06 Plant Water Relation - part 10 - Transport of mineral ions

06 Plant Water Relation - part 10 - Transport of mineral ions


Transport of mineral ions : 
  • Soil serves as main source for minerals. 
  • Constitute most commonly occuring solid, crystalline inorganic materials obtained from earth's crust. 
  • Play an important role in the day to day life of plant. 
  • Are absorbed by plants in the ionic (disolved) form, mainly through roots and then transported.
  • The analysis of plant ash demonstrates that minerals are absorbed by plants from soil and surroundings. 
  • Absorption of minerals is independent of that of water. 
  • Absorbed mineral ions are pulled in upward direction along with xylem sap because of transpiration pull. This could be understood when the ascending sap is analysed. 
  • Mineral ions are needed in the areas of the plant viz. apical, lateral, young leaves, developing flowers, fruits, seeds and storage organs. 
  • Hence, from the source (root), these are pulled and transported ascendingly through the sapand gets unloaded by fine veins through the process of diffusion in the vicinity of cells. 
  • Cells uptake them actively. 
  • Soil would not be the only source for mineral uptake. 
  • Mineral ions can be remobilized within the parts of the plant. 
  • Older parts (like leaves in deciduous plants)export their ions to younger leaves before the fall. 
  • Most readily mobilized ions are like phosphorus, sulphur, nitrogen and potassiumbut the ions from structural components like calcium is not remobilized.
  • Analysis of xylem exudate also shows that some nitrogen travels as inorganic ions whereas much of it is carried in the organic form likeamino acids and related compounds.
  • Small amount of inorganic molecules of phosphorus and sulphur are also carried. 
  • It was a belief earlier that xylem transports inorganic and phloem transports organic molecules. 
  • However, it is not correct because someexchange of materials also occurs between xylem and phloem.
Do you know ? · 
  • Minerals that play important role in the day to day life, are called essential elements. 
  • About 36 to 40 elements are incorporated in the plant's life. 
  • Some minerals like C, H, O, P, N, S, Mg required in large quantity, are called macro elements. 
  • While minerals like Cu, Co, Mn, B, Zn required in small quantity, are called micro elements.

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