The variation of osmotic potential, symplastic water content and tissu
e elasticity have been studied by the pressure-volume technique, on ac
tive growing plants under two irrigation treatments. Pressure-volume c
urves were made on terminal branches of Atriplex repanda Phil., a shru
b from the semiarid zone of Chile. Results showed that when the water
deficits is gradual, plants adjust the osmotic potential of their term
inal branches in spite of a decrease in the total water potential. The
osmotic potential at full turgor is relatively constant for plants wi
ch are not conditioned to water deficit. In constrast, conditioned pla
nts show a decrease of -0.4 MPa. Plants undergo water deficit the elas
ticity modulus decreases about 25% compared to those without water def
icit. Osmotic adjustment and elasticity modifications of cellular wall
s of plants conditioned to water deficit have a complementary effect o
n the maintenance of cell and tissue turgor.