a Mineral food. Functions of various elements in a plant

you are: a Mineral food

The Main elements participating in photosynthesis (With, N, and also nitrogen, sulphur and phosphorus make the basic building blocks of a body of a plant. For example, the cellular walls forming a skeleton of a plant, consist almost exclusively of carbohydrates and the connections close to them containing With, N and O.Belki, the main organic components of cytoplasm, are constructed mainly from With, N, About and N and small amount S. In structure of the nucleinic acids which are present at kernels and in some organellah of cytoplasm, enter With, N, About, N and R.Lipidy, containing is a lot of in all membranes, consist mainly from With, N and About, and also insignificant quantity N and the River Of 12 elements as which source the parent breed serves, four are used by a plant mainly for the structural purposes. Sulphur is a component of several amino acids (tsistein, tsistin and methionine) - structural units from which fibers finally are formed. Though rather small quantity of sulphur is necessary for plant cages, almost all it carries out the important structural function. Without sulphur-containing of amino acids many important fibers of a cage could not be synthesised. sulphur is present also in glutatione, widespread substance which as believe, plays a part in oxidation-reduction reactions thanks to the ability to reversible transformation from restored, or sulfgidrilnoj, forms (-SH), in oxidised, or disulfidnuju, the form (- S-S-):

Formation disulfidnyh bridges (- S-S-) between the next parts of the big albuminous molecules important for their final form and stability. Sulphur is also a component kofermenta And and tiamina (vitamin B1).

The Quantitatively basic function of calcium (Sa) consists in its inclusion in structure of a median plate of a cellular wall. The calcium connected with acid components zheleobraznogo of pectin of a median plate, forms insoluble salt. Therefore introduction of Sa in a cellular wall leads to hardening of its semi-fluid structure. Calcium plays also the important role in regulation of selective permeability of a cellular membrane. At cultivation of plants in the environment with a lack of Sa cellular membranes start ' to proceed ' and lose the efficiency as the barriers interfering free diffusion of ions. Magnesium, the chemical relative of calcium, makes the central part of a molecule of a chlorophyll, joining each of four pirrolnyh rings or is direct with the help kovalentnyh communications, or by means of so-called ' secondary valencies '. At a lack of magnesium it is found out in older leaves pozheltenie, characteristic for deficiency of a chlorophyll (hloroz). It is known that magnesium is also specific kofaktorom several enzymes; besides, it provides stability of nucleinic acids.

Phosphorus serves mainly as a structural component of nucleinic acids, DNA and RNK, and is a part fosfolipidov - zhiropodobnyh of substances which play an essential role in structure of membranes. Therefore the phosphorus lack represents the big danger to plants, preventing formation of a new genetic material in a kernel and cytoplasm, and also formation of new membranes round a cage and its various organell. Phosphorus directly participates in all stages of carrying over of energy in a cage as ATR and its analogues consist of three phosphates connected with nukleozidom.

Though phosphorus, magnesium, calcium and sulphur carry out in a cage and other functions, quantitatively prevail the structural functions of these elements described by us.

Kaly is osmotically active element participating in regulation tourist's mountain of vegetative cages. The majority of plants differs the high maintenance kalija though only its very small quantity is in cellular structures in the connected condition. It is typically mobile element. As membranes of many cages easily pronitsaemy for kalija, through them usually proceed big diffuzionnye streams of this element. The water maintenance in many cages, including and what supervise movements, it is often defined by concentration in them kalija. It is fair, for example, for closing cages ustits (thanking tourist's mountain they supervise opening and closing ustits), and also for the motor cages regulating daily movements of leaves (fig. 6.14 see).

It is known also that kaly activates some the important enzymes though it has been never allocated as a component of this or that fermental system.

Chlorine in shape hloridaniona also participates in regulation tourist's mountain in some plants. Moving together with kaliem, it supports an electroneutrality in cages. However the chloride maintenance seldom reaches such high level, as the maintenance kalija. Some plants characterised by considerable changes tourist's mountain, regulated kaliem, contain not enough chloride and instead of it use organic aniony, such, as malat. Thus, chloride, obviously, participates in regulation of tourist's mountains and and those cases when it is accessible, but is not absolutely necessary for this purpose. It is known also that chlorine stimulates photosynthetic fosforilirovanie, but its exact biochemical role, in this process is not established yet. Probably that in fotofosforilirovanie those are involved only is insignificant small quantities anionov С1- which are necessary for the majority of plants.

