STUDIES IN SEED DORMANCY III. THE EFFECTS OF GIBBERELLIN ON DORMANT SEEDS OFCORYLUS AVELLANAL.

Abstract

SummaryApplication of exogenous gibberellin over a concentration range of 3 × 10−7M‐3 × 10−3M has been found to break hazel seed dormancy, growth of tbe embryonic axis being detectable within a few days of gibberellin application. Metabolic studies of seeds pre‐treated with 3 × 10−4M gibberellin or water have been made during the period prior to the detection of embryonic axis growth. Imbibition of seeds in the presence or absence of gibberellin resulted in an increase of the percentage of incorporated radioactivity found in RNA and protein in both cotyledons and embryonic axes. Data on the incorporation of radioactivity into DNA were not conclusive. Gibberellin pre‐treatment has so far been found to have three clear effects on cotyledonary metabolism, namely, to increase the proportion of [8−14C]adenine incorporated into nucleotide, to reduce the proportion of [2−14C]acetate incorporated into lipid and to increase the activity of isocitrate lyase (Pinfield, 1967).It is suggested that imbibition of dormant hazel seeds initiates the synthesis of RNA and protein, both in cotyledons and embryonic axes. The primary effect of gibberellin action may occur in the cotyledons, where its role in the breaking of seed dormancy may be in the induction of increased levels of activity of certain enzymes, particularly those concerned with the mobilization of the cotyledonary oil reserves. It is not clear as to what part, if any, the gibberellin stimulated adenine nucleotide synthesis plays in the breaking of hazel seed dormancy.