Thursday, 3 September 2015

Turgor Pressure

Turgor pressure is the pressure exerted by protoplast upon the cell wall. It occurs due to the osmotic entry of water by endosmosis.
                                               As action and reaction are equal and opposite, therefore, cell wall exerts pressure on protoplast which is called wall pressure. It is denoted by W.P. and is equal to turgor pressure.

Function of Turgor presure:- i) The opening and closing of stomatal pores is regulated by the turgidity of the guard cells.
ii) Turgor pressure provides the mechanical support to the non-woody stems.
iii) It helps in keeping leaves erect and fully expanded. In case of loss of turgidity, the shoots droop down and the leaves show wilting. Wilting is observed in  many plants during summer noon.In wilting the cells of leaves and other softer parts become flaccid due to loss of water. Plants gain their turgidity during night because continued absorption of water from soil, recovery may be partial or it may not occur at all. The latter condition is known as permanent wilting.
iv) Turgor pressure controls the turgor movements, like in the leaf of Mimosa pudica.
v) It helps in cell enlargement.

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