The Physiology of Flowering Plants - KHAM PHA MOI

WATER POTENTIALS OF PLANT CELLS AND TISSUES 63(= that of pure water, with which it is in equilibrium), the osmoticpotential of the cell contents being balanced by the pressurepotential:C ¼ 0; and C p ¼ C p (3:3)This cell is at full turgidity, at maximal volume, maximal wall pressureand maximal water potential – of 0 MPa! The values of plant cellC usually vary from 0 down, i.e. are negative, and negative values areless than zero.On the other hand, as water is progressively lost from a cell, its Cdecreases, both as a result of the reduction of the pressure, as theFig: 3:1 Effect of waterabsorption and water removal on aplant cell. Starting with a turgid cell(second from top), absorption ofwater leads to increase in turgidityand C increases up to a maximumof 0. Water loss beyond a certainlevel in a solution of low C results inplasmolysis, shrinkage of cellcontents from the wall. Water lossin dry air results in wilting and thepull of the shrinking contents on thewall can lead to a wall tensioninstead of a pressure. V = vacuole.