (H 3 S) inorganic sulfur compounds are toxic to plants. Plants and organic compounds (amino acids) containing reduced sulfur are very poorly absorbed.

Sulfur is found in plants in two main forms - oxidized (in the form of inorganic sulfate) and reduced. The absolute content and ratio of oxidized and reduced forms of sulfur in plant organs depends both on the activity of the processes of reduction and assimilation of sulfate occurring in them, and on the concentration of SO 4 2- in the nutrient medium.

Some of the sulfur absorbed by the plant is retained in the sulfate pool of the roots, possibly in the form of CaSO 4 or metabolic sulfate, newly formed as a result of the secondary oxidation of reduced sulfur. The main part of the sulfate moves from the roots to the xylem vessels and is transported with the transpiration current to young growing organs, where it is intensively involved in metabolism and loses mobility.

From leaves, sulfate and reduced forms of sulfur (sulfur-containing amino acids, glutathione) can move through the phloem both acropetally and basipetally to the growing parts of plants and storage organs. In seeds, sulfur is predominantly in organic form, and during their germination it partially turns into oxidized form. Reduction of sulfate and synthesis of sulfur-containing amino acids and proteins is observed during seed ripening.

The share of sulfate in the total sulfur balance in tissues can vary from 10 to 50% or more. It is minimal in young leaves and increases sharply as they age due to increased degradation of sulfur-containing proteins.

Sulfur is part of the most important amino acids - cysteine ​​and methionine, which can be found in plants, both in free form and as part of proteins. Methionine is one of the 10 essential amino acids and, thanks to its sulfur and methyl group, has unique properties.

One of the main functions of sulfur in proteins and polypeptides is the participation of SH groups in the formation of covalent, hydrogen, and mercaptide bonds that maintain the three-dimensional structure of the protein.

Sulfur is also part of the most important biological compounds - coenzyme A and vitamins (lipoic acid, biotin, thiamine) and in the form of these compounds takes part in enzymatic reactions of the cell.

Potassium is one of the most essential elements of mineral nutrition for plants. Its content in tissues averages 0.5 - 1.2% based on dry weight. For a long time, the main source of potassium was ash, which is reflected in the name of the element (potassium comes from the word potashes - crucible ash). The potassium content in the cell is 100-1000 times higher than its level in the external environment. There is much more of it in tissues than other cations.

The potassium reserves in the soil are 8 to 40 times greater than the phosphorus content, and 5 to 50 times the nitrogen content. In the soil, potassium can be in the following forms: as part of the crystal lattice of minerals, in an exchangeable and non-exchangeable state in colloidal particles, in crop residues and microorganisms, in the form of mineral salts of the soil solution.

The best source of nutrition is soluble potassium salts (0.5 - 2% of the total reserves in the soil). As mobile forms of potassium are consumed, its reserves in the soil can be replenished at the expense of exchangeable forms, and when the latter decrease, at the expense of non-exchangeable, fixed forms of potassium. Alternate drying and moistening of the soil, as well as the activity of the root system of plants and microorganisms contribute to the transition of potassium into accessible forms.

In plants, potassium is the greatest number concentrated in young, growing tissues characterized by a high level of metabolism: meristems, cambium, young leaves, shoots, buds. In cells, potassium is present mainly in ionic form; it is not part of organic compounds, has high mobility and is therefore easily reused. The movement of potassium from old to young leaves is facilitated by sodium, which can replace it in the tissues of plants that have stopped growing.

In plant cells, about 80% of potassium is contained in vacuoles. It makes up the bulk of the cations in cell sap. Therefore, potassium can be washed out of plants by rain, especially from old leaves. During potassium starvation, the lamellar-granular structure of chloroplasts is disrupted, and the membrane structures of mitochondria are disorganized. Up to 20% of cell potassium is adsorbed on cytoplasmic colloids. In the light, the strength of the bond between potassium and colloids is higher than in the dark. At night, there may even be a release of potassium through the root system of plants.

Potassium helps maintain the hydration state of cytoplasmic colloids, regulating its water-holding capacity. An increase in protein hydration and water-holding capacity of the cytoplasm increases plant resistance to drought and frost.

Potassium is essential for the absorption and transport of water throughout the plant. Calculations show that the operation of the “lower end motor,” i.e., root pressure, is 3/4 due to the presence of potassium ions in the sap. Potassium is important in the process of opening and closing stomata. In the light, in the vacuoles of the guard cells of the stomata, the concentration of potassium ions increases sharply (4-5 times), which leads to the rapid entry of water, an increase in turgor and the opening of the stomatal fissure. In the dark, potassium begins to leave the guard cells, the turgor pressure in them drops and the stomata close.

Potassium is absorbed by plants as a cation and forms only weak bonds with various compounds in the cell. This is probably why it is potassium that creates ionic asymmetry and difference electrical potentials between the cell and the environment (membrane potential).

Potassium is one of the cations - activators of enzymatic systems. Currently, more than 60 enzymes are known that are activated by potassium with varying degrees of specificity. It is necessary for the incorporation of phosphate into organic compounds, transfer reactions of phosphate groups, for the synthesis of proteins and polysaccharides, and is involved in the synthesis of riboflavin, a component of all flavin dehydrogenases. Under the influence of potassium, the accumulation of starch in potato tubers, sucrose in sugar beets, monosaccharides in fruits and vegetables, cellulose, hemicelluloses and pectin substances in the cell wall of plants increases. As a result, the resistance of cereal straw to lodging increases, and the fiber quality of flax and hemp improves. A sufficient supply of potassium to plants increases their resistance to fungal and bacterial diseases.

