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 Rapids has been developed for the detection of germination-enhancing compound(s) in plant-derived smoke extracts. This light-sensitive species germinates within 24 h in the dark at 20 or 25°C and shows responsiveness to smoke-derived extracts over a wide concentration range. For some seed lots where the P_fr level is high and germination in the dark is unacceptably high, a brief (10 min) exposure to far-red light, one hour after the start of imbibition in the dark, is necessary to clearly demonstrate biological activity in the smoke extracts.