BY – VIGYAN ASHRAM, PABAL

Nutrient absorption / uptake in Plants.

Nutrients Absoption

Mechanisms of Nutrient Uptake

Prior to absorption, nutrients reach the root by 3 mechanisms:

Mass flow – movement with the water flow. Most prominent.

Diffusion – movement in response to a concentration gradient. Slow.

Root interception – root extension. Very important to find new nutrient sources.

Absorption through roots

Passive Uptake: Some ions such as nitrate, can move passively through the outer membrane of the root surface along with water in the transpiration stream.

Active Uptake: Not well understood, but many nutrients (e.g., K+ and H2PO4

-) must somehow bond with an ion-specific carrier (see Insight: p.270).

Maintaining an Electrical Balance: As cations are absorbed H+ is excreted or organic anions are produced. As anions are absorbed HCO3

- is excreted or compensating cations are absorbed.

For more information on this you can visit - http://www.docstoc.com/docs/20285167/PLANT-NUTRITION-AND-NUTRIENT-TRANSPORT-IN-SOILS.

Stomatal Absorption:

•Rapid absorption of soluble ions from nutrient enriched water.

•Used mostly for the immediate correction of critical nutrient deficiencies.

•Most efficient for the micronutrients. Does not build soil fertility. Danger of phytotoxic effects if over applied.

Absorption through leaves

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