1.6 Calcium

The total calcium content in different plant species is 5-30 mg per 1 g of dry weight. Plants in relation to calcium are divided into three groups: calciumphiles, calciumphobes and neutral species. Legumes, buckwheat, sunflower, potatoes, cabbage, and hemp contain a lot of calcium; grains, flax, and sugar beets contain much less. The tissues of dicotyledonous plants, as a rule, contain more of this element than that of monocotyledonous plants.

Calcium accumulates in old organs and tissues. This is due to the fact that its transport is carried out along the xylem and recycling is difficult. When cells age or their physiological activity decreases, calcium moves from the cytoplasm to the vacuole and is deposited in the form of insoluble salts of oxalic, citric and other acids. The resulting crystalline inclusions impede the mobility and reuse of this cation.

In most cultivated plants, calcium accumulates in vegetative organs. In the root system its content is lower than in the above-ground part. In seeds, calcium is present mainly as a salt of inositol phosphoric acid (phytin).

Calcium performs diverse functions in the metabolism of cells and the body as a whole. They are associated with its influence on the structure of membranes, ion flows through them and bioelectric phenomena, on cytoskeletal rearrangements, processes of polarization of cells and tissues, etc.

Calcium activates a number of cell enzyme systems: dehydrogenases (glutamate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, NADP-dependent isocitrate dehydrogenase), amylase, adenylate and arginine kinases, lipases, phosphatases. In this case, calcium can promote the aggregation of protein subunits, serve as a bridge between the enzyme and the substrate, and influence the state of the allosteric center of the enzyme. Excess calcium in ionic form inhibits oxidative phosphorylation and photophosphorylation.

An important role belongs to Ca 2 + ions in membrane stabilization. By interacting with negatively charged groups of phospholipids, it stabilizes the membrane and reduces its passive permeability. With a lack of calcium, membrane permeability increases, their ruptures and fragmentation appear, and membrane transport processes are disrupted.

It is important to note that almost the entire cation exchange capacity of the root surface is occupied by calcium and partially by H +. This indicates the participation of calcium in the primary mechanisms of ion entry into root cells. By limiting the entry of other ions into plants, calcium helps eliminate the toxicity of excess concentrations of ammonium, aluminum, manganese, and iron ions, increases plant resistance to salinity, and reduces soil acidity. It is calcium that most often acts as a balance ion in creating physiological balance in the ionic composition of the environment, since its content in the soil is quite high.

Most soil types are rich in calcium, and pronounced calcium deficiency is rare, for example, in highly acidic or salinized soils, on peat bogs, in cases of impaired development of the root system, or in unfavorable weather conditions.

1.7 Magnesium

In terms of content in plants, magnesium ranks fourth after potassium, nitrogen and calcium. In higher plants, its average content per dry weight is 0.02 - 3.1%, in algae 3.0 - 3.5%. It is especially abundant in short-day plants - corn, millet, sorghum, hemp, as well as potatoes, beets, tobacco and legumes. 1 kg of fresh leaves contains 300 - 800 mg of magnesium, of which 30 - 80 mg (i.e. 1/10) is part of chlorophyll. There is especially a lot of magnesium in young cells and growing tissues, as well as in generative organs and storage tissues. In grains, magnesium accumulates in the embryo, where its level is several times higher than the content in the endosperm and peel (for corn, 1.6, 0.04 and 0.19% by dry weight, respectively).

The accumulation of magnesium in young tissues is facilitated by its relatively high mobility in plants, which determines its secondary use (reutilization) from aging tissues. However, the degree of reutilization of magnesium is significantly lower than that of nitrogen, phosphorus and potassium. The easy mobility of magnesium is explained by the fact that about 70% of this cation in the plant is associated with anions of organic and inorganic acids. Magnesium is transported through both xylem and phloem. Some part of magnesium forms insoluble compounds that are not capable of moving throughout the plant (oxalate, pectate), the other part is bound by high molecular weight compounds. In seeds (embryo, shell), most of the magnesium is contained in phytin.

And finally, about 10-12% of magnesium is part of chlorophyll. This last function of magnesium is unique: no other element can replace it in chlorophyll. Magnesium is necessary for the synthesis of protoporphyrin IX, the immediate precursor of chlorophylls.

In the light, magnesium ions are released from the thylakoid cavity into the stroma of the chloroplast. An increase in magnesium concentration in the stroma activates RDP carboxylase and other enzymes. It is assumed that an increase in the concentration of Mg 2 + (up to 5 mmol/l) in the stroma leads to an increase in the affinity of RDP carboxylase for CO 2 and activation of CO 2 reduction. Magnesium can directly influence the conformation of the enzyme and also provide optimal conditions for it to work by influencing the pH of the cytoplasm as a counterion to protons. Potassium ions can act similarly. Magnesium activates a number of electron transfer reactions during photophosphorylation: reduction of NADP+, the rate of the Hill reaction, it is necessary for the transfer of electrons from PS II to PS I.

