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

Abstract

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.

Prescribed burning of northern heathlands: Calluna vulgaris germination cues and seed-bank dynamics

“…A subsequent wave of germination from soil-stored seed-banks is a well-known phenomenon where seed germination is stimulated indirectly through responses to micro-environmental changes or directly through responses to high temperatures or chemical cues derived from smoke, charcoal or ash (Zackrisson et al 1996;Brown and van Staden 1997;Reyes and Casal 1998;van Staden et al 2000). The ecophysiological responses to such fire-related germination cues have been studied extensively on species in ecosystems with naturally occurring frequent fires such as the South African fynbos (van Staden et al 2000;Brown et al 2003), the Australian kwongan (Dixon et al 1995;Roche et al 1997;Tieu et al 2001;Read et al 2000; Thomas et al 2007), the North American chaparral (Keeley 1987; Keeley and Fotheringham 1988, 1998 and the Mediterranean maquis (Crosti et al 2006). A major active compound in the smoke response has recently been identified as karrikinolide (3-methyl-2H-furo[2,3-c]pyran-2-one), a derivate from the combustion of cellulose.…”

Ecophysiology of Seed Dormancy in the Australian Endemic Species Acanthocarpus preissii (Dasypogonaceae)

“…Other studies have found that seeds of many Australian species are responsive to smoke and smoke products (Dixon et al, 1995;Flematti et al, 2004;Merritt et al, 2006), thermic pulsing (Tieu et al, 2001a), afterripening (Schutz et al, 2002) and light . Nevertheless, there remain a number of common Australian species that do not respond to these treatments and are difficult to germinate (Dixon et al, 1995;Tieu et al, 2001b;Merritt and Dixon, 2003). Acanthocarpus preissii, the subject of the present study, is a prime example of a species in this latter category.…”

Effects of aqueous smoke solutions and heat on seed germination of herbaceous species of the Sudanian savanna-woodland in Burkina Faso

“…It should, however, be noted that the type of smoke used is of tremendous importance; for instance, in the present study, aqueous smoke solution did not affect germination response of Andropogon gayanus while in Dayamba et al (2008), aerosol smoke delayed its germination. Seeds (even physically dormant) may also become responsive to smoke after some period of storage or soil burial (Roche et al, 1997a(Roche et al, , 1998Tieu et al, 2001a). There could also be discrepancies between laboratory results and field responses due to the fact that smoke may act as a deterrent against predation (Roche et al, 1997b), that is, untreated seed in control plots may be more palatable to predators than smoke-treated seeds.…”