Seeds of ruderal Cerrado legumes tolerate fire-related temperatures and may release dormancy after heat exposure

Abstract

Seed dormancy and heat tolerance are critical traits for plant persistence and regeneration in fire-prone ecosystems. In this study, we evaluated the effects of fire-simulated heat shocks on seed germination and survival in seven legume species from degraded areas of the Cerrado, aiming to identify strategies that may facilitate species establishment in these environments. Seeds were exposed to a range of heat treatments (60–200 °C for 1, 3, and 5 minutes) simulating natural fire conditions. Overall, the species exhibited high tolerance to elevated temperatures, with all of them tolerating up to 200°C for 1 minute. Heat-stimulated dormancy release occurred in five species (Chamaecrista flexuosa, C. ramosa, Crotalaria pallida, Mimosa dolens, and M. xanthocentra). However, in most cases, more than half of the seeds remained dormant after heat exposure, suggesting that higher temperature thresholds or additional environmental cues are required to break dormancy. Taken together, these results indicate that in ruderal Cerrado legumes, the combination of high heat tolerance and some degree of heat-stimulated dormancy release may contribute to their successful establishment and persistence in frequently burned and degraded Cerrado environments.