Activated carbon stimulated seed germination of lettuce (Lactuca sativa L.) in soil and vermiculite. Stimulation was strongly dependent upon the moisture potential. Germinating seeds were shown to excrete an inhibitor into the micro-environment which cannot diffuse away rapidly at moisture potentials near the soil field capacity or at analogous potentials in vermiculite. Increasing the moisture potential or adding activated carbon caused rapid removal of inhibitor from the seed micro-environment.
Received for publication August 5, 1977. Journal paper no. 2770. Arizona Agricultural Experiment Station.
Horticulturist, Mesa Branch Experiment Station, Mesa, AZ 85201.