Interaction of soil burial and smoke on germination patterns in seeds of selected Australian native plants

Patterns of dormancy and smoke responsiveness in artificially buried seeds were investigated in eight native plant species from the species-rich mediterranean-type climate zone of south-western Australia. A comparison was made between germination and viability behaviour of shelf- and field-soil-stored seed, with and without smoke treatment, at least every 3 months. These comparisons corresponded with each of the four seasons. The species chosen germinated with the aid of smoke under field or glasshouse conditions (termed 'dormant'; n = 4) or produced low and variable germination under glasshouse conditions with smoke (termed 'deeply dormant'; n = 4). Three trends were observed in viability of soil-stored seeds over 450 d: no decline, gradual decline or late-onset decline. In addition, various germination responses to soil burial and aerosol smoke were observed. Burial was not required for optimal germination in Anigozanthos manglesii. However, for all other species tested, maximum germination was observed only following a period of burial. This was manifested in a germination response without smoke after a short period of burial (Stylidium affine and Conospermum triplinervium) or a longer period of burial (Conostylis neocymosa, Hibbertia commutata, Leucopogon conostephioides, Stirlingia latifolia and Stylidium crossocephalum). Smoke treatment led to high germination in buried seed of S. affine, S. crossocephalum and H. commutata. The patterns of germination detected in this limited number of species indicate that a variety of mechanisms may exist, both temporally and spatially, in south-western Australian species, and support further research of this type for horticulture and land restoration.