Seed Dormancy in Acer CHANGES IN ENDOGENOUS CYTOKININS, GIBBERELLINS AND GERMINATION INHIBITORS DURING THE BREAKING OF DORMANCY IN ACER SACCHARUM MARSH

TLDR: In this article, changes in the levels of cytokinins, gibberellins, and germination inhibitors during stratification of Acer saccharum seeds suggest that the breaking of dormancy is a phasic process.

Abstract: The present studies on changes in the levels of cytokinins, gibberellins, and germination inhibitors during stratification of Acer saccharum seeds suggest that the breaking of dormancy is a phasic process Stratification at 5 °C led to a marked increase in the butanol-soluble cytokinins after 20 d Further chilling resulted in a loss of cytokinin The majority of the detectable cytokinin activity co-chromatographed with zeatin Similarly, at day 40, acidic gibberellin-like substances increased and declined with further chilling A loss of acidic germination inhibitors was also detected during stratification The acidic fraction was shown to contain abscisic acid (ABA) by its behaviour on GLC and isomerization with ultra-violet light Determinations of endogenous levels of ABA by combined GLC and isotope dilution methods indicated a loss of 97-9 per cent ABA during stratification The data suggest that the breaking of seed dormancy at low temperature involves the initiation of an ordered sequence of events that include the changes in growth hormones necessary to determine the course of development for the removal of dormancy