Studia Forestalia Suecica

Forekomst av gibberellinliknande substanser hos gran (Picea abies (L.) Karst.) och deras betydelse for tillvaxt och blomning Abstract ODC 161.4-174.7 Growing shoots and young seedlings of Norway spruce (Picea abies) contain at least six different gibberellin-like substances; most probably none o f them is identical to gibberellic acid or gibberellin A l. The gibberellin-like substances are all active in a specially designed spruce seedling bioassay, as well as in a number o f traditional gibberellin bioassays. Young spruce seedlings grown in nutrient solution are retarded by the substances Amo-1618, B-995, and CCC. Both root and shoot growth are affected. Gibberellic acid counteracts the effects o f all the retardants on shoot growth, and of Amo-1618 on root growth, but has no effect when supplied alone. Application o f the growth retardants B-995 and CCC to spruce grafts in a seed orchard results in decreased flowering. Preliminary results show, that flowering and non-flowering grafted spruce clones display remarkable differences in the dynamics o f gibberellin-like substances; a high content of these substances during the supposed time o f flower bud initiation is correlated to good flowering ability. All these findings are consistent with the hypothesis, that gibberellins are intimately involved in the process o f flower bud induction. Literature dealing with the occurrence and effects of gibberellins within the class Coniferopsida is summarized.