a Mineral food. Transport of mineral substances in a plant

you are: a Mineral food

Ions arrive in a plant as a result of their diffusion from a soil solution in cellular walls of root hairs and others epidermalnyh cages. Then, before to move to other parts of a plant, they are transported in simplast or apoplast. If the ion arrives in simplast, having passed through plazmalemmu an external cage of a root its subsequent movement from a cage to a cage will occur on plazmodesmam. Besides, it can move on apoplastu, yet will not reach a corbel of Kaspari. As neither water, nor the dissolved ions cannot diffundirovat through suberinizi-rovannye the cellular walls forming a corbel of Kaspari, all ions before moving further, should pass through cytoplasm of cages endodermy. One ions can get through membrannye barriers easier, than others. Therefore properties plazmalemmy root cages are important for exchange monitoring by mineral substances between soil and elevated parts of a plant. Along with selective permeability of membranes the big role is played also by active transport of many ions. Negatively charged ions are usually actively transported in a cage as their moving to a cage by diffusion is braked by internal negative potential. superfluous receipt of some kationov, for example Na +, thanks to diffusion will be neutralised by active allocation of these ions from a cage, i.e. They are actively thrown out by a plant.

Having got into cage cytoplasm endodermy, ions can continue movement on simplastnomu ways through plazmodesmy to any cage of a pericyclic layer or, having left simplast, they can reach by means of diffusion or active transport ksilemy or apoplastnoj zones stely. If ions continue to be transported on stele through simplast finally they should leave a protolayer and cross a cellular membrane before will get to a cavity of any dead element keilemnogo a vessel. we know that ions collect in ksilemnyh tubes during those periods when the weak water current is observed. As thus ions should move as inside at least one cage, and from it, it is obvious that two parties of some membranes, possibly, endodermalnyh the cages turned to a surface and in a root, should possess different ionotransportnymi properties.

Having arrived in ksilemu, ions cannot back pass in simplast as their diffusion is interfered by selective permeability of cellular membranes, at the same time their way to soil through apoplast is blocked by a corbel of Kaspari. Accumulation of ions in ksileme increases concentration of the dissolved substances in ksilemnom juice that can lead to development of the root pressure considered in gl. 6. Ions in ksileme, transferred ascending tranopiratsionnym a current, before penetration into a protolayer of a live cage should be again absorbed plazmalemmoj. Whichever there was a way of ions, a plant, obviously, reduces to a minimum number plazmalemmnyh barriers, which the given ion should cross to reach the ultimate goal.

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