The Effect of Weak Red Light and Chloroeholinchloride on the Gibberellin-Content of Normal Pea Seedlings, and the Cause oI the Different Sensibility of Dwar~ and Normal Pea Seedlings toward the Endogenous Gibberellin Summary Seedling's of a normal growing eultivar of Pisum sativum were grown from the third to the seventh day after soaking in weak red light or darkness, with or without cMorocholinchloride (CCC), and afterwards extracted for gibberellinbioassay.
Light grown seedlings without CCC contain more than ten times as much gibberellin-activity as dark grown plants. CCC depresses the gibberellin-content to the level present in darkgro~m plants. This loss of gibberellin is the cause, not the effect of the growth depression by CCC. It is concluded that red light enhances and COO hampers the production of gibberellin.
Different gibberellins have an additive effect on growth of seedlings in red light only when applied in small amounts. With larger amounts of gibberellin growth is much less than that which would be expected if the effects of the gibberellins were additive. The results seem to indicate that the gibberellin endogenous in peas has to be structurally altered in order to become a growth promoter. This reaction controls the growth rate in light of dwarf but not of normM pea seedlings.
I~inleitung
Der normMe Wachstumshabitus der h6heren Pf]anzen ist liehtbedingt. Dies gilt auch fiir das Streekungswachstum der Internodien, das zumeist im Dunkeln erheblich stgrker ist Ms im Lieht. Die liehtbedingte Waehstumsdepression kann bei verschiedenen Arten und Rassen derselben Art sehr unterschiedliehe AusmaBe annehmen. Bei Zwergrassen der Erbse wird das Streckungswachstum bereits dureh geringste Liehtmengen auBerordentlich stark gehemmt, wghrend NormMrassen im glei~hen Licht k~um beeinfluBt werden (Oo~, 1961). Dureh Gibberellin