The effect of magnesium on other areas of metabolism is most often associated with its ability to regulate the work of enzymes and its importance for a number of enzymes is unique. Only manganese can replace magnesium in some processes. However, in most cases, enzyme activation by magnesium (at optimal concentration) is higher than by manganese.

Magnesium is essential for many enzymes in glycolysis and the Krebs cycle. In mitochondria, with its deficiency, a decrease in the number, disruption of the shape, and ultimately the disappearance of cristae is observed. Nine of the twelve glycolytic reactions require the participation of activating metals, and six of them are activated by magnesium.

Magnesium enhances the synthesis of essential oils, rubber, vitamins A and C. It is assumed that, by forming a complex compound with ascorbic acid, it delays its oxidation. Mg2+ is necessary for the formation of ribosomes and polysomes, for the activation of amino acids and protein synthesis and is used for all processes in a concentration of at least 0.5 mmol/l. It activates DNA and RNA polymerases and participates in the formation of a certain spatial structure of nucleic acids.

With an increase in the level of magnesium supply in plants, the content of organic and inorganic forms of phosphorus compounds increases. This effect is likely due to the role of magnesium in activating enzymes involved in phosphorus metabolism.

Plants are deficient in magnesium mainly in sandy soils. Podzolic soils are poor in magnesium and calcium, while gray soils are rich; Chernozems occupy an intermediate position. Water-soluble and exchangeable magnesium in the soil is 3-10%. The soil absorption complex contains the most calcium ions, magnesium is in second place. Plants experience a deficiency of magnesium when it contains less than 2 mg per 100 g of soil. When the pH of the soil solution decreases, magnesium enters the plants in smaller quantities.

CHAPTER 2. MATERIALS AND RESEARCH METHODS

2.1 Methods for determining minerals

Determining the content of any chemical element in a plant includes, as a mandatory procedure preceding the determination itself, the stage of decomposition (digestion) of the sample.

In practice biochemical analysis There are mainly two methods used - dry and wet ashing. In both cases, the procedure ensures the mineralization of all elements, i.e., converting them into a form soluble in one or another inorganic solvent.

Wet ashing is the main method of decomposition of organic compounds of nitrogen and phosphorus, and in some cases it is more reliable in determining many other elements. When determining boron, only dry ashing can be used, since most boron compounds volatilize with water and acid vapor.

The dry ashing method is applicable for analyzing the content of almost all macro- and microelements in biological material. Typically, dry ashing of plant samples is carried out in an electric muffle furnace in porcelain, quartz or metal crucibles (or cups) at a temperature not exceeding 450-500 ° C. Crucibles made of quartz are best, but crucibles made of refractory glass or porcelain are usually used. Some special studies may require platinum crucibles. Low temperature during combustion and the correct choice of crucible material avoid losses from volatilization and losses due to the formation of poorly soluble substances. hydrochloric acid oxides of the element being determined. Oxides can form when reacting with the material from which the crucibles are made.

2.2 Microchemical analysis of ash

Materials and equipment: ash obtained by burning leaves, seeds, wood; 10% solutions of HCl and NH 3, 1% solutions of the following salts in a dropper: Na 2 HCO 3, NaHC 4 H 4 O 6, K 4, (NH 4) 2 MoO 4 in 1% HNO 3, 1% solution of H 2 SO 4 ; test tubes, glass funnels with a diameter of 4-5 cm, metal spatulas or eye spatulas, glass slides, glass rods, napkins or pieces of filter paper, paper filters, washers or flasks with distilled water, cups for rinsing water.

Brief information:

When tissue is burned, organic elements (C; H; O; N) evaporate in the form of gaseous compounds and the non-combustible part remains - ash. Its content in different organs is different: in leaves - up to 10-15%, in seeds - about 3%, in wood - about 1%. Most ash is found in living, actively functioning tissues, such as the mesophyll of a leaf. Its cells contain chlorophyll and many enzymes, which include elements such as magnesium, iron, copper, etc. Due to the high metabolic activity of living tissues, a significant amount of potassium, phosphorus and other elements are also found in them. The ash content depends on the composition of the soil on which the plant grows, and on its age and biological nature. Plant organs differ not only in the quantitative, but also in the qualitative composition of the ash.

The microchemical method makes it possible to detect in plant ash whole line elements. The method is based on the ability of some reagents, when interacting with ash elements, to produce compounds that differ in specific color or crystal shape.

Progress

Place a portion of the dried material (wood chips, leaves and crushed seeds) in a crucible, add a little alcohol and set it on fire. Repeat the procedure 2-3 times. Then transfer the crucible to an electric stove and heat until the charred material acquires an ash-gray color. The remaining coal must be burned out by placing the crucible in a muffle furnace for 20 minutes.

To detect Ca, Mg, P and Fe, it is necessary to add a portion of ash into a test tube with a glass eye spatula, pour 4 ml of 10% HCl into it and shake several times for better dissolution. To detect potassium, the same amount of ash must be dissolved in 4 ml of distilled water and filtered into a clean test tube through a small paper filter. Then, using a glass rod, apply a small drop of ash extract onto a clean glass slide, next to it, at a distance of 10 mm, a drop of the reagent, and with the rod, connect the two drops with a bridge. (Each reagent is applied with a separate pipette.) At the point of contact of the solutions, crystallization of the reaction products will occur (mixing two drops is undesirable, since rapid crystallization results in the formation of small atypical crystals; in addition, when the drop dries, crystals of the original salts may form).

