Seed tolerance to post-fire temperature fluctuation of Cerrado legume shrubs with micromorphological implications

Author(s)

Daibes, L. Felipe ^[1] ; Martins, Aline R. ^[2] ; Silveira, Fernando A. O. ^[3] ; Fidelis, Alessandra ^[1]

Affiliation

^[1] Univ Estadual Paulista UNESP, Lab Vegetat Ecol, Inst Biociencias, Ave 24-A 1515, BR-13506900 Rio Claro, SP - Brazil

^[2] Univ Estadual Paulista UNESP, Dept Biol & Zootecnia, Fac Engn Ilha Solteira, Ave Brasil 56, BR-15385000 Ilha Solteira, SP - Brazil

^[3] Univ Fed Minas Gerais, Inst Ciencias Biol, Dept Genet Ecol & Evolucao, CP 486, BR-31270901 Belo Horizonte, MG - Brazil

• Document type: Journal article
• Source: FLORA; v. 275, FEB 2021.
• Web of Science Citations: 1

Abstract

Multiple environmental cues may break seed physical dormancy (PY) in fire-prone ecosystems, but disentangling the roles of such cues remains challenging. Current research has mostly focused on the role of high temperatures (heat shocks) in PY alleviation, while post-fire environmental conditions are less understood. Here, we examined the role of post-fire temperature fluctuation on seed germination and viability of Cerrado legume shrubs. Specifically, we investigated (1) whether PY is broken by temperature fluctuation; (2) whether seed viability is affected by temperature fluctuations; and (3) micromorphological changes in the seed coat following exposure to temperature fluctuation. Seeds of nine legume species were collected in frequently burned Cerrado savannas. We simulated post-fire temperature fluctuation in germination chambers, with daily temperature fluctuation ranging from 18 to 55 degrees C for 90 days; controls consisted of untreated seeds (room temperature). We conducted germination trials with unblocked and blocked hilar region of seeds. In addition, seed samples were fixed and subjected to micromorphological analysis. Instead of dormancy break, three species showed decreased seed germination for both unblocked and blocked hilar regions, while other two species showed decreased germination in blocked seeds only. Nevertheless, random cracks formed across the seed coat were found in control and treated seeds, which displayed a proportion of nondormant seeds. Within nondormant seeds, both hilar and extra-hilar regions (such as the pleurogram) may take part on water uptake. Despite the lack of dormancy break, most Cerrado legume seeds persisted viable after post-fire temperature fluctuation, thus avoiding establishment under hazardous conditions. Seed tolerance to heat shocks and post-fire temperature fluctuation likely drives regeneration from seed in burned Cerrado areas. (AU)

• FAPESP's process: 15/06743-0 - How does fire season affect Cerrado vegetation?
• Grantee: Alessandra Tomaselli Fidelis
• Support Opportunities: Research Grants - Young Investigators Grants