Phytochrome and Seed Germination. III. Action of Prolonged Far Red Irradiation on the Germination of Tomato and Cucumber Seeds

Abstract

Proloniged irradiation with continuous or intermittent far red prevents thegerminationoftomatoandcucumberseeds. Theinhibitorvefficiencyofintermittent far red decreases with the lengthening of the interval between successive irradiations, and withtheincreaseoftemperature. Ifeachfarredirradiationisfollowedbyred,germina- tion is restored. Intermittent far red is less inhibitory than intermittent red-far red xvhenredisgivenimmediatelybeforeeachfarred. Thiseffectismoreevidentwhen the interval between stuccessive irradiation becomes longer.