After this, remove the drops of the remaining solutions from the glass with pieces of filter paper and examine the crystals under a microscope without a cover glass. After each reaction, the glass rod must be rinsed with water and wiped dry with filter paper.

To detect potassium, 1% sodium tartrate is used. As a result of the reaction with the ash extract, crystals of acid potassium tartrate KHC 4 H 4 O 6 are formed, having the form of large prisms. The potassium extract in water must first be neutralized, since in acidic and alkaline environment the reaction product is soluble. The reaction follows the equation:

NaHC 4 H 4 O 6 + K + > KNS 4 H 4 O 6 v + Na +.

Calcium detection is carried out with 1% sulfuric acid, the reaction proceeds according to the equation:

CaCl 2 + H 2 SO 4 > CaSO 4 v + 2HCl.

As a result, gypsum is formed in the form of individual or collected in bunches of needle-shaped crystals.

When magnesium is detected, a drop of 10% ammonia solution is first added to a drop of ash extract and connected by a bridge with a drop of 1% sodium phosphate solution. The reaction follows the equation:

MgCl 2 + NH 3 + Na 2 HPO 4 > NH 4 MgPO 4 v + 2NaCl.

Phosphorus-ammonium magnesium salt is formed in the form of flat, colorless crystals in the form of rectangles, wings, and caps.

Phosphorus detection is carried out using 1% ammonium molybdate in nitric acid. The reaction proceeds according to the equation:

H 3 PO 4 + 12(NH 4) 2 MoO 4 + 21HNO 3 > (NH 4) 3 PO 4 * 12MoO 3 v + 21NH 4 NO 3 + 12H 2 O.

Phosphorus-molybdenum ammonia is formed in the form of small yellow-green lumps.

To detect iron, equal amounts of ash extract from different organs (1-2 ml) are poured into two test tubes, and an equal amount of 1% yellow blood salt is added until a blue color appears. Prussian blue is formed:

4FeCl 3 + 3K 4 > Fe 4 3 + 12KCl.

CHAPTER 3. RESEARCH RESULTS AND THEIR ANALYSIS

3.1 Symptoms of mineral deficiency

The lack of minerals causes changes in biochemical and physiological processes, as a result of which morphological changes, or visible symptoms, are often observed.

Sometimes, due to deficiency, growth is suppressed before other symptoms appear.

Visible symptoms of deficiency. The most significant result of mineral deficiency is decreased growth. However, the most noticeable effect is yellowing of the leaves caused by decreased chlorophyll biosynthesis. Leaves appear to be particularly sensitive to deficiency. With a lack of minerals, they decrease in size, change in shape or structure, fade in color, and sometimes even develop dead areas at the tips, edges or between the main veins. In some cases, leaves gather in tufts or rosettes, and pine needles sometimes fail to separate and “merged needles” form. A common symptom of a certain type of mineral deficiency in herbaceous plants- suppression of stem growth and reduced growth of leaf blades, which leads to the formation of rosettes of small leaves, often with a network of chlorotic areas. Visible symptoms of deficiency various elements so characteristic that experienced observers can identify the deficiency by appearance leaves.

Sometimes, when there is a lack of minerals, trees produce excess amounts of gum. This phenomenon is called omosis. Resin excretion around the buds is common in zinc-deficient Remarkable Pine trees in Australia. Gum is also found on the bark fruit trees suffering from dryness caused by a lack of copper. Significant deficiency often causes the death of leaves, shoots and other parts, i.e. symptoms described as dryness develop. Shoot death caused by copper deficiency has been observed in many forest and fruit trees. When the apical shoots die off, apple trees suffering from copper deficiency acquire a bushy, stunted appearance. A lack of boron causes drying of the apical growth points and ultimately the death of the cambium in citrus fruits and pines, the death of the phloem and the physiological decay of fruits in other species. A deficiency of one element sometimes contributes to the appearance of several different symptoms, for example, boron deficiency in apple trees causes deformation and fragility of leaves, phloem necrosis, damage to the bark and fruits.

Chlorosis. The most common symptom observed with a lack of a variety of elements is chlorosis, which occurs as a result of impaired chlorophyll biosynthesis. The nature, degree and severity of chlorosis in young and old leaves depend on the type of plant, the element and the degree of deficiency. Most often, chlorosis is associated with a lack of nitrogen, but it can also be caused by a deficiency of iron, manganese, magnesium, potassium and other elements. Moreover, chlorosis can be caused not only by mineral deficiencies, but also by a variety of other environmental factors, including too much or too little water, unfavorable temperatures, toxic substances (such as sulfur dioxide) and excess minerals. Chlorosis can also be caused by genetic factors that cause the appearance of differently colored plants: from albinos, completely devoid of chlorophyll, to greenish seedlings or seedlings with various stripes and spots on the leaves.

Based on the numerous factors that cause chlorosis, we can conclude that it occurs as a result of both a general metabolic disorder and the specific influence of individual elements.

One of the most common and most damaging types of plant development is the type of chlorosis that is found in a large number of fruit, ornamental and forest trees growing on alkaline and calcareous soils. It is usually caused by unavailability of iron at high pH values, but is sometimes caused by manganese deficiency.

