Effects of soil temperature regimes after fire on seed dormancy and germination in six Australian Fabaceae species

Abstract

M. (2010). Effects of soil temperature regimes after fire on seed dormancy and germination in six Australian Fabaceae species. Australian Journal of Botany, 58 (7), 539-545.Effects of soil temperature regimes after fire on seed dormancy and germination in six Australian Fabaceae species AbstractIn addition to direct fire cues such as heat, smoke and charred wood, the passage of fire leads indirectly to changes in environmental conditions which may be able to break physical dormancy in hard-coated seeds. After a fire, the open canopy and the burnt material lying on the surface alter the thermal properties of the soil, resulting in elevated soil temperatures for long periods of time. We simulated daily temperature regimes experienced at different depths of soil profile after a summer fire. Our aim was to determine whether these temperature regimes and the duration of exposure (5, 15 and 30 days) play an important role breaking physical seed dormancy in six legumes from south-eastern Australia. Our results showed that simulated temperature regimes break seed dormancy. This effect is specially pronounced at temperatures that are expected to occur near the soil surface (0-2 cm depth). The duration of exposure interacts with temperature to break dormancy, with the highest germination rates reached after the longest duration and highest temperatures. However, the germination response varied among species. Therefore, this indirect post-fire cue could play a role in the regeneration of plant communities, and could stimulate seedling emergence independent of direct fire cues as well as in interaction with direct cues. © 2010 CSIRO. Abstract. In addition to direct fire cues such as heat, smoke and charred wood, the passage of fire leads indirectly to changes in environmental conditions which may be able to break physical dormancy in hard-coated seeds. After a fire, the open canopy and the burnt material lying on the surface alter the thermal properties of the soil, resulting in elevated soil temperatures for long periods of time. We simulated daily temperature regimes experienced at different depths of soil profile after a summer fire. Our aim was to determine whether these temperature regimes and the duration of exposure (5, 15 and 30 days) play an important role breaking physical seed dormancy in six legumes from south-eastern Australia. Our results showed that simulated temperature regimes break seed dormancy. This effect is specially pronounced at temperatures that are expected to occur near the soil surface (0-2 cm depth). The duration of exposure interacts with temperature to break dormancy, with the highest germination rates reached after the longest duration and highest temperatures. However, the germination response varied among species. Therefore, this indirect post-fire cue could play a role in the regeneration of plant communities, and could stimulate seedling emergence independent of direct fire cues as well as in interaction with direct cues.

Growth and Yield of Guar (<i>Cyamopsis tetragonoloba</i> L.) Genotypes under Different Planting Dates in the Semi-Arid Southern High Plains

“…Plant count done at 40 DAP had the higher number of plants m −2 than at 20 DAP ( Table 3) among all planting dates and genotypes in both years. Temperature plays an important role in facilitating the germination of seed legumes [43]. Soil temperature greater than 30˚C accelerates guar seed germination [9].…”

Is the post-disturbance composition of a plant population determined by selection for outcrossed seedlings or by the composition of the seedbank?

“…With few exceptions (for example, Dolan et al, 2008;Ayre et al, 2009), we know little about the genetic composition of soil-stored seedbanks and their likely interaction with the potentially patchy effects of fire, or indeed, in general, the extent to which the genetic structure of standing adults reflects structure within groups of post-germination seedlings or the effects of natural selection (Honnay et al, 2008). However, it is known that the likelihood of seedling emergence varies with factors such as the age of the seed, depth of seed burial, and the timing, intensity and duration of fire (Ooi et al, 2004;Santana et al, 2010;Anderson et al, 2012) and for many species, seeds are likely to be aggregated in full and half-sib clusters representing the seed shadow of pre-fire adults (for example, Ayre et al, 2009) or in seed caches (Chung et al, 2003).…”

The effect of simulated heat-shock and daily temperature fluctuations on seed germination of four species from fire-prone ecosystems

“…), suggesting that resprouting may be the dominant mechanism for persistence after fire in these species, as in many Cerrado species (Simon et al 2009;Simon & Pennington 2012). On the other hand, germination percentage of U. parviflorus and C. albidus seeds were enhanced with F treatments, suggesting that temperatures reached with the passage of fire are effective in breaking seed dormancy and enabling germination in these species, which is particularly important for obligate seeder species, whose regenerating strategy after fire relays exclusively on seed germination and establishment (Bond & Midgley 2001;Pausas et al 2004), as is the case for both these species (Baeza & Vallejo 2006;Santana et al 2010).…”

“…50-55 o C) and wide temperature fluctuations. Recent studies have indicated that these temperature fluctuations also act as germination cues in hard-seeded species, breaking physical dormancy and enabling germination (Baeza & Roy 2008;Santana et al 2010;Jaganathan 2015). Moreover, in non-dormant seeds, daily temperature fluctuations may affect the rate of germination (Musso et al 2015;Le Stradic et al 2015).…”