Osmoregulation or Turgor Regulation in Chara ?

Abstract

Chara corallina Klein ex Willd. wm. R.D.W. (= C. australis R. Br.), a fresh water alga, maintains a constant internal osmotic pressure when external osmotic pressure is increased. This results in a decrease in turgor pressure. Chara osmoregulates effectively in the presence of high CaCl(2) and raffinose, but is less efficient in response to increased NaCl. Decreasing external pH from 7 to 5 results in a decrease in turgor, but increasing it to values as high as 9 has no effect. Increasing the daily amount of light from 0.5 to 24 hours has no effect on turgor.