RED-LIGHT-INDUCED GERMINATION OF LETTUCE SEEDS: RELATIONSHIP BETWEEN ESCAPE FROM REVERSIBILITY AND FLUENCE*

Abstract— Dormant seeds of Lactuca saliva L. (cv. ‘May Queen’) germinate after a brief light treatment. The seeds escape from photoreversibility by far-red irradiation after a lag time. The duration of the lag decreases with increasing levels of the far-red absorbing form of phytochrome (P_fr). During the lag time the percentage of seeds germinating after the reversing far-red irradiation is slowly rising. This is not due to an escape reaction proper, but to an increase of sensitivity to P_fr.