When chlorosis occurs in angiosperms, the midribs and smaller veins of the leaves remain green, but the areas between the veins become pale green, yellow, or even white. Typically, the youngest leaves are most affected by chlorosis. In coniferous trees, young needles turn pale green or yellow, and with a large deficiency, the needles can turn brown and fall off.

Chlorosis caused by iron deficiency can be partially or completely eliminated by lowering the soil pH.

3.2 Physiological effects of mineral deficiency

The visible morphological effects or symptoms of mineral deficiency are the result of changes in various internal biochemical or physiological processes. However, due to the complex relationships between them, it can be difficult to determine how the deficiency of a single element causes the observed effects. For example, a lack of nitrogen can inhibit growth due to a worse supply of nitrogen to the processes of biosynthesis of new protoplasm. But at the same time, the rate of synthesis of enzymes and chlorophyll decreases and the photosynthetic surface decreases. This causes a weakening of photosynthesis, impairing the supply of growth processes with carbohydrates. As a result, a further decrease in the rate of absorption of nitrogen and minerals is possible. One element often performs several functions in a plant, so it is not easy to determine which function or combination of functions is disrupted and causes visible symptoms. Manganese, for example, in addition to activating certain enzyme systems, is also necessary for synthesis. Chlorophyll. Its deficiency causes some functional disorders. A lack of nitrogen usually leads to a noticeable decrease in photosynthesis, but the effect of a lack of other elements is not so certain.

A lack of minerals reduces both the biosynthesis of carbohydrates and their movement to growing tissues. Deficiencies often affect photosynthesis and respiration differently. For example, a significant potassium deficiency slows photosynthesis and increases respiration, thereby reducing the amount of carbohydrates that can be used for growth. Sometimes the movement of carbohydrates is also inhibited. This effect is pronounced in boron-deficient trees with phloem necrosis. As a result of the reduction in the amount of available carbohydrates, the rate of tissue growth in one part of the tree decreases, but at the same time, accumulation of carbohydrates in another part can occur. Sometimes, due to the low content of storage carbohydrates, seed formation is reduced. Abundant application of nitrogen fertilizer led to a significant increase in the process of seed formation in beech and sugar maple trees, the percentage of healthy seeds and the dry weight of maple seeds increased. The formation of cones and seeds in young incense pine also increased sharply after applying fertilizer. If trees are not deficient in minerals, the application of large amounts of nitrogen fertilizers can reduce the formation of fruits and seeds by stimulating vegetative growth.

3.3 Excess minerals

Forest soils rarely contain an excess of mineral nutrients, but heavy fertilization of gardens and nurseries sometimes results in salt concentrations sufficient to cause harm. There are also large areas of dry lands where most plant species cannot exist due to the high salt content. Irrigation with water containing a lot of salts also causes damage. This occurs due to an increase in osmotic pressure, unfavorable pH shifts for plants, an imbalance of various ions, or a combination of these factors.

Increased osmotic pressure of the soil solution reduces water uptake, increases water deficiency in the leaves and results in tissue damage from drying out on days when wind and high temperatures cause high transpiration. With longer and deeper dehydration, stomatal closure is also observed, preventing photosynthesis. High concentrations of salts in the soil can cause root damage through plasmolysis, especially in sandy soils, which interferes with root synthetic activity. Sometimes leaves are damaged as a result of applying liquid fertilizers in high concentrations.

The harmful effects of excess fertilizer depend on the plant species, the type of fertilizer used and the time of application.

Excessive fertilization of fruit and ornamental trees sometimes extends the growing season to such an extent that trees and shrubs do not have time to acquire cold resistance before frost. Excessive fertilization sometimes encourages the production of many branches, flowers and fruits on older trees. Other types of plant responses to overfertilization include fasciation, or stem flattening, and internal bark necrosis. On seedlings, the undesirable effect of excess fertilizer manifests itself in the form of excessive apical growth, leading to a low ratio of underground and aboveground parts, as a result of which plants often do not take root well after transplanting.

Using excess fertilizer is economically wasteful. It is also undesirable for the environment, since excess can be washed out and end up in water bodies or groundwater. Of particular importance is the leaching of excess nitrogen, usually in the form of nitrate, but the problem of environmental pollution can arise when any element is introduced in excess quantities.

3.4 Nitrogen deficiency

With a lack of nitrogen in the habitat, plant growth is inhibited, the formation of lateral shoots and tillering in cereals is weakened, and small leaves are observed. At the same time, root branching decreases, but the ratio of the mass of roots and aerial parts may increase. One of the early manifestations of nitrogen deficiency is a pale green color of leaves caused by weakened chlorophyll synthesis. Prolonged nitrogen starvation leads to the hydrolysis of proteins and the destruction of chlorophyll, primarily in the lower, older leaves and the outflow of soluble nitrogen compounds to younger leaves and growing points. Due to the destruction of chlorophyll, the color of the lower leaves, depending on the type of plant, acquires yellow, orange or red tones, and with severe nitrogen deficiency, necrosis, drying out and tissue death may occur. Nitrogen starvation leads to a shorter period of vegetative growth and earlier seed ripening.

3.5 Phosphorus deficiency

An external symptom of phosphorus starvation is a bluish-green color of the leaves, often with a purple or bronze tint (evidence of a delay in protein synthesis and accumulation of sugars). The leaves become small and narrower. Plant growth stops and crop ripening is delayed.

