The first methods for chemical analysis of plants were developed. Agrochemical analysis of soils, plants, fertilizers. Obtaining a water solution of soils
Gross analysis is carried out either on the leaves of a certain position on the plant, or in the entire aerial part, or in other indicator organs.
Diagnostics by gross analysis leaves - mature, completed growth, but actively functioning, was called "leaf diagnostics". It was proposed by the French scientists Lagatu and Mom and was supported by Lundegard. This type is currently chemical diagnostics is widely used both abroad and in our country, especially for plants whose roots almost completely restore nitrates and therefore it is impossible to control nitrogen nutrition in this form in the aerial parts (apple and other seed and stone fruits, conifers, rich in tannins, bulbous, etc.).
In the bulk analysis of leaves or other parts of plants, the usual methods of ashing organic matter are used to determine N, P, K, Ca, Mg, S, and other elements in it. More often, the determination is carried out in two portions: in one, nitrogen is determined by Kjeldahl, in the other, the remaining elements after wet, semi-dry or dry ashing. In wet ashing, either strong H2SO4 with catalysts is used, or mixed with HNO3, or with HClO4, or with H2O2. In dry ashing, careful temperature control is necessary, since when burned at temperatures above 500 ° C, there may be losses of P, S and other elements.
At the initiative of France, in 1959, the Inter-Institute Committee for the Study of the Technique of Chemical Sheet Diagnostics was organized, consisting of 13 French, 5 Belgian, 1 Dutch, 2 Spanish, 1 Italian and 1 Portuguese institutes. In 25 laboratories of these institutes, chemical analyzes of the same samples of leaves of 13 crops (field and garden) were carried out for the total content of N, P, K, Ca, Mg, Fe, Mn, Cu, and Zn. This allowed the committee, after mathematical processing of the data, to recommend methods for obtaining standard leaf samples and to give standard methods for their chemical analysis to control the accuracy of such analyzes in sheet diagnostics.
Ashing of leaf samples is recommended as follows: to determine the total nitrogen according to Kjeldahl, ash with H2SO4 (sp. weight 1.84), with catalysts K2SO4 + CuSO4 and selenium. To determine other elements, dry ashing of the sample in platinum dishes is used with gradual (2 hours) heating of the muffle to 450 ° C; after cooling in a muffle for 2 hours, the ash is dissolved in 2-3 ml of water + 1 ml of HCl (sp. weight 1.19). Evaporate on the stove until the first vapors appear. Add water, filter into a 100 ml volumetric flask. The filter cake is ashed at 550°C (maximum), 5 ml of hydrofluoric acid are added. Dry on a tile at a temperature not exceeding 250 ° C. After cooling, 1 ml of the same HCl is added and filtered again into the same flask, washing off warm water. The filtrate, brought to 100 ml with water, is used for analysis of the content of macro- and microelements.
There is a fairly large variation in the methods of ashing plant samples, which differ mainly in plant species - rich in fats or silicon, etc., and in the tasks of determining certain elements. Enough detailed description The technique for using these methods of dry ashing was given to the Polish scientist Novosilsky. They also give descriptions various ways wet ashing with the help of certain oxidizing agents: H2SO4, HClO4, HNO3 or H2O2 in one or another combination, depending on the elements being determined.
To speed up the analysis, but not at the expense of accuracy, ways are being sought for such a method of incinerating a plant sample, which would make it possible to determine several elements in one sample. V. V. Pinevich used the ashing of H2SO4 to determine N and P in one sample and subsequently added 30% H2O2 (checking it for the absence of P). This principle of ashing, with some refinements, has found wide application in many laboratories in Russia.
Another widely used method of acid ashing of a sample for the simultaneous determination of several elements in it was proposed by K.E. Ginzburg, G.M. Shcheglova and E.A. Wolfius and is based on the use of a mixture of H2SO4 (sp. weight 1.84) and HClO4 (60%) in a ratio of 10: 1, and the mixture of acids is preliminarily prepared for the entire batch of the analyzed material.
If it is necessary to determine sulfur in plants, the described ashing methods are not suitable, since they include sulfuric acid.
P.X. Aydinyan and his collaborators suggested burning a plant sample to determine sulfur in it, mixing it with bartholite salt and clean sand. The method of V. I. Kuznetsov with his co-workers is a somewhat revised Schöniger method. The principle of the method consists in the rapid ashing of the sample in a flask filled with oxygen, followed by titration of the resulting sulfates with a solution of barium chloride with a barium nitchromase metal indicator. To ensure greater accuracy and reproducibility of the analysis results, we recommend passing the resulting solution through a column with an ion exchange resin in the H + form in order to free the solution from cations. The sulfate solution obtained in this way should be evaporated on a hotplate to a volume of 7-10 ml and titrated after cooling.
