Smoke as an environmental chemical filter for seedling traits of ground-layer Cerrado species

Although smoke water (SW) stimulates germination across fire-prone ecosystems, its effects on Neotropical savannas are still unclear. In the Cerrado, germination patterns are highly species-specific, while seedling traits have been less addressed. Therefore, we currently have a limited understanding of SW effects at different plant life stages. We evaluated the effects of SW concentrations of 10 mL L⁻¹ and 25 mL L⁻¹ (SW 1% and SW 2.5% , respectively) on seedling growth (shoot length, root length, and root: shoot ratio) of six ground-layer Cerrado species. Seeds were exposed to the different SW concentrations for 60 days, and root and shoot length of the resulting seedlings were measured at the end of the experiment. Stimulatory effects were observed in either the root or shoot length of three species at the lower SW concentration. In contrast, while no inhibitory effects were detected for shoot length, the higher SW concentration inhibited the root length in three species. Concomitantly, this inhibition at SW 2.5% led to a lower root: shoot ratio in two of these species. Our results demonstrate that smoke can produce differential effects on seedling growth, acting as an environmental chemical filter that influences the most vulnerable stage of regeneration in post-fire ecosystems.