VEGETATIVE PROPAGATION OF ATMOSPHERIC TIL LANDSIAS .3. CHANGES IN ACIDITY OF THE MEDIUM DURING IN-VITRO PROPAGATION

The example of Tillandsia stricta shows the ability of CAM-plants for changing the acidity of the medium in vitro. Small quantities of plant material can alter and stabilize the pH-value within a few days. Duri ng the light period the medium turns sour and the plant material react s exactly vice versa. There seems to be an open exchange of H+ ions am ong the medium and the plant material in vitro. The high acidity in th e medium can possibly be responsible for the decay of plant material d uring in vitro culture.