Hydrogen Metabolism in Higher Plants.

Kinetin interacts with light in the promotion of the germination of Grand Rapids lettuce seeds. In the dark, there is only a slight stimulating effect. The optimal condition for the study of this interaction was the use of very small quantities of light given after 7 hours of soaking. Kinetin modified neither the germination rate of the seeds nor the general time course of germination. Kinetin was given as late as 8 hours after illumination and still showed the maximum interaction with light. The seeds showed a maximum sensitivity to kinetin between the fifth and seventh hours after the beginning of imbibition. At this moment of the time course, a soaking of 5 minutes in kinetin is sufficient to induce the interaction with light. The contradictory results found previously on the action of kinetin on seeds soaked in the dark are due to the different photosensitivity of the seed lots.