THE EFFECT OF A PLANT-DERIVED SMOKE EXTRACT ON THE GERMINATION OF LIGHT-SENSITIVE LETTUCE SEED

A simple and rapid bioassay using seeds of Lactuca sativa L. Grand Rap ids has been developed for the detection of germination-enhancing comp ound(s) in plant-derived smoke extracts. This light-sensitive species germinates within 24 h in the dark at 20 or 25 degrees C and shows res ponsiveness to smoke-derived extracts over a wide concentration range. For some seed lots where the P-fr level is high and germination in th e dark is unacceptably high, a brief (10 min) exposure to far-red ligh t, one hour after the start of imbibition in the dark, is necessary to clearly demonstrate biological activity in the smoke extracts.