The Physiological Dormancy and Germination Responses of <i>Brunonia australis</i> and <i>Rhodanthe floribunda</i> to Gibberellic Acid Treatment

Abstract

Brunonia australis (Goodeniaceae) and Rhodanthe
floribunda (Asteraceae) are two potential Australian
native ower species desired by oricultural markets.
However, the species are difcult to propagate. This
study examined internal factors that constraint seed
germination, seed viability and physiological dormancy.
The study was conducted during April to May 2009 at the
Gatton nursery, The University of Queensland Gatton
Campus to identify the underlying reasons for poor
germination and to provide recommendations for
improving propagation effectiveness. Seeds of B.
australis collected in 2003 germinated readily
irrespective of germination media, whereas seeds
collected in 2007 and 2008 with high proportion of viable
seeds could only germinate with the presence of GA3
(100 mg.L ) in germination media though with relatively -1
low rates (8.75% and 10.00% respectively) of seed
germination. Seeds of R. floribunda collected in 2003
showed a signicant improvement in germination in
agar media supplemented with 100 mg.L GA (67.5%) -1
3 compared to control treatment (10.0%). The results
suggest that physiological dormancy occurs in both
species. The use of GA is recommended for improving 3
germination rates of the two species. Further studies on
the effects of different GA concentrations to improve 3
seed germination should be conducted.

Keywords: Dormancy, germination, gibberellic acid, TZ,
viability.