Elements Of Mineral Nutrition Of Plants

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

The main functions of minerals

Mineral nutrition is of great importance for the physiology of a plant, since a sufficient supply of mineral elements is simply necessary for its normal growth and development. Plants, in addition to love and care, require: oxygen, water, carbon dioxide, nitrogen and a whole series (more than 10) of mineral elements that serve as raw materials for various processes of the organism's existence.

Mineral nutrients in plants have many important functions. They can play the role of structural components of plant tissues, catalysts for various reactions, regulators of osmotic pressure, components of buffer systems, and regulators of membrane permeability.

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Examples of the role of minerals as constituents of plant tissues are calcium in cell walls, magnesium in chlorophyll molecules, sulfur in certain proteins, and phosphorus in phospholipids and nucleoproteins. As for nitrogen, although it does not belong to mineral elements, it is often included in their number, in this regard, it should be noted again as an important component of protein.

Some elements, for example, such as iron, copper, zinc, are required in micro doses, but these small amounts are also necessary, since they are part of prosthetic groups or coenzymes of certain enzyme systems. There are a number of elements (boron, copper, zinc) that are deadly poisonous to the plant in higher concentrations. Their toxicity is most likely associated with a negative effect on the enzyme systems of the plant organism.

The importance of providing plants with sufficient mineral nutrition has long been appreciated in horticulture and is an indicator of good growth and, therefore, good and stable yields.

Essential elements

As a result of various studies, the presence in plants of more than half of the elements of the periodic system of Mendeleev was established, and it is quite possible that any element in the soil can be absorbed by the roots. For example, more than 27 elements (!) Were found in some samples of Weymouth pine wood. It is believed that not all of the elements available in plants are necessary for them.

For example, elements such as platinum, tin, silver, aluminum, silicon and sodium are not considered necessary. For the necessary mineral elements, it is customary to take those in the absence of which plants cannot complete their life cycle, and those that are part of the molecule of any necessary plant component.

The main functions of mineral nutrition elements

Most of the studies on the role of various elements have been carried out on herbaceous plants, since their life cycle is such that they can be studied within a short time. In addition, some experiments were carried out on fruit trees and even forest seedlings. As a result of these studies, it was found that various elements in both herbaceous and woody plants perform the same functions.

Nitrogen. The role of nitrogen is well known as a constituent of amino acids - protein builders. In addition, nitrogen is included in many other compounds, such as purines, alkaloids, enzymes, growth regulators, chlorophyll, and even in cell membranes. With a lack of nitrogen, the synthesis of the normal amount of chlorophyll is gradually disrupted, as a result of which, with its extreme deficiency, chlorosis of both older and young leaves develops.

Phosphorus. This element is an integral component of nucleoproteins and phospholipids. Phosphorus is irreplaceable due to the macroenergetic bonds between phosphate groups, which serve as the main mediator in the transfer of energy in plants. Phosphorus is found in both inorganic and organic forms. It easily moves through the plant, apparently in both forms. Lack of phosphorus primarily affects the growth of young trees in the absence of any symptoms.

Potassium. The organic forms of potassium are not known to science, but plants need a large enough amount of it, apparently, for the activity of enzymes. An interesting fact is that plant cells distinguish between potassium and sodium. Moreover, sodium cannot be fully replaced by potassium. It is generally accepted that potassium plays the role of an osmotic agent in the opening and closing of stomata. It should also be noted that potassium in plants is very mobile, and its deficiency impedes the movement of carbohydrates and nitrogen metabolism, but this action is more indirect than direct.

Sulfur. This element is a component of cystine, cysteine and other amino acids, biotin, thiamine, coenzyme A and many other compounds belonging to the sulfhydryl group. If we compare sulfur with nitrogen, phosphorus and potassium, then we can say that it is less mobile. Lack of sulfur causes chlorosis and disruption of protein biosynthesis, which often leads to the accumulation of amino acids.

Calcium. Calcium can be found in rather significant amounts in cell walls, and it is there in the form of calcium pectate, which most likely affects the elasticity of the cell walls. In addition, it is involved in nitrogen metabolism by activating several enzymes, including amylase. Calcium is relatively little mobile. The lack of calcium is reflected in the meristematic areas of the root tips, and the excess accumulates in the form of calcium oxylate crystals in the leaves and lignified tissues.

Magnesium. It is part of the chlorophyll molecule and participates in the work of a number of enzyme systems, participates in maintaining the integrity of ribosomes and moves easily. With a lack of magnesium, chlorosis is usually observed.

Iron. Most of the iron is located in chloroplasts, where it participates in the synthesis of plastic proteins, and is also included in a number of respiratory enzymes, such as peroxidase, catalase, ferredoxin, and cytochrome oxidase. Iron is relatively immobile, which contributes to the development of iron deficiency.

Manganese. An essential element for the synthesis of chlorophyll, its main function is the activation of enzyme systems and probably affects the availability of iron. Manganese is relatively immobile and poisonous, and its concentration in the leaves of some tree crops often approaches toxic levels. Manganese deficiency often causes leaf deformation and the formation of chlorotic or dead spots.

Zinc. This element is present in the composition of carbonic anhydrase. Zinc, even in relatively low concentrations, is very toxic, and its lack leads to leaf deformations.

Copper. Copper is a component of several enzymes, including ascorbinotoxidase and tyrosinase. Plants usually require very small amounts of copper, high concentrations of which are toxic, and lack of it causes dry tops.

Bor. The element, as well as copper, is necessary for the plant in very small quantities. Most likely, boron is necessary for the movement of sugars, and its deficiency causes serious damage and death of apical meristems.

Molybdenum. This element is necessary for the plant in negligible concentration, is part of the nitrate reductase enzyme system and most likely performs other functions. The deficiency is rare, but if it is present, nitrogen fixation in sea buckthorn may decrease.

Chlorine. Its functions have been little studied; apparently, it is involved in the splitting of water during photosynthesis.

Mineral deficiency symptoms

The lack of minerals causes changes in biochemical and physiological processes, which leads to morphological changes. Often, due to a deficiency, suppression of shoot growth is observed. Their most noticeable disadvantage is the yellowing of the leaves, which, in turn, is caused by a decrease in chlorophyll biosynthesis. Based on observations, it can be noted that the most vulnerable part of the plant is the leaves: they decrease in size, shape and structure, the color fades, dead areas are formed at the tips, edges or between the main veins, and occasionally the leaves are collected in bunches or even rosettes.

Examples of the lack of various elements in a number of the most common cultures should be given.

Lack of nitrogen primarily affects the size and color of the leaves. In them, the chlorophyll content decreases and the intense green color is lost, and the leaves turn light green, orange, red or purple. The leaf petioles and their veins become reddish. At the same time, the size of the leaf blade decreases. The angle of inclination of the petiole to the shoot becomes sharp. Early leaf fall is noted, the number of flowers and fruits sharply decreases simultaneously with a weakening of the growth of shoots.

Shoots turn brown-red, and fruits are small and brightly colored. Separately, it is worth mentioning strawberries, in which a lack of nitrogen leads to weak whisker formation, redness and early yellowing of old leaves. But the abundance of nitrogen also adversely affects the plant, causing excessive enlargement of leaves, their saturated, too dark green color and, on the contrary, a weak color of fruits, their early abscission and poor storage. An indicator plant for a lack of nitrogen is an apple tree.

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