STIMULATION OF GERMINATION OF QUANDONG (SANTALUM-ACUMINATUM) AND OTHER AUSTRALIAN NATIVE PLANT SEEDS

Intact seeds of quandong (Santalum acuminatum), Ixodia achillaeoides, Ptilotus exaltatus, Codonocaupus pyramidalis and Exocarpos aphyllus wh ich are normally difficult to germinate responded to vacuum infiltrati on with gibberellins. In most cases GA(4) was far more effective than GA(3). Cytokinins, ethylene and silver ions did not affect quandong ge rmination but abscisic acid (ABA) was inhibitory. If imbibed quandong seeds were subject to a rapid drying and re-wetting cycle, subsequent germination was inhibited. This transient drying was associated with a rise in endogenous ABA and the effect of the drying could be overcome by gibberellin. There was no correlation between ABA level and state of dormancy in recently imbibed seed suggesting that ABA was not neces sary for the maintenance of dormancy. These results suggest that the m echanisms controlling quandong seed germination are hormonally based a lthough the mechanical constraints imposed by the rigid shell may also be important.