Seed Dormancy in Aristida armata

Abstract

Dormancy in stored seed of Aristida armata was most pronounced in seed up to 6 months old and was associated with the persistent hull. Dormant seeds imbibed readily, although few were capable of germinating when the hull was removed after remaining imbibed at 30/25°C for 55 days or longer.

Short periods of dry storage at 70°C or stratification at 4°C reduced dormancy.

In some dormant seeds, imbibition was followed by the exsertion of the radicle up to 0.5 mm through the hull without further germination occurring. The significance of this phenomenon is unclear as it did not appear to promote subsequent germination, and such seeds were unable to survive desiccation.

Seed production of A. armata occurs mostly in autumn in south-western Queensland. Seed dormancy would be expected to facilitate seedling establishment in the following spring or autumn rather than during the temperature extremes of winter and summer.