With phosphorus deficiency, the rate of oxygen absorption decreases, the activity of enzymes involved in respiratory metabolism changes, and some non-mitochondrial oxidation systems (glycolic acid oxidase, ascorbate oxidase) begin to work more actively. Under conditions of phosphorus starvation, the processes of decomposition of organophosphorus compounds and polysaccharides are activated, and the synthesis of proteins and free nucleotides is inhibited.

Plants are most sensitive to phosphorus deficiency in the early stages of growth and development. Normal phosphorus nutrition in a later period accelerates the development of plants (as opposed to nitrogen nutrition), which in the southern regions makes it possible to reduce the likelihood of them falling under drought, and in the northern regions - under frost.

3.6 Sulfur deficiency

Insufficient supply of plants with sulfur inhibits the synthesis of sulfur-containing amino acids and proteins, reduces photosynthesis and the growth rate of plants, especially the aerial parts. In acute cases, the formation of chloroplasts is disrupted and their disintegration is possible. Symptoms of sulfur deficiency - blanching and yellowing of leaves - are similar to those of nitrogen deficiency, but appear first in the youngest leaves. This shows that the efflux of sulfur from older leaves cannot compensate for the insufficient supply of sulfur to plants through the roots.

3.7 Potassium deficiency

With a lack of potassium, the leaves begin to turn yellow from bottom to top - from old to young. The leaves turn yellow at the edges. Subsequently, their edges and tops acquire a brown color, sometimes with red “rusty” spots; dying and destruction of these areas occurs. The leaves look as if they are burnt. The supply of potassium is especially important for young, actively growing organs and tissues. Therefore, with potassium starvation, the functioning of the cambium decreases, the development of vascular tissues is disrupted, the thickness of the cell wall of the epidermis and cuticle decreases, and the processes of cell division and elongation are inhibited. As a result of shortening the internodes, rosette forms of plants can form. Potassium deficiency leads to a decrease in the dominant effect of the apical buds. The apical and apical-lateral buds stop developing and die, the growth of lateral shoots is activated and the plant takes on the shape of a bush.

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Mineral elements play an important role in plant metabolism, as well as the colloid-chemical properties of the cytoplasm. Normal development, growth and physiological processes cannot be without mineral elements. They can play the role of structural components of plant tissues, catalysts of various reactions, regulators of osmotic pressure, components of buffer systems and regulators of membrane permeability.

Some elements, including iron, copper and zinc, are required in very small quantities but are essential because they form part of prosthetic groups or coenzymes of certain enzyme systems.

Other elements, such as manganese and magnesium, function as activators or inhibitors of enzyme systems.

Some elements, such as boron, copper and zinc, which are necessary for enzyme function in small quantities, are very toxic in higher concentrations. Copper is part of the oxidative enzymes polyphenol oxidase and ascorbic oxidase. Iron is part of the cytochromes and enzymes catalase and peroxidase. Manganese - stimulates plant respiration, redox processes, photosynthesis, formation and movement of sugars. Its main function is to activate enzyme systems. In addition, it affects the availability of iron. The average manganese content in plants is 0.001%.

Excess or deficiency of macro or microelements has a negative effect on plants. A high concentration of elements causes coagulation of plasma colloids and its death.

Currently, environmental pollution, including heavy metals, is increasing every year, which has an impact on negative impact on soils and plants and poses a threat to human health.

Excessive intake of heavy metals into organisms disrupts metabolic processes, inhibits growth and development, and leads to a decrease in the productivity of agricultural crops.

The greatest danger is posed by those metals that, under normal conditions, are needed by plants as microelements. These primarily include zinc, copper, manganese, cobalt and others. Accumulating in plants cause negative effects. With an excess of copper in plants, chlorosis and necrosis of young leaves occurs, the veins remain green, and the growth of the root system and the entire plant stops. The leaves take on a darker shade. If, for some reason, the excess of iron turns out to be very strong, then the leaves begin to die and fall off without any visible changes. Petroleum products disrupt the permeability of membranes, block the action of a number of enzymes, have a negative effect on plants, and reduce the yield and timing of fruit ripening.

GOU Gymnasium 1505

"Moscow City Pedagogical Gymnasium-Laboratory"

“The influence of various substances on the growth and development of plants”

Supervisor:

Moscow, 2011

Introduction…………………………………………………………………………………3

Theoretical part

1.1 Factors of plant growth and development…………………………………………………………….5

1.2 Effect of heavy metals on plant growth and development…………………………6

2. Experimental part

2.1. Research results. Dry residue analysis…………………………….14

3. Conclusion……………………………………………………………………………….19

References……………………………………………………………………………….21

Introduction

The relevance of research. Megacities are large centers of intense environmental pollution with heavy metals: Moscow is one of them. In such a densely populated city, it is necessary to take into account the impact of heavy metal salts on human health both in homes and in working and educational places. The relevance of my research follows from the fact that homes and workplaces are almost always poorly ventilated, and sources of heavy metals are usually ignored. Especially, harmful effects plants that are in every house or apartment are susceptible to heavy metal salts. Plants easily accumulate various substances and are not capable of active movement. Consequently, their condition can be used to judge the environmental situation. And since plants are bioindicators, that is, many changes have specific manifestations, they are ideal for research work. Thus, in this work it is necessary to find out exactly how heavy metal salts affect the growth and development of plants.