Novosilsky, pointing out the large losses of sulfur during dry ashing, gives recipes for ashing plants for these analyses. The author considers one of the simplest and fastest methods of ashing according to Butters and Chenery with nitric acid.
The determination of the content of each element in a sample ashed in one way or another is carried out by various methods: colorimetric, complexometric, spectrophotometric, neutron activation, using autoanalyzers, etc.
properties of all plant organisms and internal structures inherent certain types, are determined by the multifaceted, constantly changing influence environment. The influence of such factors as climate, soil, as well as the circulation of substances and energy is significant. Traditionally, to reveal properties medicinal products or food, the proportions of substances that can be isolated analytically are determined. But these individual substances cannot cover all the internal properties, for example, of medicinal and aromatic plants. Therefore, such descriptions of the individual properties of plants cannot satisfy all our needs. For an exhaustive description of the properties of herbal medicinal preparations, including biological activity, a comprehensive, comprehensive study is required. There are a number of methods to identify the quality and quantity of biologically active substances in the composition of the plant, as well as the places of their accumulation.
Luminescent microscopic analysis based on the fact that the biologically active substances contained in the plant give a bright colored glow in a fluorescent microscope, and different chemicals are characterized by different colors. So, alkaloids give a yellow color, and glycosides - orange. This method is used mainly to identify areas of accumulation of active substances in plant tissues, and the intensity of the glow indicates a greater or lesser concentration of these substances. Phytochemical analysis is designed to identify a qualitative and quantitative indicator of the content of active substances in the eastenium. Chemical reactions are used to determine the quality. The amount of active substances in a plant is the main indicator of its good quality, therefore, their volumetric analysis is also carried out using chemical methods. For the study of plants containing active substances such as alkaloids, coumarins,
glavones, which require not a simple summary analysis, but also their separation into components, are called chromatographic analysis. Chromatographic method of analysis was first introduced in 1903 by a botanist
color, and since then its various variants have been developed, which have an independent
meaning. This method of separating a mixture of g-zeets into components is based on the difference in their physical and chemical properties. Using the photographic method, with the help of panoramic chromatography, you can make visible the internal structure of the plant, see the lines, shapes and colors of the plant. Such pictures, obtained from aqueous extracts, are retained on silver-nitrate filter paper and reproduced. The method for interpreting chromatograms is being successfully developed. This methodology is supported by data obtained using other, already known, proven methods.
Based on the circulation chromodiagrams, the development of a panoramic chromatography method for determining the quality of a plant by the presence of concentrated in it nutrients. The results obtained using this method should be supported by data from the analysis of the acidity level of the plant, the interaction of the enzymes contained in it, etc. The main task of further development of the chromatographic method of plant analysis should be to find ways to influence plant raw materials during their cultivation, primary processing , storage and at the stage of direct receipt of dosage forms in order to increase the content of valuable active substances in it.
Updated: 2019-07-09 22:27:53
- It has been established that the adaptation of the organism to various environmental influences is ensured by the corresponding fluctuations in the functional activity of organs and tissues, the central nervous
Since botany studies quite a lot of different aspects of the organization and functioning of plant organisms, in each specific case, its own set of research methods is used. Botany uses both general methods (observation, comparison, analysis, experiment, generalization) and many
special methods (biochemical and cytochemical methods, light methods (conventional, phase-contrast, interference, polarization, fluorescence, ultraviolet) and electron (transmission, scanning) microscopy, cell culture methods, microscopic surgery, molecular biology methods, genetic methods, electrophysiological methods, freezing and chipping methods, biochronological methods, biometric methods, mathematical modeling, statistical methods).
Special methods take into account the peculiarities of one or another level of organization of the plant world. So, to study the lower levels of organization, various biochemical methods, methods of qualitative and quantitative chemical analysis are used. Various cytological methods are used to study cells, especially electron microscopy methods. To study tissues and the internal structure of organs, methods of light microscopy, microscopic surgery, and selective staining are used. To study the flora at the population-species and biocenotic levels, various genetic, geobotanical and ecological research methods are used. In the taxonomy of plants, an important place is occupied by such methods as comparative morphological, paleontological, historical, and cytogenetic.
