Open access publications in the SLU publication database

Abstract

Growing shoots and young seedlings of Norway spruce (Picea abies) contain at least six different gibberellin-like substances; most probably none of them is identical to gibberellic acid or gibberellin A1. The gibberellin-like substances are all active in a specially designed spruce seedling bioassay, as well as in a number of 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 of all the retardants on shoot growth, and of Amo-1618 on root growth, but has no effect when supplied alone. Application of 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 of gibberellin-like substances; a high content of these substances during the supposed time of 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 of flower bud induction. Literature dealing with the occurrence and effects of gibberellins within the class Coniferopsida is summarized.