DORMANCY STUDIES IN SEED OF AVENA FATUA: 2. A GIBBERELLIN-SENSITIVE INHIBITORY MECHANISM IN THE EMBRYO

Abstract

Natural inhibition of germination in A. fatua L. involves restriction of both sugar accumulation and utilization of sugar in growth. Both these metabolic blocks are independently overcome by exogenous gibberellic acid (GA). Evidence has been found for the presence of a natural gibberellin in seeds of A. fatua L. The control of dormancy is probably by a gibberellin-inhibitor antagonism since at least one inhibitor has been shown to intervene specifically in sugar production and this latter effect can be reversed by GA. The evidence presented here supports the view that control of germination during the period of after-ripening is through changes in inhibitor content rather than in endogenous gibberellin.