The assimilation of material from different sections of botany is the theoretical basis for the training of future specialists in agricultural chemists and soil scientists. Due to the inextricable relationship between the plant organism and the environment of its existence, morphological features and internal structure plants are largely determined by the characteristics of the soil. At the same time, the direction and intensity of the course of physiological and biochemical processes also depend on the chemical composition of the soil and its other properties, which ultimately determines the increase in plant biomass and the productivity of crop production as an industry as a whole. Therefore, botanical knowledge makes it possible to substantiate the need and doses of applying various substances to the soil, to influence the yield cultivated plants. In fact, any impact on the soil in order to increase the yield of crops and wild plants based on data obtained in various branches of botany. The methods of biological control of plant growth and development are based almost entirely on botanical morphology and embryology.
In its turn vegetable world is an important factor in soil formation and determines many properties of the soil. Each type of vegetation is characterized by certain types of soils, and these patterns are successfully used for mapping soils. Plant species and their individual systematic groups can be reliable phytoindicators of food (ground) conditions. Indicator geobotany gives soil scientists and agrochemists one of the important methods for assessing the quality of soils, their physicochemical and chemical properties,
Botany is the theoretical basis of agricultural chemistry, as well as applied areas such as crop production and forestry. About 2,000 plant species have now been introduced into cultivation, but only an insignificant part of them is widely grown. Many wild-growing species of flora can become very promising crops in the future. Botany substantiates the possibility and expediency of agricultural development of natural areas, carrying out land reclamation measures to increase the productivity of natural plant groups, in particular meadows and forests, promotes the development and rational use of plant resources on land, fresh water bodies and the World Ocean.
For specialists in the field of agrochemistry and soil science, botany is the basic basis, which allows a deeper understanding of the essence of soil-forming processes, to see the dependence of certain soil properties on the characteristics of the vegetation cover, and to understand the needs of cultivated plants for specific nutrients.
When determining the needs of plants for fertilizers, along with agrochemical analyzes of the soil, field and vegetation experiments, microbiological and other methods, methods of plant diagnostics began to be used more and more.
Currently, the following methods of plant diagnostics are widely used: 1) chemical analysis of plants, 2) visual diagnostics and 3) injection and spraying. Chemical analysis of plants is the most common method for diagnosing the need for fertilizer application.
Chemical diagnostics is represented by three types: 1) leaf diagnostics, 2) tissue diagnostics, and 3) fast (express) methods of plant analysis.
Important steps in plant diagnostics using chemical analysis are: 1) taking a plant sample for analysis; 2) taking into account the accompanying conditions of plant growth; 3) chemical analysis of plants; 4) processing of analytical data and drawing up a conclusion on the need for plants in fertilizers.
Taking plant samples for analysis. When selecting plants for analysis, care should be taken to ensure that the plants taken correspond to the average condition of plants in a given section of the field. If the sowing is homogeneous, then one sample can be limited; if there are spots of better developed or, conversely, worse developed plants, then a separate sample is taken from each of these spots to determine the cause of the altered state of the plant. The nutrient content of well-developed plants can be used in this case as an indicator of the normal composition of a given plant species.
When conducting analyzes, it is necessary to unify the technique of taking and preparing a sample: taking the same parts of a plant by layering, position on the plant, and physiological age.
The choice of plant part for analysis depends on the method of chemical diagnostics. To obtain reliable data, it is necessary to take samples from at least ten plants.
In tree crops, due to the peculiarities of their age-related changes, taking plant samples is somewhat more difficult than in field crops. It is recommended to conduct research in the following age periods: seedlings, seedlings, young and fruiting plants. Leaves, their petioles, buds, shoots or other organs should be taken from the upper third of the shoots from the middle zone of the crown of trees or shrubs of the same age and quality, adhering to the same order, namely: either only from fruit shoots, or only from non-fruit shoots, or from shoots of current growth, or leaves in direct sunlight or diffused light. All these points must be taken into account, since they all affect the chemical composition of the leaves. It is noted that the best correlation between the chemical composition of the leaf and the yield of fruits is obtained if a leaf is taken as a sample, in the axil of which a flower bud develops.
At what phase of plant development should samples be taken for analysis? If we keep in mind obtaining the best correlation with the harvest, then the analysis of plants in the flowering or maturation phase turns out to be the best. So, Lundegard, Kolarzhik and other researchers believe that flowering is such a phase for all plants, since by this moment the main growth processes are over and the mass gain will not “dilute” the percentage of substances.
To solve the problem of how to change the nutrition of plants in order to ensure the formation best harvest, it is necessary to analyze plants in earlier periods of development and not once, but several times (three or four), starting with the appearance of one or two leaves.
