INDUCING DORMANCY IN LETTUCE SEED WITH COUMARIN

Abstract

Dormancy was induced in non-dormant Black Seeded Simpson lettuce seeds by soaking the seeds in 25 ppm. of coumarin soln. for 24 hrs. at 18[degree]-20[degree]C. After soaking the seeds were rinsed in dist. water and germinated on blotters in petr dishes in light and darkness at 18[degree]-20[degree]C. Coumarin is photosensitive after entering the seed and thus exhibits no inhibitive effects on germination if the seeds are soaked in light or if light strikes the wet seed. Approx. 80% of the seed could be made dormant when tested in the dark;; about 99% of the seed germinated when tested in the light. Inhibitive effects of coumarin were overcome by exposure of seed to light; coumarin-tested seed responded to pre-chilling and to treatment with thiourea in a manner similar to naturally dormant lettuce seed. The processes of mak-ing dormant seed non-dormant by exposure to light and high humidity and of inducing dormancy in non-dormant seeds with coumarin were in large degree reversible in* these expts. It is possible that coumarin, its derivatives or compounds closely related to it, may be the inhibiting factor in lettuce seeds.