UPTAKE OF NUTRIENTS IN PLANTS

UPTAKE OF NUTRIENTS IN PLANTS

Mineral uptake is the process in which minerals enter the cellular
material, typically following the same pathway as water. The
uptake of nutrients occurs at both the roots and the ​leaves.

Ions may be taken up by the plant cells by two methods:


•​ 1. Passive Absorption. • 2. Active Absorption.

PASSIVE ABSORPTION


It is the absorption of minerals ​without direct
expenditure of metabolic energy​.

• I. Mineral salt absorption is not affected by temperature and
metabolic inhibitors •

II. Rapid uptake of ions occurs when plant tissues are
transferred from a medium of low concentration to high
concentration.

, Theories of passive absorption​ • :

• 1. Mass flow theory. -

According to this theory ions are absorbed by the root along with
mass flow of water under the effect of transpiration. An increase
in transpiration pull increases the uptake of ions by the roots,
(the uptake of ions by free diffusion). Thus, mass flow of ions
through the root tissues occurs due to transpiration pull in the
absence of metabolic energy.

This theory failed to explain the salt accumulation against
osmotic gradients.


• 2. Contact Exchange theory.