Plant nutrition elements.
Nitrogen is the most important element of nutrition for all plants. This is due to the fact that it is part of organic compounds, many of which play a huge role in the processes of metabolism. Nitrogen is also an integral part of chlorophyll, without which photosynthesis is impossible. In addition, nitrogen is an integral part of a protein molecule, and thus, along with carbon, phosphorus and sulfur, it also serves as a building material for the formation of living plant tissue. That is why nitrogen is often a factor limiting crop growth.
Without phosphorus, as well as without nitrogen, life is impossible. Phosphorus is a part of compounds involved in the synthesis of protein, fats, starch, sugars, amino acids, growth and reproduction, and the transmission of hereditary traits. The lack of phosphorus leads to violations in such vital processes as photosynthesis and respiration. There are no natural sources of phosphorus replenishment in nature, so a violation of its balance may occur earlier than nitrogen. In contrast to nitrogen, it shortens the growing season. Moreover, the amount of nitrogen and phosphorus in the plant's nutrition should be balanced, otherwise, if there is a lack of phosphorus, the effect of nitrogen will sharply increase, as if it is contained in excess.
In cold weather, the threat of phosphorus starvation increases. Most of the metabolic processes are carried out only with his participation. It ensures the health of the roots, the laying of buds, the ripening of fruits and seeds, increases winter hardiness.
The functions of potassium in the plant body are very diverse. It contributes to the good general condition of plants, increases their resistance to low temperatures. Especially a lot of potassium is required for young plants. The manifestations of the deficiency of this element are not as noticeable as the lack of other macronutrients. It participates in carbohydrate and protein metabolism, increases the formation of sugars in the leaves and their movement to other organs. In addition, potassium improves the flow of water into plant cells and reduces the evaporation process, thereby increasing the resistance of plants to drought.
Plants experience a lack of calcium on strongly acidic soils, and sometimes on saline ones. Calcium stimulates the growth and development of plants, their root system. Increases the resistance of plants to the harmful effects of acids, as well as cations (sodium, aluminum, iron). Calcium plays an important role in the metabolic processes, it promotes the movement of carbohydrates, the conversion of nitrogenous substances, accelerates the consumption of spare seed proteins during germination, etc.
Magnesium is a part of the chlorophyll molecule and is directly involved in photosynthesis. It participates in the movement of phosphorus in plants, activates enzymes, accelerates the formation of carbohydrates. It is also a building element, being part of the ribosomes.
When magnesium is deficient, the protein metabolism of plants is disrupted due to the weak functioning of enzyme synthesis, and the assimilation and synthetic activity of plants is also limited. Magnesium affects the growth dynamics of the root system and the assimilation of nutrients from the soil, especially nitrogen.
Sulfur is a very important element of nutrition, as it is part of proteins, some amino acids, vitamins (B1 and H), antibiotics, vegetable oils. It plays an important role in metabolic processes, in the activation of enzymes, promotes the fixation of nitrogen from the atmosphere, enhances the formation of nodules in leguminous plants.
With a lack of sulfur, protein synthesis slows down, so the symptoms of sulfur starvation are similar to the signs of nitrogen starvation. The growth and development of plants slows down, the size of the leaves decreases, the stems lengthen.
This element is a part of many enzymes and therefore takes part in redox processes: respiration, photosynthesis, nitrogen assimilation. Manganese contributes to the accumulation of sugars in sugar beet, an increase in protein in wheat and corn grains, the formation of ascorbic acid and other vitamins in plants. The lack of manganese in the soil can occur for various reasons, but the most common is the high content of calcium carbonates: in their presence, the solubility of manganese decreases sharply. The availability of manganese also decreases during loosening of the soil, as well as in dry years.
Iron is part of the enzymes involved in the formation of chlorophyll, so its lack affects the intensity of photosynthesis processes and is manifested by a disease called chlorosis. The most common sign of chlorosis is light yellow, almost white leaves. Moreover, since iron is weakly mobile in the plant, the old leaves remain green for a long time, while the young ones turn yellow or turn white (the veins remain green longer), and then die. On carbonate soils, iron can also go into an inaccessible state, since in a slightly alkaline environment it binds to iron carbonates.
Plants react negatively to the lack of boron when its water-soluble forms are contained in the soil in an amount of less than 0.3 mg per 1 kg of soil. For the successful development, vital activity and reproduction of plants, boron (B) is one of the most important trace elements. In terms of importance, it is assigned the second place after zinc, and in some regions it has the greatest practical significance. Boron is a unique element that is not included in the group of metals. It is necessary for plants throughout their life, as it participates in the transport of carbohydrates, in particular sugars, the synthesis of cell walls, a sufficient amount of it for a plant increases the intensity of photosynthesis, improves hydrocarbon, nucleic and protein metabolism, activates the activity of enzymes, has a beneficial effect on the processes of cell division. At the same time, the need for different cultures in the bar is different. Vegetables and fruits (dicotyledons) consume boron 10 times more than cereals (monocotyledons). The lack of boron in plants is most often manifested on carbonate soils.
Without copper, plant seedlings die. This is due to the fact that this element is part of many enzymes, in the absence or insufficient number of which most physiological processes are disrupted: respiration, photosynthesis, carbohydrate and protein metabolism. Copper is involved in regulating the water balance of plants, so when there is a lack of it, plants lose turgor, the leaves droop, despite the sufficient amount of water in the soil.
Zinc, as well as copper, is a part of many enzymes and therefore participates in protein, carbohydrate, lipid, phosphorus metabolism. In its absence or lack, the biosynthesis of vitamins (ascorbic acid, vitamin B1) and growth substances – auxins is disrupted. With a sharp lack of zinc, the process of chlorophyll formation is disrupted, resulting in spotty chlorosis.
Usually, zinc starvation is manifested on carbonate soils, since carbonates contribute to the transfer of zinc to a sedentary state. In addition, calcium is an antagonist of zinc and on carbonate soils can delay the supply of zinc to plants.
There is little molybdenum in the soils. Meanwhile, molybdenum plays a very important role in the plant's body, as it is associated with nitrogen metabolism. It activates the binding of atmospheric nitrogen by nodule bacteria living on the roots of leguminous plants. It promotes the synthesis and exchange of protein substances in plants, as it is part of an enzyme that reduces nitrate nitrogen to an ammonium form. Therefore, with a lack of molybdenum, nitrates accumulate in plants, less proteins are formed, and the exchange of nitrogenous compounds is disrupted. Molybdenum is also involved in the synthesis of vitamins and chlorophyll, carbohydrate metabolism, therefore, with its lack, the formation of chlorophyll slows down, chlorosis is observed, the content of ascorbic acid in the plant sharply decreases.
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Cobalt (Co) is a trace element known mainly for the fact that its presence in a living organism is necessary for the synthesis of vitamin B12 (this complex organic compound plays an important role in the processes of hematopoiesis). In plants, cobalt is necessary for the fixation of molecular nitrogen, it promotes the formation of bacteria in the nodules and leaves of legumes. Cobalt accumulates in pollen and accelerates its germination, participates in auxin metabolism, i.e. stimulates plant growth processes (including promotes stretching of cell membranes). This metal is involved in the cellular reproduction of leaves (an increase in the thickness and volume of the mesophyll, the size and number of cells of the columnar and spongy parenchyma of the leaf). In addition, cobalt increases the total water content in plants, which contributes to an increase in the drought resistance of crops.