In essence value of chlorine for plants is found out rather recently after experiences in which all air in experimental hothouses was filtered for removal of the slightest traces of atmospheric chlorine have been put. It has thus appeared that such sledovyh quantities of chlorine it is sufficient for favorable growth of the majority of plants.

From other six elements (iFe, Mn, Si, Zn, Mo, first five function in a cage mainly as an essential component of enzymes. Earlier it was already noticed that many important enzymes represent specific fibers to whom the special groups named prosteticheskimi groups, or kofermentami are attached. These groups can consist in full or in part of metals, such, as Fe Si, Mn, Zn OR Mo.

Iron is A PART some many important enzymes, including tsitohromov - carriers elektronov, participating in breath process, and also oxidising enzymes peroksidazy and katalazy. In all these enzymes iron is present in proeteticheskoj to group at a kind gema (analogue of a chlorophyll) in which the central atom of iron is connected with four pirrolnymi the rings connected in the big cyclic structure.

In such enzymes iron functions thanks to the ability reversible to be oxidised and restored (Fe3 ++ e -=Fe2 +); negeminovoe iron can operate in the same way. Copper also possesses property reversible to be oxidised and restored (Сu2 ++ e -=Сu +). It is quite probable that the manganese which is a part of enzyme superoksiddismutazy, plays the same role in many oxidising reactions. Iron has essential value and for the enzymes participating in synthesis of a chlorophyll. Besides, it is a component ferredoksina - the connection functioning as a carrier elektronov in the course of photosynthesis. The iron lack causes deep hloroz in developing leaves which can become absolutely white.

Molybdenum, apparently, is involved in functioning only those enzymes (nitratreduktaza, nitrogenaza), which katalizirujut restoration or nitrogen fixing. If under plants the restored or organic nitrogen the requirement for molybdenum decreases is brought or disappears at all.

Copper is a component of some oxidising enzymes, such, as tirozinaza and askorbatoksidaza, oxidising accordingly amino acid tirozin and vitamin C (ascorbic acid).

Zinc is a part some enzyme karboangidrazy, katalizirujushchej hydration СО2 in Н2СО3. This enzyme, possibly, plays the important role in maintenance of stocks potential СО2 for photosynthesis as Н2СО3 easily dissociates with bicarbonate formation (НСО3-) or free СО2. Besides.tsink in quality kofaktora participates in synthesis of a vegetative hormone - indoliluksusnoj acids - from amino acid triptofana. In the absence of zinc sickly plants with poorly developed apikalnym domination are formed.

The pine forest Lack usually leads to death meristematichesnih of cages, however the exact mechanism of its action is not found out. As it is known that the pine forest forms complexes from sugar mi and related it substances, in its function, probably, distant transport of sugars in a plant enters. Some experiences with mechenymi sugars have confirmed the point of view that the pine forest in certain conditions accelerates movement of sugars in a plant. However not all experts in the field agree with this statement. Till now it is not established, whether the pine forest participates in other aspects of cellular development.

Except the elements absolutely necessary for growth, a plant contain significant amounts of others, minor, elements. In certain cases they can promote growth or power balance of a plant. As it was marked above, grain grow better in the presence of silicon: so, the plants of wheat which has been grown up for lack of silicon, are much more sensitive to defeat by mushrooms, than at their cultivation in the presence of silicon. The plants of the beet which has been grown up in the presence of sodium (Na +), form larger and fleshy root crops, than for lack of this element. Despite favorable physiological action of such elements, strictly speaking, they cannot be considered as essential to a plant. Other minor elements containing in plants, can be physiologically inert, and in certain cases even harmful.

Really, a number of the microcells, which insignificant quantities are necessary for growth, become highly toxic in superfluous doses. Them concern Мn, Сu and at high concentration Fe. The pine forest is characterised extremely narrow ·intervalom between deficiency and toxicity. As the plant cannot prevent penetration of this element through a membrane only because it has on it harmful influence, it is necessary to show the big care at regulation of concentration of a pine forest in an environment.