Purpose research is the accumulation and processing of data on the effect of heavy metal salts on the growth and development of plants, as well as comparison of information from the literature used with the results of a scientific experiment that I am going to conduct and then describe in my work. Before starting experimental activities, I raised several important questions: tasks:

Plant development table

1 Plants of groups 3 and 4 were watered with solutions exceeding the MPC (Maximum Permissible Concentration)

CuSO4 - 0.05g/10l - exceeded 10 times

Pb(NO,02mg/10l - exceeded 200 times

Group of plants	Date of observation	Observation (plant growth)
(Control)
	1pcs broken 2.9cm-5.7cm
	2pcs broken 3.4cm-6.3cm
	1 piece broke and stopped absorbing water. Plant size: 3.8cm-6.8cm
	1 piece broke, a real leaf began to grow, the stems of the plant grew strongly, I stopped watering the plants 3.9cm-6.8cm a real leaf began to emerge
	4.1cm-7.2cm, watering has not started, the plants still do not absorb water.
	4.3cm –7.5cm
	4.5cm–7.7cm last day of observations, due to the death of most plants
	The smallest of all plant groups. Plant size: 1.5cm–2.5cm
	1pcs broken 2.5cm-4.9cm
	1 piece died, the plants became frail and looked worse than other groups of plants. Plant size: 3.6cm-6.2cm
	2 pieces broke and stopped watering because they stopped absorbing water. Plant size 3.8cm-6.7cm
	4.1cm-7cm, real leaf appeared
	They have practically not changed in growth, the real leaf has become even larger, I have not started watering, since they still do not absorb water
	4.2cm-7.3cm, the largest number of surviving plants
	4.6cm-7.4cm, last day of observations, due to the death of most plants
III group
	1 piece died 1.5cm-3.2cm
	1pcs broken 2.7cm-6cm
	the plants look frail, 1 has wilted, and become dark green in color, much darker than other groups of plants. Plant size: 3.2cm-6.7cm
	1 piece withered, 5 pieces fell, 1 piece broke, they began to absorb water poorly. Plant size: 3.3cm-6.9cm
	A new true leaf began to emerge, the plants completely stopped absorbing water, and therefore stopped watering; 7 of them were growing, the rest fell and broke. Plant size 3.4cm-7.3cm
	Almost all plants have fallen; they look limp and lifeless compared to other groups of plants. 2 pieces have fallen
	3.7cm-7.8cm are only worth 5pcs, all the rest have fallen, look lifeless
	3.8cm-8cm last day of observations, due to the death of most plants
IV group (Pb)
	1.6cm-2.3cm 1pc wilted
	Several plants have fallen; leaves 2.7cm-5.8cm begin to curl up.
	1 piece fell and broke, all the plants leaned to one side, the leaves curled even more. Plant size: 3.1cm–6.2cm
	2 pieces fell and broke, a real leaf began to grow, I stopped watering because the plants stopped absorbing water. Plant size: 3.4cm–6.7cm,
	2 pieces have fallen, the real leaf is clearly visible, some plants look quite frail. Plant size 3.6cm–7cm
	1 piece is broken, almost all plants look frail and lifeless, have practically not changed in growth, the largest true leaf of all groups of plants
	They look sick, 1 piece has wilted. Plant size: 4.5-7.9
	4.6cm-8cm last day of observations, due to the death of most plants

From the data given in the table, it follows that, compared with the control group, plants watered with a solution of lead nitrate grew more intensively, the growth of watercress watered with melt water and a solution of copper sulfate was slowed down.

The condition of the plants of different groups differed: after 6 days of observation, plants of groups 2 and 3 began to break, leaves of plants of group 4 began to curl. In plants watered with melt water, growth retardation was observed earlier than others (after 8 days); watercress with lead outpaced the growth of plants in the control group.

2.2. Analysis of dry residue for lead and copper ions.

After completing the study of the growth rate of watercress, I analyzed the dry residue for the presence of lead and copper ions in each sample. For this purpose, the plants were dried, each group of plants was burned separately, and analyzed for the presence of ions. The following are examples of qualitative reactions to lead ions and copper ions:

1. Qualitative reaction to lead ions: lead ions in solution are determined using iodide ion I -

A solution of potassium iodide was taken as a source of iodide ions.

2. Qualitative reaction to copper ions: copper ions in solution are determined with the power of sulfide ions S2-

A sodium sulfide solution was taken as a source of sulfide ions.

Analysis results:

In the control group of plants, none of the studied ions was detected. In the group of plants watered with melted snow, lead ions and copper ions were detected in very small quantities. Only traces of copper were found in the dry residue of plants watered with a solution containing copper. In the group of plants watered with a solution of lead nitrate, lead ions were detected only the next day.

As a result of the work carried out, I came to the following conclusions:

1. Lead stimulates the growth of watercress, while causing leaves to curl and premature death of plants.

2. Copper accumulates in plants and causes a slight slowdown in the growth of watercress and brittleness of the stems.

3. Analysis of plants watered with melt water showed that in the snow collected along the road on the street. Playing water contains both lead ions and copper ions, which have a detrimental effect on the growth and development of plants.

3. Conclusion

Conducted study of literary sources and experimental study made it possible to compare the obtained data.

