Light Effects on the Germination of Seeds of Henbit (Lamium amplexicaule L.).

Abstract

Freshly-harvested henbit seeds are dormant, apparently because they contain a water-soluble inhibitor which decreases during dry storage of seeds. Germination of non-dormant seeds is inhibited by light. Incandescent light at an intensity of one ft-c reduced germination from 70 to 14%. Higher intensities prevented germination of all seeds when applied for 72 hrs. to the moistened seeds. The inhibiting effect of light was temporary, the length of the inhibition period depending to some extent on the intensity of light used. Henbit seeds are most sensitive to light after 12 hrs. of imbibition of water. Shorter or longer periods of soaking reduce light sensitivity and dry seeds are unaffected. Germination is prevented by far-red radiation (7300-8700 A) and this inhibition is overcome by a subsequent treatment with red light (5800-7000 A). The effect of an alternating sequence of the 2 types of radiation was determined entirely by the final light treatment.