Sampling time. I term: for spring cereals (wheat, oats, corn) - in the three-leaf phase, i.e., before the start of differentiation of the embryonic ear or panicle; for flax - the beginning of the "Christmas tree"; for potatoes, legumes, cotton and others - the phase of four to five true leaves, i.e. before budding; for sugar beet - the phase of three true leaves.
II term: for spring cereals - in the phase of five leaves, i.e., in the phase of piping; for beets - in the phase of deployment of the sixth leaf; for everyone else - during the formation of the first small green buds, i.e., to the very beginning of budding.
III term: in the flowering phase; for beets - when deploying the eighth-ninth leaf.
IV term: in the phase of milk ripeness of seeds; for beets - a week before harvesting.
In woody plants and berries, samples are taken according to the following phases of crop formation: a) before flowering, i.e. at the beginning of strong growth, b) flowering, i.e. during the period of strong growth and physiological shedding of ovaries, c) fruit formation, d ) ripening and harvesting; and e) the period of autumn leaf fall.
When establishing the timing of plant sampling, it is also necessary to take into account during which period of growth and development critical nutritional levels occur. The term "critical levels" means the lowest concentrations of nutrients in plants during the critical period of their development, i.e., concentrations below which the plant deteriorates and yield decreases. The optimal composition of a plant is understood as such a content of nutrients in it in the critical phases of its development, which ensures a high yield.
The values of critical levels and the optimal composition are given for some cultures below. Samples are taken in all cases at the same hours of the day, preferably in the morning (at 8-9 o'clock), in order to avoid changes in the composition of plants due to the daily diet.
Accounting for related conditions. It is not always correct to judge the sufficiency or insufficiency of plant nutrition with certain elements only according to chemical analysis. Many facts are known when a lack of one or more nutrients, a delay in photosynthesis or a violation of water, thermal and other vital regimes can cause the accumulation of one or another element in a plant, which in no case should characterize the sufficiency of this element in the nutrient medium (soil ). To avoid possible errors and inaccuracies in the conclusions, it is necessary to compare the data of the chemical analysis of plants with a number of other indicators: with the weight, growth and rate of development of plants at the time of sampling and with the final harvest, with visual diagnostic signs, with the features of agricultural technology, with the agrochemical properties of the soil , with weather conditions and a number of other indicators that affect plant nutrition. Therefore, one of the most important conditions for the successful use of plant diagnostics is the most detailed account of all these indicators for their subsequent comparison with each other and with the analysis data.
History of the study of plant physiology. The main sections of plant physiology
Plant physiology as a branch of botany.
The topic of the work must be agreed with the curator of the discipline of choice (elective) A.N. Luferov.
Features of the structure of a plant cell, chemical composition.
1. History of the study of plant physiology. The main sections and tasks of plant physiology
2. Basic methods for studying plant physiology
3. Structure of a plant cell
4. Chemical composition of the plant cell
5. Biological membranes
Plant physiology is a science that studies the life processes that occur in a plant organism.
Information about the processes occurring in a living plant accumulated with the development of botany. The development of plant physiology as a science was determined by the use of new, more perfect methods chemistry, physics and the needs of agriculture.
Plant physiology originated in the 17th-18th centuries. The beginning of plant physiology as a science was laid by the experiments of J.B. Van Helmont on the water nutrition of plants (1634).
The results of a number of physiological experiments proving the existence of descending and ascending currents of water and nutrients, air nutrition of plants are set out in the classic works of the Italian biologist and physician M. Malpighi "Plant Anatomy" (1675-1679) and the English botanist and physician S. Gales "Statics plants "(1727). In 1771, the English scientist D. Priestley discovered and described the process of photosynthesis - air nutrition of plants. In 1800, J. Senebier published a treatise “Physiological vegetale” in five volumes, in which all the data known by that time were collected, processed and comprehended, the term “physiology of plants” was proposed, tasks were defined, methods for studying plant physiology, experimentally proved that carbon dioxide is the source of carbon in photosynthesis, laid the foundations of photochemistry.