3.1. Literary information

Information from the literature indicates that with an excess of lead, there is a decrease in yield, suppression of photosynthesis processes, the appearance of dark green leaves, curling of old leaves and leaf fall. In general, the effect of excess lead on plant growth and development has not been sufficiently studied.

Copper causes toxic poisoning and premature death of plants.

3.2 Experimental data

Our research on growing watercress plants under conditions of various heavy metal ions (lead and copper), as well as the influence of melted snow on the growth and development of lettuce, showed that lead causes increased plant growth when leaves curl; copper slows down the growth rate and increases the fragility of the stems. Melted snow causes early growth retardation and increased fragility of plants.

3.3 Conclusions

Comparing data from literature sources and obtained experimental data, we came to the conclusion that literary sources confirmed by research. However, there are some peculiarities: we did not conduct a study of the effect of lead on plant productivity; an interesting fact is that lead in the group of plants watered with a solution of lead nitrate was determined only the next day. Additional study of literature data showed that lead accumulates primarily in plant roots. To analyze the dry residue for lead and copper ions, we took only the above-ground part of the shoot. Increasing the concentration of copper ions in the solution by 200 times the MPC did not give the expected results - instead of the expected rapid death of the watercress, growth retardation was observed. The presence of lead and copper ions in melted snow did not cause a net effect (increased plant growth and stem fragility), but slowed down the rate of plant growth and development with increased fragility.

Applications

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Development of watercress plants

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Fragility of stems in individual groups of watercress

Bibliography.

Dobrolyubsky and life, - M.: Mol. Guard, 1956. Drobkov and natural radioactive elements in the life of plants and animals, - Popular Science Series., M.: USSR Academy of Sciences, 1958. Harmful chemicals. Inorganic compounds of groups I-IV, Ed. prof. Filov. V. A. - M.: Chemistry, 1988. Shapiro Ya. S. Biological chemistry, M. - Ventana-Graf Publishing Center, 2010. General chemistry, Ed. , - M.: graduate School, 2005. Podgorny, - M.: Publishing house of agricultural literature, magazines and posters, 1963. , Kovekovdova in soils and plants of Ussuriysk and the Ussuriysk region, - El. journal Researched in Russia, 2003. zhurnal. ape. *****/articles/2003/182.pdf Medical reference book. www. *****

The influence of chemicals on plant growth and development. Completed by: Ignatieva Victoria, 6th grade student Supervisor: Putina Yu.K., teacher of biology and chemistry Municipal state educational institution "Nizhnesanarskaya Secondary comprehensive school Troitsky municipal district Chelyabinsk region 2017

Purpose: to study the influence of chemicals on the growth and development of plants. Objectives: Study the available literature on this issue; Get acquainted with available methods for studying the influence of chemicals on the growth and development of plants. Draw a conclusion about the effects of chemicals based on your own research. Develop recommendations for improving conditions for growing cultivated plants. Hypothesis: We hypothesize that chemicals will negatively affect plant growth and development.

Subject of research: Onions, common beans Subject of research: the effect of chemicals on plants.

Chemical Sampling Technique

To study the influence of chemicals, 6 samples were taken: No. 1 - copper sulfate CuSO4 * 5H2O No. 2 - zinc sulfate ZnSO4 * 7H2O No. 3 - - iron sulfate FeSO4 * 7H2O No. 4 - potassium permanganate KMnO4 No. 5 - lead sulfate PbSO4 No. 6 - control sample (without added chemicals)

Results of the study of control samples Control sample No. 6 (onion bulb) development proceeds intensively with the formation of many adventitious roots) Control sample No. 6 (Bean plant) - growth and development proceeds within normal limits

Results of the study of test samples exposed to copper sulfate Sample No. 1 The appearance of a small number of roots, their growth soon stops, they darken. Sample No. 1 of the plant, after adding a solution of copper sulfate, the leaves immediately curled, the plant died by the end of the 1st week of the experiment

Results of the study of test samples exposed to zinc sulfate Sample No. 2 The appearance of a large number of roots, their growth is insignificant. Sample No. 2 In a plant after adding a solution of zinc sulfate, the leaves usually developed during the first week of experiments, then with increasing concentration of the solution the leaves turned yellow and curled

Results of the study of test samples exposed to iron sulfate Sample No. 3 The appearance of a small number of roots, their growth soon stops, they darken. Sample No. 3. The plant developed three leaves, but then they began to curl and turn yellow.

Results of the study of test samples under the influence of potassium permanganate Sample No. 4 The bulb with the addition of a solution of potassium permanganate (No. 4) developed weakly, the roots were 1-2 mm, then growth stopped Sample No. 4 The plant lost 3 leaves on the 4th day, then the rest dried out

Results of the study of test samples exposed to lead sulfate Sample No. 5 The onion had a sufficient number of roots, but small in size. The bean plant had large leaves, but pale color, which at the end of 2 weeks also curled slightly

The control sample (No. 6) had smooth, light cells without signs of any deformation.

Onion cells from the test sample with the addition of iron sulfate (No. 3) had an even structure, but their cytoplasm was darkly colored.

Onion cells from a test sample with the addition of potassium permanganate (No. 4) acquired a blue color. The cells had an even structure.

Conclusions: Excess iron sulfate stains cells in dark color and slows down the growth of the root system. Potassium permanganate has a similar effect. Excess copper sulfate destroys plant cells and stops its growth.