Lamprothamnium, a euryhaline charophyte: II. Time course of turgor regulation

Changes in the concentrations of K⁺ and Cl^- occur in parallel during turgor regulation, and account for the changes in osmotic pressure. Thus it is impossible to single out one ion whose concentration is directly controlled by a turgor regulatory mechanism. After an increase in external osmolality (π^o) of 400 mosmol kg^-1, turgor is restored to its normal value in 4-5 d. The response to a decrease in π^o is much more rapid, with most of the change in π¹ occurring in the first 2 h. Apparent cytoplasmic concentrations of sucrose are similar to vacuolar concentrations, and increase slightly with increasing π¹.