In the 19th - 20th centuries, a number of discoveries were made in the field of plant physiology:
1806 - T.A. Knight described and experimentally studied the phenomenon of geotropism;
1817 - P.J. Peltier and J. Kavantou isolated a green pigment from leaves and called it chlorophyll;
1826 - G. Dutrochet discovered the phenomenon of osmosis;
1838-1839 - T. Schwann and M. Ya. Schleiden substantiated the cellular theory of the structure of plants and animals;
1840 - J. Liebig developed the theory of mineral nutrition of plants;
1851 - V.Hofmeister discovered the alternation of generations in higher plants;
1859 - C. Darwin laid the foundations of evolutionary plant physiology, flower physiology, heterotrophic nutrition, movement and irritability of plants;
1862 - J. Sachs showed that starch is a product of photosynthesis;
1865 - 1875 - K.A. Timiryazev studied the role of red light in the processes of photosynthesis, developed an idea of the cosmic role of green plants;
1877 - W. Pfeffer discovered the laws of osmosis;
1878-1880 - G. Gelrigel and J. B. Boussengo showed the fixation of atmospheric nitrogen in legumes in symbiosis with nodule bacteria;
1897 M. Nentsky and L. Markhlevsky discovered the structure of chlorophyll;
1903 - G. Klebs developed the doctrine of the influence of environmental factors on the growth and development of plants;
1912 - V.I. Palladin put forward the idea of anaerobic and aerobic stages of respiration;
1920 - W. W. Garner and G. A. Allard discovered the phenomenon of photoperiodism;
1937 - G.A. Krebs described the cycle citric acid;
1937 - M.Kh Chailakhyan put forward the hormonal theory of plant development;
1937 -1939 – G.Kalkar and V.A.Blitser discovered oxidative phosphorylation;
1946 - 1956 - M. Calvin and co-workers deciphered the main pathway of carbon in photosynthesis;
1943-1957 – R. Emerson experimentally proved the existence of two photosystems;
1954 - D.I. Arnon et al. discovered photophosphorylation;
1961-1966 – P. Mitchell developed the chemiosmotic theory of coupling of oxidation and phosphorylation.
As well as other discoveries that determined the development of plant physiology as a science.
The main sections of plant physiology were differentiated in the 19th century - these are:
1. physiology of photosynthesis
2. physiology of the water regime of plants
3. physiology of mineral nutrition
4. physiology of growth and development
5. physiology of resistance
6. physiology of reproduction
7. physiology of respiration.
But any phenomena in a plant cannot be understood within the framework of only one section. Therefore, in the second half of the XX century. in plant physiology, there is a tendency to merge into a single whole biochemistry and molecular biology, biophysics and biological modeling, cytology, anatomy and genetics of plants.
Modern plant physiology is a fundamental science, its main task is to study the patterns of plant life. But it is of great practical importance, so its second task is to develop theoretical foundations obtaining maximum yields of agricultural, industrial and medicinal crops. Plant physiology is the science of the future, its third, as yet unsolved, task is the development of installations for the implementation of photosynthesis processes in artificial conditions.
Modern plant physiology uses the entire arsenal scientific methods that exists today. These are microscopic, biochemical, immunological, chromatographic, radioisotope, etc.
Let us consider the instrumental research methods widely used in the study of physiological processes in a plant. Instrumental methods of working with biological objects are divided into groups depending on any criterion:
1. Depending on where the sensitive elements of the device are located (on the plant or not): contact and remote;
2. By the nature of the value obtained: qualitative, semi-quantitative and quantitative. Qualitative - the researcher receives information only about the presence or absence of a substance or process. Semi-quantitative - the researcher can compare the capabilities of one object with others in terms of the intensity of a process, in terms of the content of substances (if it is not expressed in numerical form, but, for example, in the form of a scale). Quantitative - the researcher receives numerical indicators characterizing any process or content of substances.
3. Direct and indirect. When using direct methods, the researcher receives information about the process under study. Indirect methods are based on measurements of any accompanying quantities, one way or another related to the studied one.
4. Depending on the conditions of the experiment, the methods are divided into laboratory and field.
When conducting research on plant objects, the following types of measurements can be carried out:
1. Morphometry (measurement of various morphological indicators and their dynamics (for example, leaf surface area, ratio of areas of aboveground and underground organs, etc.)
2. Weight measurements. For example, determining the daily dynamics of the accumulation of vegetative mass
3. Measurement of solution concentration, chemical composition of samples, etc. using conductometric, potentiometric and other methods.
4. Study of gas exchange (when studying the intensity of photosynthesis and gas exchange)
Morphometric indicators can be determined by visual counting, measuring with a ruler, graph paper, etc. To determine some indicators, for example, the total volume of the root system, special installations are used - a vessel with a graduated capillary. The volume of the root system is determined by the volume of water displaced.
When studying any process, use various methods. For example, to determine the level of transpiration, use:
1. Weight methods (initial sheet weight and its weight after some time);
2. Temperature (use special climate chambers);
3. With the help of porometers, the humidity of the chamber where the test plant is placed is determined.