Growth-Promoting Substance and Illumination

Abstract

Seedlings of Lupinus albus were grown under controlled (identical) conditions of temp.and moisture, in (a) artificial light, and (b) in darkness. When the hypocotyl was 3 1/2-4 cm. long (i.e., before the characteristic elongation could begin in the seedlings in darkness), they were decapltated (cut 2-3 mm. below insertion of cotyledons), and the part was put for 1 hr. on a block of agar. The auxin content of the agar block was estimated by the technique of Dolk (1931) and of Navez (1932), using decapltated coleoptiles of Avena as test objects. The illuminated seedlings were found to have released about twice as much auxin into the agar blocks as the non-illuminated.